Swelling and network parameters of high oil‐absorptive network based on 1‐octene and isodecyl acrylate copolymers

Crosslinked 1‐octene‐isodecyl acrylate copolymers were synthesized and evaluated for oil‐absorbency applications. The copolymer was crosslinked at different concentrations of ethylene glycol diacrylate (EGDA) and EG dimethacrylate (EGDMA) crosslinkers via catalytic initiation or by electron‐beam irradiation at a dose rate 80 kGy. The concentration of both crosslinkers was varied from 0.5 to 2%. The effects of the crosslinking conditions such as crosslinker concentration, method of polymerization and monomer concentrations on the conversion and gel fraction were examined through oil‐ absorption tests using petroleum crude oil. It was found that the oil absorbency was influenced mainly by the degree of crosslinking and the hydrophobicity of the copolymer units. The final equilibrium oil content, volume fraction of the polymer, and swelling capacity were determined at 298 K. The effective crosslinking density, average molecular weight between the crosslinks, and polymer–toluene interaction parameter were determined from stress–strain measurements. The crosslinking efficiencies of EGDA and EGDMA toward copolymers were determined. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 80–91, 2005     

Swelling behavior and diffusion studies of high‐water‐retaining acrylamide/potassium methacrylate hydrogels

Poly(acrylamide‐co‐potassium methacrylate) hydrogels were prepared by free‐radical simultaneous polymerization with aqueous solutions of acrylamide (AAm) and potassium methacrylate (KMA) with a redox initiator. The copolymerization was performed with eight different compositions of KMA at a fixed concentration of oil‐soluble crosslinkers, including 1,4‐butanediol diacrylate and ethylene glycol dimethacrylate (EGDMA). For every composition of AAm/KMA copolymer, the percentage swelling, swelling equilibrium, and diffusion characteristics were investigated. The copolymers were further studied for deswelling properties. The power law relationships of the hydrogels were evaluated for variation in terms of saline concentration. The AAm/KMA copolymers were confirmed by IR spectroscopy. Thermal studies of hydrogels were performed with differential scanning calorimetry and thermogravimetric analysis. EGDMA was found to be a better crosslinker for obtaining higher swelling and deswelling properties for the AAm/KMA hydrogels. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1153–1164, 2005     

Preparation of acrylic copolymers and crosslinking agents and properties as a film

Copolymers of butyl acrylate (BA)‐methyl methacrylate (MMA)‐acrylic acid (AA) and intraparticle crosslinking agents containing N‐methylol acrylamide (NMA) and ethylene glycol dimethacrylate (EGDMA) were prepared by emulsion copolymerization. After that, films were prepared from the mixture of copolymers and the interparticle crosslinking agents. The interparticle crosslinking agents were prepared from hexamethylene diisocyanate and aziridine ethanol. Mixtures of the copolymer and the interparticle crosslinking agent were cast to films and crosslinked in a convection oven. The effects of the contents of the intra/interparticle crosslinking agents were also evaluated. By increasing the contents of EGDMA, roughness of the films was increased because of the effects of EGDMA acting as an intraparticle crosslinking agent. By increasing the contents of the interparticle crosslinking agent, roughness was also increased by the reaction between the copolymers and interparticle crosslinking agent. Tensile strength and water and chemical resistance of the film were increased, whereas elongation of film was decreased by increasing the contents of interparticle crosslinking agents. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Properties of n‐butyl methacrylate copolymer latex films derived from crosslinked latex particles

Films obtained from copolymer latexes of n‐butyl methacrylate (BMA) with a series of crosslinking monomers [i.e., a macromonomer crosslinker (Mac), ethylene glycol dimethacrylate (EGDMA), and aliphatic urethane acrylate] exhibited differences in their tensile properties and swelling behaviors. For P(BMA‐co‐EGDMA) copolymer, a dependence on the initiator type was obtained. It is postulated that the network microstructures for the various copolymers evolved as the result of the copolymerization reactions between the monomer pairs during the synthesis in the miniemulsion free‐radical copolymerization. These network microstructures are, therefore, hypothesized to influence the mechanical properties of the resultant films. Copolymers prepared with Mac were tough in comparison with copolymers made with EGDMA. The presence of longer linear or lightly crosslinked poly(n‐butyl methacrylate) (PBMA) chains and the looseness of the crosslinked network structures in the PBMA‐co‐Mac copolymers appear to be the factors responsible for the differences. All of the copolymer films disintegrated into swollen individual microgels when they were immersed in tetrahydrofuran. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 42–49, 2003     

HEMA/NVP共聚水凝胶的合成与性能

以甲基丙烯酸2-羟乙酯(HEMA)和N-乙烯基吡咯烷酮(NVP)为原料,偶氮二异丁腈为引发剂,二甲基丙烯酸乙二醇酯(EGDMA)为交联剂,采用溶液聚合法合成HEMA／NVP共聚水凝胶。对其进行了红外光谱分析,考察了交联剂用量(EGDMA)和NVP用量等对该水凝胶材料性能的影响,研究表明该水凝胶具有良好的力学性能与合适的含水量,是一种性能良好的人工角膜材料。     

Swelling and mechanical properties of crosslinked hydrogels containing N-vinylpyrrolidone

Copolymers of 2-hydroxyethyl methacrylate/N-vinyl-2-pyrrolidone (HEMA/NVP) and methyl methacrylate (MMA)/NVP were prepared in the presence of varying amounts of ethylene glycol dimethacrylate (EGDMA) and methylene diacrylamide (MDA) as crosslinkers by photopolymerisation. The resultant solid polymers were swollen to equilibrium in water at 293 K to produce hydrogels. These hydrogels were characterised by soluble fraction and equilibrium water content. The gels were also characterised by compression—strain measurements, which enabled the calculation of Young's modulus and effective crosslink density. The differences in these properties of HEMA/NVP and MMA/NVP polymer series and the effects of MDA versus EGDMA as a crosslinker were explained in terms of compositional drift of polymerisation, heterogeneous crosslinking and hydrophilicity/hydrophobicity of the components involved. In comparison with EGDMA, MDA was found to be more effective in reducing the soluble fraction of the polymers studied and to produce less rigid networks when swollen.     

Effect of crosslinkers on size and temperature sensitivity of poly(N-isopropylacrylamide) microgels

In this work, we study the effect of crosslinkers on the size and swelling properties of temperature sensitive N-isopropylacrylamide (NIPAAm) microgels produced by dispersion polymerization. The crosslinkers studied were N,N′-methylenebisacrylamide (MBA), ethylene glycol dimethacrylate (EGDMA) an 3,9-divinyl-2,4,8,10-tetra-oxaspiro[5.5] undecane (DVA). The type of crosslinker had a major impact on the size and swelling behavior, although the proportion of crosslinker used in each case was low (maximum 5 mol%). The effect can be related to the hydrophilic/hydrophobic characteristics of the crosslinkers. DVA produces smaller hydrogels with reduced swelling ratio, MBA produces bigger microgels with higher swelling ratio, while EGDMA results in an intermediate behavior. With increasing amount of crosslinker used in the synthesis, the extent of the swelling ratio decreases for DVA and EGDMA crosslinked microgels, while increases for MBA crosslinked microgels. There is also a slight effect on the critical transition temperature (T _c) of the microgels from 30 °C (DVA) to 34 °C (MBA) as observed in copolymers of NIPAAm with hydrophilic or hydrophobic comonomers.     

Polymeric absorbent for water sorption based on chemically crosslinked poly (acrylamide/2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt) hydrogels

Summary Swelling equilibrium of polyelectrolyte copolymer gels containing of acrylamide (AAm) and 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPS) have been studied as a function of copolymer composition. AAm/AMPS hydrogels were prepared by free radical solution polymerization in aqueous solution of AAm with AMPS as anionic comonomer and two multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and trimethylolpropane triacrylate (TMPTA). Swelling experiments were performed in water at 25 °C, gravimetrically. The influence of AMPS content in hydrogels was examined. Swelling of AAm/AMPS hydrogels was increased up to 1018% (for containing 2% AMPS and crosslinked by EGDMA) 15246% (for containing 8% AMPS and crosslinked by TMPTA), while AAm hydrogels swelled up to 804% (crosslinked by TMPTA)–770% (crosslinked by EGDMA). The values of equilibrium water content of the hydrogels are 0.8851–0.9935. Diffusion behavior was investigated. Water diffusion into hydrogels was found to be non-Fickian in character.     

Behaviors of Chemically Crosslinked CAAMPS Hydrogels in Uptake of Uranyl Ions from Aqueous Solutions

Uranyl ion adsorption from aqueous solutions has been investigated by chemically crosslinked (C) polyelectrolyte acrylamide/2-acrylamido-2-methyl-1-propanesulfonic acid (CAAMPS) hydrogels. CAAMPS hydrogels with various compositions were prepared from ternary mixtures of acrylamide (A), 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), and water by free radical polymerization in an aqueous solution using multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and 1,4 butanediol dimethacrylate (BDMA). The swelling equilibrium of polyelectrolyte copolymer gels containing of CAAMPS hydrogels has been studied as a function of copolymer composition. Swelling experiments were performed in water at 25°C, gravimetrically. The influence of AMPS content in hydrogels was examined. The weight-swelling ratio of CAAMPS hydrogels was increased up to 127.03 (for 300 mg AMPS and crosslinked by EGDMA) and 93.32 (for 300 mg AMPS and crosslinked by BDMA), while acrylamide hydrogels swelled up to 10.27 (crosslinked by EGDMA) and 10.06 (crosslinked by BDMA). Uranyl ion adsorption from aqueous solutions was studied by batch sorption technique at 25°C. The effect of uranyl ion concentration and mass of AMPS on the uranyl ion adsorption were examined. In the experiments of the sorption, L type sorption in the Giles classification system was found. Finally, the amount of sorbed uranyl ion per gram of dry hydrogel (q) was calculated to be 0.67 × 10^?3–2.11 × 10^?3 mol uranyl ion per gram for CAAMPS hydrogels. Removal effiency of uranyl ions (RE%) was changed range 9.05–29.92%. The values of partition ratio, (K _d ) of uranyl ions was calculated to be 0.10–0.43 for CAAMPS hydrogels.     

Biodegradability of poly(ethylene terephthalate) copolymers with poly(ethylene glycol)s and poly(tetramethylene glycol)

Poly(ethylene terephthalate) copolymers were prepared by melt polycondensation of dimethyl terephthalate and excess ethylene glycol with 10–40mol% (in feed) of poly(ethylene glycol) (E) and poly(tetramethylene glycol) (B), with molecular weight (MW) of E and B 200–7500 and 1000, respectively. The reduced specific viscosity of copolymers increased with increasing MW and content of polyglycol comonomer. The temperature of melting (T_m), cold crystallization and glass transition (T_g) decreased with the copolymerization. T_m depression of copolymers suggested that the E series copolymers are the block type at higher content of the comonomer. T_g was decreased below room temperature by the copolymerization, which affected the crystallinity and the density of copolymer films. Water absorption increased with increasing content of comonomer, and the increase was much higher for E1000 series films than B1000 series films. The biodegradability was estimated by weight loss of copolymer films in buffer solution with and without a lipase at 37°C. The weight loss was enhanced a little by the presence of a lipase, and increased abruptly at higher comonomer content, which was correlated to the water absorption and the concentration of ester linkages between PET and PEG segments. The weight loss of B series films was much lower than that of E series films. The abrupt increase of the weight loss by alkaline hydrolysis is almost consistent with that by biodegradation.     

Adsorption of Cr(VI) ions onto poly(ethylene glycol dimethacrylate‐1‐vinyl‐1,2,4‐triazole)

Poly(ethylene glycol dimethacrylate‐1‐vinyl‐1,2,4‐triazole) [poly(EGDMA‐VTAZ)] beads (average diameter = 150–200 μm) were prepared by copolymerizing ethylene glycol dimethacrylate (EGDMA) with 1‐vinyl‐1,2,4‐triazole (VTAZ). Poly(EGDMA‐VTAZ) beads were characterized by swelling studies and scanning electron microscope (SEM). The adsorption of Cr(VI) from solutions was carried at different contact times, Cr(VI) concentrations, pH, and temperatures. High adsorption rates were achieved in about 240 min. The amount of Cr(VI) adsorbed increased with increasing concentration and decreasing pH and temperature. The intraparticle diffusion rate constants at various temperatures were calculated. Adsorption isotherms of Cr(VI) onto poly(EGDMA‐VTAZ) have been determined and correlated with common isotherm equations such as Langmuir and Freundlich isotherm models. The Langmuir isotherm model appeared to fit the isotherm data better than the Freundlich isotherm model. The pseudo first‐order kinetic model was used to describe the kinetic data. The study of temperature effect was quantified by calculating various thermodynamic parameters such as Gibbs free energy, enthalpy, and entropy changes. The dimensionless separation factor (R_L) showed that the adsorption of metal ions onto poly(EGDMA‐VTAZ) was favorable. It was seen that values of distribution coefficient (K_D) decreasing with Cr(VI) concentration in solution at equilibrium (C_e) indicated that the occupation of activate surface sites of adsorbent increased with Cr(VI). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Kinetics of silane grafting and moisture crosslinking of polyethylene and ethylene propylene rubber

Peroxide initiated graft copolymerization of vinyl trimethoxy silane (VTMO) and vinyl triethoxy silane (VTEO) onto polyethylene (PE) and ethylene propylene copolymer (EPR) was studied. The kinetics of grafting, studied by differential scanning calorimetry, are the same for all the systems and the activation energy for VTMO is 170 ± 4 KJ/mol. Activation energy for VTEO is 185 ± 5 KJ/mol. The VTMO and VTEO graft copolymers of PE and EPR were prepared by reactive processing in a Brabender extruder in the temperature range of 150–200°C. Moisture catalyzed crosslinking of the silane grafted copolymer was also studied. The influence of the structure of the catalyst, its concentration, moisture concentration, temperature, and time on degree and rate of crosslinking has been evaluated. Crosslinking reactions follow first order kinetics with respect to both catalyst and moisture concentration. Activation energy (E_a) of the crosslinking reaction has been determined as 65 KJ mol^?1. The mechanism of grafting and crosslinking is discussed.     

Dynamic and equilibrium swelling studies: crosslinked pH sensitive methyl methacrylate-co-itaconic acid (MMA-co-IA) hydrogels

In the present work crosslinked methyl methacrylate-co-itaconic acid (MMA-co-IA) hydrogels were prepared by free radical copolymerization of methyl methacrylate (MMA) with itaconic acid (IA) using ethylene glycol dimethacrylate (EGDMA) and N, N methylene bisacrylamide (MBAAm) as crosslinkers and benzoyl peroxide as initiator. Prepared hydrogels were investigated for dynamic and equilibrium swelling studies. For swelling behaviour, effect of pH, monomeric compositions, degree of crosslinking and type of crosslinking agent were investigated. Swelling studies were performed in the USP phosphate buffer solutions of varying pH 1.2, 4.5, 5.5, 6.5 and 7.0. Results showed that swelling increased by increasing IA content in hydrogels structure. This may be due to the presence of more carboxylic groups available for ionization. Swelling was decreased with increase in crosslinking ratio owing to tighter hydrogel structure. Hydrogels were characterized by Fourier transform infrared (FTIR), and scanning electron microscope (SEM). Polymer-solvent interaction parameters (χ) of hydrogels were determined by using Flory–Rehner theory of equilibrium swelling values. The analysis of diffusion mechanism from gels using Peppas model showed that all monomeric compositions and degrees of crosslinking followed Fickian diffusion.     

Synthesis, characterization and evaluation of amphiphilic star copolymeric emulsifiers based on methoxy hexa(ethylene glycol) methacrylate and benzyl methacrylate

Amphiphilic star copolymers were synthesized by sequential monomer and cross-linker additions using group transfer polymerization (GTP). Benzyl methacrylate (BzMA) and methoxy hexa(ethylene glycol) methacrylate (HEGMA) served as the hydrophobic and hydrophilic monomers, respectively, whereas the also hydrophobic ethylene glycol dimethacrylate (EGDMA) was used as the cross-linker. In total, twelve star copolymers were prepared, covering three different overall hydrophobic compositions, 39, 53 and 70% w/w, and four different architectures, AB star-block, BA star-block, heteroarm star and random star. The theoretical molecular weight of each arm was kept constant at 5000 g mol⁻¹. The molecular weights and molecular weight distributions of the linear precursors and of all the star copolymers were characterized by gel permeation chromatography (GPC) in tetrahydrofuran (THF), while their compositions were confirmed by proton nuclear magnetic resonance (¹H NMR) spectroscopy. Moreover, all the star copolymers were characterized by static light scattering (SLS) in THF to determine the absolute weight-average molecular weight, M_w, and the weight-average number of arms. After polymer characterization, xylene-water and diazinon (pesticide)-water emulsions were prepared using these star copolymers as stabilizers at 1% w/w copolymer concentration and at different overall organic phase/water ratios. The most important factor in determining the emulsion type was the star copolymer composition in hydrophobic units. The four most hydrophilic star copolymers (39% w/w hydrophobic composition) always formed o/w emulsions, while the four most hydrophobic star copolymers (70% w/w hydrophobic composition) always formed w/o emulsions. The type of the emulsion in the case of the star copolymers with the more balanced composition, 53% w/w hydrophobic units, also depended on the emulsion content in the organic solvent, similar to particulate-stabilized emulsions. Considering that the best o/w emulsifier is that star copolymer which can emulsify the largest quantity of organic phase in water resulting in low viscosity, o/w emulsions without excess oil or water phase, it appeared that the most hydrophilic random copolymer star is the optimal emulsifier. Moreover, this star copolymer presented the smallest droplet size in its emulsions. It is also noteworthy that the resulting emulsions almost never had high viscosity, a feature attributable to the compact nature of star polymers.     

ABA triblock copolymers from poly(p‐dioxanone) and poly(ethylene glycol)

Poly(p‐dioxanone)–poly(ethylene glycol)–poly(p‐dioxanone) ABA triblock copolymers (PEDO) were synthesized by ring‐opening polymerization from p‐dioxanone using poly(ethylene glycol) (PEG) with different molecular weights as macroinitiators in N₂ atmosphere. The copolymer was characterized by ¹H NMR spectroscope. The thermal behavior, crystallization, and thermal stability of these copolymers were investigated by differential scanning calorimetry and thermogravimetric measurements. The water absorption of these copolymers was also measured. The results indicated that the content and length of PEG chain have a greater effect on the properties of copolymers. This kind of biodegradable copolymer will find a potential application in biomedical materials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1092–1097, 2006     

Controlled release of perfumes from polymers. II. Incorporation and release of essential oils from glassy polymers

Release of essential oils from glassy hydrophilic copolymers of 2-hydroxyethyl methacrylate (HEMA) and ethylene glycol dimethacrylate (EGDMA) was studied in a range of releasing media at 30°C. The release of carvone, limonene, and eugenol was investigated using swelling-controlled release systems based on these copolymers. By changing the crosslinking ratio of the copolymers it was possible to achieve zero-order release. The amount of essential oil release was correlated to the thermodynamic compatibility of the oil-polymer pair, as judged by the solubility parameter difference. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 509–513, 1997     

Synthesis and characterization of oil sorbers based on docosanyl acrylate and methacrylates copolymers

Docosanyl acrylate (DCA) monomer was copolymerized with different monomer feed ratios of cinnamoyloxy ethyl methacrylate (CEMA) or methyl methacrylate (MMA) monomer to produce different compositions for DCA/CEMA or DCA/MMA copolymer with low conversions.¹H NMR spectroscopy was used to confirm the copolymer structure. DCA was crosslinked with different mol % of CEMA or MMA using dibenzoyl peroxide as initiator and various weight percentages of either 1,1,1‐trimethylolpropane triacrylates or 1,1,1‐trimethylolpropane trimethacrylates crosslinkers. The effects of monomer feed composition, crosslinker concentration, and the hydrophobicity of the copolymer units on swelling properties of the crosslinked polymers were studied through the oil absorbency tests. The network parameters, such as polymer solvent interaction (χ), effective crosslink density (υ_e), equilibrium modulus of elasticity (G_T), and average molecular weight between crosslinks (M_c), were determined and correlated with the structure of the synthesized copolymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Characterization and comparison of diblock and triblock amphiphilic copolymers of poly(δ‐valerolactone)

Three types of pegylated amphiphilic copolymers of poly(δ‐valerolactone) (PVL) were copolymerized with methoxy poly(ethylene glycol) (MePEG) and poly(ethylene glycol) (PEG₄₀₀₀ and PEG_10,000), respectively. Pegylation of PVL allowed copolymers possessing amphiphilic property and efficiently self‐assembled to form micelles with a low critical micelle concentration (CMC) in the range of 10^?7–10^?8M. The average molecular weight of copolymers was in the range of 10,000–20,000 Da, and the polydispersity of copolymers was about 1.7–1.8. Higher mobility of low molecular weight PEG (i.e., MePEG and PEG₄₀₀₀) than high molecular weight PEG_10,000 allowed valerolactone ring opening more efficient in terms of PVL/MePEG and PVL/PEG₄₀₀₀ copolymers possessing longer chain length in hydrophobic domain. Pegylated PVL with low CMC and triblock structure was preferred to encapsulate drug during micelle formation. Although all of these amphiphilic copolymers exhibited controlled release character, the micelles formed by triblock copolymer possessed a more stable core‐shell conformation than that by diblock copolymer, and resulted in the release of drug from triblock micelles slower than that from diblock micelles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1836–1841, 2006     

Miniemulsion copolymerization of n‐butyl methacrylate with crosslinking monomers

Miniemulsion copolymerization of n‐butyl methacrylate and crosslinking monomers such as a macromonomer crosslinker (Mac), ethylene glycol dimethacrylate (EGDMA), or an aliphatic urethane acrylate macromonomer (AUA) was utilized to obtain crosslinked latex particles. The crosslinking monomers were added at 0.2 mol %, on the basis of the amount of n‐butyl methacrylate utilized in a polymerization. The development of the gel content during the copolymerization reaction differs depending on the type of the crosslinking monomer. In addition to the crosslinking reactions between the n‐butyl methacrylate and the crosslinking monomers, other kinetic events, such as microphase separation, may have occurred, giving rise to different particle morphologies, dependent on the type of initiator used (i.e., oil‐soluble or water‐soluble). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1721–1730, 2001     

Synthesis and evaluation of biodegradable segmented multiblock poly(ether ester) copolymers for biomaterial applications

Based on 1,4‐succinic acid, 1,4‐butanediol, poly(ethylene glycol)s and dimethyl terephthalate, biodegradable segmented multiblock copolymers of poly[(butylene terephthalate)‐co‐poly(butylene succinate)‐block‐poly(ethylene glycol)] (PTSG) were synthesized with different poly(butylene succinate) (PBS) molar fractions and varying the poly(ethylene glycol) (PEG) segment length, and were evaluated as biomedical materials. The copolymer extracts showed no in vitro cytotoxicity. However, sterilization of the copolymers by gamma irradiation had some limited effect on the cytotoxicity and mechanical properties. A copolymer consisting of PEG‐1000 and 20 mol% PBS, assigned as 1000PBS20 after SO₂ gas plasma treatment, sustained the adhesion and growth of dog vascular smooth muscle cells. The in vivo biocompatibility of this sample was also measured subcutaneously in rats for 4 weeks. The assessments indicated that these poly(ether ester) copolymers are good candidates for anti‐adhesion barrier and drug controlled‐release applications. Copyright © 2004 Society of Chemical Industry