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Novel functionalized and/or grafted crosslinked chitosan adsorbents were synthesized and used to remove several toxic heavy metal ions such as nickel, lead, chromium, and cadmium ions from contaminated water. The chitosan biopolymer was functionalized by maleic anhydride (CS_MA) acting also as a crosslinking agent. Glutaraldehyde-crosslinked chitosan (CS_GA) grafted with poly(methyl methacrylate) (CS_MMA) was also synthesized. The synthesized adsorbents were characterized using a variety of analytical techniques such as SEM, TGA, and FTIR, which confirmed their chemical structures and morphology. The adsorption capacity of the adsorbents was analyzed under various conditions of contact time, adsorbent dose, initial concertation, temperature, and pH and evaluated against those of pure chitosan (CS) and the crosslinked chitosan(CS_GA). The ultimate removal conditions were 0.5 g/100 mL adsorbent dose, an initial metal ion concentration of 50 ppm, a temperature of 45 °C, and pH 9. CS_MMA had the highest removal percentages for all metal ions, ranging from 92% to 94%. The adsorption was demonstrated to fit a pseudo-first-order model that followed a Langmuir adsorption isotherm. The results highlight the capacity of the synthesized polymers to efficiently remove major toxic contaminants at low cost from contaminated water, present especially in low-income areas, without harming the environment. [ABSTRACT FROM AUTHOR]

One of the most effective strategies for modifying the surface properties of nano-fillers and enhancing their composite characteristics is through polymer grafting. In this study, a coprecipitation method was employed to modify hydroxyapatite (HAP) with epoxidized soybean oleic acid (ESOA), resulting in ESOA-HAP. Subsequently, oligomeric poly(lactic acid) (OPLA) was grafted onto the surface of ESOA-HAP, yielding OPLA-ESOA-HAP. HAP, ESOA-HAP, and OPLA-ESOA-HAP were comprehensively characterized. The results demonstrate the progressive grafting of ESOA and OPLA onto the surface of HAP, resulting in enhanced hydrophobicity and improved dispersity in organic solvent for OPLA-ESOA-HAP compared to HAP. The vitality and adhesion of Wistar rat mesenchymal stem cells (MSCs) were assessed using HAP and modified HAP materials. Following culture with MSCs for 72 h, the OPLA-ESOA-HAP showed an inhibition rate lower than 23.0% at a relatively high concentration (1.0 mg/mL), which is three times lower compared to HAP under similar condition. The cell number for OPLA-ESOA-HAP was 4.5 times higher compared to HAP, indicating its superior biocompatibility. Furthermore, the mechanical properties of the OPLA-ESOA-HAP/PLLA composite almost remained unaltered ever after undergoing two stages of thermal processing involving melt extrusion and inject molding. The increase in the biocompatibility and relatively high mechanical properties render OPLA-ESOA-HAP/PLLA a potential material for the biodegradable fixation system. [ABSTRACT FROM AUTHOR]

The surface of SBA‐15 mesoporous silica was modified by N‐hydroxyphthalimide (NHPI) moieties acting as immobilized active species for aerobic oxidation of alkylaromatic hydrocarbons. The incorporation was carried out by four original approaches: the grafting‐from and grafting‐onto techniques, using the presence of surface silanols enabling the formation of particularly stable O−Si−C bonds between the silica support and the organic modifier. The strategies involving the Heck coupling led to the formation of NHPI groups separated from the SiO2 surface by a vinyl linker, while one of the developed modification paths based on the grafting of an appropriate organosilane coupling agent resulted in the active phase devoid of this structural element. The successful course of the synthesis was verified by FTIR and 1H NMR measurements. Furthermore, the formed materials were examined in terms of their chemical composition (elemental analysis, thermal analysis), structure of surface groups (13C NMR, XPS), porosity (low‐temperature N2 adsorption), and tested as catalysts in the aerobic oxidation of p‐xylene at atmospheric pressure. The highest conversion and selectivity to p‐toluic acid were achieved using the catalyst with enhanced availability of non‐hydrolyzed NHPI groups in the pore system. The catalytic stability of the material was additionally confirmed in several subsequent reaction cycles. [ABSTRACT FROM AUTHOR]

Porous membranes play a crucial role in alkaline water electrolyzer, and addressing the urgent need for the development of membranes with enhanced ion-transferring properties and superior gas-retarding properties is of utmost importance. This work presents a simple and efficient method for preparing the superhydrophilic polyphenylene sulfide (PPS) membrane, which includes surface oxidation to generate photosensitive sulfone groups, then UV irradiation radical reaction to introduce amine groups as the reaction site, and finally covalently grafting chitosan oligosaccharide (COS) monomers containing hydrophilic groups onto the PPS surface via interfacial polymerization to form a superhydrophilic coating on the surface of fibers. The application of ATR-FTIR, XPS, and SEM has been employed to illustrate that the monomers utilized in the preparation procedure are chemically bonded to the membrane surface, resulting in the formation of a hydrophilic surface layer. The modified PPS membrane can fast adsorb water droplets, promote ion transfer and gas bubbles detachment in an alkaline solution. When used as a membrane in an alkaline water electrolyzer with a 30% KOH electrolyte solution, the cell voltage of 1.90 V at 80oC and 5000 A m−2, and the hydrogen and oxygen produced with a purity of 99.88% and 99.49%, respectively, which was better than the commercial PPS membrane, and the performance was remained essentially unchanged after 120 h of operation. As a result, the superhydrophilic PPS membrane generated by this process has a wide range of applications in alkaline water electrolysis. [Display omitted] • Superhydrophilic PPS membrane was prepared and tested in alkaline water electrolysis. • The area resistance of SHL-PPS used in the electrolyzer is 0.11 Ω cm2 (80 °C, 30% KOH). • AWE using SHL-PPS produces H 2 and O 2 with higher purities than using commercial PPS. • SHL-PPS membrane facilitates the long-term stable operation of AWE. [ABSTRACT FROM AUTHOR]

The structure and scaling properties of inwardly curved polymer brushes, tethered under good solvent conditions to the inner surface of spherical shells such as membranes and vesicles, are studied by extensive molecular dynamics simulations and compared with earlier scaling and self-consistent field theory predictions for different molecular weights of the polymer chains N and grafting densities σg in the case of strong surface curvature, R−1. We examine the variation of the critical radius R*(σg), separating the regimes of weak concave brushes and compressed brushes, predicted earlier by Manghi et al. [Eur. Phys. J. E 5, 519–530 (2001)], as well as various structural properties such as the radial monomer- and chain-end density profiles, orientation of bonds, and brush thickness. The impact of chain stiffness, κ, on concave brush conformations is briefly considered as well. Eventually, we present the radial profiles of the local pressure normal, PN, and tangential, PT, to the grafting surface, and the surface tension γ(σg), for soft and rigid brushes, and find a new scaling relationship P N (R) ∝ σ g 4 , independent of the degree of chain stiffness. [ABSTRACT FROM AUTHOR]

Owing to their special structure and excellent physical and chemical properties, conducting polymers have attracted increasing attention in materials science. In recent years, tremendous efforts have been devoted to improving the comprehensive performance of conducting polymers by using the technique of "doping." Spherical polyelectrolyte brushes (SPBs) bearing polyelectrolyte chains grafted densely to the surface of core particles have the potential to be novel dopant of conducting polymers not only because of their spherical structure, high grafting density and high charge density, but also due to the possibility of their being applied in printed electronics. This review first presents a summary of the general dopants of conducting polymers. Meanwhile, conducting polymers doped with spherical polyelectrolyte brushes (SPBs) is highlighted, including the preparation, characterization, performance and doping mechanism. It is demonstrated that comprehensive performance of conducting polymers has improved with the addition of SPBs, which act as template and dopant in the synthesis of composites. Furthermore, the applications and future developments of conductive composites are also briefly reviewed and proposed, which would draw more attention to this field. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of surface properties of nanoparticles (NPs) on the crystallization behavior of nanocomposite, three kinds of silica (SiO2) NPs are dispersed in isotactic polypropylene (iPP) matrix by solution blending method. Specifically, the poor compatibility between inorganic bare SiO2 NPs and organic PP matrix triggers the formation of aggregates and induces the fractionated crystallization with two crystallization peaks at higher particle loading (Φ), i.e., main crystallization peak (MCP) and low temperature crystallization peak (LCP, always located at 124.0 °C). Once short PP chains (0.9 × 104 g mol−1) are grafted onto the surface of SiO2 NPs, the nanocomposites with all Φ only exhibit a single MCP which is attributed to the strong interfacial interaction. With the increase of grafting chain length (9 × 104 g mol−1), the more stretched conformation of grafting chains can provide numerous heterogeneous nucleation sites and significantly accelerate the crystallization rate of PP chains near the surface of SiO2 NPs, which lead to the formation of an extra high temperature crystallization peak (HCP, almost kept constant at 133.0 °C). The occurrence of various crystallization peaks implies that the surface properties of nanoparticles play a vital role in the nucleation ability of nanoparticles. [ABSTRACT FROM AUTHOR]

This paper uses a very effective way for surface modification of thermoplastic polymers during moulding. It is based on a grafting reaction between a thin layer of a functional polymer, deposited on a substrate in advance, and a polymer melt. In this paper, a glycol-modified polyethylene terephthalate (PETG) that was brought in contact with a polyethyleneimine layer during fused filament fabrication is investigated. The focus of this paper is the investigation of the reaction product. Grafting was realised by the formation of stable amide bonds by amidation of ester groups in the main chain of a PETG. XPS investigations revealed that the conversion of amino groups was very high, the distribution was even, and the quantity of amino groups per polyester surface area was still very high. The surface properties of the produced polyester part were mainly characterised by polyethyleneimine. The grafting was able to resist several cycles of extraction in alkaline solutions. The stability was only limited by saponification of the polyester. The degree of surface modification was dependent on the molar mass of polyethyleneimine. This could be rationalised, because grafting only occurred with the one polyethyleneimine molecule that is in close vicinity to the polyester surface when both components come in contact. Fused deposition modelling was chosen as the model process with control over each processing step. However, any other moulding process may be applied, particularly injection moulding for mass production. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) materials based on metal‐organic framework (MOF) nanosheets are highly useful for electronic devices, catalysis, and energy storage systems because of their high structural designability and anisotropy. However, their high surface energy often causes aggregation and low dispersibility, which reduces their processability and performance. To address these fundamental issues, it is reported a new approach involving polymer grafting from the surfaces of MOF nanosheets. A newly discovered one‐step synthetic pathway provides MOF nanosheets functionalized with a polymerization initiator agent on the surface with over 90% yield. Successive nitroxide‐mediated living polymerization of vinyl monomers from the MOF nanosheet surfaces provides polymer‐grafted nanosheets with superior dispersibility in many organic solvents. The polymer‐decorated MOF nanosheets exhibit versatile property modulation, which allows for their protection and efficient use in applications such as photoredox catalysts and oil/water separation membranes. This polymer‐grafting approach can facilitate the fabrication of surface‐functionalized MOF nanosheets, which can lead to the wider application of 2D materials in various fields. [ABSTRACT FROM AUTHOR]

With the advancement of industrial economies, incidents involving spills of petroleum products have become increasingly frequent. The resulting pollutants pose significant threats to air, water, soil, plant and animal survival, as well as human health. In this study, microcrystalline cellulose served as the matrix and benzoyl peroxide (BPO) as the initiator, while butyl acrylate (BA) and N,N′-methylene bisacrylamide (MBA) were employed as graft monomers. Through free radical graft polymerization, cellulose-graft-poly(butyl acrylate-N,N′-methylene bisacrylamide) [Cell-g-P(BA-MBA)], possessing oil-adsorbing properties, was synthesized. The chemical structure, elemental composition, surface morphology and wetting properties of the graft polymerization products have been characterized, using infrared spectroscopy, elemental analysis, scanning electron microscopy and contact angle testing. The adsorption properties of Cell-g-P(BA-MBA) for various organic solvents and oils were then assessed. The experimental results demonstrated that Cell-g-P(BA-MBA) exhibited a maximum adsorption capacity of 37.55 g/g for trichloromethane. Adsorption kinetics experiments indicated a spontaneous and exothermic process involving physical adsorption, conforming to the Freundlich isotherm model. Furthermore, adsorption kinetics experiments revealed that Cell-g-P(BA-MBA) displayed favorable reuse and regeneration performance, maintaining its adsorption capacity essentially unchanged over fifteen adsorption–desorption cycles. [ABSTRACT FROM AUTHOR]

Jujube residue is an abundant and low-cost dietary fiber resource, but its relatively lower hydration and functional properties limit its utilization as an ingredient of functional food. Thus, cellulase and hemicellulase hydrolysis, enzymatic hydrolysis assisted by phosphate grafting (EPG), and enzymatic hydrolysis assisted by acrylate grafting (EAG) were used to improve the functional properties of jujube residue dietary fiber (JRDF) in this study. The results evidenced that these modifications all increased the porosity of the microstructure of JRDF and increased the soluble fiber content, surface area, and hydration properties, but reduced its brightness (p < 0.05). Moreover, JRDF modified by enzymolysis combined with acrylate grafting offered the highest extractable polyphenol content, oil, sodium cholate, and nitrite ion sorption abilities. Meanwhile, JRDF modified via enzymolysis assisted by phosphate grafting showed the highest soluble fiber content (23.53 g∙100 g−1), water-retention ability (12.84 g∙g−1), viscosity (9.37 cP), water-swelling volume (10.80 mL∙g−1), and sorption ability of copper (II) and lead (II) ions. Alternatively, JRDF modified with cellulase hydrolysis alone exhibited the highest glucose adsorption capacity (21.9 g∙100 g−1) at pH 7.0. These results indicate that EPG is an effective way to improve the hypolipidemic effects of JRDF, while EAG is a good choice to enhance its hydration and hypoglycemic properties. [ABSTRACT FROM AUTHOR]

The development of convective technologies for antibody purification is of interest to the bioprocessing industries. This study developed a Protein A membrane using a combination of graft polymerization and copper(I)-catalyzed alkyne–azide click chemistry. Regenerated cellulose supports were functionalized via surface-initiated copolymerization of propargyl methacrylate (PgMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMEMA300), followed by a reaction with azide-functionalized Protein A ligand. The polymer-modified membranes were characterized using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), gravimetric analysis, and permeability measurements. Copolymer composition was determined using the Mayo–Lewis equation. Membranes clicked with azide-conjugated Protein A were evaluated by measuring static and dynamic binding (DBC10) capacities for human immunoglobulin G (hIgG). Copolymer composition and degree of grafting were found to affect maximum static binding capacities, with values ranging from 5 to 16 mg/mL. DBC10 values did not vary with flow rate, as expected of membrane adsorbers. [ABSTRACT FROM AUTHOR]

As the criteria of energy conservation, emission reduction, and environmental protection become more important, and with the development of wet-end papermaking, developing excellent retention aids is of great significance. Spherical polyelectrolyte brushes (SPBs) bearing polyelectrolyte chains grafted densely to the surface of core particle have the potential to be novel retention aids in wet-end papermaking not only because of their spherical structure, but also due to controllable grafting density and molecular weight. Such characteristics are crucial in order to design multi-functional retention aids in sophisticated papermaking systems. This review presents some important recent advances with respect to retention aids, including single-component system and dual-component systems. Then, basic theory in papermaking is also briefly reviewed. Based on these advances, it emphatically describes spherical polyelectrolyte brushes, focused on their preparation methods, characterization, conformation, and applications in papermaking. This work is expected to contribute to improve a comprehensive understanding on the composition, properties, and function mechanisms of retention aids, which helps in the further investigation on the design of novel retention aids with excellent performance. [ABSTRACT FROM AUTHOR]

We developed a facile and widely applicable approach to fabricate multifunctional coatings by grafting functional polymer brushes on the silica-stabilized candle soot, which exhibited excellent near-infrared-activated biocidal ability and desired bioactivities such as antifouling property and controllable bioadhesion. [Display omitted] • A facile method is developed for fabrication of a multifunctional coating based on candle soot (CS). • The coating exhibits excellent near-infrared-activated biocidal ability due to the inherent photothermal property of CS. • The coating shows desired biofunctions originated from the grafted polymers, which are enhanced by the nanoscale structure of CS. Functional coatings with desired bioactivities are required for various biomedical applications. Candle soot (CS) composed of carbon nanoparticles has attracted significant attention as a versatile component of functional coatings because of its unique physical and structural characteristics. However, the application of CS-based coatings in the biomedical field is still limited due to the lack of modification methods that can endow them with specific biofunctionality. Herein, a facile and widely applicable approach to fabricate multifunctional CS-based coatings is developed by grafting functional polymer brushes on the silica-stabilized CS. The resulting coatings not only exhibited excellent near-infrared-activated biocidal ability (the killing efficiency was over 99.99 %) due to the inherent photothermal property of CS but also showed desired biofunctions (such as antifouling property or controllable bioadhesion; the repelling efficiency and bacterial release ratio were nearly 90 %) originated from the grafted polymers. Moreover, these biofunctions were enhanced by the nanoscale structure of CS. Because the deposition of CS is a simple substrate-independent process while the grafting of polymer brushes via surface-initiated polymerization is applicable to a wide range of vinyl monomers, the proposed approach can be potentially used for the fabrication of multifunctional coatings and would extend the applications of CS in the biomedical field. [ABSTRACT FROM AUTHOR]

Thermoplastic polyurethane (TPU) membrane has super physical-mechanical properties and biocompatibility, but the surface is inert and lack of active groups which limit its application in cell culture. Silk sericin (SS) can improve cell adhesion, proliferation, growth and metabolism. In this paper, SS was grafted onto the surface of TPU membrane by -NH2 bridge to build a high efficiency cell culture membrane. The FT-IR spectrum results indicated SS was grafted by chemical bond. According to the SEM and AFM results, we found that the grafting of SS reduced the water contact angle by 43.31% and increased the surface roughness by about four times. When TPU-SS was used for HepG2 cell culture, the cell adhesion rate of TPU-SS was significantly higher than that of the general TCPS cell culture plate, and the cell proliferation rate was close to that of TCPS. FDA/EB staining showed that HepG2 cells remained a better cellular growth behavior. HepG2 cells had higher cell vitality including the albumin secretion and the intracellular total protein synthesis. Grafting SS maintained the stability of cell and significantly decreased the cytotoxicity by decreased LDH release. In conclusion, SS grafting is beneficial to cell culture in vitro, and provides a key material for bioartificial liver culture system. [ABSTRACT FROM AUTHOR]

Macromolecules such as proteins conjugated to polyethylene glycol (PEG) have been employed in therapeutic drug applications, and recent research has emphasized the potential of varying polymer architectures and conjugation strategies to achieve improved efficacy. In this study, we performed atomistic molecular dynamics simulations of bovine serum albumin (BSA) conjugated to 5 kDa PEG polymers in an array of schemes, including varied numbers of attached chains, grafting density, and nonlinear architectures. Nonlinear architectures included U-shaped PEG, Y-shaped PEG, and poly(oligoethylene glycol methacrylate) (POEGMA). Buried surface area calculations and polymer volume map analyses revealed that volume exclusion behaviors of the high grafting density conjugate promoted additional protein–polymer interactions when compared to simply increasing numbers of conjugated chains uniformly across the protein surface. Investigation of nonlinear polymer architectures showed that stable polymer-lysine loop-like conformations seen in previous conjugate designs were more variable in prevalence, especially in POEGMA, which contained short oligomer PEG chains. The findings of this comprehensive study of alternate PEGylation schemes of BSA provide critical insight into molecular patterns of interaction within bioconjugates and highlight their importance in the future of controlled modification of conjugate system parameters. [ABSTRACT FROM AUTHOR]

Arylazo sulfonates (Ar−N=N−SO3Na) have been found to undergo photografting on gold surface through both Au−Nsp2− and Au−Csp2− bond formation. The functionalized materials have been fully characterized by infrared reflection absorption spectroscopy (IRRAS), Raman, XPS, DFT calculations and UV‐Vis absorption spectroscopy. These methods permit to evidence aromatic substituents (IRRAS), the Au−N=N signature (Raman and XPS spectroscopy), and the bond dissociation energy values of the two linkages (DFT calculation). The grafting proceeds through two competitive paths, namely a stepwise reaction involving an aryl radical (for the formation of the Au−Ar bonds) and a concerted reaction on the surface of gold (for Au−N=N−Ar bond formation). The occurrence of an aryl radical upon irradiation has been fully evidenced by EPR spectroscopy. Finally, E/Z photoisomerisation of the N=N bonds present on prepared few layer films has been observed by means of UV‐Vis absorption spectroscopy. [ABSTRACT FROM AUTHOR]

The use of solid‐contact ion‐selective electrodes (ISEs) is of interest to many clinical, environmental, and industrial applications. However, upon extended exposure to samples and under thermal and mechanical stress, adhesion between these membranes and underlying substrates often weakens gradually. Eventually, this results in the formation of a water layer at the interface to the underlying electron conductor and in delamination of the membrane from the electrode body, both major limitations to long‐term monitoring. To prevent these problems without increasing the complexity of design with a mechanical attachment, we use photo‐induced graft polymerization to simultaneously attach ionophore‐doped crosslinked poly(decyl methacrylate) sensing membranes covalently both to a high surface area carbon as ion‐to‐electron transducer and to inert polymeric electrode body materials (i.e., polypropylene and poly(ethylene‐co‐tetrafluoroethylene)). The sensors provide high reproducibility (standard deviation of E0 of 0.2 mV), long‐term stability (potential drift 7 μV h−1 over 260 h), and resistance to sterilization in an autoclave (121 °C, 2.0 atm for 30 min). For this work, a covalently attached H+ selective ionophore was used to prepare pH sensors with advantages over conventional pH glass electrodes, but similar use of other ionophores makes this approach suitable to the fabrication of ISEs for a variety of analytes. [ABSTRACT FROM AUTHOR]

The use of solid‐contact ion‐selective electrodes (ISEs) is of interest to many clinical, environmental, and industrial applications. However, upon extended exposure to samples and under thermal and mechanical stress, adhesion between these membranes and underlying substrates often weakens gradually. Eventually, this results in the formation of a water layer at the interface to the underlying electron conductor and in delamination of the membrane from the electrode body, both major limitations to long‐term monitoring. To prevent these problems without increasing the complexity of design with a mechanical attachment, we use photo‐induced graft polymerization to simultaneously attach ionophore‐doped crosslinked poly(decyl methacrylate) sensing membranes covalently both to a high surface area carbon as ion‐to‐electron transducer and to inert polymeric electrode body materials (i.e., polypropylene and poly(ethylene‐co‐tetrafluoroethylene)). The sensors provide high reproducibility (standard deviation of E0 of 0.2 mV), long‐term stability (potential drift 7 μV h−1 over 260 h), and resistance to sterilization in an autoclave (121 °C, 2.0 atm for 30 min). For this work, a covalently attached H+ selective ionophore was used to prepare pH sensors with advantages over conventional pH glass electrodes, but similar use of other ionophores makes this approach suitable to the fabrication of ISEs for a variety of analytes. [ABSTRACT FROM AUTHOR]

The great success of controlled radical polymerizations has encouraged researchers to develop more facile and robust approaches for surface‐initiated polymerizations (SIPs) to fabricate polymer brushes, even for non‐experts. In recent years, external‐stimuli‐mediated radical polymerization methods have come to the fore as SIPs because of their less rigorous synthetic procedures and high controllability, which expand the opportunities for synthesizing macromolecules with desired chemical compositions and structures, as well as tailor‐made polymers and bioconjugates that show broad applicability and physiological compatibility. This review discusses the latest developments in surface‐initiated polymerization methods, in particular, external‐stimuli mediated atom transfer radical polymerization (ATRP), photo‐induced polymerizations, and reversible addition‐fragmentation chain transfer (RAFT) polymerization, as well as other methods and their combination for the application in surface grafting. The implementation of these methods is of great interest due to their unique possibilities to temporally control a polymerization process, fast and straightforward polymerization, and environmentally benign features, which lead to established and emerging applications in biolubrication, antifouling, and biosensing. [ABSTRACT FROM AUTHOR]

The great success of controlled radical polymerizations has encouraged researchers to develop more facile and robust approaches for surface‐initiated polymerizations (SIPs) to fabricate polymer brushes, even for non‐experts. In recent years, external‐stimuli‐mediated radical polymerization methods have come to the fore as SIPs because of their less rigorous synthetic procedures and high controllability, which expand the opportunities for synthesizing macromolecules with desired chemical compositions and structures, as well as tailor‐made polymers and bioconjugates that show broad applicability and physiological compatibility. This review discusses the latest developments in surface‐initiated polymerization methods, in particular, external‐stimuli mediated atom transfer radical polymerization (ATRP), photo‐induced polymerizations, and reversible addition‐fragmentation chain transfer (RAFT) polymerization, as well as other methods and their combination for the application in surface grafting. The implementation of these methods is of great interest due to their unique possibilities to temporally control a polymerization process, fast and straightforward polymerization, and environmentally benign features, which lead to established and emerging applications in biolubrication, antifouling, and biosensing. [ABSTRACT FROM AUTHOR]

This study demonstrates the hybridization of polyelectrolyte brushes with anti‐inflammatory drug‐loaded nanoMOFs that can achieve highly efficient aqueous lubrication and sustained drug release for the synergistic therapy of osteoarthritis (OA). Poly(3‐sulfopropyl methacrylate potassium salt) (PSPMK) brushes are grown on the surface of the UiO‐66‐NH2 via one‐pot grafting polymerization, which served as a general surface modification method of NH2‐MOFs to grow the polymer brushes. The growth of the PSPMK brushes greatly enhance the stability, dispersity, and swollen property of the AS‐UiO‐66‐NH2@PSPMK in aqueous media. Using as lubricating additives, the UiO‐66‐NH2@PSPMK achieves not only reductions in both coefficient of friction and wear volume over 70% and 99% but also supports high load‐carrying capacity and long‐term durability. The PSPMK brushes can be served as an universal interfacial modification soft layer that can significantly improve the aqueous lubricating performance of other types of NH2‐MOFs. After encapsulating the anti‐inflammatory aspirin (AS), the AS‐UiO‐66‐NH2@PSPMK shows both sustained drug release and good biocompatibility toward the human normal chondrocytes. This work establishes anti‐inflammatory drug‐loaded UiO‐66‐NH2@PSPMK as a potential multifunctional joint lubricant for OA treatment. [ABSTRACT FROM AUTHOR]

In this work, a novel nanoadsorbent is reported for the surface grafting of poly[(N, N- dimethylacrylamide)-co-(allyl acetoacetate)] onto zinc oxide nanoparticles by free radical polymerization method for removal of Pb(II) in water and biological samples. The obtained nanoadsorbent was characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy. The calibration curve was linear in the concentration range of 2–100 mg L−1 with a removal efficiency in the range of 70–98%. Under the optimal conditions, the nanoadsorbent offered high adsorption capacity (56.20 mg g−1), low limit of detection (S/N = 3) of 11 ng mL−1 and the limit of quantification (S/N = 10) of 37 ng mL−1 with a relative standard deviation of <2% (n = 3). The results indicate that the Freundlich isotherm model and pseudo-second-order kinetic model are the best models that describe the sorption system. [ABSTRACT FROM AUTHOR]

The paper presents a feasible strategy through one-step bulk-suspension polymerization, grafting PEG onto an in situ synthesized copolymer. In more detail, PEG was grafted onto a homemade polystyrene/maleic anhydride copolymer (SMA) via bulk-suspension polymerization with poly(vinyl alcohol) as a suspending agent. According to the optimal reaction conditions, the grafting rate of PEG was 56.2% through chemical titration experiments. At the same time, the quantitative relationship between the grafting rate and enthalpy was demonstrated for the first time in a PEG-based solid–solid phase change material (S-SPCM). Morphology observation revealed that the obtained S-SPCM is made up of white microspheres of approximately 100–150 μm. The powdery product polystyrene/maleic anhydride grafted polyethylene glycol (SMA-g-PEG) obtained through bulk-suspension polymerization endowed that the whole product could be used directly as a phase change material without postprocessing. The melting enthalpy and crystallization enthalpy of SMA-g-PEG were 79.3 J/g and 76.9 J/g, respectively. Based on the effective fixed load of PEG, the macrostructure of SMA-g-PEG was almost unchanged at 70 °C compared with the macrostructures at 20 °C, and the latent heat of SMA-g-PEG was decreased slightly after 1000 thermal cycles. Overall, the obtained SMA-g-PEG can be used as a filler in insulation materials and composited with fibers to obtain phase change thermoregulated smart textiles. [ABSTRACT FROM AUTHOR]

This study aimed to describe the fabrication of a novel dental composite by surface modification of silica fillers with polyether ether ketone (PEEK) and assess surface coverage of fillers and the effect of different concentration of modified fillers on degree of conversion, flexural strength, polymerization shrinkage, water sorption and solubility, viscosity and thermal expansion of the formulated composites. In this experimental study, aminosilane derivative of PEEK was synthesized and grafted to the silica filler surface, then evaluated using a fourier transform infrared spectroscopy (FTIR), and thermo-gravimetric analysis (TGA). Silica-PEEK fillers were then mixed with Bis-GMA/TEGDMA resin base in 10, 30, and 50 wt%. The most relevant physico-chemical properties were evaluated and compared with a control composite resin group containing conventional 3-(methacryloxypropyl) trimethoxysilane (γ-MPS) modified fillers. Data were analyzed by ANOVA and Tukey's HSD test. (α = 5%). The experimental composite with 30% modified fillers showed highest flexural strength and degree of conversion (DC) (p < 0.05), and comparable polymerization shrinkage and viscosity to the control composites (p > 0.05). After thermocycling, the composite with 30% modified fillers showed the lowest solubility and water sorption (p < 0.05). Surface modification of silica fillers with PEEK polymer significantly increases the resistance of the filler–matrix interface to hydrolysis. The above mentioned intervention can improve mechanical properties of the composite and may be considered as a promising protocol to reduce the failure of dental composites. [ABSTRACT FROM AUTHOR]

Poly(N-isopropyl acrylamide) (PNIPAM) is a commonly investigated thermoresponsive polymer that exhibits a number of interesting physical behaviors. Here, we use small-angle neutron scattering (SANS) measurements to determine the conformation of PNIPAM in two regions of the chain when it is grafted at moderate grafting densities to the surface of SiO2 nanoparticles (rNP ≈ 10 nm). At these grafting densities, polymer chains may adopt two primary conformations, depending on the specific value of the second virial coefficient, the molecular weight of the chains, and other properties. The nanoparticles are studied in D2O and ethanol-d6 to ascertain the effect of solvent quality on the chain conformation in both the inner and outer regions of the brush. The SANS measurements are interpreted using a modified Daoud–Cotton model that connects the Flory–Rehner theory of microgel thermodynamics to the structure of polymer-grafted nanoparticles. [ABSTRACT FROM AUTHOR]

Zwitterionic brush grafting is considered a serious strategy for surface modification on mesoporous silica nanoparticles (MSN) and a prominent alternative to polyethylene glycol films for antifouling applications. In this study, the solution behavior of poly(sulfobetaine methacrylate) (pSBMA) polymer brushes grafted on MSN (95 ± 15 nm particle diameter, 2.8 nm pore size) was evaluated. The layers increased their hydrodynamic diameter (dH) with increasing temperature, indicating a conformational change from a surface-collapsed state to a fully solvated brush. This development was marked by a transition temperature, related to the molecular weight and the theoretical length of the polymer chains. Variation of dH with pH values was studied and a zwitterionic range of 5–9 was established where the electric charges in the molecule were balanced. Zeta potential (ZP) values for all pSBMA-MSN products were also measured. A decreasing trend of ZP with pH and an isoelectric point around 5.5–6.5 was obtained for all dispersions. Furthermore, the influence of temperature was analyzed on ZP and a directly proportional correlation was found, with increasing rates of 0.50–0.87%/°C. Finally, ZP variation with electrolyte concentration was determined and a range of 40–60mM of NaCl concentration was established to reach an almost zero-charge point for all nanoparticles. It was demonstrated that the solution response of pSBMA-MSN can be modulated by temperature, pH, and ionic concentration of the media. These behaviors could be used as controlled release mechanisms for the application of pSBMA-MSN as carriers in biomedicine and nanophamaceutical fields in the future. [ABSTRACT FROM AUTHOR]

Control of nanoparticle dispersion within a polymer matrix is a critical consideration when designing solid state hybrid polymer/inorganic nanoparticle materials. Polymer-functionalized nanoparticles are effective hybrid components for increasing particle miscibility in polymer matrices. Entropic and enthalpic contributions to the dispersion state of polymer-functionalized nanoparticles are well-understood and have been used extensively to enhance nanoparticle miscibility in polymer matrices. However, systems of immiscible graft and matrix chains remain understudied, in part due to the challenges associated with mixing unlike components. Here, a new method for stabilizing polymer-functionalized nanoparticles in an immiscible matrix is reported. Poly(cyclooctadiene) (PCOD) functionalized nanoparticles are dispersed within poly(styrene) and poly(methyl methacrylate) matrices by an in situ polymerization and polymer grafting process in which polymer-grafted nanoparticles are initially well-solubilized in a monomer solution prior to monomer polymerization. The in situ polymerization arrests particle mobility as the matrix increases in chain length, and thermodynamic penalties to mixing are reduced by the in situ grafting of matrix chains from the PCOD segments on the nanoparticle surfaces. This method adapts commercially relevant free-radical polymerization processes for the development of well-dispersed hybrid polymer/inorganic nanoparticle materials. The reported method is a potential avenue to improve particle dispersion needed for solid state material reinforcement without relying on miscible particle and polymer components. [ABSTRACT FROM AUTHOR]

Utilizing a reverse micelle process, we have grafted polyacrylate (P) on graphene oxide (GO) to realize polyacrylate grafted graphene oxide (P-GO) nanocomposites, upon whose subsequent reduction, polyacrylate grafted reduced graphene oxide (P-rGO) nanocomposites are achieved. Using techniques such as ultraviolet photoelectron spectroscopy (UPS), x-ray photoelectron spectroscopy, and x-ray absorption near edge structure (XANES) spectroscopy, in conjunction with high-resolution microscopy, Raman spectroscopy, and superconducting quantum interference device analysis, we have studied in depth the electronic, microstructural, electrical, and magnetic properties of these P-GO and P-rGO nanocomposites. While polyacrylate grafting ensures a high solubility of P-GO and P-rGO, the P-rGO nanocomposites additionally show a near doubling of the paramagnetic response (9.6 × 10−3 emu/g) as compared to the r-GO (5.6 × 10−3 emu/g) and P-GO (5.5 × 10−3 emu/g), respectively, at 2 K. The grafting of diamagnetic polyacrylate enhances the magnetic response for the P-GO and P-rGO owing to the increase in the defect states, sp3-type bonding, and enhanced magnetic coupling between the magnetic moments arising due to the presence of nitrogen functionalities. This behavior is further corroborated via the measurements of the electronic structure by XANES and UPS measurements. Thus, the possibility of manipulation of the magnetic behavior along with the abundance of surface functional groups makes both P-GO and P-rGO nanocomposites highly conducive for deriving water-soluble functionalized graphene by linking affinity molecules with polyacrylate backbone for biological and biomedical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] Mixed polymer brushes (MPBs) could be synthesized by surface dilution of homopolymer brushes and subsequent grafting of other type of chains in the formed voids. Nanophase separation and dynamics of surface-grafted chains could be tailored by modification of their molecular architecture. Mixed polyelectrolyte and conjugated chains contribute synergistically to tailor properties of the coating. A new synthetic strategy that allowed spatially controlled grafting of poly(sodium 4-styrenesulfonate) chains (PSSNa) in close neighborhood of poly(3-methylthienyl methacrylate) (PMTM) brushes (precursors of the conjugated chains) using surface-initiated polymerizations was developed. The final mixed conjugated/polyelectrolyte brushes were prepared by template polymerization of pendant thiophene groups in PMTM chains. Surface dynamics and nanophase separation of MPBs were studied by nanoscale resolution IR imaging, SIMS profiling and AFM mapping in selective solvents. Unconjugated MPBs were shown to undergo vertical, and horizontal nanophase separation, while the size and shape of the nanodomains were dependent on molar ratio of the mixed chains and their relative lengths. Generation of the conjugated chains led to diminishing of nanophase separation thanks to stronger mutual interactions of conjugated PMTM and PSSNa (macromolecular mixing). The obtained systems demonstrated tunable interfacial structure and resistance switching phenomenon desired in construction of smart surfaces or memristive devices. [ABSTRACT FROM AUTHOR]

The choice of carrier material is critical in the study of natural drug release preparations and glycosylated magnetic molecularly imprinted materials. The stiffness and softness of the carrier material affect the efficiency of drug release and the specificity of recognition. The dual adjustable aperture-ligand in molecularly imprinted polymers (MIPs) provides the possibility of individualized design for sustained release studies. In this study, a combination of paramagnetic Fe3O4 and carboxymethyl chitosan (CC) was used to enhance the imprinting effect and improve drug delivery. A combination of tetrahydrofuran and ethylene glycol was used as a binary porogen to prepare MIP-doped Fe3O4-grafted CC (SMCMIP). Salidroside serves as the template, methacrylic acid acts as the functional monomer, and ethylene glycol dimethacrylate (EGDMA) serves as the crosslinker. Scanning and transmission electron microscopy were used to observe the micromorphology of the microspheres. The structural and morphological parameters of the SMCMIP composites were measured, including the surface area and pore diameter distribution. In an in vitro study, we found that the SMCMIP composite had a sustained release property of 50% after 6 h of release time in comparison to the control SMCNIP. The total amounts of SMCMIP released at 25 °C and 37 °C were 77% and 86%, respectively. In vitro results showed that the release of SMCMIP followed Fickian kinetics, meaning that the rate of release is dependent on the concentration gradient, with diffusion coefficients ranging from 3.07 × 10−2 cm2/s to 5.66 × 10−3 cm2/s. The results of cytotoxicity experiments showed that the SMCMIP composite did not have any harmful effects on cell growth. The survival rates of intestinal epithelial cells (IPEC-J2) were found to be above 98%. By using the SMCMIP composite, drugs may be delivered in a sustained manner, potentially leading to improved therapeutic outcomes and reduced side effects. [ABSTRACT FROM AUTHOR]

The study of peptides (synthetic or corresponding to discrete regions of proteins) has facilitated the understanding of protein structure–activity relationships. Short peptides can also be used as powerful therapeutic agents. However, the functional activity of many short peptides is usually substantially lower than that of their parental proteins. This is (as a rule) due to their diminished structural organization, stability, and solubility often leading to an enhanced propensity for aggregation. Several approaches have emerged to overcome these limitations, which are aimed at imposing structural constraints into the backbone and/or sidechains of the therapeutic peptides (such as molecular stapling, peptide backbone circularization and molecular grafting), therefore enforcing their biologically active conformation and thus improving their solubility, stability, and functional activity. This review provides a short summary of approaches aimed at enhancing the biological activity of short functional peptides with a particular focus on the peptide grafting approach, whereby a functional peptide is inserted into a scaffold molecule. Intra-backbone insertions of short therapeutic peptides into scaffold proteins have been shown to enhance their activity and render them a more stable and biologically active conformation. [ABSTRACT FROM AUTHOR]

The use of technologies based on combustion of carbon-containing fossil fuel leads to emission of large amounts of CO2, one of the main greenhouse gases, into the atmosphere. To reduce the CO2 level in the atmosphere, systems for CO2 sorption from various gas sources are being developed. The systems allowing the CO2 sorption and desorption at low temperatures (25–200°С) are of most interest. Most frequently, such systems are composite materials consisting of a porous support and a CO2 chemisorbent dispersed on it. Low-volatile amine-containing compounds are the most promising among organic chemisorbents. Classification of the amine-containing sorbents with respect to the preparation procedure is discussed. The procedures include impregnation, covalent grafting, and in situ polymerization on the support surface. The impregnation procedure is simple and cheap in implementation. The sorption characteristics of materials prepared by impregnation depend on the efficiency of the dispersion of the active component, which is determined by the characteristics of the support pore structure, in particular, by the ability of the pore surface for chemical or electrostatic interaction with the supported amine-containing compound. The covalent grafting is based on immobilization of alkoxyaminosilanes on the surface of porous silica materials. The supports for implementing this approach should contain a large amount of silanol groups on the surface and should have the pore size sufficient for the efficient transport of CO2 molecules to amino groups. The main drawback of the grafting method is low thickness of the amine-containing component layers obtained. In situ polymerization is used for preparing materials with high content of grafted functional groups. Provided that the blocking of support pores is excluded in the course of in situ polymerization, materials of this type exhibit the highest sorption capacity for CO2. [ABSTRACT FROM AUTHOR]

In order to achieve smart biomedical micro/nanomaterials, promote interaction with biomolecules, improve osteogenic/chondrogenic differentiation, exhibit better dispersion in bone implants and ultimately maximize functionality, we innovatively and successfully designed and synthesized polymer PBLG-modified GdPO4·H2O nanobunches by hydroxylation, silylation and glutamylation processes. The effects of different feeding ratios on the surface coating of GdPO4·H2O with Si-OH, the grafting γ-aminopropyltriethoxysilane (APS) and the in situ ring-opening polymerization reaction of poly(g-benzyl-L-glutamate) (PBLG) were investigated, and the physical and chemical properties were characterized in detail. When GdPO4·H2O@SiO2–APS:NCA = 4:1, the PBLG-g-GdPO4·H2O grafting rate was 5.93%, with good stability and dispersion in degradable polymeric materials. However, the MRI imaging signal was sequentially weakened as the modification process proceeded. Despite this, the biological effects had surprising findings. All the modifiers at appropriate concentrations were biocompatible and biologically active and the biomacromolecules of COL I and COL II in particular were expressed at least 3 times higher in GdPO4·H2O@SiO2 compared to the PLGA. This indicates that the appropriate surface modification and functionalization of gadolinium-containing micro/nanomaterials can promote interaction with cells and encourage bone regeneration by regulating biomacromolecules and can be used in the field of biomedical materials. [ABSTRACT FROM AUTHOR]

This paper reports on the study that gamma-ray irradiation-induced polymerization of N-isopropyl acrylamide (NIPA) to form Poly(N-isopropyl acrylamide) (PNIPA), which was then grafted on the surface of polyvinylidene fluoride (PVDF) membrane to prepare modified PVDF-g-PNIPA membrane. We analyzed the influence of different irradiation doses and dose rates on the grafting rate of modified membranes, and the grafting rate increased with the irradiation dose under a certain irradiation dose. Through analysis of Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TGA), the efficient progress of the grafting reaction was confirmed. With the increase of the grafting rate, the pore size of the membrane surface decreased gradually, but the surface roughness of the membrane tended to increase through the analyse of scanning electron microscopy (SEM) and atomic force microscopy (AFM). Finally, a mechanistic explanation for the grafting of PNIPA on the surface of PVDF membranes based on these experimental results was proposed. [ABSTRACT FROM AUTHOR]

Redox-responsive and magnetic nanomaterials are widely used in tumor treatment separately, and while the application of their combined functionalities is perspective, exactly how such synergistic effects can be implemented is still unclear. This report investigates the internalization dynamics of magnetic redox-responsive nanoparticles (MNP-SS) and their cytotoxicity toward PC-3 and 4T1 cell lines. It is shown that MNP-SS synthesized by covalent grafting of polyethylene glycol (PEG) on the magnetic nanoparticle (MNP) surface via SS-bonds lose their colloidal stability and aggregate fully in a solution containing DTT, and partially in conditioned media, whereas the PEGylated MNP (MNP-PEG) without S-S linker control remains stable under the same conditions. Internalized MNP-SS lose the PEG shell more quickly, causing enhanced magnetic core dissolution and thus increased toxicity. This was confirmed by fluorescence microscopy using MNP-SS dual-labeled by Cy3 via labile disulfide, and Cy5 via a rigid linker. The dyes demonstrated a significant difference in fluorescence dynamics and intensity. Additionally, MNP-SS demonstrate quicker cellular uptake compared to MNP-PEG, as confirmed by TEM analysis. The combination of disulfide bonds, leading to faster dissolution of the iron oxide core, and the high-oxidative potential Fe3+ ions can synergically enhance oxidative stress in comparison with more stable coating without SS-bonds in the case of MNP-PEG. It decreases the cancer cell viability, especially for the 4T1, which is known for being sensitive to ferroptosis-triggering factors. In this work, we have shown the effect of redox-responsive grafting of the MNP surface as a key factor affecting MNP-internalization rate and dissolution with the release of iron ions inside cancer cells. This kind of synergistic effect is described for the first time and can be used not only in combination with drug delivery, but also in treatment of tumors responsive to ferroptosis. [ABSTRACT FROM AUTHOR]

In this work, the effect of functionalized hydroxyapatite (HAp-g-PEG) on the thermal degradation behaviour and flammability of polyoxymethylene copolymer (POM_C) was investigated. Organic–inorganic hybrid additive, obtained by grafting of poly(ethylene glycol) on HAp surface using 1,6-hexamethylene diisocyanate as a linker, has been incorporated into POM matrix through an extrusion process. TG analyses show that the incorporation of HAp-g-PEG into POM_C leads to the significant improvement in the thermal stability of the polymer matrix. This is an important finding as POM, being an engineering polymer, suffers from a relatively low thermal stability that limits processing options to develop advanced composite materials. Based on TG results kinetic parameters of the thermal degradation process using Friedman isoconversional method and nonlinear regression method have been calculated; an increase in activation energy of POM degradation process after incorporation of HAp-g-PEG has been found. Thermoanalytical analyses (TG-FTIR/MS) show that incorporation of HAp-g-PEG has no significant effect on the composition of the thermal degradation products. Flammability investigations showed small effect of HAp-g-PEG 600 on the burning time and rate, however, there was a significant reduction in the amount of dripping during the material's burning process. [ABSTRACT FROM AUTHOR]

In orthopedic, dental, and maxillofacial fields, joint prostheses, plates, and screws are widely used in the treatment of problems related to bone tissue. However, the use of these prosthetic systems is not free from complications: the fibrotic encapsulation of endosseous implants often prevents optimal integration of the prostheses with the surrounding bone. To overcome these issues, biomimetic titanium implants have been developed where synthetic peptides have been selectively grafted on titanium surfaces via Schiff base formation. We used the retro-inverted sequence (DHVPX) from [351–359] human Vitronectin and its dimer (D2HVP). Both protease-resistant peptides showed increased human osteoblast adhesion and proliferation, an augmented number of focal adhesions, and cellular spreading with respect to the control. D2HVP-grafted samples significantly enhance Secreted Phosphoprotein 1, Integrin Binding Sialoprotein, and Vitronectin gene expression vs. control. An estimation of peptide surface density was determined by Two-photon microscopy analysis on a silanized glass model surface labeled with a fluorescent analog. [ABSTRACT FROM AUTHOR]

To overcome the disadvantages generated by the lack of interfacial bonding between hydroxyapatite nanocrystals (HAPN) and agglomeration of particles in the development of biodegradable nanocomposites a chemical grafting method was applied to modify the surface of HAPN through grafting of the three-arms star-shaped poly(ε-caprolactone) (SPCL) onto the nanoparticles. The chemical grafting of SPCL onto HAPN (SPCL-g-HAPN) has been investigated using Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy (TEM), photoelectron spectroscopy, X-ray diffraction, zeta potential (ZP) and contact angle (CA). TEM micrographs of the SPCL-g-HAPN revealed the existence of hybrid organic/inorganic (O/I) nanoscale domains. The results of albumin (HSA) and fibrinogen (HFb) adsorption indicate resistance to HFb adsorption by SPCL-g-HAPN relatively to unmodified HAPN. The ZP and CA measurement suggest a heterogeneous topology for SPCL-g-HAPN likely due to the existence of hydrophobic-hydrophilic regions on the nanocomposite surface. The enzyme degradation by cholesterol esterase and lipase indicates that the rates of hydrolysis for SPCL-g-HAPN were very slow relative to the SPCL/HAPN blends. The in vitro biological studies showed that the human osteoblast-like cells (MG-63) cells had normal morphology and they were able to attach and spread out on SPCL-g-HAPN surfaces. A higher overall cellular proliferation was observed on SPCL-g-HAPN scaffolds compared to pure HAPN or SPCL materials. [ABSTRACT FROM AUTHOR]

Grafting polyethylene glycol (PEG) onto a polymer's surface is widely used to improve biocompatibility by reducing protein and cell adhesion. Although PEG is considered to be bioinert, its incorporation onto biomaterials has shown to improve cell viability depending on the amount and molecular weight (MW) used. This phenomenon was studied here by grafting PEG of three MW onto polyurethane (PU) substrata at three molar concentrations to assess their effect on PU surface properties and on the viability of osteoblasts and fibroblasts. PEG formed a covering on the substrata which increased the hydrophilicity and surface energy of PUs. Among the results, it was observed that osteoblast viability increased for all MW and grafting densities of PEG employed compared with unmodified PU. However, fibroblast viability only increased at certain combinations of MW and grafting densities of PEG, suggesting an optimal level of these parameters. PEG grafting also promoted a more spread cell morphology than that exhibited by unmodified PU; nevertheless, cells became apoptotic-like as PEG MW and grafting density were increased. These effects on cells could be due to PEG affecting culture medium pH, which became more alkaline at higher MW and concentrations of PEG. Results support the hypothesis that surface energy of PU substrates can be tuned by controlling the MW and grafting density of PEG, but these parameters should be optimized to promote cell viability without inducing apoptotic-like behavior. [ABSTRACT FROM AUTHOR]

In this work, the chemical modification of cellulose nanocrystals (NCs) using an enzyme as a catalyst has been performed by a "grafting from" reaction, in order to covalently functionalize the external surface of NCs with both poly(L-lactic acid) (PLLA) and poly(ε-caprolactone) (PCL) by ring-opening polymerization. Firstly, cellulose nanocrystals were prepared from commercial cellulose microcrystals by acid hydrolysis and then functionalized by using Yarrowia lipolytica lipase immobilized on Lewatit resin as a catalyst. To confirm the success of the grafting reactions, 1H-NMR has been performed as well as FT-IR and Raman spectroscopy. Moreover, thermogravimetric analysis has been used to determine the amount of polymeric chains grafted onto the surface of cellulose nanocrystals. Furthermore, the crystalline nature of the polymeric chains grafted onto the cellulose surface has been studied by DSC, X-ray scattering, as well as SAXS analysis. To our knowledge, it is the first time that a biocatalyst approach has been used to obtain biopolymeric functionalized cellulose nanocrystals. [ABSTRACT FROM AUTHOR]

Well-defined polypropylene grafted silica nanoparticles (PP-g-SiO2) were prepared through the reaction of maleic anhydride grafted polypropylene (PP-g-MAH) with amino-functionalized silica (SiO2-NH2) by the 'grafting-to' method. The grafting density of PP-g-SiO2 is found to be controlled by the concentration of silane coupling agent 3-[2-(2-aminoethylamino) ethyl amino] propyl trimethoxy silane (TAMS). The maximum grafting density of grafted PP-g-MAH chains with molecular weight of 9100 g/mol could reach 0.34 chains/nm2, when the critical concentration of TAMS was 0.0194 mol/L. The critical concentration of TAMS can be explained by the maximum amounts of primary amino groups, which can totally react with PP-g-MAH on the surface of SiO2-NH2, when the silane monolayer is formed. The synthesized PP-g-SiO2 with different molecular weights was mixed with PP by solution mixing to form a series of nanocomposites. The crystallization temperature (Tc) of nanocomposites increased significantly with the particle loading. The PP-g-SiO2 with high molecular weight of grafted chains exhibits a high nucleation ability at 1 wt% nanoparticle loading in PP/PP-g-SiO2 nanocomposites. In summary, we provide an effective method to synthesize the well-defined PP-g-SiO2 with controlled grafting density, which shows excellent nucleation ability. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations are used to study the diffusion of polymer-grafted nanoparticles (PGNPs) in polymer. The diffusivity of PGNPs in the homopolymer matrix is investigated as a function of graft length and grafting density, and it is compared to that of bare nanoparticles with comparable effective size. Our results indicate that, in addition to the increase in the effective size of PGNPs due to grafting, the interpenetration of matrix polymers into the grafted layer also plays an important role in the mobility of PGNPs. In systems consisting of both PGNPs and bare particles, the spatial arrangement of the bare particles was found to be having a significant influence on the mobility of PGNPs. At low graft length and high grafting density, the matrix chains dewets the grafted layer, due to autophobic dewetting, creating a sharper interface between the matrix and the grafted layer. The bare particles then migrate to the interface creating a barrier around the PGNPs that hinders the matrix-graft interpenetration and results in the higher mobility of PGNPs. Our results emphasize the importance of polymer-particle interface on the dynamic properties of polymer nanocomposites. [ABSTRACT FROM AUTHOR]

Maximizing the re-endothelialization of vascular implants such as prostheses or stents has the potential to significantly improve their long-term performance. Endothelial progenitor cell capture stents with surface-immobilized antibodies show significantly improved endothelialization in the clinic. However, most current antibody-based stent surface modification strategies rely on antibody adsorption or direct conjugation via amino or carboxyl groups which leads to poor control over antibody surface concentration and/or molecular orientation, and ultimately bioavailability for cell capture. Here, we assess the utility of a bioaffinity-based surface modification strategy to immobilize antibodies targeting endothelial cell surface antigens. A cysteine-tagged truncated protein G polypeptide containing three Fc-binding domains was conjugated onto aminated polystyrene substrates via a bi-functional linking arm, followed by antibody immobilization. Different IgG antibodies were successfully immobilized on the protein G-modified surfaces. Covalent grafting of the protein G polypeptide was more effective than surface adsorption in immobilizing antibodies at high density based on fluorophore-labeled secondary antibody detection, as well as endothelial colony-forming cell capture through anti-CD144 antibodies. This work presents a potential avenue for enhancing the performance of cell capture strategies by using covalent grafting of protein G polypeptides to immobilize IgG antibodies. [ABSTRACT FROM AUTHOR]

Vesicles formed by DMPC liposomes externally conjugated with branched polyglycerol-dendrons as well as linear PEG in water solution were simulated using the DPD method. Such a structure of vesicles corresponds to the structure of polymer-grafted liposomes obtained experimentally by the post-insertion method, in which polymer chains are fixed on the outer surface of the liposome. The grafting density, generation number and spacer length of grafted dendrons were varied. It was shown that modification of the outer surface of liposomes due to grafting of hydrophilic dendrons has practically no effect on the size and shape of the vesicle, as well as on the morphology of the lipid membrane up to certain critical thresholds of grafting density, degree of polymerization, and generation number of grafted molecules. Exceeding the threshold values of these structural parameters leads to irreversible deformation of the lipid membrane. Diffusion through the membrane and the transition of grafted molecules from the outer surface of the liposome to the inner surface is not observed for dendrons with a generation number higher than one, even at high grafting densities. The critical values of the generation number and the characteristics of the molecular coating at these values were determined for various grafting densities and spacer lengths of the grafted chains. It was shown that the chemical potential of the grafted dendron can serve as a stability metric for the conjugated liposome. The chemical potential of grafted molecules was calculated using the mean field model of the spherical brush on the liposome surface. An analysis of the simulation data shows that, within the framework of the applicability of the mean field approach, the value of the chemical potential is a sufficient criterion for separating vesicles into stable and unstable forms. These results can be used as a guide for the experimental design of nanocontainers based on lipid vesicles with an external protective coating of branched macromolecules. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA), a polymer derived from renewable resources, is gaining increasing attention in the development of biomedical devices due to its cost-effectiveness, low immunogenicity, and biodegradability. However, its inherent hydrophobicity remains a problem, leading to poor cell adhesion features. On this basis, the aim of this work was to develop a method for functionalizing the surface of PLA films with a biopolymer, chitosan (CH), which was proved to be a material with intrinsic cell adhesive properties, but whose mechanical properties are insufficient to be used alone. The combination of the two polymers, PLA as a bulk scaffold and CH as a coating, could be a promising combination to develop a scaffold for cell growth. The modification of PLA films involved several steps: aminolysis followed by bromination to graft amino and then bromide groups, poly(glycidyl methacrylate) (PGMA) grafting by surface-initiated supplemental activator and reducing agent atom transfer radical polymerization (SI-SARA ATRP) and finally the CH grafting. To prove the effective adhesive properties, conjugated and non-conjugated films were tested in vitro as substrates for neuronal cell growth using differentiated neurons from human induced pluripotent stem cells. The results demonstrated enhanced cell growth in the presence of CH. [Display omitted] • Functionalization of PLA films with chitosan is developed. • Grafting is performed by SI-SARA ATRP. • The functionalized films prove to be efficient scaffolds for neuronal cell growth. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microemulsion sol–gel chemistry used to prepare loaded silica nanoparticles. • Polylactide-silica nanoparticle nanocomposites prepared with enhanced functionality depending on the cargo. • Surface-grafting of PLA to silica nanoparticles enhances dispersion of nanoparticle in PLA-matrix and prevents aggregation. • Accelerated hydrolysis and composting rates of nanocomposites compared to neat PLA depending on the cargo. Polylactide (PLA) stands as a prominent commodity biodegradable polymer, yet its inherent slow biodegradation under certain conditions has been a persistent challenge. This study introduces a general approach for enhancing the biodegradation of PLA by employing silica nanoparticles (SiNPs) loaded with diverse cargoes. The SiNPs with diameters of ca. 100 nm are synthesized through a sol–gel process in an inverse microemulsion, enabling in situ loading with functional cargoes such as poly(acrylic acid), lignosulfonate, and chitosan. Surface grafting with PLA (PLA-grafted SiNPs) serves to prevent aggregation, thereby enhancing the dispersion of nanoparticles within the PLA matrix and improving composite properties preventing depletion. Lignin-loaded SiNPs demonstrate the capability to block UV light and enhance antioxidant activity in the composite compared to neat PLA. Notably, SiNPs loaded with poly(acrylic acid) and chitosan exhibit the capacity to accelerate PLA hydrolysis in aqueous environments, while lignin as cargo results in faster composting with an increased weight loss of ca. 20 wt% compared to neat PLA at only 1 wt% loading of SiNPs. This research outlines a versatile strategy utilizing SiNPs to address the slow biodegradation profile of PLA, offering valuable insights and a promising avenue for advancing the environmental sustainability of degradable polyester-based materials in diverse applications. [ABSTRACT FROM AUTHOR]

Crystallization-driven self-assembly (CDSA) is a versatile technique for inducing the formation of two-dimensional (2D) nanoplates by amphiphilic block copolymers. However, most of studies have primarily focused on dilute solution (<1 wt%), neglecting the aggregation behavior of 2D nanoparticles at high concentrations. In this study, we performed the self-assembly of 2D nanoplates composed of linear-brush block copolymers (LBCPs) at a concentration of 10 wt%. Solution reversible addition-fragmentation chain transfer (RAFT) polymerization was employed to synthesize a series of LBCPs from poly (N,N -dimethylacrylamide)- block -[poly (2-hydroxyethyl methacrylate- graft -poly (ε -caprolactone)] (PDMA- b -P(HEMA- g -PCL)) via the grafting-through strategy using hydroxyethyl methacrylate poly (ε -caprolactone) (HEMA-PCL) as the macromonomer. Upon cooling and termination of polymerization, crystallization-induced phase separation occurred, resulting in the formation of spherical micelles and subsequent 2D nanoplates composed of brush PCL side chains and residual HEMA-PCL seeds. Further assembly leaded to layer-upon-layer stacking, ultimately leading to the formation of three-dimensional (3D) olive-shaped nanosheets. The terraced edges of these 3D nanosheets exhibit monolayer heights ranging from 15 to 20 nm. The morphology control over these nanoassemblies was achieved by varying LBCP configuration, such as block ratio and side chain length. Comprehensive characterization through transmission electron microscope (TEM), scanning electron microscope (SEM) and polarizing microscope (POM) tests confirmed the regular morphologies, while atomic force microscope (AFM) analysis verified their 3D layered structure. This preparation strategy for high concentration 3D nanosheets exhibits promising potential for applications in photocatalysis, microelectronics, and drug delivery. The three-dimensional (3D) olive-shaped nanosheets are formed through the successive stacking of two-dimensional (2D) nanoplates layer upon layer in situ. [Display omitted] • The synthesis of LBCPs is achieved through solution RAFT polymerization. • The 2D nanoplates and 3D olive-shaped nanosheets are prepared via the CDSA of LBCPs at a high concentration of 10 wt%. • The formation of 3D olive-shaped nanosheets is achieved in situ through the layer-upon-layer stacking of 2D nanoplates. [ABSTRACT FROM AUTHOR]

Physical vapor deposition (PVD) of chromium coatings represents an interesting alternative to electroplating to obtain metallized plastic parts for a variety of manufacturing sectors. This process is however hampered by the limited adhesion of the metallic layer on the underlying polymeric substrates. Within this context, PVD metallization of polypropylene substrates has so far been particularly challenging given the low surface energy and poor wettability of this commodity plastics. To address this issue, a comprehensive approach is proposed here to enable the production of PVD-metallized PP substrates with excellent and stable interlayer adhesion. The adhesive properties of the PP substrate are modified by a selective UV-induced photografting process in which vinyl-, glycidyl- or 2-hydroxyethyl methacrylate species are covalently attached to the PP surface, as confirmed by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and surface wettability measurements. Based on the chemistry of the photografted functionality, different resin systems are selected and investigated for use as primers to enable subsequent chromium deposition, including acrylic, epoxy and polyurethane systems. The effect of the photografting process on the adhesion between PP and the primers is systematically assessed by means of pull-off tests, highlighting a significant improvement of the adhesion force after surface functionalization with appropriate grafting agents. Finally, functionalized PP substrates are chromated through PVD, obtaining homogeneous and crack-free chromium surfaces upon judicious selection of suitable primer-grafting agent combinations. This also led to outstanding interlayer adhesion and micromechanical performance. This work provides the first demonstration of chromium-metallization of PP substrates via PVD for metallized plastic components with excellent surface characteristics, and paves the path for the design of mechanically durable and aesthetically-compliant PVD-metallized PP components. • Polypropylene substrates are metallized with chromium by physical vapor deposition. • Excellent interlayer adhesion is achieved by functionalization via UV-photographing. • Homogeneous crack-free chromium coatings are obtained via surface chemistry tuning. [ABSTRACT FROM AUTHOR]

[Display omitted] • A hydrophilic TPU with excellent stability is prepared by plasma-induced graft polymerization of PVP. • The water contact angle of TPU is reduced from 109.2° to 9.2°, and keeps within 20° after 80 days in air. • The substrate does not suffer from any damage via the plasma-induced grafting. Hydrophilic thermoplastic polyurethane (TPU) is applicable in the fields of packaging, oil–water separation, and biomedical. Nevertheless, the process of its preparation is still a great challenge. The objective of this study is to develop TPU with excellent wettability and hydrophilic stability by surface modification. Four methods were evaluated: coating with PVP (polyvinylpyrrolidone) solution, immersion in PVP solution, N 2 /Ar plasma treatment, and N 2 /Ar plasma-induced graft polymerization with PVP. Finally, the results indicate that the sample called TPU-g-PVP, which utilizes plasma-induced grafting, exhibits the best performance. The water contact angle (WCA) reduces from 109° to 9.2°, and maintains within 20° after 80 days under atmospheric conditions. Its surface energy (72.4 mN/m) is increased by 2.8 times than untreated TPU. The surface morphology and roughness are almost unchanged when compared to the original TPU. Some characteristic peaks (–OH and C = O) of PVP on the TPU-g-PVP were found by infrared spectroscopy. X-ray photoelectron spectroscopy (XPS) examination revealed a reduction in C on the TPU surface as the content of N and O increases. Experiments on biocompatibility showed that the PVP deposited substrates improved cell adherence without generating new cytotoxicity. [ABSTRACT FROM AUTHOR]