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In this study, a series of crosslinked waterborne polyurethane/acrylate copolymer latexes with different compositions were fabricated via emulsion polymerization using oil-soluble initiator (AIBN) based on a solvent-/emulsifiers-free method. Using the blend of styrene (St), butyl acrylate (BA) and crosslinkers (pentaerythritol triacrylate (PET3A) and pentaerythritol tetraacrylate (PET4A)) instead of acetone as a diluent and modifier, polyurethane prepolymers terminated with hydroxyethyl acrylate composite emulsions were prepared using polypropylene glycol (PPG), toluene diisocyanate (TDI), 2,2-dihydroxymethylpropionic acid (DMPA) and diethylene glycol (DEG) without other solvents. It was found that for all the emulsion polymerization of waterborne polyurethane and acrylates initiated by AIBN, the monomer conversions exceeded 96% when the concentration of AIBN was in the range of 0.5% to 0.9% (w/w) and the optimal reaction temperature was 75 °C. The introduction of St, BA and crosslinkers would form the polymer network, improving the tensile strength, water absorption of the copolymer latex films. Dynamic light scattering analyses showed that the copolymer latexes exhibited a unimodal distribution and showed no precipitates and unstable aggregates. The average particle size distribution was in the range of 131–154 nm. Transmission electron microscopy studies have confirmed the similar results and the latex particles possessed the core–shell morphology structure. [ABSTRACT FROM AUTHOR]

Cyclodextrin nanosponges are solid nanoparticles, designed by cross-linking of cyclodextrin polymer; it has been used widely as a good delivery system for water insoluble drugs. The aim of this study is to enhance the solubility of Piroxicam (PXM) using β-Cyclodextrin based nanosponges formulations. PXM nanosponge (PXM-NS) formulations were prepared using β-cyclodextrin and carbonyldiimidazole as a cross linker, three ratios of β-cyclodextrin to crosslinker in addition to three drug to nanosponges ratios were tested. Piroxicam nanosponge formulations were characterized for its particle size, zeta potential, physical compatibility and in vitro release. Stability studies at three temperatures (4 °C, 25 °C and 40 °C) were done for optimal formula. Finally, the in vivo analgesic activity and pharmacokinetic parameters of the optimal formula were conducted. The optimized PXM-NS formula (PXM-NS10) showed particle size (362 ± 14.06 nm), polydispersity index (0.0518), zeta potential (17 ± 1.05 mV), and %EE (79.13 ± 4.33). The dissolution study showed a significant increase in the amount of PXM dissolved compared with the unformulated drug. Stability studies confirmed that nanosponge showed accepted stability for 90 days at 4 °C and 25 °C. In vivo analgesic studies verified that there was a significant enhancement in the analgesic response to PXM in mice, and 1.42 fold enhancement in the relative bioavailability of PXM-NS10 as compared to commercial tablets. Nanosponge prepared under optimal conditions is an encouraging formula for increasing the solubility and therefore the bioavailability of Piroxicam. [ABSTRACT FROM AUTHOR]

It has become crucial to develop new adsorbents to remove toxic dye wastes from wastewater to protect our existing aquatic ecosystem. Here, to remove methyl orange azo dye from aqueous solutions, a new p(HEMA-co-AETAC)/VMt nanocomposite hydrogel was prepared by using 2-hydroxyethyl methacrylate and [2-(acryloyloxy)ethyl]trimethylammonium chloride monomers using vinyl-based montmorillonite crosslinker. Obtained new types of crosslinker and nanocomposite hydrogels have been characterized by various analysis methods. In addition, the effects of crosslinker amount, monomer amount and pH on the swelling behavior of nanocomposite hydrogel were investigated. The effects of essential parameters such as contact time, initial dye concentration, pH effect of the solution, adsorbent amount, and temperature on adsorption were evaluated. It was determined that there was no significant change in the adsorption ability of the nanocomposite hydrogel in the pH range of 3–10. Experimental results showed that the Langmuir isotherm model fit better, and the calculated maximum adsorption capacity was 961.54 mg/g. In addition, it was determined that vinyl-based montmorillonite used as a crosslinker supported MO adsorption. p(HEMA-co-AETAC)/VMt nanocomposite hydrogel may be a new type of adsorbent to remove toxic synthetic dye residues from aqueous media. A new adsorbent for the removal of toxic synthetic dye residues from aqueous media in a wide range of pH. Hydrogels containing AETAC and HEMA are easily obtained with modified montmorillonite. The adsorption properties of the nanocomposite hydrogel were evaluated with methyl orange dye molecules. According to Langmuir isotherm, the maximum adsorption capacity was determined to be 961.54 mg/g. [ABSTRACT FROM AUTHOR]

Cashmere fiber is pretreated with oxygen low temperature plasma to increase the content of polar groups (-OH, -COOH) on the surface. Then by using aziridine crosslinker and polycarbodiimide crosslinker, the sericin with health-care function is grafted onto the surface of the pretreated cashmere fiber. Plasma treatment is optimized after the assessing of methylene blue staining and fiber tensile strength. The grafting rate of sericin indicates that both aziridine and polycarbodiimide crosslinker could play a bridging role. Compared with untreated fiber, oxygen plasma treatment can improve the grafting rate significantly. The chemical changes and morphological structures of the fiber surface are analyzed by infrared spectroscopy and scanning electron microscope. After modification, cashmere exhibited good antibacterial and antioxidant properties. In addition, the fiber still has excellent dyeability while its crimp property and whiteness are slightly reduced. [ABSTRACT FROM AUTHOR]

Hyaluronan (HA)-based soft-tissue fillers are injectable crosslinked hydrogels aimed to counteract facial skin aging signs via minimally invasive procedures. The crosslinking step is required to drastically improve HA residence time in vivo and provide the gel with specific viscoelastic properties matching the clinical indications. While HA as a raw material and HA fillers are widely studied, little is reported about crosslinkers themselves used in commercial fillers. This article introduces the specifications of the ideal crosslinker in HA fillers. The properties of commercially used crosslinkers are reviewed. An up-to-date review of innovative hydrogel fabrication alternatives is conducted, and advantages and drawbacks are discussed. HA fillers are predominantly manufactured using 1,4-butanediol diglycidyl ether (BDDE) which is considered as the gold standard crosslinker worldwide due to its proven and unrivaled clinical track record of more than 20 years. Extensive studies have been published covering BDDE-crosslinked HA fillers' chemistry, gel properties, and clinical effectiveness and safety. However, new hydrogel fabrication strategies have emerged, paving the way for innovative alternatives potentially bringing novel features to HA fillers. Nevertheless, major efforts must still be implemented to assess their safety, efficacy, stability and suitability for industrialization. [ABSTRACT FROM AUTHOR]

Polymer-dispersed liquid crystal (PDLC) is a striking material that has a great role in optoelectronic display devices. In this paper, PDLC films were prepared by the polymerisation-induced phase separation (PIPS) process under the same curing temperature, UV intensity, and photo-initiator dosage. The morphology and electro-optical properties of PDLC with crosslinker content, the liquid crystal content, and magnetic nanomaterial doping were comprehensively investigated. Different crosslinker and liquid crystal contents changed the crosslinker degree and free radical content in the blends, which changed the polymer network size while changing the electro-optical properties of PDLC. The magnetic nanomaterials dispersed in PDLC established the intrinsic potential and reduced the threshold voltage (24.1 V) and saturation voltage (54.5 V) were obtained at a Fe3O4 NPs doping concentration of 1.0 wt%, which led to a CR of 89.9 and a toff of 14.1 ms. This work provides a feasible method to optimise the electro-optical properties of PDLC and provides the possibility for the wide application of PDLC. [ABSTRACT FROM AUTHOR]

This paper presents the optimization of synthesis of gelatin-coated magnetite nanoparticles (MNPs) and their application as a draw solute in forward osmosis (FO) process. Persicaria bistorta root extract is used as the gelatin crosslinker, and its efficiency is compared with glutaraldehyde as a common crosslinker. Also, the impact of the concentration of gelatin and the draw solution on the osmotic pressure of the produced draw solution has been investigated using response surface methodology. Using Persicaria bistorta root extract as the crosslinker in the optimized conditions, the highest osmotic pressure (1.01 bar) was achieved in a concentration of 7.7%w/v and 14246 mg/l for gelatin and draw solution, respectively. Using glutaraldehyde under the same conditions resulted in osmotic pressure of 1.06 bar which is very close to the pressure found for Persicaria bistorta root extract (1.01 bar), confirming the benefit of the latter as a gelatin crosslinker. Further, using a solution with gelatin-coated MNPs as the draw solution, deionized water as the feed solution, and an osmotic pressure difference of 1.5 in the FO process generated an initial water flux of 1.54 LMH. By repeating the process in nine more cycles, the initial water flux was reduced to 0.365 LMH. These experiments confirm the as-prepared gelatin-MNPs as a promising draw solution in the FO process. [ABSTRACT FROM AUTHOR]

The study is aimed to investigate the thermophysiological comfort properties of shirt linen fabrics subjected to various finishing treatments such as enzymatic, softening and wrinkle-resistant treatments. After finishing treatments, thermal conductivity, thermal resistance, thermal absorbtivity, maximum heat flow, water vapor permeability, and air permeability measurements were carried out. All test results were evaluated statistically in terms of the effects of enzyme and treatment types. According to the findings, all finishing processes provided improvements on the thermal conductivity and thermal resistance values of the linen fabrics and caused higher thermal absorbtivity values and cooler feeling at the first touch to the fabric. The enzyme and treatment types had important effects on maximum heat flow. When the enzyme, softener, and crosslinker were applied to the fabric together, the highest water vapor permeability values were obtained. However, the finishing treatments affected air permeability values negatively due to the high shrinkage feature. As a result, the effects of mostly applied finishing processes on the thermophysiological comfort of shirt linen fabrics were found to be favorable especially for the usage in the summer season. [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]

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]

The aqueous adsorption of a fluorescent dye (pyranine) onto crosslinked chitosan-graphene oxide composite films was studied. In situ fluorescence monitoring technique is introduced as easy and fast experimental technique to select optimal adsorbent conditions. The effect of ionic crosslinker on adsorption was studied with sodium tripolyphosphate, trisodium citrate, and sodium sulfate, respectively. Among the crosslinkers, it was realized that sodium sulfate crosslinked films showed a greater adsorption rate for pyranine than the other two types of crosslinked films. Recently, graphene oxide is of interest as a filler compound for many biopolymer applications due to its favorable thermal, mechanical and surficial properties. In the present study, graphene oxide incorporation increased adsorption rate of the dye and the mechanical strength of ionically crosslinked chitosan films. The adsorption behavior of the adsorbent was explained by a kinetic model. Samples were characterized using scanning electron microscopy, thermogravimetric analysis, swelling experiments and tensile testing method. [ABSTRACT FROM AUTHOR]

Three dimensional (3D) bioplotting requires appropriate crosslinkers to crosslink the hydrogel precursor while simultaneously maintaining the viability of embedded cells. However, the evaluation and comparison of various types of crosslinkers in bioplotting remains underexplored to date. This paper presents our study of the influence of three ionic crosslinkers—calcium chloride (CaCl2), barium chloride (BaCl2), and zinc chloride (ZnCl2)—on the mechanical and biological properties of 3D bioplotted alginate scaffolds. The scaffold mechanical properties characterized included the elastic modulus, swelling, and degradation while the biological properties considered included Schwann cell viability and surface morphology. The mechanical and biological properties of the bioplotted scaffolds were both dependent on the crosslinkers used for fabrication; specifically, crosslinking ions resulted in the elastic modulus of the hydrogels decreasing in the order BaCl2>CaCl2>ZnCl2 over 42 days while Schwann cell viability decreased in the order CaCl2>BaCl2>ZnCl2 over 7 days. Taken together, these results offer insights that are effective in terms of manipulating the 3D bioplotting process so as to tune and optimize the mechanical and biological performance of the plotted scaffolds for tissue engineering applications. [ABSTRACT FROM AUTHOR]

In this work, novel nematic monomer (M1), chiral monomer (M2) and crosslinker (CL) have been synthesised to form a series of side chain chiral liquid crystalline elastomers (ChLCEs) LCE1-LCE7 by graft copolymerisation with poly(methylhydrogeno)siloxane backbone. M1 and M2 were both dimer type with great length, and the chiral 2-octyl terminal group was seldomused in liquid crystal elastomer system. The chemical structures, thermal stability and LC phase behaviours of monomers, crosslinker and ChLCEs were examined by different experimental techniques. The helical structure of combining the chiral and achiral liquid crystalline side chains endowed the obtained ChLCEs with chiral nematic liquid crystalline properties. By changing the dosages of the crosslinker, the mesomorphic properties of ChLCEs could be adjusted. The mesophase-isotropic phase range of the ChLCEs were lightly broadened with increasing addition of CL according to the differential scanning calorimetry (DSC). The synthesised ChLCEs exhibited excellent thermal stability from thermal analysis (TG) results. The effective crosslink density (...c) of the ChLCEs was characterised by swelling experiments showing the molecular weight between the crosslinking points decreasing with the increase of the CL. The FT-IR imaging system indicates the functional groups of all the ChLCEs are well distributed. [ABSTRACT FROM AUTHOR]

A novel approach is presented for the synthesis of thermoresponsive and pH-sensitive magnetic nanohydrogels by using the biodegradable starch-maleate as a crosslinker and magnetic nanoparticles stabilizer. Chemically modified starch-maleate produces highly stable Fe3O4magnetic nanopaticles (MNPs) aqueous dispersion. Then,N-isopropylacrylamide (NIPAAm) and itaconic acid (IA) are successfully polymerized from the vinyl double bonds of the starch-maleate-MNPs to prepare the thermo- and pH-responsive magnetic nanohydrogels. The obtained PNIPAAm-g-(starch-MNPs) and (PNIPAAm-co-IA)-g-(starch-MNPs) nanohydrogels are characterized by transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectrometer, X-ray diffraction, differential scanning calorimetry, thermal gravimetric analysis, and vibrating sample magnetometer. Also, pH- and temperature-responsive behaviors of the synthesized magnetic nanohydrogels are investigated and, finally, the cytotoxicity and drug loading are examined with mitoxantrone (MTX) as an anticancer drug model. The results confirm the low toxicity and enhanced anticancer effect of MTX-loaded magnetic nanohydrogels. [ABSTRACT FROM AUTHOR]

A systematic study was conducted to evaluate the crosslinker and method of incorporation for bovine serum albumin (BSA) into chitosan hybrid scaffolds (CH-ALG) for better cartilage tissue engineering applications. Formaldehyde and sodium tripolyphosphate were used crosslinkers for fabrication of CH-ALG scaffolds using BSA as growth factor by direct incorporation and microencapsulation methods. An in vitro release study of BSA with maximum release (80%) for scaffolds of formaldehyde crosslinked was found. The present findings show that the CH-ALG hybrid scaffolds have been potential use in biomedical applications. [ABSTRACT FROM AUTHOR]

Polyurethane (PU)-based pressure-sensitive adhesive (PSA) has been manufactured by electron beam (e-beam) irradiation using urethane-acrylate. The effect of variation of e-beam dose and crosslinkers viz. triallyl cyanurate (TAC), triallyl isocyanurate, polymeric methylene diphenyl diisocyanate, carbodiimide-modified methylene diphenyl di-isocyanate, methylene diphenyl di-isocyanate, and isophorone di-isocyanate (IPDI) has been studied concerning the shrinkage, adhesion properties, and gel content of the PU-PSA. It was found that with increasing e-beam dose the shrinkage is increased up to 25 kGy, but remained constant thereafter with further increasing the dose up to 60 kGy. Similarly, with increasing concentration of crosslinkers from 2 to 6%, shrinkage is increased but beyond that there is no appreciable change. A comparative study of the effect of different crosslinkers on shrinkage, adhesion properties, and gel content of PU-PSA was carried out, and it was found that TAC leads to the maximum, while IPDI to the lowest shrinkage. However, the opposite was observed for the adhesion properties, i.e. the use of IPDI ensures the maximum and of TAC, the minimum adhesive performance characteristics. [ABSTRACT FROM AUTHOR]

Three series of linear and crosslinked polyurethane urea with heterocyclic triazine moieties in the main chain were synthesized and the films were prepared by casting and thermal curing. The molecular dynamics of the polyurethane urea have been studied by dielectric spectroscopy in the wide frequency range of 100–106Hz and in the temperature range of −100 to 100 °C, by variation of the hard segments structure. Relaxation processes were observed in the dielectric spectra in proximity of the glass transition temperatures. All of the investigated samples showed two local relaxations (γ and β) and a primary relaxation (α), depending on the temperature and frequency range. For crosslinked samples, the α relaxation temperature increases with increasing the amount of crosslinkers. The dangling chains of castor oil (used as crosslinker) lead to the formation of imperfections in the network structure, affecting the relaxation process. It was found that inserting triazine derivatives in the hard segments modified dielectric behavior in comparison with linear chain extenders. [ABSTRACT FROM PUBLISHER]

The orientational order parameters, Szz and Biax, of UB-d4 [1,4-bis(undec-10-en-1-yloxy)benzene-d4 ] in the ZLI1167 nematic mixture are studied by means of 2H NMR at variable temperature. The Szz(T) trend fairly follows the Maier–Saupe theoretical curve; therefore, UB-d4 can be considered an excellent probe to monitor the ordering of the nematic phase itself, provided that Biax is not neglected and the complete analysis of quadrupolar and dipolar splittings is performed. UB-d4 is a typical crosslinker in liquid crystal elastomers (LCEs): the order parameters here collected help us to discuss the peculiarities of the crosslinker as a probe for the study of internal order in LCEs. From the analysis of our data and of data in the literature, we infer that the order parameter Biax of the crosslinker in the LCE matrix is low enough to be neglected without severely perturbing the determination of . The crosslinker UB-d4 is a reliable probe to monitor the nematic order degree inside the LSCE-UB-d4 sample. [ABSTRACT FROM AUTHOR]

Recent advances in drug delivery have been directed towards the design of a number of intelligent systems for the treatment of various diseases. In this regard, we developed novel surfactant-modified hydrogels which are synthesized from acrylamide (AM) and acrylamido propane sulphonic acid (AMPS), in the presence of a surfactant (Latemul PD-104) using ammonium persulfate/N,N,N',N'-tetramethylethylene diamine (APS)/(TMEDA) as an initiating system and N,N'-methylenebisacrlyamide (MBA) as a crosslinker. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The variation in the hydrogel networks formation employing different levels of synthetic parameters was verified by swelling studies. Influences of salt, biological fluids, and buffer solutions on the developed systems were also investigated. It was found that, compared to PAM hydrogel, all the surfactant-modified hydrogels were responsive towards salt concentration and pH. A robust drug release behavior was observed from surfactant-modified hydrogel systems. [ABSTRACT FROM AUTHOR]

A series of acrylamide-potassium methacrylate superabsorbent copolymers were synthesized by simultaneous free radical aqueous polymerization using acrylamide (AAm), potassium methacrylate (KMA), and ammonium persulfate (APS)/ N,N,N′,N′-tetramethylethylenediamine (TMEDA) as initiating system in the presence of a crosslinker. The effects of variables such as concentration of hydrophilic monomer (KMA), crosslinker, initiator and activator, and polymerization temperature on swelling capacity have been investigated in detail. In these polymerizations, two different crosslinking agents, namely 1,4-butanediol diacrylate (BDDA) and ethylene glycol dimethacrylate (EGDMA), were employed to study the effect of crosslinker on swelling properties. The swelling kinetic parameters as well as type of water diffusion into the polymer matrix were evaluated at different temperatures for two series of superabsorbent copolymers. The swelling experiments revealed that EGDMA crosslinked superabsorbents have shown higher swelling capacity for all the compositions of AAm/KMA ratio than BDDA crosslinked analogues. Further, the salt sensitivity and de-swelling capacity of the superabsorbent polymers were studied. The pH effect on the swelling ratio of crosslinked copolymers was also investigated. [ABSTRACT FROM AUTHOR]

Hydrolyzable functional silanes are used as silicone elastomer crosslinkers. The hydrolysis, triggered by air moisture, leads to crosslinking of linear polymer chains to three-dimensional networks. The properties of these elastomers depend on the silane structure. The influence of the structure has been studied for RSi(OR)[sub 3] silanes with R = Me, Et, Pr, Bu, Pentyl (Pe), Vinyl (Vi) and Phenyl (Ph) for hydrolyzable acetoxy or oximino groups. Reactivity differences have been observed. The cure kinetics follows the order Vi > Ph ~ Me > Et > Pr > Bu > Pe leading to a decrease in surface curing rate from Vi to Pe. The cure thermodynamics, i.e. completeness of cure, follows the order Me > Et > Pr > Bu > Pe and Vi > Ph leading to a decrease in the crosslink density from Me to Pe. The lower degrees of cure are related to steric and inductive effects of the functional groups. Oximinosilanes showed a lower reactivity compared to acetoxysilanes, because of a Si—ON bond being more stable than a Si—OAc bond. This also leads to slower surface cure and lower crosslink density. Organometallic tin used for the catalysis of oximinosilane systems gave results similar to organometallic titanium. For acetoxysilane systems, the titanium system was found to be more efficient. Silicone materials tailored to specific requirements can be designed. So the cure rate, release and mechanical properties can be adjusted with the selection of appropriate silanes. [ABSTRACT FROM AUTHOR]

N-isopropylacrylamide (NIPAAm)- and methacryloyl-L-alanine methyl ester (MA-ALa-OMe)-grafted cellulose samples were prepared by photografting on dissolving pulp from softwoods, which was oxidized with periodic acid. The grafted samples exhibited a temperature-responsive character, where they swelled and shrank in water at 0°C and 50°C, respectively. The magnitude of the character increased with an increase in the percentage of grafting, and it was nearly equal between the NIPAAm- and MA-ALa-OMe-grafted samples. The temperature-responsive character of the grafted samples was improved by treating them with crosslinkers such as N,N′-methylenebis-acrylamide and di-ethylene glycol dimethacrylate. The extent of the improvement largely depended on the concentration of crosslinker, temperature of crosslinking treatment, and nature of grafted chains. [ABSTRACT FROM AUTHOR]