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Hydrogels are hydrophilic macromolecular systems that swell in water without dissolving. The nature of the solvent has a significant effect on the amount of water absorbed. Poly(acrylamide) hydrogel and its copolymer with diprotic maleic acid are prepared in this work by copolymerization and chemical crosslinking with methylene bisacrylamide; at different mass percentages of acrylamide (AAm, %) and maleic acid (MA, %), respectively: (100, 0%) and (80, 20%). The obtained results show the formation of copolymers with intermolecular hydrogen bonding between carboxylic groups and amide groups. The content of maleic acid within the crosslinked polymer (acid value) is determined. Two acid values are obtained; 14 and 57.2 mg g–1. Thermal stability of hydrogels is examined through TGA analysis. The thermal degradation of poly(acrylamide) occurs via two stage process; (204–330°C) and at temperature higher than 330°C. The thermal stability of the copolymer increases with incorporates of MA. The copolymer degrades in a multistage process; less than 230°C, (230–350°C) and above 350°C. Different percentages of crosslinker between 1–5 wt % and copolymer with maleic acid are used to study their swelling behavior in different aqueous solutions (NaCl, pH 9.18 and pH 2.2). The swelling is reduced with increasing degree of the cross-linking agent. The obtained hydrogels have shown substantial percent swelling in water and basic buffer and shrinking in saline solution and acidic buffer. The results show that MA20 hydrogel has pH and ionic sensitive characters. These sensitivities exhibit hydrogels an important utility in water treatments, especially as adsorbent of heavy metal ions. The study of oscillatory swelling of hydrogels at pH 4.01 and 9.18 as function of time are demonstrated in this work. The result shows that the synthesized hydrogels exhibit excellent reversible pH-sensibility character. [ABSTRACT FROM AUTHOR]

3-(1H,1H,2H,2H-Perfluorooctyl)-1-vinylimidazolium chloride [2126844–17–3], a strong fluorosurfactant with remarkably high solubility in water, was expediently converted into the respective doubly NHC-complexed silver salt with nitrate as counter ion in quantitative yield. Due to its vinyl substituents, [bis(3-(1H,1H,2H,2H-perfluorooctyl)-1-vinylimidazol-2-ylidene)silver(I)] nitrate, Ag(FNHC)2NO3, represents a polymerizable N-heterocyclic carbene transfer reagent, thus potentially offering simple and robust access to coordination polymers with crosslinking metal bridges. The compound was characterized by infrared and NMR spectroscopy, mass spectrometry as well as elemental analysis, and supplemented by X-ray single-crystal structure determination. It crystallizes in the monoclinic crystal system in the space group P21/c. With 173.3°, the geometry of the Ag-carbene bridge deviates slightly from linearity. The disordered perfluoroalkyl side chains exhibit a helical conformation.

[Display omitted] • Effect of crosslinker KH571 on membrane forming were detailed evaluated. • Using PDMS-PTFPMS block copolymer not conventional PDMS to enhance membrane hydrophobicity. • Showing the ultrafast curing time within 30−50 s. • A high water contact angle >110° was obtained. • An outstanding PV performance for ethanol recovery. Crosslinker is a vital factor for the preparation of polymeric membranes, which has a substantial effect not only on the membrane-forming process, but also on the membrane structure as well as separation performance. However, little attention has been paid on UV-crosslinked membrane for organics pervaporation. In this work, the effect of crosslinker 3-methacryloxypropylmethyldimethoxysilane (KH571) on (1) the UV-crosslinking kinetics was characterized by real-time infrared spectroscopy and photo-rheology, (2) the membrane structure was characterized by crosslinking density, and (3) separation performance was evaluated by ethanol pervaporation. Moreover, the conventional polydimethylsiloxane (PDMS) was replaced by polydimethylsiloxane-poly[(3,3,3-trifluoropropyl)methylsiloxane] (PDMS-PTFPMS) block copolymer, where the strong C–F bond contributes to enhance membrane hydrophobicity. Results show an ultrafast membrane-forming process (30−50 s) for all coating solution systems and an outstanding separation performance, including 11.3 of ethanol separation factor and 1149 g m−2 h-1 of total flux for pervaporation recovery of 5 wt% ethanol/water solution at 60 °C. [ABSTRACT FROM AUTHOR]

Itaconic acid (IA) is a bio-based unsaturated monomer, which has been limitedly used in free-radical polymerization due to low reactivity of its carbon-carbon double bond and lack of tendency toward homo-polymerization. In the present work, IA was modified with glyceryl methacrylate (GMA) or epichlorohydrin (ECH) to synthesize two new IA-based materials, i.e., IA-GMA and IA-ECH, respectively. After the characterization of the crosslinkers by 1H NMR and FTIR, IA-GMA containing two methacrylate groups in the structure was used as an internal crosslinker for the preparation of a superabsorbent polymer (SAP). The obtained IA-GMA crosslinked SAP showed a high water absorbency under load (AUL) up to 23.9 g/g compared to commercial SAPs (14–18 g/g), so it can be a potential crosslinker for SAP preparation without a requirement of the surface treatment process as a time and energy-consuming process. Moreover, the application of IA-ECH, possessing hydroxyl or epoxy functionalities as an internal and surface crosslinker in the synthesis of SAPs was investigated. The unique ion structure of IA-ECH as an external crosslinker resulted in improvement in gel strength, as well as AUL up to 30.7 g/g. The SAPs crosslinked by IA-ECH as internal crosslinker presented a high water absorbency (Qw) and saline absorbency (Qs). [ABSTRACT FROM AUTHOR]

Hydraulic fracturing (HF) is currently the most widespread and effective method of oil production stimulation. The most commonly used fracturing fluid is crosslinked guar gels. However, when using these systems, problems such as clogging of the pore space, cracking, and proppant packing with the remains of the undestroyed polymer arise. Therefore, the efficiency of the hydraulic fracturing process decreases. In this work, compositions based on viscoelastic surfactants (VES) and synthetic polymers (SP) were considered as alternatives capable of minimizing these disadvantages. Most often, the possibility of using a composition as a fracturing fluid is evaluated using rotational viscometry. However, rotational viscometry is not capable of fully assessing the structural and mechanical properties of fracturing fluid. This leads to a reduced spread of systems based on VES and SP. This paper proposes an integrated approach to assessing the effectiveness of a water-based fracturing fluid. The proposed comprehensive approach includes an assessment of the main characteristics of water-based fracturing fluids, including an analysis of their structural and mechanical properties, which is based on a combination of rotational and oscillatory rheology and a comparative analysis of methods for studying the influence of fluids on the reservoir rock. The use of the developed approach to assess the technological properties of fracturing fluids makes it possible to demonstrate the potential applicability of new, unconventional fracturing fluids such as systems based on VES and SP.

Crosslinkers are indispensable constituents for the preparation of SPE materials with ethylene glycol dimethacrylate (EGDMA) and divinylbenzene (DVB) among the most prominent representatives. A crosslinker that has not yet been used for the preparation of SPE sorbents is 3,3’-(hexane-1,6-diyl)bis(1-vinylimidazolium) bromide [C6-bis-VIM] [Br]. In this study, we synthesized differently crosslinked vinylimidazole polymers with EGDMA, DVB and [C6-bis-VIM] [Br] and evaluated their extraction efficiencies towards phenolic acids. Dispersive SPE experiments performed with the [C6-bis-VIM] [Br] crosslinked polymers exhibited significantly higher extraction recoveries for the majority of analytes. Due to these promising results, the [C6-bis-VIM] [Br] crosslinked polymer was optimized in terms of the monomer to crosslinker ratio and an efficient dispersive SPE protocol was developed, with maximum recoveries ranging from 84.1–92.5% and RSD values ˂ 1%. The developed extraction procedure was also applied to cartridges resulting in recoveries between 97.2 and 98.5%, which were on average 5% higher than with the commercial anion exchange sorbent Oasis® MAX. Furthermore, the sorbent was regenerated showing a good reusability for the majority of analytes. In conclusion, this study clearly highlights the yet untapped potential of the crosslinker, [C6-bis-VIM] [Br], with respect to the synthesis of efficient anion exchange polymers for SPE.

The folate receptor alpha (FR), which is overexpressed in solid tumors including NSCLC, can be utilized for active tumor targeting to afford more effective cancer therapies. In this context, cytochrome c (Cyt c) has drawn attention to cancer research because it is non-toxic, yet, when delivered to the cytoplasm of cancer cells, can kill them by inducing apoptosis. Cyt c nanoparticles (NPs, 169 ± 9 nm) were obtained by solvent precipitation with acetonitrile, and stabilized by reversible homo-bifunctional crosslinking to accomplish a Cyt-c-based drug delivery system that combines stimulus-responsive release and active targeting. Cyt c was released under intracellular redox conditions, due to an S–S bond in the NPs linker, while NPs remained intact without any release under extracellular conditions. The NP surface was decorated with a hydrophilic folic acid–polyethylene glycol (FA–PEG) polymer for active targeting. The FA-decorated NPs specifically recognized and killed cancer cells (IC50 = 47.46 µg/mL) that overexpressed FR, but showed no toxicity against FR-negative cells. Confocal microscopy confirmed the preferential uptake and apoptosis induction of our NPs by FR-positive cancer cells. In vivo experiments using a Lewis lung carcinoma (LLC) mouse model showed visible NP accumulation within the tumor and inhibited the growth of LLC tumors.

Controlled radical polymerization (CRP) has both revolutionized the synthesis of linear polymers and enabled unprecedented topological complexity. While the synthesis of many polymeric architectures requires careful planning and specialized precursors, branched macromolecules such as segmented hyperbranched polymers (SHPs), knotted polymers, core‐crosslinked stars (CCSs), and more can be synthesized through the copolymerization of vinyl monomers and divinyl crosslinkers in only a few steps. In the nearly two decades since its discovery, this strategy has helped elucidate the fundamental polymerization behavior of crosslinkers and also yielded a variety of functional and stimuli‐responsive materials. The purpose of this mini‐review is to therefore overview critical fundamental aspects of CRP of crosslinkers and materials derived therefrom. The process by which both SHPs and CCS polymers are synthesized, the effect of key reaction parameters and intriguing recent advances are described with the intent of both educating new researchers and inspiring new directions in this area. © 2020 Society of Industrial Chemistry [ABSTRACT FROM AUTHOR]

The contributions of castor seed oil (CSO) as a useful, nontoxic, and sustainable base material for coating systems cannot be overemphasized. This paper took advantage of the predominant fatty acid composition in CSO (i.e., ricinoleic acid). It blended a synthesized crosslinker, poly(epichlorohydrin-triol) (PECH-triol), in percentages within its polymeric matrix. Physicochemical and spectroscopic (FTIR, 1H-NMR, and 13C-NMR) examinations were carried out on the polyols. Thermal stability, hydrophobicity, anticorrosion, mechanical, and antibacterial properties of the prepared polyurethane (PU) coatings were examined. The 20% PECH-triol–CSO-PU film having its TON and TEND at 230.5 and 511.0°C, respectively, showed improved thermal stability when compared with the pristine film (CSO-PU). The derivative of TGA reveals a three-stage degradation step. Hydrophobicity was seen to increase from 73.3° to 92.2°, a reflection of the crosslinking effect of PECH-triol within the urethane matrix. The improved adhesion of 20% PECH-triol–CSO-PU coating on mild steel gave a better chemical resistance. [ABSTRACT FROM AUTHOR]

The investigation of the mechanical, thermal, and adsorption properties of hydroxyethyl methacrylate (HEMA) cryogels as a function of a reactant ratio is herein reported to better address materials for specific applications. To this aim, cryogels have been synthesized using different monomer/crosslinker (N,N'-methylene-bisacrylamide-MBAA) ratios. The study of SEM images made it possible to identify the trend in the material's macroporosity. As would be expected, the average measured pore width decreased as the amount of MBAA increased while the number of pores grew. Swelling capacity ranges from 8.7 gW/g gel (grams of water per gram of gel) to 9.3 gW/g gel . These values are strictly connected with the pore's size and distribution, revealing that the water uptake for the most crosslinked sample is inferior to other samples. The equilibrium-adsorption capacity (Qe) towards the methylene violet (MV) was also assessed, revealing no remarkable differences after 24 h of a batch test. As expected, thermogravimetric analysis (TGA) also showed no significant changes in stability that ranged from a maximum weight loss temperature (T Max) of 420 °C to 425 °C, which increased as a function of crosslinker content. Conversely, compression strength measurements showed a notable difference of about 50% in modulus (Ec), moving from the higher to the lower HEMA/MBAA ratio. These new comparative results indicate how slight variations in the reactant's ratio can steadily improve the mechanical properties of the HEMA cryogel without affecting its adsorption efficiency. This can be helpful in the design of materials for water and energy purposes. Since swelling properties are needed in the case of biomedical applications, the HEMA/MBAA ratio should be tuned versus high values.

In this article, borax was used as the prime agent, and the organic boron that cross-linked agent was synthesized using adding sodium tartrate. The synthesis response shapes were optimized using unmarried factor way. The temperature opposition and crosslinking time of the fracturing fluid were used as the appraisal standards to decide the organic boron. The cross-linking agent's optimal synthesis statuses were measured, and the chemical and forcible holdings of the fracturing fluid after cross-linking with the polyvinyl alcohol-based liquid were measured.

The objective of this study was to determine and evaluate a controlled release implant of ciprofloxacin using bovine hydroxyapatite (BHA)-chitosan composite and glutaraldehyde or genipin as crosslinking agents. Ciprofloxacin implants were prepared using BHA, chitosan, ciprofloxacin at 30:60:10 and using three different concentrations of glutaraldehyde or genipin (0.3, 0.5, or 0.7%) as crosslinkers. Implants were formed as mini-tablet with 4.0 mm diameter weighing 100 mg using compression method. Further, the prepared ciprofloxacin implants were characterized for porosity, density, water absorption capacity, swelling, degradation, compressive strength, compatibility (Fourier transforms-infrared spectroscopy (FT-IR)), morphology (scanning electron microscope (SEM)), X-ray diffraction (X-RD), and in vitro drug release. The addition of glutaraldehyde or genipin as crosslinkers in ciprofloxacin implant showed controlled release profile of ciprofloxacin over a time period of 30 days. SEM photomicrograph revealed low porosity of the implant after crosslinking with glutaraldehyde or genipin. The FTIR study confirmed the formation of covalent imine bonds between chitosan and glutaraldehyde. Moreover, the addition of glutaraldehyde or genipin as crosslinkers caused a decrease in the mechanical strength of the implant. Increased concentration of glutaraldehyde or genipin reduced the crystallinity of BHA and chitosan, which were confirmed by X-RD studies. The results obtained from this study indicated that glutaraldehyde or genipin had the potential effect to retard ciprofloxacin release from BHA-chitosan-ciprofloxacin implant for 30 days.

RNAi technology has aroused wide public interest due to its high efficiency and specificity to treat multiple types of diseases. However, the effective delivery of siRNA remains a challenge due to its large molecular weight and strong anionic charge. Considering their remarkable functions in vivo and features that are often desired in drug delivery carriers, biomimetic systems for siRNA delivery become an effective and promising strategy. Based on this, covalent attachment of synthetic cell penetrating peptides (CPP) to siRNA has become of great interest. We developed a monomeric covalent conjugate of low molecular weight protamine (LMWP, a well-established CPP) and siRNA via a cytosol-cleavable disulfide linkage using PEG as a crosslinker. Results showed that the conjugates didn't generate coagulation, and exhibited much better RNAi potency and intracellular delivery compared with the conventional charge-complexed CPP/siRNA aggregates. Three different synthetic and purification methods were compared in order to optimize synthesis efficiency and product yield. The methodology using hetero-bifunctional NHS–PEG–OPSS as a crosslinker to synthesize LMWP–siRNA simplified the synthesis and purification process and produced the highest yield. These results pave the way towards siRNA biomimetic delivery and future clinical translation.

A regenerable immunoaffinity layer comprising covalently immobilized orientation-controlled antibodies was developed for use in a surface plasmon resonance (SPR) biosensor. For antibody orientation control, antibody-binding Z-domain-autodisplaying Escherichia coli (E. coli) cells and their outer membrane (OM) were utilized, and a disuccinimidyl crosslinker was employed for covalent antibody binding. To fabricate the regenerable immunoaffinity layer, capture antibodies were bound to autodisplayed Z-domains, and then treated with the crosslinker for chemical fixation to the Z-domains. Various crosslinkers, namely disuccinimidyl glutarate (DSG), disuccinimidyl suberate (DSS) and poly (ethylene glycol)-ylated bis (sulfosuccinimidyl)suberate (BS(PEG)5), were evaluated, and DSS at a concentration of 500 μM was confirmed to be optimal. The E. coli-cell-based regenerable HRP immunoassay was evaluated employing three sequential HRP treatment and regeneration steps. Then, the Oms of E. coli cells were isolated and layered on a microplate and regenerable OM-based HRP immunoassaying was evaluated. Five HRP immunoassays with four regeneration steps were found to be feasible. This regenerable, covalently immobilized, orientation-controlled OM-based immunoaffinity layer was applied to an SPR biosensor, which was capable of quantifying C-reactive protein (CRP). Five regeneration cycles were repeated using the demonstrated immunoaffinity layer with a signal difference of

Economical and environmental concerns have forced the oil and gas industry to consider reusing flowback and produced water for fracturing operations. The major challenge is that the high-salinity of flowback water usually prevents its compatibility with several fracturing fluid additives. In this paper, the authors explored an economic and effective method to prepare guar fracturing fluids with different salinity waters. The main research idea was to use chelating agents to mask metal ions, such as calcium and magnesium, that are harmful to crosslinking. Firstly, a complexometric titration test was conducted to measure the chelating ability of three chelating agents. Secondly, through viscosity, crosslinking, and hanging tests, it was verified that the complex masking method could cope with the problem of high-valence metal ions affecting crosslinking. Thirdly, the preferred chelating agent was mixed with several other additives, including thickeners, crosslinkers, and pH regulators, to prepare the novel guar fracturing fluid. The comprehensive performances of the novel fluid system were tested such as temperature and shear resistance, friction reduction, gel-breaking performance, and core damage rate. The results show that the organophosphate chelating agent (i.e., CA-5) had the greatest ability to chelate calcium and magnesium ions. There was a good linear relationship between the dosage of CA-5 and the total molar concentration of calcium and magnesium ions in brine water. The main mechanism was that the chelating agent formed a complex with calcium and magnesium ions at a chelation ratio of 1:5. The test results of the comprehensive performance evaluation indicate that the prepared guar fracturing fluid met the requirements for field application, and the lower the salinity of the flowback water, the more it is economical and effective.

Rational manipulation of the carbon framework from the microporous to nonporous via a molecular design approach is interesting but challenging. Herein, we report a versatile strategy for transforming the microporous carbon framework to the low porous one by an elaborate molecular crosslinker design in the polystyrene (PS) precursor. Direct coupling of benzene rings in PS via Scholl reaction yields hypercrosslinked PS-derived carbon with low porous framework, while insertion of methylene crosslinker into PS via a solvent knitting strategy leads to microporous carbon framework. The results show that methylene crosslinker functions as molecular-scale soft templates for facilitating micropores, whereas direct linking PS chains promotes aromatization and mitigates micropore formation during the pyrolysis. The distinct carbon frameworks derived from similar precursor and pyrolysis condition provide an intriguing platform for structure-property relationship study, as preliminarily exemplified by the application in Na ion storage. The low-porosity carbon shows higher initial Coulombic efficiency and superior capacity thanks to its low surface area and enhanced Na insertion into pseudo-graphitic microcrystal structure. The present protocol opens up new avenues towards flexible carbon framework porosity manipulation at molecular level and would trigger further efforts for low-porosity carbons in energy storage. Image 1 [ABSTRACT FROM AUTHOR]

Through precipitation polymerization approach, bovine serum albumin (BSA) molecularly imprinted polymer (MIP) was synthesized with various reagents to ascertain the optimal synthesis condition. The optimized synthesis condition is methacrylic acid (MAA) as functional monomer, N,N′-methylenebisacrylamide (MBA) as crosslinker, template molecular/functional monomer/initiator ratio of 1:6:3, and K2S2O8/NaHSO3 initiator ratio of 1:2. BSA adsorption by synthesized MIP conformed to second-order kinetic adsorption equation and Langmuir adsorption isotherm. The maximum adsorption amount of MIP was 106.2 mg/g. Moreover, when the lysozyme (LYZ) was introduced as interfering adsorbate, the separation factor was up to 3.09, indicating that the MIP has a high affinity towards BSA. [ABSTRACT FROM AUTHOR]

Currently, development of a single network hydrogel with a high fracture toughness in swelling equilibrium remains challenging. In this work, a novel T-shaped trifunctional crosslinker (T-NAGAX) with dual vinyl on the backbone and dual amide group on the side chain is synthesized by Michael addition and acylation. The T-NAGAX is used to prepare chemically crosslinked hydrogel by one-pot photo-initiated polymerization. The resulting single network hydrogels of representative polyacrylamide (PAAm), poly(N-acryloyl 2-glycine) (PACG), and poly(N-isopropyl acrylamide) (PNIPAM) crosslinked with T-NAGAX with additional hydrogen-bonds exhibit much better fracture toughness than that of the corresponding hydrogels crosslinked by N,N′ -methylene bisacrylamide, a conventional crosslinker; higher mechanical strengths are observed in the T-NAGAX crosslinked hydrogels. These hydrogels are promising to be exploited as load-bearing soft tissue substitutes. This T-NAGAX crosslinker can be expanded to toughen various types of hydrogels. [ABSTRACT FROM AUTHOR]

Cellulose-based superabsorbent hydrogel (SAH) has been successfully prepared by the grafting method with cellulose and sodium acrylate as well as aluminum hydroxide as a novel crosslinker. The factors influencing water absorption such as the neutralization degree of acrylic acid (AA), the amount of initiator ammonium persulfate (APS) and crosslinker, and the proportion of cellulose to AA were investigated. The chemical structure and thermal behavior of the SAH were analyzed by fourier-transform infrared spectrometry, field-emission scanning electron microscopy, and thermal gravimetry, respectively. Results showed that the water absorbency of the SAH in distilled water and 0.9 wt% NaCl solution reached 922 and 118 g/g when the mass ratio of cellulose to AA, APS to AA, Al(OH) to AA, and the neutralization degree of AA was 39 wt%, 0.67 wt%, 0.89 %, and 76 %, respectively. Under the same condition, the hydrogel synthesized by traditional crosslinker N,N-methylenebisacrylamide was only 530 and 84 g/g in distilled water and 0.9 wt% NaCl solution, respectively. The mechanism of polymerization reaction was analyzed. And the cost and feasibility for the mass-producing the hydrogel were analyzed. [ABSTRACT FROM AUTHOR]

Fluorine-containing chain extender(DEFA) was synthesized by the Michael addition reaction of diethanolamine(DEOA)and dodecafluoroheptyl methacrylate(G04). Next,a series of modified polyurethane prepolymers by the fluoroalkyl side groups(FPU)were synthesized from isoferone diisocyanate(IPDI)，polybutyleneadipate(CMA1044)，1，4-butanediol(BDO)， 2,2-dihydroxymethylpropionic acid(DMPA)and different content of DEFA. Then, the synergistically modified polyurethane intermediates by terminal and pendant fluoroalkyl segments (FPUF)were unilaterally blocked using perfluorohexyl ethanol(S104). Finally, pentaerythritol(PE)was used to react with FPUF and a series of the latexes were prepared by neutrafizing and emulsifing operaions. Structure and performance properties of the resultants were characterized by IR,1H NMR, TGA , DSC, XRD, XPS, TEM and contact angle measure­ments, etc. Results confirmed that the product had the due structure. With the increase of DEFA dosage, the latex stability decreased slightly while the average particle size increased gradually. By comparison of HBFPUF-7 and HBFPUF-1 , thermal decomposition temperature at 50 % weight loss was increased by 18 °C and the glass transition temperature was increased by 15. 4 °C. Moreover, water absorption was decreased from 8. 25% to 2. 73% while static water contact angle was increased from 92. 8 °C to 105. 6 °. XPS results showed that fluorine- containing segments tended to migrate to the film surface, which will enhance hydrophobicity of HBFPUF films. XRD analysis demonstrated that there were a certain crystalline zones in HBFPUF films. [ABSTRACT FROM AUTHOR]

Depletion of the petroleum resources and poor flame-retardant properties of the epoxy resins drive researchers to develop an epoxy resin with good heat stability from bio-resources. In the current research work, we have reported the synthesis of a novel crosslinking agent for epoxy from the catechol as a bio-resource which can be further modified to form epoxy resin as well. The synthesis of the flame-retardant epoxy resin (TOMPP) was performed in two separate steps which include the reaction of the catechol with phosphoryl chloride followed by the reaction of the remaining hydroxyl groups with the epichlorohydrin. The structures of the synthesized products were confirmed using Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy and hydroxyl and epoxy values. The thermogravimetric analysis and differential scanning calorimetry were performed to analyse the thermal stability of the cured films which showed thermal degradation temperatures of both TOMPP and THPP formulations were decreased as the concentration of the TOMPP and THPP increased, while glass transition temperature (Tg) values increased. The char yield value of the THPP formulations was increased with increasing concentration of the intermediate, but for TOMPP it decreased. 40% THPP showed the least current density in electrochemical impedance spectroscopy suggesting the good corrosion resistance property. Mechanical properties were found to be similar for both THPP and TOMPP formulations. Flame retardancy was checked by LOI and UL-94 tests which revealed 40% THPP formulation had the maximum LOI as 28 and self-extinguishing behaviour. [ABSTRACT FROM AUTHOR]

In order to further improve the quality of transfer printing products, the transfer printing process and performance of cotton/wool printed fabrics were studied and analyzed. The crosslinking agent 632 was applied on the transfer paper to improve the color fastness of the fabric, good color fastness was obtained and the strength of the fabric is less affected. The printing color depth, color fastness and breaking strength retention rate should be considered duiring cotton/wool fabric transfer printing process. The results showed that the pressing temperature of the transfer printing is 180 T and the pressing time is 90s. Under this process condition, the K/S value is higher, the rubbing fastness is higher than grade 3, the soaping fastness is also higher than grade 3 and the fabric strength is less influenced. The hand feeling of the cotton/wool fabric is less influenced before and after the transfer printing process. Under appropriate pressing temperature and pressing time, the total average bending length of the fabric does not change much. [ABSTRACT FROM AUTHOR]

Elastomers were obtained by physical bonding between amino–siloxane copolymer and dicarboxylic acids as crosslinkers. The structural interactions trigger the fluorescence property in the materials due to a stiffening of the dicarboxylic acid structure within the amino moieties of the copolymer. This effect can be attributed to an aggregation induced emission effect. [ABSTRACT FROM AUTHOR]

Gelatin is a representative hydrophilic protein material with remarkable biocompatibility and biodegradability. From the aspect of materials processing, gelatin also has the advantage that its entire fabrication process can be performed in an aqueous solution. However, practical application of various gelatin materials—in particular gelatin films—has thus far been limited because of their weak mechanical properties and vulnerability under aqueous environments. To overcome these disadvantages, both physical reinforcement approaches and chemical cross-linking agents have been tested. However, little research has been done to make these two roles work at the same time. In this study, cellulose nanocrystals containing aldehyde groups were prepared via a periodate oxidation process and used for cross-linkable reinforcement of gelatin-based bio-composite films. The results revealed that the di-aldehyde cellulose nanocrystal (D-CNC) could react and covalently cross-link with the amine group of the gelatin molecules via Schiff base formation and compared with neat CNC. The gelatin bio-composite film reinforced with the prepared D-CNC exhibited excellent tensile properties and water resistance, and its mechanical and hydrophilic properties could be easily controlled by adjusting the D-CNC content and was greater than addition of same amount in CNC. Therefore, D-CNC will facilitate the widespread use of existing water-soluble polymers, especially natural hydrophilic proteins and can be used in conventional application fields such as the food, pharmaceutical, and biomedical industries. Unlabelled Image [ABSTRACT FROM AUTHOR]

Cell and tissue morphogenesis depend on the production and spatial organization of tensional forces in the actin cytoskeleton. Actin network architecture is made of distinct modules characterized by specific filament organizations. The assembly of these modules are well described, but their integration in a cellular network is less understood. Here, we investigated the mechanism regulating the interplay between network architecture and the geometry of the extracellular environment of the cell. We found that α-actinin, afilament crosslinker, is essential for network symmetry to be consistent with extracellular microenvironment symmetry. It is required for the interconnection of transverse arcs with radial fibres to ensure an appropriate balance between forces at cell adhesions and across the actin network. Furthermore, this connectivity appeared necessary for the ability of the cell to integrate and to adapt to complex patterns of extracellular cues as they migrate. Our study has unveiled a role of actin filament crosslinking in the spatial integration of mechanical forces that ensures the adaptation of intracellular symmetry axes in accordance with the geometry of extracellular cues. [ABSTRACT FROM AUTHOR]

In this study, we developed aptamer-conjugated hydroxyapatite (Apt-HA) that promotes bone regeneration and angiogenesis. The 3R02 bivalent aptamer specific to vascular endothelial growth factor (VEGF) was grafted to the hydroxyapatite (HA) surface. Apt-HA was tested for its VEGF protein capture ability to determine the optimal aptamer concentration immobilized on the HA. Apt-HA showed higher VEGF protein capture ability, and faster growth of human umbilical vein endothelial cell (HUVEC) compared to a neat HA with no cytotoxic effects on human osteoblasts. To examine in vivo angiogenesis and bone regeneration, Apt-HA and HA were bilaterally implanted into rabbit tibial metaphyseal defects and analyzed after eight weeks using micro-CT, histology, and histomorphometry. Apt-HA showed significantly increased the volume of new bones, the percentage of bone, and the density of bone mineral in cortical bone. Apt-HA also exhibited the enhanced bone formation at the cortical region in a histomorphometric analysis. Finally, Apt-HA showed significantly increased blood vessel number compared to a neat HA. In summary, the engineered Apt-HA has potential as a bone graft material that may simultaneously promote bone regeneration and angiogenesis. This work presents a functional hydroxyapatite bone graft using a DNA-based aptamer which overcomes the limitations of existing bone graft materials, which use bound signaling peptides. DNA aptamer immobilized hydroxyapatite enhances the in vitro proliferation of human umbilical vascular endothelial cells as well as in vivo angiogenesis and bone regeneration. DNA aptamer immobilized hydroxyapatite shows no cytotoxic effect on human osteoblasts. [ABSTRACT FROM AUTHOR]

In this work, a hydrogel system was produced via radical polymerization of N,N-dimethylacrylamide and 2-acrylamido-2-methylpropanesulfonic acid in the presence of N,N-methylene-bis-acrylamide as a crosslinker and ammonium persulfate as an initiator. Parameters that impact the conversion of copolymerization (such as initial concentration of monomers, temperature, initiator dose, and time) were studied. The swelling degree of the hydrogel was investigated with the addition of a crosslinker and initiator at different pH levels. A hydrogel with high conversion and high swelling degree was selected to investigate their ability for adsorption of Pb(II) ions from solutions. Adsorption behavior of Pb(II) ions in a hydrogel was examined as a function of reaction time and concentration of lead ions from a solution of Pb(II) ions.

Electrospinning can be used to prepare nanofiber mats from diverse polymers, polymer blends, or polymers doped with other materials. Amongst this broad range of usable materials, biopolymers play an important role in biotechnological, biomedical, and other applications. However, several of them are water-soluble, necessitating a crosslinking step after electrospinning. While crosslinking with glutaraldehyde or other toxic chemicals is regularly reported in the literature, here, we concentrate on methods applying non-toxic or low-toxic chemicals, and enzymatic as well as physical methods. Making gelatin nanofibers non-water soluble by electrospinning them from a blend with non-water soluble polymers is another method described here. These possibilities are described together with the resulting physical properties, such as swelling behavior, mechanical strength, nanofiber morphology, or cell growth and proliferation on the crosslinked nanofiber mats. For most of these non-toxic crosslinking methods, the degree of crosslinking was found to be lower than for crosslinking with glutaraldehyde and other common toxic chemicals.

Achieving the desired properties of paper such as strength, durability, and printability remains challenging. Paper mills employ calcium carbonate (CaCO 3 ) as a filler to boost paper's brightness, opacity, and printability. However, weak interaction between cellulose fibers and CaCO 3 particles creates different issues in the papermaking industry. Therefore, this study explores the influence of various inorganic additives as crosslinkers such as mesoporous SiO 2 nanospheres, TiO 2 nanoparticles, h-BN nanoflakes, and hydroxylated h-BN nanoflakes (h-BN-OH) on inorganic fillers content in the paper. They were introduced to the paper pulp in the form of a polyethylene glycol (PEG) suspension to enable bonding between the inorganic particles and the paper pulp. Our findings have been revealed based on detailed microscopic and structural analyses, e.g., transmission and scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and N 2 adsorption/desorption isotherms. Finally, the inorganic fillers (CaCO 3 and respective inorganic additives) content was evaluated following ISO 1762:2001 guidelines. Conducted evaluations allowed us to identify the most efficient crosslinker (SiO 2 nanoparticles) in terms of inorganic filler retention. Paper sheets modified with SiO 2 enhance the retention of the fillers by ~12.1%. Therefore, we believe these findings offer valuable insights for enhancing the papermaking process toward boosting the quality of the resulting paper.

This work demonstrates the use of a modified mica to concentrate proteins, which is required for proteomic profiling of blood plasma by mass spectrometry (MS). The surface of mica substrates, which are routinely used in atomic force microscopy (AFM), was modified with a photocrosslinker to allow "irreversible" binding of proteins via covalent bond formation. This modified substrate was called the AFM chip. This study aimed to determine the role of the surface and crosslinker in the efficient concentration of various types of proteins in plasma over a wide concentration range. The substrate surface was modified with a 4-benzoylbenzoic acid N-succinimidyl ester (SuccBB) photocrosslinker, activated by UV irradiation. AFM chips were incubated with plasma samples from a healthy volunteer at various dilution ratios (10 2 X, 10 4 X, and 10 6 X). Control experiments were performed without UV irradiation to evaluate the contribution of physical protein adsorption to the concentration efficiency. AFM imaging confirmed the presence of protein layers on the chip surface after incubation with the samples. MS analysis of different samples indicated that the proteomic profile of the AFM-visualized layers contained common and unique proteins. In the working series of experiments, 228 proteins were identified on the chip surface for all samples, and 21 proteins were not identified in the control series. In the control series, a total of 220 proteins were identified on the chip surface, seven of which were not found in the working series. In plasma samples at various dilution ratios, a total of 146 proteins were identified without the concentration step, while 17 proteins were not detected in the series using AFM chips. The introduction of a concentration step using AFM chips allowed us to identify more proteins than in plasma samples without this step. We found that AFM chips with a modified surface facilitate the efficient concentration of proteins owing to the adsorption factor and the formation of covalent bonds between the proteins and the chip surface. The results of our study can be applied in the development of highly sensitive analytical systems for determining the complete composition of the plasma proteome.

• Bisimidazolium PEG-mediated crosslinked polyimides were prepared. • PEG and bisimidazolium groups were used as both CO 2 -solubilizing group and croslsinker. • High permeability to CO 2 and high selectivities to CO 2 /CH 4 and CO 2 /N 2 were achieved. • High resistance to CO 2 plasticization was also obtained. A series of bisimidazolium PEG-mediated crosslinked polyimides (BI-PEG-xPIs) with different PEG chain lengths were prepared for CO 2 separation membranes. Both the ionic group (bisimidazolium) and PEG were used not only as CO 2 -solubilizing groups to enhance the CO 2 selectivity but also as crosslinkers to inhibit plasticization. The crosslinked BI-PEG-xPI membranes displayed excellent chemophysical properties, together with high CO 2 /N 2 (up to 31) and CO 2 /CH 4 (up to 46) permselectivities while maintaining high CO 2 permeability (up to 350 Barrer) due to their high solubility and solubility selectivity. Moreover, the crosslinked membrane showed good plasticization resistance up to 25 atm. Finally, the chain length effects of the crosslinkers on the physicochemical properties and the gas separation performance of the corresponding membranes are also discussed. [ABSTRACT FROM AUTHOR]

Abstract Exploring a desirable cross-linker applied in cation exchange membranes (CEMs) to improve dimensional stability as well as electrochemical performance has a great signifcance for the current membrane science and technology. In this investigation, a sequence of crosslinked sulphonated polysulfone (SPSF) CEMs has been prepared to explore the influence of the crosslinking functionality on the dimensional stability and electrodialysis (ED) performance of modified membranes. Different cross-linker structures were obtained according to the cross-linker agent content added during the synthesis route. As expected, the membrane surface became smoother with increasing cross-linker content, presumably as result of the denser structure established. The dimension stability increases according to the crosslinking degree applied, whereas the permselectivity of membranes depends on the conjunction of many important and interlinked factors, including the formation of narrow ion transport channels and the variations in the exchanges sites concentration. It was observed that the optimized CEM (60SPSF-C2#) showed the highest NaCl removal ratio (91.7%) during the desalination experiments and exhibited the higher current efficiency (95.7%) and lowest energy consumption (6.55 kWh kg−1). These results suggest the formation of the optimum three-dimensional network configuration for the membrane structure determined by the functionality of cross-liker selected in this investigation. [ABSTRACT FROM AUTHOR]

Free‐standing chitosan membranes were prepared using genipin as crosslinker, using several molecular weights of polyethylene glycol (PEG) as a void‐forming agent. The membrane surface formation and chitosan polymer chain crosslinking were confirmed through SEM and FTIR, respectively. The water flux was remarkably increased with increasing molecular weight of PEG employed in preparation of composite chitosan membrane (J∝[PEG(MW)]0.85), it appeared over 6000 Da of PEG. During Chlorella vulgaris harvest using chitosan membranes, focus was made on algae‐fouling caused by the deposition of cells and extracellular organic matter, and it was found that membranes employing lower molecular weight of PEG (under 10000 Da) had been maintaining the high flux recovery after alternating filtration cycles, in addition to PEG20000 containing membrane. The chitosan membrane prepared with lower molecular weight of PEG exhibited better suppression of algae‐fouling properties. The Chlorella vulgaris harvesting results indicated that cell rejection rate reached above 98%. [ABSTRACT FROM AUTHOR]

In this manuscript, synthesis of TGA (thioglycolic acid) capped core@shell CdSe@CdS nanoparticles (NPs) has been done using chemical route. PEG-diamine has been used to functionalize spherical core@shell CdSe@CdS NPs by carbodiimide chemistry, which is very simple and effective method to make stable bond between NH2 group and COOH group. Optical properties include UV-Visible absorption and fluorescence emission that show the higher polydispersity and enhanced emission intensity of CdSe@CdS-PEG NPs in comparison to CdSe@CdS core@shell NPs. FT-IR results of CdSe@CdS-PEG NPs indicate the intermolecular interaction between PEG-diamine and TGA capped CdSe@CdS core@shell NPs. The emission intensity of CdSe@CdS and CdSe@CdS-PEG NPs is highest when dispersed in pH 6 medium which is low acidic in nature. Therefore, these colloidal NPs can be used for applications in the pH range (6–8), due to their stability and higher fluorescence emission in this pH range. [ABSTRACT FROM AUTHOR]

An interpenetrating polymer network (IPN) with shape memory properties was prepared by using poly(2‐hydroxyethyl methacrylate) (PHEMA) and poly(ethylene oxide) (PEO). PHEMA acts as a fixed phase and PEO as a switching phase. The switching action of PEO is due to the reversible process of melting and crystallization. It was observed that the shape recovery of the IPN increases with increasing crosslinker concentration up to an optimum value and decreases thereafter. In addition to the shape memory property, the IPNs show a reversible change in optical properties from translucent to opaque. The change in optical properties is quite different from that observed in a semicrystalline polymer system where the transparency increases as a result of the melting of crystals. This behaviour of the IPN is explained in terms of H‐bonding of PEO with PHEMA. Fourier transform infrared spectroscopy was used to study the H‐bonding between PEO and PHEMA. © 2019 Society of Chemical Industry Interpenetrating polymer network based shape memory polymers with reversible change in optical properties from translucent to opaque were prepared for the first time using poly(2‐hydroxyethyl methacrylate) and poly(ethylene oxide). [ABSTRACT FROM AUTHOR]

Paraffin, the most common phase change material, has been widely utilized as the core component in thermal energy storage in the form of microcapsules. In this study, semi-crystalline paraffin is capsulated into a poly(urea-formaldehyde) (PUF) shell by a two-step polymerization process. To obtain the microcapsule with good morphology and high latent heat, sodium chloride and crosslinker (a mixture of ammonium chloride and resorcinol with a weight ratio of 1:1) are incorporated and their addition amounts were optimized through differential scanning calorimetry (DSC) and SEM. The optimized microcapsules were obtained by adding 4 wt% sodium chloride, and 0.25 wt% crosslinker exhibits a diameter of several microns and a melting enthalpy of 110 J/g. This detailed study shows that sodium chloride strongly affects the morphology of paraffin emulsion by enlarging droplets, widening the size distribution, and enhancing the stability, which should be attributed to the enhancement of electric double layer strength. In addition, sodium chloride can weaken the Zeta potential of prepolymer and provides more opportunity for prepolymer to deposit on the surface of emulsion droplets. The two components in crosslinker play different roles in the polymerization process. Ammonium chloride reacts with prepolymers and reduces the pH of system, which can accelerate the curing process, while resorcinol probably participates in polymerization as a comonomer. [ABSTRACT FROM AUTHOR]

Locust bean milling dust (LBMD) is an agrifood byproduct rich in proteins and polysaccharides able to form hydrophilic, flexible, and antioxidant bioplastics. Aiming a broad application for LBMD-based bioplastics, in this work, it was hypothesized that glycerol, milled eggshells, or genipin amount fine-tuning can originate rigid and hydrophobic antioxidant LBMD-based materials. With 20 g/100 g glycerol, the films became more 10-fold stiff (Young's modulus of 253 MPa), 1.7-fold hydrophobic (water contact angle of 109°), and 22-fold resistant to water vapor (5 pg/Pa.s.m) than pristine films (Young's modulus of 26 MPa, water contact angle of 64°, and water vapor permeability of 109 pg/Pa.s.m), keeping their yellowish color and transparency. Apart from stiffness that did not change, this profile was also evidenced when 1 g/100 g milled eggshells were incorporated, increasing hydrophobicity 1.5 times and decreasing water vapor permeability 1.6 times. The use of 0.03 g/100 g genipin conferred a blue color to LBMD-based bioplastics and more 5-fold rigidity, 1.7-fold hydrophobicity, and 2.2-fold water vapor barrier. Therefore, rigid, water tolerant, and antioxidant LBMD-based bioplastics can be developed by tailoring glycerol, milled eggshells, or genipin amount, with 20 g/100 g glycerol or 0.03 g/100 g genipin as best conditions to improve these features. [Display omitted] • Locust bean milling dust (LBMD) gives rise to flexible and antioxidant bioplastics. • 20 g/100 g glycerol originates the most hydrophobic and stiff LBMD-based films. • Eggshells increase the water tolerance of LBMD-based films. • LBMD protein-genipin networks increase the films hydrophobicity and stiffness. • LBMD blended with glycerol, eggshells, or genipin originates antioxidant bioplastics [ABSTRACT FROM AUTHOR]

Crosslinked chitosan (CS) is one of the most useable hydrogels in biomedicine and tissue engineering. Unlike most chitosan crosslinkers that are toxic, such as glutaraldehyde, vanillin is a natural, biocompatible, and antimicrobial alternative. The crosslinking of chitosan and vanillin consists of Schiff base bonds between the amines of chitosan and the aldehydes of vanillin, in addition to hydrogen bonds formed across the network. In most studies, the combination of chitosan and vanillin has been investigated in small sizes (micro/nanoscale and biofilms). In this study, a chitosan-vanillin (CV) hydrogel was studied on a macroscale with a three-dimensional porous structure, and it was compared with chitosan crosslinked with glutaraldehyde (CG) on the same scale. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (FE-SEM) used to identify the bonds formed and examine the morphology of the hydrogels. The gel content, swelling, porosity, mechanical properties, cell viability (on L929 and mesenchymal cells), and antibacterial activity (against Escherichia coli and Staphylococcus aureus) of the samples were investigated. The results showed that the CV had both gel content and high porosity (>90%), with an interconnected porous network of uniform pore size. The CV hydrogel exhibited good antibacterial activity and cell viability. In terms of mechanical properties, CV has weaker mechanical properties compared to CG in the dry state, while the mechanical properties of CV have more improved in the swollen state compared to CG. [ABSTRACT FROM AUTHOR]

Here we synthesize a waterproof cross-linked gasochromic thin film obtained by incorporating Prussian blue nanoparticles, polyvinyl alcohol, crosslink agent: 3-glycidoxypropyltrimethoxysilane and catalytic platinum nanoparticles, applied by a single coating and heat process onto a substrate. The cross-linked polyvinyl alcohol-Prussian blue (PVA-PB) films reveal an excellent hydrophilic character. The contrast ratio at 700 nm reaches 87.2. The cycle stability exceeds 200 cycles. The switching time from deep blue to transparency took 14.3 s for bleaching and 600 s for darkening. Surface electron microscopy, electrochemical analysis and Fourier-transform IR spectroscopy were used to investigate a series of waterproof Prussian blue films. The results showed the redox mechanism between polymer matrix, chrome and catalytic nanoparticles. [Display omitted] • Waterproof gasochromic thin film with Prussian blue nanoparticles. • Applied in a single coating and heat process onto a substrate. • Excellent hydrophilic properties with high contrast ratio and cycle stability. • Investigated redox mechanism between polymer matrix, chrome, and catalytic nanoparticles. [ABSTRACT FROM AUTHOR]

ABSTRACT Galectin-4, a tandem repeat member of the β-galactoside-binding proteins, possesses two carbohydrate-recognition domains (CRD) in a single peptide chain. This lectin is mostly expressed in epithelial cells of the intestinal tract and secreted to the extracellular. The two domains have 40% similarity in amino acid sequence, but distinctly binding to various ligands. Just because the two domains bind to different ligands simultaneously, galectin-4 can be a crosslinker and crucial regulator in a large number of biological processes. Recent evidence shows that galectin-4 plays an important role in lipid raft stabilization, protein apical trafficking, cell adhesion, wound healing, intestinal inflammation, tumor progression, etc. This article reviews the physiological and pathological features of galectin-4 and its important role in such processes.

Biomolecule immobilization has attracted the attention of various fields such as fine chemistry and biomedicine for their use in several applications such as wastewater, immunosensors, biofuels, et cetera. The performance of immobilized biomolecules depends on the substrate and the immobilization method utilized. Electrospun nanofibers act as an excellent substrate for immobilization due to their large surface area to volume ratio and interconnectivity. While biomolecules can be immobilized using adsorption and encapsulation, covalent immobilization offers a way to permanently fix the material to the fiber surface resulting in high efficiency, good specificity, and excellent stability. This review aims to highlight the various covalent immobilization techniques being utilized and their benefits and drawbacks. These methods typically fall into two categories: (1) direct immobilization and (2) use of crosslinkers. Direct immobilization techniques are usually simple and utilize the strong electrophilic functional groups on the nanofiber. While crosslinkers are used as an intermediary between the nanofiber substrate and the biomolecule, with some crosslinkers being present in the final product and others simply facilitating the reactions. We aim to provide an explanation of each immobilization technique, biomolecules commonly paired with said technique and the benefit of immobilization over the free biomolecule.

Muscovite mica with an amino silane-modified surface is commonly used as a substrate in atomic force microscopy (AFM) studies of biological macromolecules. Herein, the efficiency of two different protein immobilization strategies employing either (N-hydroxysuccinimide ester)-based crosslinker (DSP) or benzophenone-based photoactivatable crosslinker (SuccBB) has been compared using AFM and mass spectrometry analysis. Two proteins with different physicochemical properties—human serum albumin (HSA) and horseradish peroxidase enzyme protein (HRP)—have been used as model objects in the study. In the case of HRP, both crosslinkers exhibited high immobilization efficiency—as opposed to the case with HSA, when sufficient capturing efficiency has only been observed with SuccBB photocrosslinker. The results obtained herein can find their application in commonly employed bioanalytical systems and in the development of novel highly sensitive chip-based diagnostic platforms employing immobilized proteins. The obtained data can also be of interest for other research areas in medicine and biotechnology employing immobilized biomolecules.

Star-shaped cyclophosphazene (ACP) was employed as covalent crosslinker to form a rigid segment in polyurethanes network, to enhance the mechanical performance and to add extra flame retardant property. The effects of different ACP contents on the shape memory ability and fire resistance performance of polyurethane (PU) were studied. Tensile tests suggested high flexibility of the PUs with the maximum elongation-at-break of 161.59%. Dynamic mechanical analysis (DMA) indicated good shape recovery ratio of 72.58% after more than three repeated cycles. Under thermal treatment, the temporary shape could recover to its original state in 10 s. The peak heat release rate (pHRR), total heat released (THR) and temperature at pHRR (Tp) of flame-retardant shape memory polyurethane (FSPU) by micro-combustion calorimeter (MCC) was as low as 183.2 W/g, 21.4 KJ/g, 330.8 °C respectively, suggesting good inherent fire-resistant performance. As amine-containing crosslinkers are one of the most common building units in thermosetting polymers, we anticipate that our finding will have significant benefits beyond shape memory and fire-resistance.

Polyurethanes (PUs) from Polyethylene glycol (PEG) and polycaprolactone diol (PCL) and a crosslinker, Pentaerythritol (PE), were synthetized with isophorone diisocyanate (IPDI). In this study, we investigated the effect of polyol and crosslinker composition on phase separation and thermo-mechanical properties. The properties were studied through dynamic mechanical analysis, X-ray scattering, atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The results showed changes in PUs properties, microphase structure, and separation due to the composition of polyol/crosslinker blend. So, the largest concentration of PE produced multimodal loss factor patterns, indicating segment segregation while PUs with a PEG/PCL = 1 displayed a monomodal loss factor pattern, indicating a homogeneously distributed microphase separation. Additionally, the increase of the PEG concentration enhanced the damping capacity. On the other hand, agglomeration and thread-like structures of hard segments (HS) were observed through AFM. Finally, the thermal behavior of PUs was affected by chemical composition. Lower concentration of PE reduced the crosslinking; hence, the temperature with the maximum degradation rate.

A molecularly imprinted polymers (MIP) can be synthesized using functional monomers and template molecules through polymerization with the aid of cross linker. In previous studies, MIP_TFMAA-co-EGDMA was synthesized using the main ingredient tryfluoromethylacrylic acid (TFMAA) as functional monomer, b-sitosterol as a template molecule and ethyleneglycol dimethacrylate (EGDMA) as cross linker. The ability of adsorption against the effects of pH and contact Time of MIP has been evaluated. Variations of pH standard solution b-sitosterol were 4, 5, 6, and 7, while the time variation used were 30, 60, 90, and 120 minutes. The data of b- sitosterol concentrations adsorbed by MIP_TFMAA-co-EGDMA because of the influence of pH and contact times were analyzed using high pressure liquid chromatography (HPLC). pH5 gives the most influence on the adsorption capacity MIP_TFMAA-co-EGDMA against b-sitosterol. The number of b-sitosterol adsorbed on the pH was 1.0265 mg/g, while at 90 minutes was the best time for the MIP b- sitosterol adsorb as much as 1.3486 mg/g. Based on the adsorption kinetics study, the adsorption ability MIP_TFMAA-co-EGDMA against b-sitosterol in accordance with the pseudo second order kinetic model.

Hydrogels have gained significant attention in scientific communities for their versatile applications, but several challenges need to be addressed to exploit their potential fully. Conventional hydrogels suffer from poor mechanical strength, limiting their use in many applications. Moreover, the crosslinking agents used to produce them are often toxic, carcinogenic, and not bio-friendly. This study presents a novel approach to overcome these limitations by using bio-friendly modified nanocrystalline cellulose as a crosslinker to prepare highly stretchable and tough thermosensitive hydrogels. The surface of nanocrystalline cellulose was modified with 3-methacryloxypropyltrimethoxysilane (MPTS) to obtain modified nanocrystalline cellulose (M-NCC) crosslinker and used during free radical polymerization of thermosensitive N -isopropyl acrylamide (NIPA) monomer to synthesize NIPA/M-NCC hydrogel. The resulting nanocomposite hydrogels exhibit superior mechanical, thermal, and temperature-responsive swelling properties compared to conventional hydrogels prepared with traditional bi-functional N , N '-methylene bis (acrylamide) (MBA) as a crosslinker. The elongation at break, tensile strength, and toughness of the NIPA/M-NCC hydrogels significantly increase and Young's modulus decrease than conventional hydrogel. The designed M-NCC crosslinker could be utilized to improve the mechanical strength of any polymeric elastomer or hydrogel systems produced through chain polymerization., (© 2023 IOP Publishing Ltd.)