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Thermoresponsive hydrogels were 3D-printed with embedded gold nanorods (GNRs), which enable shape change through photothermal heating. GNRs were functionalized with bovine serum albumin and mixed with a photosensitizer and poly(N-isopropylacrylamide) (PNIPAAm) macromer, forming an ink for 3D printing by direct ink writing. A macromer-based approach was chosen to provide good microstructural homogeneity and optical transparency of the unloaded hydrogel in its swollen state. The ink was printed into an acetylated gelatin hydrogel support matrix to prevent the spreading of the low-viscosity ink and provide mechanical stability during printing and concurrent photocrosslinking. Acetylated gelatin hydrogel was introduced because it allows for melting and removal of the support structure below the transition temperature of the crosslinked PNIPAAm structure. Convective and photothermal heating were compared, which both triggered the phase transition of PNIPAAm and induced reversible shrinkage of the hydrogel–GNR composite for a range of GNR loadings. During reswelling after photothermal heating, some structures formed an internally buckled state, where minor mechanical agitation recovered the unbuckled structure. The BSA-GNRs did not leach out of the structure during multiple cycles of shrinkage and reswelling. This work demonstrates the promise of 3D-printed, photoresponsive structures as hydrogel actuators. [ABSTRACT FROM AUTHOR]

Low‐density polyethylene (LDPE) is one of the most important plastics, which is produced unfortunately under extreme conditions. In addition, it consists of robust aliphatic C─C bonds which are challenging to cleave for plastic recycling. A low‐pressure and ‐temperature (pethylene = 2 bara, T = 70 °C) macromonomer‐based synthesis of long chain branched polyethylene is reported. The introduction of recycle points permits the polymerization (grafting to) of the macromonomers to form the long chain branched polyethylene and its depolymerization (branch cleavage). Coordinative chain transfer polymerization employing ethylene and co‐monomers is used for the synthesis of the macromonomers, permitting a high flexibility of their precise structure and efficient synthesis. The long chain branched polyethylene material matches key properties of low‐density polyethylene. [ABSTRACT FROM AUTHOR]

Herein, a series of ternary amphiphilic amide-containing bottlebrushes were synthesized by photoiniferter (PI-RAFT) polymerization of macromonomers in continuous-flow mode using trithiocarbonate as a chain transfer agent. Visible light-mediated polymerization of macromonomers under mild conditions enabled the preparation of thermoresponsive copolymers with low dispersity and high yields in a very short time, which is not typical for the classical reversible addition–fragmentation chain transfer process. Methoxy oligo(ethylene glycol) methacrylate and alkoxy(C12–C14) oligo(ethylene glycol) methacrylate were used as the basic monomers providing amphiphilic and thermoresponsive properties. The study investigated how modifying comonomers, acrylamide (AAm), methacrylamide (MAAm), and N-methylacrylamide (-MeAAm) affect the features of bottlebrush micelle formation, their critical micelle concentration, and loading capacity for pyrene, a hydrophobic drug model. The results showed that the process is scalable and can produce tens of grams of pure copolymer per day. The unmodified copolymer formed unimolecular micelles at temperatures below the LCST in aqueous solutions, as revealed by DLS and SLS data. The incorporation of AAm, MAAm, and N-MeAAm units resulted in an increase in micelle aggregation numbers. The resulting bottlebrushes formed uni- or bimolecular micelles at extremely low concentrations. These micelles possess a high capacity for loading pyrene, making them a promising choice for targeted drug delivery. [ABSTRACT FROM AUTHOR]

The integration of liposomes into hydrogels through direct soaking presents advantages such as facile formulation, enhanced drug stability, and controlled release kinetics. However, the feasibility of this approach is impeded by the difficulty of developing matching porous structures within hydrogels and achieving appropriate affinity with liposomes. To address these challenges, an alternative method is proposed for synthesizing macroporous hydrogels using thiolated hyaluronic acid and hyperbranched polyethylene glycol macromonomers in combination with a freezing‐induced secondary crosslinking process. This approach allows the locking of macropores formed by ice crystals during freezing and enables easy modification of the hydrogels with cholesterol groups to promote liposome association. Furthermore, these macroporous hydrogels can be crushed into granular hydrogels, which offer numerous benefits such as high loading capacity, injectability, self‐healing properties, and convenience in storage, dosing, and administration. Therefore, a liposome‐in‐hydrogel system can be formulated without any gelation or pre‐treatment, providing valuable insights for the further development of liposome‐based formulations for medical and cosmetic applications. [ABSTRACT FROM AUTHOR]

The presented work deals with the photocuring of telechelic macromonomers derived from plant-based fatty acids to obtain a soft polymer network. Compositions were made by mixing macromonomers with three different concentrations (0.5, 1, and 2%) of two type I photoinitiators (Omnirad 2022 and Omnirad 819). All formulations were then subjected to photopolymerization studies by applying UV-assisted differential scanning calorimetry (UV-DSC) measurements at isothermal conditions at 37 °C with a narrow light source wavelength of 365 nm and irradiation (light intensity) of 20 and 50 mW/cm2. The percentage conversions, reaction orders, and constants were estimated based on autocatalytic Sestak–Berggen and Avrami models. In this work, for the first time, the influence of the curing conditions on the photopolymerization process, such as the photoinitiator concentration, light intensity, and oxygen presence/absence, were investigated for these novel systems. The results indicated significant differences between the two commercially available photoinitiators and their effects on photopolymerization kinetics. The maximum reaction rate was found to be considerably higher for Omnirad 2022 (which is a blend of three different compounds), especially at a lower light intensity, i.e., 20 mW/cm2, compared to Omnirad 819. However, it led to lower maximum conversion in an air atmosphere. The dynamic thermomechanical analysis (DMTA) revealed that light intensity, photoinitiator concentration, and oxygen presence had a strong effect on the storage modulus and loss modulus values. It was concluded that the chemical structure of the photoinitiator and curing conditions had a strong effect on the photopolymerization kinetics and properties of the prepared soft polymer networks. [ABSTRACT FROM AUTHOR]

Highly efficient one-pot synthesis of hexakis(m-phenyleneimine) macrocycle Cm6 from acetalprotected AB-type monomer, m-aminobenzaldehyde diethylacetal, was successfully achieved based on imine dynamic covalent chemistry and precipitation-driven cyclization. The structure of Cm6 in the solid state was determined using CP/MAS NMR, X-ray single crystallographic analysis, and WAXD. Macrocycle Cm6 is composed of six phenylene and imine bonds facing the same direction, with nitrogen atoms arranged on the outside of the ring, and has a chair conformation, as predicted from DFT calculation. The macrocycle forms π-stacked columnar aggregates and hexagonally closest-packed structure. The cyclization process was investigated using MALDI-TOF MS and NMR. A mechanism of precipitation-driven cyclization based on imine dynamic covalent chemistry and π-stacked columnar aggregation is proposed. Both the nature of imine linkage and the shape anisotropy of the macrocycle played an important role in the single one-pot synthesis. The water-mediated mutual conversion between macrocycle Cm6 and linear oligomers driven by thermal stimulation was analyzed using MALDI-TOF MS and GPC methods. Macrocycle Cm6 with a dynamic covalent imine bond exhibited self-healing properties when stimulated using heat. [ABSTRACT FROM AUTHOR]

Engineered polylactic acid (PLA) nanoparticles synthesized from oligo(lactic acid) macromonomers have been studied over the last decades for controlled drug delivery. These macromonomers are typically produced via ring‐opening polymerization (ROP) of the cyclic dimer lactide, initiated by 2‐hydroxyethyl methacrylate (HEMA). This reaction route, despite leading to well‐defined macromonomers, relies on the production of lactide from lactic acid, which burdens the ROP overall cost for more than 30%. In this work, we report the synthesis of PLA‐based macromonomers by direct polycondensation of lactic acid in the presence of HEMA as a valuable alternative to ROP. In particular, we compare the two processes side by side, focusing on the production of three HEMA‐LAn macromonomers, with n = 2, 4, and 6. Detailed kinetic models are developed for both reaction systems, and the corresponding parameters are estimated by fitting the experimental data. Through these models, the reaction kinetics as well as the time evolution of the entire chain length distributions of the products from polycondensation and ROP could be reliably predicted. This way, we demonstrated that polycondensation is a valuable alternative to ROP only for macromonomers with an average chain length of up to 4 and that ROP remains the main route to longer chains, when a strict control over the chain length distribution is required. [ABSTRACT FROM AUTHOR]

Aiming at the creation of polymers with attractive dynamic properties, herein, rotaxane-branched dendronized polymers (DPs) with rotaxane-branched dendrons attached onto the polymer chains are proposed. Starting from macromonomers with both rotaxane-branched dendrons and polymerization site, targeted rotaxane-branched DPs are successfully synthesized through ring-opening metathesis polymerization (ROMP). Interestingly, due to the existence of multiple switchable [2]rotaxane branches within the attached dendrons, anion-induced reversible thickness modulation of the resultant rotaxane-branched DPs is achieved, which further lead to tunable thermal and rheological properties, making them attractive platform for the construction of smart polymeric materials. Enriching the toolbox of polymers, the design and construction of novel polymers with desired properties and functions remains an attractive topic in polymer chemistry. Here the authors demonstrate rotaxane-branched dendronized polymers with rotaxane-branched dendrons attached onto the polymer chains as polymers with attractive dynamic properties. [ABSTRACT FROM AUTHOR]

Macromolecules obtained from renewable natural sources are gaining increasing attention as components for a vast variety of sustainable polymer-based materials. Natural raw materials can facilitate continuous-flow production due to their year-round availability and short replenishment period. They also open new opportunities for chemists and biologists to design and create "bioreplacement" and "bioadvantaged" polymers, where complex structures produced by nature are being modified, upgraded, and utilized to create novel materials. Bio-based macromonomers are expected not only to compete with but to replace some petroleum-based analogs, as well. The development of novel sustainable materials is an ongoing and very dynamic process. There are multiple strategies for transforming natural macromolecules into sophisticated value-added products. Some methods include chemical modification of macromolecules, while others include blending several components into one new system. One of the most promising approaches for incorporating renewable macromolecules into new products is the synthesis of hybrid networks based on one or more natural components. Each one has unique characteristics, so its incorporation into a network brings new sustainable materials with properties that can be tuned according to their end-use. This article reviews the current state-of-the-art and future potential of renewable natural macromolecules as sustainable building blocks for the synthesis and use of hybrid polymer networks. The most recent advancements and applications that involve polymers, such as cellulose, chitin, alginic acid, gellan gum, lignin, and their derivatives, are discussed. [ABSTRACT FROM AUTHOR]

Methacrylic acid‐co‐poly(ethylene glycol methacrylate) (MAA‐co‐PEGMA) copolymers (MPEG‐type polycarboxylate ether (PCE) superplasticizers) are characterized by a comb‐like structure. Although they have been used for years as dispersants in cementitious formulations, their structure–property relationship is still not fully understood. In this work, PCEs with uniform composition and different charge‐density (N) or different side chain lengths (P) are synthesized by free‐radical copolymerization varying the MAA/PEGMA ratios and ethylene oxide units in the PEGMA macromonomers. The effect of these copolymers on the hydration kinetics of an Ordinary Portland Cement (OPC) is analyzed, and it is observed that by increasing the PCE concentration the hydration is delayed. For a given PCE concentration, the delay is longer as the MAA/PEGMA ratio increases or the side chain length of the PEGMA decreases. The hydration delay is proportional to the carboxylate dosage and all PCEs fit in a master curve proving that the microstructure of the PCEs synthesized by free‐radical copolymerization can be correlated with the hydration delay of a commercial OPC. [ABSTRACT FROM AUTHOR]

In this article, the biocatalytic oxidation of ethanol into acetaldehyde was studied using a catalase entrapped within a monolithic polyampholyte cryogel, p(APTAC-co-AMPS), as catalyst. When an anionic monomer, 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPS), was mixed with a cationic monomer, (3-acrylamidopropyl) trimethylammonium chloride (APTAC), under cryo-polymerization conditions at a molar ratio of monomers [APTAC]:[AMPS] = 75:25 mol.% in the presence of 10 mol.% cross-linking agent, N,N-methylenebisacrylamide (MBAA), the macroporous polyampholyte cryogels containing various amounts of catalase were synthesized in situ. The conversion of ethanol into acetaldehyde in good-to-high yields was observed in flow-through and batch-type reactors under optimal conditions: at T = 10–20 °C, pH = 6.9–7.1, [C2H5OH]:[H2O2] = 50:50 vol.%. According to the SEM images, the pore sizes of the p(AMPS-co-APTAC) cryogel vary from 15 to 55 μm. The catalytic activity of catalase entrapped within a monolithic polyampholyte cryogel in the conversion of ethanol into acetaldehyde was evaluated through the determination of kinetic parameters such as the Michaelis constant (Km), maximum enzymatic rate (Vmax), activation energy (Ea), turnover number (TON) and turnover frequency (TOF). The catalase encapsulated within the monolithic polyampholyte cryogel exhibits a high conversion of ethanol into acetaldehyde. The key parameters of ethanol oxidation in flow and batch reactors in the presence of the cryogel monolith were calculated. [ABSTRACT FROM AUTHOR]

Pollution with organic dyes is one of the most typical environmental problems related to industrial wastewater. The removal of these dyes opens up new prospects for environmental remediation, but the design of sustainable and inexpensive systems for water purification is a fundamental challenge. This paper reports the synthesis of novel fortified hydrogels that can bind and remove organic dyes from aqueous solutions. These hydrophilic conetworks consist of chemically modified poly(ethylene glycol) (PEG-m) and multifunctional cellulose macromonomers ("cellu-mers"). Williamson etherification with 4-vinylbenzyl chloride (4-VBC) is used to modify PEGs of different molecular masses (1, 5, 6, and 10 kDa) and cellobiose, Sigmacell, or Technocell™ T-90 cellulose (products derived from natural renewable resources) with polymerizable/crosslinkable moieties. The networks are formed with good (75%) to excellent (96%) yields. They show good swelling and have good mechanical properties according to rheological tests. Scanning electron microscopy (SEM) reveals that cellulose fibers are visibly embedded into the inner hydrogel structure. The ability to bind and remove organic dyes, such as bromophenol blue (BPB), methylene blue (MB), and crystal violet (CV), from aqueous solutions hints at the potential of the new cellulosic hydrogels for environmental cleanup and clean water safeguarding. [ABSTRACT FROM AUTHOR]

This work establishes the design of a fully synthetic, shear-thinning hydrogel platform that is injectable and can isolate engineered, allogeneic cell therapies from the host. We utilized RAFT to generate a library of linear random copolymers of N,N-dimethylacrylamide (DMA) and 2-vinyl-4,4-dimethyl azlactone (VDMA) with variable mol% VDMA and degree of polymerization. Poly(DMA- co -VDMA) copolymers were subsequently modified with either adamantane (Ad) or β-cyclodextrin (Cd) through amine-reactive VDMA to prepare hydrogel precursor macromers containing complementary guest-host pairing pendant groups that, when mixed, form shear-thinning hydrogels. Rheometric evaluation of the hydrogel library enabled identification of lead macromer structures comprising 15 mol% pendants (Ad or Cd) and a degree of polymerization of 1000; mixing of these Ad and Cd functionalized precursors yielded hydrogels possessing storage modulus above 1000 Pa, tan(δ) values below 1 and high yield strain, which are target characteristics of robust but injectable shear-thinning gels. This modular system proved amenable to nanoparticle integration with surface-modified nanoparticles displaying Ad. The addition of the Ad-functionalized nanoparticles simultaneously improved mechanical properties of the hydrogels and enabled extended hydrogel retention of a model small molecule in vivo. In studies benchmarking against alginate, a material traditionally used for cell encapsulation, the lead hydrogel showed significantly less fibrous encapsulation in a subcutaneous implant site. Finally, this platform was utilized to encapsulate and extend in vivo longevity of inducible transgene-engineered mesenchymal stem cells in an allogeneic transplant model. The hydrogels remained intact and blocked infiltration by host cells, consequently extending the longevity of grafted cell function relative to a benchmark, shear-thinning hyaluronic acid-based gel. In sum, the new synthetic, shear-thinning hydrogel system presented here shows potential for further development as an injectable platform for delivery and in situ drug modulation of allograft and engineered cell therapies. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Polymerization kinetics of linear and branched Poly(HEA) via RDRP in aqueous solution were investigated. • Linear and branched Poly(HEA) coatings were prepared by SI-RDRP to membrane surfaces. • Branched Poly(HEA) brush coating showed more excellent antifouling performance. Fabrication of hydrophilic coatings on membrane surface is one of the best methods to solve membrane fouling caused by oil or other pollutants. Recently, branched macromonomer as cross-linker in polymerization are proved to favor the uniformity and stability of coatings. Herein, we synthesized a branched macromonomer poly(ethylene glycol dimethacrylate) (BP(EGDMA)), which had abundant vinyl groups via catalytic chain transfer polymerization (CCTP), for fabrication of zwitterionic hydrophilic coatings with low volume shrinkage on different surface through photopolymerization. The low molecular weight cross-linkers with different functionality were used as control groups. The results of polymerization on glass plate showed that the hydrophilic coatings cross-linked by BP(EGDMA) was more uniform and stable. The surface chemistry, wettability and permeability of membranes were further investigated. The results showed that coatings which used macromonomer BP(EGDMA) as cross-linker on porous membrane surface was still more uniform than those which used low molecular weight cross-linkers. Meanwhile, the effects of the irradiation time and monomer usage on membrane coatings were explored to choose the best fabrication condition. Under the suitable conditions, the membrane used BP(EGDMA) as cross-linker showed a high oil rejection of >99 % among several oil-in-water emulsion. Moreover, the anti-biofouling experiment revealed that the macromonomer BP(EGDMA) would endow hydrophilic coatings with better fouling resistance by longer irradiation time and larger total monomer usage. [ABSTRACT FROM AUTHOR]

The properties of polymer brushes based on three macromonomers were investigated in aqueous and organic solutions. Methacrylic monomers with different compositions of the oligo(oxyalkylene) substituents and arrangements of the oligo(ethylene glycol) and oligo(propylene glycol) blocks were used for the synthesis of polymers. There were methoxy [oligo(ethylene glycol)10.3-block-oligo(propylene glycol)4.7] methacrylate, methoxy [oligo(propylene glycol)8.3-block-oligo(ethylene glycol)6.6] methacrylate, and methoxy oligo(propylene glycol)4.2 methacrylate. Molecular brushes were investigated by the methods of molecular hydrodynamics and optics in dilute solutions in acetonitrile, chloroform, and water. The peculiarities of behavior of poly[oligo(oxyalkylene) methacrylates] in aqueous solutions and water-toluene systems have been found; in particular, the solubility of the polymers in water and organic solvents, the polymers equilibrium distribution between the phases, and the surface activity in the water-toluene system have been established. The thermo-responsibility in aqueous solutions and values of a critical concentration of micelle formation were shown. Depending on the arrangement of blocks in the side chains of molecular brushes, they are characterized by different intramolecular density. [ABSTRACT FROM AUTHOR]

Featured Application: Stimuli-responsive hydrogels encompassing biobased polymers are anticipated for utilization in various fields, starting from drug delivery systems through temporal actuators and water reservoirs to biodegradable microelements and nutrient delivery depots. This paper describes the results of the radiation-induced crosslinking of polysaccharides modified with hydroxypropyl and carboxymethyl functional groups, hydroxypropylcellulose (HPC) and carboxymethylcellulose (CMC), respectively, without and with poly(ethylene glycol) diacrylate (PEGDA) as a crosslinking agent, to obtain dual stimuli-responsive hydrogels. The gels were characterized in terms of water uptake and gel fraction, parameters that mainly depend on the HPC–CMC compositions, but also on the macromer crosslinker content and the absorbed dose. The swelling of hydrogels is controlled by both the temperature, due to the amphiphilic character of HPC and pH, due to the anionic functional groups of CMC. In spite of a similar degree of substitution in both cellulose derivatives, 1.4 for HPC and 1.2 for CMC, the pH response of hydrogels with an equal content of both polysaccharides is considerably higher—a reduction in swelling of up to 95% with a decrease in the pH to 2 was recorded—than the response to thermal-stimulus—wherein a reduction in swelling of less than 70% with an increasing in temperature to 55 °C was found. These biopolymers-based hydrogels of specific, stimuli-responsive swelling properties are anticipated in applications where a combination of two stimuli is essential and biodegradation may be required. [ABSTRACT FROM AUTHOR]

This study targets the synthesis of novel semi-interpenetrating networks and amphiphilic conetworks, where hydrophilic soft matter (Gellan Gum, GG) was combined with hydrophobic rigid poly(styrene), PSt. To achieve that, GG was chemically modified with 4-vinyl benzyl chloride to form a reactive macromonomer with multiple double bonds. These double bonds were used in a copolymerization with styrene to initially form semi-interpenetrating networks (SIPNs) where linear PSt was intertwined within the GG-PSt conetwork. The interpenetrating linear PSt and unreacted styrene were extracted over 3 consecutive days with yields 18–24%. After the extraction, the resulting conetworks (yields 76–82%) were able to swell both in organic and aqueous media. Thermo-mechanical tests (thermal gravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis) and rheology indicated that both SIPNs and conteworks had, in most cases, improved thermal and mechanical properties compared to pure poly(styrene) and pure GG gels. This crosslinking strategy proved that the reactive combination of a synthetic polymer and a bio-derived constituent would result in the formation of more sustainable materials with improved thermo-mechanical properties. The binding ability of the amphiphilic conetworks towards several organic dyes was high, showing that they could be used as potential materials in environmental clean-up. [ABSTRACT FROM AUTHOR]

Direct pacing of the mid myocardium where re-entry originates can be used to prevent ventricular arrhythmias and circumvent the need for painful defibrillation or cardiac ablation. However, there are no pacing electrodes small enough to navigate the coronary veins that cross these culprit scar regions. To address this need, we have developed an injectable ionically conductive hydrogel electrode that can fill the epicardial coronary veins and transform them into flexible electrodes. A new hydrogel chemistry based on a polyether urethane diacrylamide macromer was developed that matches myocardial stiffness and is resistant to hydrolysis. Conductivity was imparted using ionic precursor solutions with values in the range of 2-3X of native myocardium that was retained after implantation. Ionic hydrogel electrodes provided stable electrical stimuli over many cycles and across a substantial length of the cardiac vein. Rapid in situ cure was achieved with redox initiation after injection from a double-barrel syringe with a mixing head. An ex vivo porcine model was used to identify the requisite viscosity and cure rate for hydrogel retention and homogeneity. Finally, successful in vivo deployment and pacing in a porcine model demonstrated that the ionic hydrogel electrode filled the anterior interventricular vein to depths far more distal and refined than current technologies. Collectively, these studies demonstrate the potential of this injectable ionic hydrogel electrode to pace previously inaccessible mid-myocardial tissue and pave the pathway for painless defibrillation. An injectable ionic hydrogel electrode is used to convert cardiac veins to flexible electrodes to provide a new pacing modality to prevent ventricular arrhythmias. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • lignin-based macromonomer (LATU) prepared via grafting allylthiourea. • Vinylacetate and LATU were used to prepare Poly(VAc-Co-LTUA) copolymer. • Poly(VAc-Co-LTUA) copolymer was hydrolized (saponification) to produce lignified PVA. • Poly(VA-co-LATU) outperformed pure PVA in UV-blocking and water solubility properties. The increasing environmental concerns have heightened the pursuit of sustainable materials, with a particular emphasis on biodegradable polymers. Polyvinyl alcohol (PVA), a recognized biodegradable synthetic polymer, faces challenges such as cost, slow biodegradation, and limited UV resistance. This study explores lignin, an abundant and eco-friendly biopolymer, as a cost-effective additive to enhance PVA properties via the copolymerization technique. The Mannich reaction was utilized to effectively alkylate lignin with allylthiourea, leading to the synthesis of a lignin-based macromonomer (LATU). Subsequently, the LATU macromonomer was copolymerized with vinyl acetate, producing Poly(VAc-Co-LATU) copolymer in a reaction conducted at 70 °C for 6 h. Finally, the copolymers were hydrolyzed (saponification) with potassium hydroxide to obtain Poly(VA-Co-LATU) copolymers. Extensive investigations, including FTIR, XPS, XRD, and 1H NMR, effectively validated the synthesis of the copolymers. The high monomer conversion rate above 89 % emphasizes the effectiveness of the synthesis method. The addition of LATU has a direct impact on the crystalline structure of the copolymer. X-ray diffraction patterns indicate a reduction in crystallinity, which in turn affects the other properties of the synthesized copolymers. Consequently, the lignified copolymer, Poly(VA-co-LATU), exhibited slight decrease in molecular weight (Mw), improved UV-blocking effectiveness, and greater solubility in water as comparison to PVA. This study demonstrates the feasibility of using lignin as a monomer to create novel bio-based polymeric materials that exhibit the necessary properties for certain applications. [ABSTRACT FROM AUTHOR]

Self-healing materials and self-healing mechanisms are two topics that have attracted huge scientific interest in recent decades. Macromolecular chemistry can provide appropriately tailored functional polymers with desired healing properties. Herein, we report the incorporation of glycidyl methacrylate-based (GMA) copolymers in waterborne polyurethanes (WPUs) and the study of their potential healing ability. Two types of copolymers were synthesized, namely the hydrophobic P(BA-co-GMAy) copolymers of GMA with n-butyl acrylate (BA) and the amphiphilic copolymers P(PEGMA-co-GMAy) of GMA with a poly(ethylene glycol) methyl ether methacrylate (PEGMA) macromonomer. We demonstrate that the blending of these types of copolymers with two WPUs leads to homogenous composites. While the addition of P(BA-co-GMAy) in the WPUs leads to amorphous materials, the addition of P(PEGMA-co-GMAy) copolymers leads to hybrid composite systems varying from amorphous to semi-crystalline, depending on copolymer or blend composition. The healing efficiency of these copolymers was explored upon application of two external triggers (addition of water or heating). Promising healing results were exhibited by the final composites when water was used as a healing trigger. [ABSTRACT FROM AUTHOR]

Single-network hydrogels can have an internal porous structure and biocompatibility, but have lower mechanical properties. Combining these properties with another biocompatible and mechanically strong network can help in mimicking the extracellular matrix of native tissues to make them suitable for tissue scaffolds with desired performance. In the current objective, we combine the properties of poly (ethylene glycol) dimethacrylate (PEGDMA) macromer and polysaccharides as the two components in double networks (DN) for synergistic effects of both components resulting in the interpenetrating polymeric network for making it functional for replacement of injured tissues. The hydrogels were characterized by physical properties like swelling ratio, mechanical properties like tensile and compressive modulus, and rheological behavior. The chemical composition was studied using Fourier transform infrared spectroscopy (FTIR), and the thermal behavior using differential scanning calorimetry (DSC) experiments. Biodegradability and mechanical strength both are gained using double networks (DN), thus making it resemble more like living tissues. DN hydrogels were tested for cell compatibility for possible application in tissue engineering. Furthermore, these properties may allow their application as tissue-engineered scaffolds. [ABSTRACT FROM AUTHOR]

In recent years, polymer-based advanced drug delivery and tissue engineering have grown and expanded steadily. At present, most of the polymeric research has focused on improving existing polymers or developing new biomaterials with tunable properties. Polymers with free functional groups offer the diverse characteristics needed for optimal tissue regeneration and controlled drug delivery. Allyl-terminated polymers, characterized by the presence of a double bond, are a unique class of polymers. These polymers allow the insertion of a broad diversity of architectures and functionalities via different chemical reactions. In this review article, we shed light on various synthesis methodologies utilized for generating allyl-terminated polymers, macromonomers, and polymer precursors, as well as their post-synthesis modifications. In addition, the biomedical applications of these polymers reported in the literature, such as targeted and controlled drug delivery, improvement i aqueous solubility and stability of drugs, tissue engineering, and antimicrobial coatings, are summarized. [ABSTRACT FROM AUTHOR]

Hydrogels with dynamically tunable crosslinking are invaluable for directing stem cell fate and mimicking a stiffening matrix during fibrosis or tumor development. The increases in matrix stiffness during tissue development are often accompanied by the accumulation of extracellular matrices (e.g., collagen, hyaluronic acid (HA)), a phenomenon that has received little attention in the development of dynamic hydrogels. In this contribution, we present a gelatin-based cell-laden hydrogel system capable of being dynamically stiffened while accumulating HA, a key glycosaminoglycans (GAG) increasingly deposited by stromal cells during tumor progression. Central to this strategy is the synthesis of a dually-modified gelatin macromer – gelatin-norbornene-carbohydrazide (GelNB-CH), which is susceptible to both thiol-norbornene photopolymerization and hydrazone click chemistry. We demonstrate that the crosslinking density of cell-laden thiol-norbornene hydrogels can be dynamically tuned via simple incubation with aldehyde-bearing macromers (e.g., oxidized dextran (oDex) or oHA). The GelNB-CH hydrogel system is highly cytocompatible, as demonstrated by in situ encapsulation of pancreatic cancer cells (PCC) and cancer-associated fibroblasts (CAF). This unique dynamic stiffening scheme provides a platform to study tandem accumulation of HA and elevation in matrix stiffness in the pancreatic tumor microenvironment. Hydrogels permitting on-demand and secondary crosslinking are ideal for mimicking a stiffening tumor microenvironment (TME). However, none of the current dynamic hydrogels account for both stiffening and accumulation of hyaluronic acid (HA), a major extracellular matrix component increasingly deposited in tumor stromal tissues, including pancreatic ductal adenocarcinoma (PDAC). The current work addresses this gap by developing a dynamic hydrogel system capable of simultaneously increasing stiffness and HA accumulation. This is achieved by a new gelatin macromer permitting sequential thiol-norbornene (for primary network crosslinking) and hydrazone click chemistry (for bioinert or biomimetic stiffening with oxidized dextran (oDex) or oHA, respectively). The results of this study provide new insights into how dynamically changing physicochemical matrix properties guide cancer cell fate processes. [Display omitted] [ABSTRACT FROM AUTHOR]

A desire to develop biorenewable materials has led to lactide-caprolactone copolymers being used in adhesive, medical, and pharmaceutical products. Use of this alternative material may diminish human impact on the environment and create products that are biocompatible. One advantage of these materials compared with other typical petroleum-based polymers is that they are easily degraded by microorganisms. In this study, the biodegradation of representative lactide-caprolactone macromonomers and an acrylic pressure sensitive adhesive incorporating these macromonomers was followed by a respirometric method using a consortium of microorganisms found in a typical wastewater treatment facility. The weight loss data of lactide-caprolactone macromonomers showed that the lowest molecular weight macromonomers with a high percentage of lactide had the greatest weight loss, which could have been caused by the greater number of ester linkages. Proton nuclear magnetic resonance data showed that for lower molecular weight copolymers, there was a preferential loss of caprolactone. Promisingly, testing of the full acrylic adhesives showed that they were easily degraded and thus provided a route to more environmentally friendly adhesive products. [ABSTRACT FROM AUTHOR]

The chemistry of poly(2-oxazoline) has resurfaced in the last two decades due to their easy synthesis, as well as the ability to modulate their chemical structure and properties. Furthermore, poly(2-oxazoline)s are biocompatible and many have thermoresponsive properties. 2-Oxazoline macromonomers are usually used as a starting material to perform the synthesis of graft copolymers, star copolymers and also dendrimers. But also macromonomers can be introduced in the synthesis of materials with more complex structures as hydrogels or nanogeles. For this reason, this manuscript describes fundamental and important chemical aspects about the polymerization and preparation of macromonomers by the initiator and terminator method of the living polymerization of 2-oxazoline. The importance of the initiator, terminator as well as the substituent on 2-oxazoline is discussed. [ABSTRACT FROM AUTHOR]

Three azido-terminated poly(ethylene glycol) macromonomers (ATPEGs) were synthesized from poly(ethylene glycol)s (PEGs) and characterized. The extended polytriazole (EPTA) resins were prepared from the macromonomers, azide and alkyne monomers. Toughening effect of PEGs on polytriazole resins was analyzed by means of mechanical, thermal and electronic microscope characterization. The results show that molecular weight and content of ATPEGs have great influence on the thermal and mechanical properties of cured EPTA resins. The impact strength of cured EPTA resins increases with the increase of the amount and molecular weight of ATPEGs. The flexural strength and heat resistance of cured EPTA resins decrease with the increase of addition amount and molecular weight of ATPEGs. High impact EPTA resins were obtained. [ABSTRACT FROM AUTHOR]

[Display omitted] • Scalable synthesis of photoactivatable poly(2-oxazoline) macromonomers. • Poly(2-oxazoline) is a novel polymer for anti-fouling hydrogel membrane coatings. • Bottle brush hydrogel architecture controls swelling and permeance. • Pore coated ultrafiltration membrane shows permeances of > 100 kg m−2 h−1 bar−1. In recent years, hydrophilic poly(2-oxazoline)s have been examined as an alternative polymer to poly(ethylene glycol) (PEG) with added stability and chemical versatility. They show excellent anti-fouling properties and, like PEG, are of interest in many fields where bio-inertness or anti-adhesiveness are important such as for medical devices, tissue engineering, biosensors, or drug delivery carriers. Surprisingly few studies have utilized this polymer class for the preparation of anti-fouling membranes. Here we describe a new termination reaction of the living cationic ring-opening polymerization of 2-oxazolines in which a benzophenone group is introduced as a photoactivatable terminal head group of poly(2-oxazoline)s. Using 4-vinylbenzyl chloride as initiator, heterotelechelic poly(2-methyl-2-oxazoline) (PMOXA) macromonomers were synthesized and copolymerized with hydroxyl-functional PMOXA macromonomers to yield photoactivatable PMOXA-based prepolymer bottle brushes. Likewise, star-PMOXAs were synthesized by using a trifunctional initiator. Photoactivatable PMOXA prepolymers allowed us to readily form anti-fouling hydrogels by a simple and versatile CH-insertion cross-linking (CHic) process. Hydrogels were applied to poly(ether sulfone) ultrafiltration membranes as pore coating and the pure water permeance (PWP) was investigated as a function of hydrogel architecture and cross-link density. Anti-fouling hydrogel pore-coated membranes having PWPs on the order of hundred kg·m−2·h−1·bar−1 were obtained. [ABSTRACT FROM AUTHOR]

2-oxazoline based polymers are attracting more and more attention in the last decade owing to their unique properties not only in biomedical applications but also in lubrication. Their combination with widely used polymers that are usually synthesized via controlled/"living" polymerisation techniques allows the design of novel polymer architectures and further increases the range of properties accessible from poly(2-oxazoline) based materials. However, there are several synthetic challenges to achieve a successful combination of these polymers and various techniques, such as click reactions, macromonomers, and heterobifunctional initiators have been reported in the literature to overcome these challenges. In this review, various synthetic methods to combine poly(2-oxazoline)s with vinyl based polymers have been discussed including the pros and cons of each method. [ABSTRACT FROM AUTHOR]

• A novel octene-terminated PDMS macromonomer is synthesized with good yield. • The first study on the efficient preparation of PE-g-PDMS by direct copolymerization. • The effect of PDMS content on copolymer microstructure is studied. • Small addition of PE-g-PDMS into HDPE can improve the melting flow property. This paper discusses the synthesis of polyethylene-g-polydimethylsiloxane (PE-g-PDMS) graft copolymers through a facile macromonomer approach. A novel octene-terminated PDMS macromonomer was synthesized via anionic ring-opening polymerization of hexamethylcyclortrisiloxane and the subsequent chain-end capping with dimethyl(oct-7-enyl)chlorosilane. A systematic investigation was conducted on the VCl 3 (THF) 3 /Et 2 AlCl-catalyzed copolymerizations of the PDMS macromonomer with ethylene by varying the macromonomer feed. The relatively high activity of 11.6 kg/(mmol V ·h) was observed even at a rather high macromonomer feed of 160 mmol/L, which is first reported and of great significance in the efficient fabrication of polyethylene-g-polysiloxane graft copolymers. The resulting PE-g-PDMS copolymers were characterized to determine the chain structure, molecular weight and molecular weight distribution. The highest macromonomer incorporation (3.77 mol%) was achieved at the highest macromonomer feed with a decreased molecular weight and a narrower molecular weight distribution. DSC analysis revealed that melting temperature and crystallinity of PE-g-PDMS copolymers systematically decreased with increasing of the PDMS macromonomer incorporation. When quite a small amount (2 wt%) of PE-g-PDMS copolymers was added to HDPE via melt blending, the melt flow rate of HDPE increased by 32% and the mechanical properties remained almost unchanged. [ABSTRACT FROM AUTHOR]

Hydrogels have been widely used as the carrier material of therapeutic cell and drugs for articular cartilage repair. We previously demonstrated a unique host-guest macromer (HGM) approach to prepare mechanically resilient, self-healing and injectable supramolecular gelatin hydrogels free of chemical crosslinking. In this work, we show that compared with conventional hydrogels our supramolecular gelatin hydrogels mediate more sustained release of small molecular (kartogenin) and proteinaceous (TGF-β1) chondrogenic agents, leading to enhanced chondrogenesis of the encapsulated human bone marrow-derived mesenchymal stem cells (hBMSCs) in vitro and in vivo. More importantly, the supramolecular nature of our hydrogels allows injection of the pre-fabricated hydrogels containing the encapsulated hBMSCs and chondrogenic agents, and our data show that the injection process has little negative impact on the viability and chondrogenesis of the encapsulated cells and subsequent neocartilage development. Furthermore, the stem cell-laden supramolecular hydrogels administered via injection through a needle effectively promote the regeneration of both hyaline cartilage and subchondral bone in the rat osteochondral defect model. These results demonstrate that our supramolecular HGM hydrogels are promising delivery biomaterials of therapeutic agents and cells for cartilage repair via minimally invasive procedures. This unique capability of injecting cell-laden hydrogels to target sites will greatly facilitate stem cell therapies. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Synthesis of AB x polysiloxane macromonomers via anionic ring opening copolymerization. • Control over molar mass and degree of functionality via monomer feed ratio and end-functionalization. • Complex branched architecture achieved via Pt(0) catalyzed hydrosilylation coupling reaction. Abstract This work focuses on the synthesis of polysiloxane AB x macromonomers with functional groups (A [Si-H] and B [vinyl]) incorporated on to the polymer backbone, and the coupling of these functionalities to form randomly, but highly, branched polymers. The synthesis of the AB x macromonomers was performed by the anionic copolymerization of hexamethylcyclotrisiloxane (D 3) and 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane (V 3) monomers, followed by an end-capping/termination reaction with chloro(methyl)phenylsilane. The resulting macromonomers were coupled by a Pt(0) catalyzed hydrosilylation reaction, to yield highly branched polysiloxanes. The coupling reaction was investigated at different solution concentrations and using macromonomers with different extents of vinyl content. It was shown that a higher solution concentration resulted in higher degrees of chain coupling and branching, arising from efficient intermolecular coupling in preference to (the competing) intramolecular coupling (cyclization) reaction. Moreover, an increase in the mole fraction of vinyl monomer also resulted in higher levels of branching. With the ability to control the degree of branching, the strategy reported here provides a facile route to synthesize branched polysiloxanes (silicones) with varying flexibility and elasticity. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Isoprene‐terminated polybutadiene macromonomers synthesized in high yield. • Well‐behaved anionic copolymerization accomplished with 1,4‐butadiene. • High cis ‐1,4‐microstructure content maintained in the backbone and the side chains. Abstract Polybutadiene macromonomers with a high 1,4-microstructure content and a polymerizable isoprene end group were synthesized by termination of living polybutadienyllithium chains. While different isoprene derivatives were investigated as terminating agents for the preparation of the macromonomers, 2-bromomethyl-1,3-butadiene provided the best results. The termination reaction was optimized in terms of solvent composition, reaction temperature and reactivity-modifying additives used. The addition of 10 eq of terminating agent in equal volumes of hexane and tetrahydrofuran at −110 °C provided the macromonomer in 95% yield. Anionic copolymerization of the macromonomer with 1,3-butadiene in hexane yielded branched polybutadiene with a narrow molecular weight distribution (M w /M n = 1.07), but seeded initiation was necessary to avoid side reactions leading to multimodal molecular weight distributions. [ABSTRACT FROM AUTHOR]

In this work, we synthesized end group functionalization of the cis-Norbornene-5-6-endo-dicarboxylic anhydride species via the ring-opening metathesis polymerization (ROMP) of oxanorbornene derivatives generated a chiseled poly(cis-Norbornene-5-6-endo-Dicarboxylic anhydride) acrylate macromonomer. Further, acrylate oxanorbornene based macromonomer further polymerized via reversible addition fragmentation chain transfer (RAFT) polymerization technique. Chain transfer is exhibited in the structure during the radical polymerizations so that free radical polymerization could also be used to comb structure copolymers with a PDI value below 1.2 with the help of acrylate oxanorbornene. Atomic force microscopy reveals the comb shape of branched polymer brushes structure. This method involves polymerizable end-group attachment to a macromonomer, and the backbone of the comb polymer is created in a second step of the polymerization. We believe that this kind of comb structured polymers can be considered for different biological applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A new renewable monomer, 10,11-dihydroxyundecanoic acid, is described. • Hyperbranched hydroxypolyesters were obtained by self-polycondensation using CALB. • Amphiphilic copolyesters with methoxypolyethylenglycol were prepared. • mPEG carboxylic acid derivatives were grafted onto the hydroxypolyesters. • Self-assembly of amphiphilic polyesters form multimolecular micelles of 100–300 nm. Abstract The synthesis of a partially renewable hydroxyl hyperbranched polyester: poly(10,11-dihydroxyundecanoic acid) (PDHU), by polycondensation using CALB as catalyst, has been described. The synthesized polymers were structurally characterized in detail, using model compounds previously synthesized, by 1H, 13C and 19F NMR. The synthesis of amphiphilic copolymers by incorporation of mPEG moieties and utilizing CALB, was carried using two methods: by copolymerization of mPEG-OH and 10,11-dihydroxyundecanoic to produce block hyperbranched copolymers, and grafting onto hydroxyl groups of linear and hyperbranched PDHU, mPEG containing carboxylic acid. The microstructure of block and grafted copolymers was determined in detail by NMR spectroscopy by using models and 1H-13C heteronuclear bidimensional correlations. The self-assembly of these amphiphilic polyesters form well-defined multimolecular micelles ranging 100–300 nm in very diluted aqueous solutions, showing potential application in drug delivery among other applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • First PBAE (cryo)gels with phosphonate functionalization and redox-responsiveness. • Degradation profile tailorable hours to months. • Degradation-tailoring by selection of macromer structure and gelation method. • Degradation products biocompatible (NIH 3T3, Saos-2) Abstract Poly(β-amino ester) networks have gained attention as a class of degradable polymers for biomedical applications, particularly as scaffolds for tissue engineering. In this work, two novel phosphonated diamines (one containing a redox-responsive disulfide group) are reacted with diacrylates via aza-Michael addition reaction to form acrylate terminated poly(β-amino ester)s which are subsequently used as macromolecular precursors for fabrication of degradable gels and cryogels. The degradation rates of the gels and cryogels are monitored in phosphate buffer saline (PBS) and dithiothreitol (DTT), and the degradation times are found to range from hours to months depending on the design of chemical structure. The in vitro cytotoxicities of the degradation products are assessed with mouse embryonic fibroblast cells (NIH 3T3) and human osteosarcoma cells (Saos-2). The tailorability of the degradation rates and the non-toxicity of the degradation products make these poly(β-amino ester) gels and cryogels good candidates as scaffolds for tissue engineering applications. [ABSTRACT FROM AUTHOR]

Dispersion copolymerization of styrene (St) with either acrylonitrile (AN) or methyl methacrylate (MMA) in 1-propanol/deionized water medium were carried out using Bisomer S20W (polyethylene oxide macromonomer with a methacrylic end group) as stabilizer. The serums of the St/AN and St/MMA latexes were characterized in terms of molar mass and composition by the combination of Size Exclusion Chromatography (SEC) and Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS). This work demonstrates that the combination of SEC and MALDI techniques is necessary for an accurate identification of the composition and molar mass of the oligomeric species present in the continuous phase of a dispersion polymerization that cannot be achieved by using either SEC or MALDI alone. For the particular latexes analyzed in this work it was found that unreacted macromonomer was present in both copolymer systems. However, in the case of the copolymerization with AN besides the presence of the macromonomer there were also some pAN oligomers. [ABSTRACT FROM AUTHOR]

A novel electroactive macromonomer based on poly( l -lactic acid) (PLLA) with (3,4-ethylenedioxythiophene) (EDOT) functional end groups, was prepared by a traditional approach of organometallic polymerization with stannous octanoate [Sn(oct 2 )] and enzymatic polymerization using immobilized Candida antarctica Lipase B (CAL-B) and Amano lipase Pseudomonas cepacia (PS-IM), as catalysts. In the synthetic strategy, (2,3-dihydrothieno[3,4-b] dioxin-2-yl)methanol (EDOT-OH) was used to initiate the ring opening polymerization of lactide to yield PLLA with EDOT end group. All macromonomers (EDOT-PLLA) were characterized by 1 H and 13 C RMN, MALDI-TOF, GPC and EDX. Moreover, ICP-OES analysis showed the presence of Sn traces in the material synthesized by the traditional approach, but that pathway led to macromonomers with higher molecular weight while the enzymatic route led to completely metal-free macromonomers with medium and lower molecular weights. Also, electrochemical and chemical polymerization of EDOT-PLLA were tested showing that it is possible to prepare degradable conducting polymers based on poly(3,4-ethylenedioxythiphene) (PEDOT). The biocatalytic synthesis is a very promising and environmental friendly pathway for the preparation of biodegradable materials for short time applications. [ABSTRACT FROM AUTHOR]

Poly(ethylene glycol) (PEG) can be functionalized and modified with various moieties allowing for a multitude of cross-linking chemistries. Here, we investigate how vinyl sulfone, acrylate, and maleimide functional end groups affect hydrogel formation, physical properties, viability of encapsulated cells, post-polymerization modification, and inflammatory response of the host. We have shown that PEG-VS hydrogels, in the presence of a co-monomer, N -vinyl-2-pyrrolidone (NVP), form more efficiently than PEG-Ac and PEG-Mal hydrogels, resulting in superior physical properties after 6 min of ultraviolet light exposure. PEG-VS hydrogels exhibited hydrolytic stability and non-fouling characteristics, as well as the ability to be modified with biological motifs, such as RGD, after polymerization. Additionally, unmodified PEG-VS hydrogels resulted in lesser inflammatory response, cellular infiltration, and macrophage recruitment after implantation for 28 days in mice. These findings show that altering the end group chemistry of PEG macromer impacts characteristics of the photo-polymerized network. We have developed a tunable non-degradable PEG system that is conducive for cell or tissue encapsulation and evokes a minimal inflammatory response, which could be utilized for future immunoisolation applications. Statement of Significance The objective of this study was to develop a tunable non-degradable PEG system that is conducive for encapsulation and evokes a minimal inflammatory response, which could be utilized for immunoisolation applications. This study has demonstrated that reactive functional groups of the PEG macromers impact free radical mediated network formation. Here, we show PEG-VS hydrogels meet the design criteria for an immunoisolating device as PEG-VS hydrogels form efficiently via photo-polymerization, impacting bulk properties, was stable in physiological conditions, and elicited a minimal inflammatory response. Further, NVP can be added to the precursor solution to expedite the cross-linking process without impacting cellular response upon encapsulation. These findings present an additional approach/chemistry to encapsulate cells or tissue for immunoisolation applications. [ABSTRACT FROM AUTHOR]

The development of new peroxide-curable poly(isobutylene-co-isoprene) (IIR) elastomers is described, wherein pendant oligomerizable C=C groups are introduced in combination with a range of serviceable functional groups. Ring-opening of itaconic anhydride with functional alcohols or amines, followed by esterification of the resulting acids with brominated IIR, yield macromonomers that crosslink efficiently under the action of dicumyl peroxide alone. More importantly, the additional graft functionality improves the physical and chemical properties of the resulting thermosets. The introduction of fluorocarbon functionality is shown to lower surface energy and improve the material's extrusion characteristics, and trialkoxysilane functionality is used to improve filler dispersion within silica-reinforced composites. This strategy is extended to prepare thermosets bearing polymer-bound phenolic antioxidant. Details of macromonomer production are followed by demonstrations of their utility as engineering materials. [ABSTRACT FROM AUTHOR]

Polyphenylene ether (PPE) telechelic macromonomers are unique hydrophobic polyols which have been used to prepare amphiphilic block copolymers. Various polymer compositions have been synthesized with hydrophilic blocks. Their macromolecular nature affords a range of structures including random, alternating, and di- and triblock copolymers. New macromolecular architectures can offer tailored property profiles for optimum performance. Besides reducing moisture uptake and making the polymer surface more hydrophobic, the PPE hydrophobic segment has good compatibility with polystyrene (polystyrene-philic). In general, the PPE contributes to the toughness, strength, and thermal performance. Hydrophilic segments go beyond their affinity for water. Improvements in the interfacial adhesion between polymers and polar substrates via hydrogen bonding and good compatibility with polyesters (polyester-philic) have been exhibited. The heterogeneity of domains in these PPE based block copolymer offers important contributions to diverse applications. [ABSTRACT FROM AUTHOR]

A synthetic method that taps into the facile Lewis base (LB)→Lewis acid (LA) adduct forming reaction between the semiconducting polymeric LB and all carbon LA C60 for the construction of covalently linked donor-acceptor dyads and brush polymer of dyads is reported. The polymeric LB is built on poly(3-hexylthiophene) (P3HT) macromers containing either an alkyl or vinyl imidazolium end group that can be readily converted into the N-heterocyclic carbene (NHC) LB site, while the brush polymer architecture is conveniently constructed via radical polymerization of the macromer P3HT with the vinyl imidazolium chain end. Simply mixing of such donor polymeric LB with C60 rapidly creates linked P3HT-C60 dyads and brush polymer of dyads in which C60 is covalently linked to the NHC junction connecting the vinyl polymer main chain and the brush P3HT side chains. Thermal behaviors, electronic absorption and emission properties of the resulting P3HT-C60 dyads and brush polymer of dyads have been investigated. The results show that a change of the topology of the P3HT-C60 dyad from linear to brush architecture enhances the crystallinity and Tm of the P3HT domain and, along with other findings, they indicate that the brush polymer architecture of donor-acceptor domains provides a promising approach to improve performances of polymer-based solar cells. [ABSTRACT FROM AUTHOR]

Branched polymers are a valuable class of polymeric materials. In the present study, anionic polymerization techniques were employed for the synthesis of low molecular weight poly(ethylene oxide) (PEO) macromonomers bearing norbornenyl end groups. The macromonomers were characterized by SEC, MALDI-TOF and NMR spectroscopy. Subsequent ring opening metathesis polymerization (ROMP) of the macromonomers using ruthenium catalysts (Grubbs catalysts of the 1st, 2nd and 3rd generations) afforded the corresponding polymacromonomers. The effects of the macromonomer molecular weight, the type of the catalyst, the nature of the solvent, the monomer concentration and the polymerization temperature on the molecular characteristics of the branched polymers were examined in detail. The crystallization behavior of the macromonomers and the corresponding polymacromonomers were studied by Differential Scanning Calorimetry (DSC). The thermal stability and the kinetics of the thermal decomposition of the samples were also studied by Thermogravimetric Analysis (TGA). The activation energies of the thermal decomposition were analyzed using the Ozawa-Flynn-Wall and Kissinger methodologies. [ABSTRACT FROM AUTHOR]

An in situ nuclear magnetic resonance spectroscopy (NMR) technique is used to monitor the aqueous-phase copolymerization kinetics of methacrylic acid (MAA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) macromonomers. In particular, the study analyses the effect of the number of ethylene glycol (EG) groups along the lateral chains of PEGMA and is carried out under fully ionized conditions of MAA at different initial monomer ratios and initial overall monomer concentrations (5-20 wt % in aqueous solution). The composition drift with conversion indicates that PEGMA macromonomer is more reactive than MAA. Individual monomer consumption rates show that the rates of consumption of both monomers are not first order with respect to overall concentration of the monomer. The reactivity ratios estimated from the copolymerization kinetics reveal, that for the short PEGMA, the reactivity ratios rMAA and rPEGMA increase with the solids content (SC). A totally different trend is obtained for the longer PEGMA, whose reactivity ratio (rPEGMA23) decreases with solids content, whereas the reactivity ratio of MAA remains roughly constant. [ABSTRACT FROM AUTHOR]

[Display omitted] • Several water-soluble photo-initiators (PI) for two-photon polymerization (2PP) based on cyclopentanone with a D-π-A-□π-D structure have been investigated. • PIs equipped with poly(2-ethyl-2-oxazoline) chains reveal good water solubility and successfully initiate polymerization under 2PP conditions. • Bisacrylate funcational poly(2-ethyl-2-oxazoline) macromonomers were directly polymerized by 2PP to compare fabrication window (FW) of each PI. Hydrogels, mostly known for their use in biomedical applications, are of particular interest in recent research fields. Beside their usage in biomedical applications, 3D-structured hydrogels possess properties which are interesting for other fields of research like the fabrication of lenses, sensors or electronics. Two-photon polymerization (2PP) emerged as a suitable technique to process hydrogels, due to its high spatio-temporal resolution. In order to obtain precise 3D structues via 2PP from aqueous solutions, efficient water-soluble two-photon photo-initiators (2PIs) are required. In this contribution, several 2PIs based on benzylidene cyclopentanone structures bearing carboxyl or amino groups were synthesized via aldol condensation. These 2PIs were converted into sodium carboxylate or ammonium chloride salts to increase water solubility. Also, 2PIs equipped with oligo(2-ethyl-2-oxazoline) chains to enhance water solubility were investigated concerning their suitability for two-photon polymerization. Z-scan measurements of the synthesized 2PIs revealed two-photon cross-sections of 80 to 253 GM at a wavelength of 800 nm in water. Cytotoxicity tests showed that six of the initiators featured low or no cytotoxicity up to a concentration of 1 mg mL−1. Five out of the nine tested 2PIs revealed good initiation efficiencies at a concentration of 0.5 wt% in aqueous formulations containing 50 wt% of poly(2-ethyl-2-oxazoline) diacrylate (PEtOx-DA, DP = 10), showing broad fabrication windows at a writing speed of up to 10 mm s−1. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new tandem dual catalytic system for the formation of long branches is introduced. • Regenerative chain transfer polymerization is combined with chain displacement reaction. • Macromers are released upon displacement of dormant chains with ethylene. • Macromer reincorporation results in formation of long chain branches (LCBs) • LCB formation has a profound effect on microstructure and rheology of polymers. • The displacement reaction pathways are analyzed by DFT simulation. The controlled introduction of long chain branches (LCBs) in the commonly linear structure of polyolefins has been frequently pursued by researchers to improve their melt processability. To account for that, we introduce a new tandem dual catalytic system for the formation of LCB in ethylene polymerization. Coordinative chain transfer polymerization in the first step produces Al-alkyls via frequent transfer of growing polymer chains from the single-site α-diimine nickel polymerization catalyst to AlEt 2 Cl chain transfer agent (CTA). Next, the displacement catalyst, Ni(acac) 2 , converts the dormant alkyl chains into macromers through a β-hydride elimination and retrieves the Al-based CTA. Due to the high comonomer affinity of the polymerization catalyst, the released macromers are incorporated in growing polymer chains. By repeating this reaction cycles, a branch-on-branch structure is formed. Interestingly, a separate cocatalyst is not required, as AlEt 2 Cl serves as both the cocatalyst and the CTA for the CCTP system. This reaction scheme employs the "nickel-effect" mechanism for the formation of LCB in coordinative polymerization for the first time. The efficiency of the proposed mechanism in the formation of LCBs is confirmed by comprehensive rheological studies and NMR spectroscopy. Moreover, density functional theory (DFT) simulations rationalize the formation of LCBs through the proposed Ni-based displacement reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • The combination of CROP and RAFT polymerization was applied to synthesize graft copolymers presenting oligosiloxane and oligoalkyloxazoline side chains with fully tunable composition. • Poly(oxazoline)-based graft copolymers were applied to fabricate PDMS-based antifouling coatings. • Graft copolymers featuring oligoalkyloxazoline side chains emerged as valid alternatives to PEG-based derivatives as surface-active additives to fabricate antibiofouling coatings. • Graft copolymers including oligoalkyloxazoline grafts proved more efficient than their PEG-containing counterparts in inhibiting the settlement and promoting the removal of marine macrofoulers. Poly(ethylene glycol) (PEG)-based graft copolymers have been widely applied for the modification of poly(dimethyl siloxane) (PDMS)-based coatings that resist marine biofouling. In this research, we synthesized oligo(2-alkyl-2-oxazoline) (OAOXA)-based graft copolymer analogues, and subsequently tested their applicability in the formulation of structurally similar coatings, aiming to highlight the influence of polymer composition on biopassive properties. In particular, poly(dimethyl siloxane methacrylate)- co -oligo(2-alkyl-2-oxazoline)methacrylate copolymers were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization, starting from oligo(2-ethyl-2-oxazoline)- and oligo(2-methyl-2-oxazoline)-methacrylate macromonomers (OEOXMA and OMOXMA, respectively). Amphiphilic copolymer films with OAOXA grafts were found to be more hydrophilic with respect to those obtained using PEG analogues. PDMS coatings containing the graft copolymers as surface additives were tested towards the settlement of the macrofouler Ficopomatus enigmaticus and the diatom Navicula salinicola. The biofouling experiments indicated that OAOXA-containing films showed a comparable and in some cases improved performance with respect to their PEG-based counterparts, thus highlighting how OAOXA-based graft copolymers represent a valid alternative to PEG derivatives as surface-active additives to design antibiofouling coatings. [ABSTRACT FROM AUTHOR]

[Display omitted] A general method for the arm-first synthesis of star polymers through a formal A 2 + B 3 step-growth process is introduced. The synthesis relies on copper-catalyzed azide-alkyne cycloaddition (CuAAC) of N 3 -C(CR 2)C-N 3 macromonomers with a trifunctional alkyne crosslinker, and is enabled by the special mode of reactivity of 1,3-diazides in CuAAC. A variety of synthetic conditions were systematically evaluated, and effects of macromonomer size and feed ratio on the product structures have been investigated. Due to functional group tolerance of CuAAC, the presented methodology has a broad scope and can be extended to other macromonomers. [ABSTRACT FROM AUTHOR]

A UV-curable poly(butyl fumarate) (PBF)/poly(propylene fumarate)-diacrylate (PPF-DA) hybrid material with good performance for LED encapsulation is introduced in the paper. They have been prepared by radical polymerization using PBF and PPF-DA macromers with a UV curing system. PBF and PPF-DA were characterized by Fourier-transform infrared (FT-IR) and H-nuclear magnetic resonance (1H NMR). The thermal behavior, optical and mechanical properties of the material were examined by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), ultraviolet-visible spectroscopy (UV-vis), and a material testing system mechanical testing machine, respectively. The results indicated that the hybrid material has a suitable refractive index (n = 1.537) and high transmittance (99.64% in visible range) before/after thermal aging. With the increasing of the double bond ratio from 0.5 to 2, the water absorption ratios of the prepared encapsulation material were 1.22%, 1.87% and 2.88%, respectively. The mechanical property experiments showed that bonding strength was in the range of 1.86-3.40 MPa, tensile-shear strength ranged from 0.84 MPa to 1.57 MPa, and compression strength was in the range of 5.10-27.65 MPa. The cured PBF/PPF-DA hybrid material can be used as a light-emitting diode (LED) encapsulant, owing to its suitable refractive index, high transparency, excellent thermal stability, lower water absorption, and good mechanical properties. [ABSTRACT FROM AUTHOR]