Studies of dimethylacrylates as crosslinkers for styrene

Styrene has been thermally copolymerized to low conversions with small quantities of ¹⁴C labelled ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and poly(ethylene glycol) (mol. wt ≈ 400) dimethacrylate. The competition between intramolecular cyclization and intermolecular crosslinking has been examined via studies of intrinsic viscosity, variation of the proportion of the crosslinker reacted at both vinyl groups with conversion, and changes in the polydispersity ratio. These studies indicate that in the early stages of reaction, reductions in intrinsic viscosity are found to be maximum in PEG(400)DM copolymers, followed by TEGDM—styrene copolymers and least in the EGDM—styrene system. Also, in zero conversion extrapolation analysis, the fraction of the crosslinker reacted at both the ends increases with the molecular weight of the ethylene glycol unit. These observations imply that intramolecular cyclization is favoured by increasing the distance of separation between the two vinyl end groups of the dimethacrylate crosslinker. The increase in the fraction of the crosslinker reacted at both ends with conversion is found to be most rapid in the PEG(400)DM—styrene copolymers and least in the EGDM—styrene copolymers. The increase in polydispersity ratio with conversion is also found to fall into the same sequence. These observations suggest that intermolecular crosslinking is also favoured by increasing separation between the two vinyl groups of the crosslinker, i.e. the reactivity of the double bond attached to the polymer chain is greater both for cyclization and intermolecular reaction when the length of the poly(ethylene glycol) unit is increased.     

Immobilization of catalase on a novel polymer support,crosslinked polystyrene ethylene glycol acrylate resin: Role of the macromolecular matrix on enzyme activity

Crosslinked polystyrene ethylene glycol acrylate resin (CLPSER) was developed for the immobilization of the enzyme catalase by the introduction of a crosslinker, O,O′‐bis(2‐acrylamidopropyl) poly(ethylene glycol)₁₉₀₀, to styrene. The crosslinker was prepared by the treatment of acryloyl chloride with O,O′‐bis(2‐aminopropyl) poly(ethylene glycol)₁₉₀₀ in the presence of diisopropylethylamine. The resin was characterized with IR and ¹³C‐NMR spectroscopy. The catalytic activity of the catalase‐immobilized system of CLPSER was compared with divinylbenzene‐crosslinked polystyrene, ethylene glycol dimethacrylate crosslinked polystyrene, and 1,4‐butanediol dimethacrylate crosslinked polystyrene systems. Crosslink levels of 2, 8, and 20 mol % were evaluated. Among these crosslinked systems, the 2 mol % system was found to be most suitable to support catalytic activity. When a long flexible hydrophilic poly(ethylene glycol) crosslink, introduced between the polystyrene (PS) backbone and functional groups was used for immobilization, the extent of coupling and enzyme activity increased. Depending on the nature of the support, the catalytic activity of the system varied. The hydrophilic CLPSER support was most efficient for immobilization compared to the other PS‐based supports. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 8–19, 2005     

Polymers for information storage systems. II. Polymerization kinetics for preparation of highly crosslinked polydimethacrylates

Polymers of ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and tetraethylene glycol dimethacrylate were prepared by photoinitiated polymerizations in the presence of 2,2-dimethoxy-2-phenyl-acetophenone at 27°C. The reactions led to highly crosslinked polymeric networks. The volume shrinkage observed during polymerization was a function of the number of ethylene glycol units in the dimethacrylate monomer. The kinetic rate constants of polymerization, as determined from the photopolymerization characteristics using a dilatometric technique, were again dependent on the number of ethylene glycol units in the monomer. The importance of these results on the crosslinked structure of the prepared networks is discussed.     

Styrene–dimethacrylate copolymerization kinetic modeling

A model for the copolymerization of styrene with dimethacrylate including the post‐gelation period, diffusion effects and cyclization reactions was developed. The numerical fractionation method, balance of sequences and pseudo‐homopolymerization hypothesis were used for such a purpose. Diffusion effects were taken into account through an exponential correlation between the termination rate coefficient and the monomer conversion. Average rate coefficients of cyclization and crosslinking reactions were fitted. The model was validated through literature data for the copolymerizations of styrene with ethylene glycol dimethacrylate and styrene with tetraethylene glycol dimethacrylate. The predictions were satisfactory in the range 1–20% of dimethacrylate and temperature at 95 °C. © 2015 Society of Chemical Industry     

GMA‐based emulsion‐templated solid foams: Influence of co‐crosslinker on morphology and mechanical properties

Highly open porous polymer foams formed from high internal phase emulsions (polyHIPEs) are attracting significant interest because of their potential applications in many areas of advanced materials science. In this work, the influence of the crosslinker or co‐crosslinkers of different molecular weights on the morphology and mechanical properties of polyHIPEs containing glycidyl methacrylate (GMA) was studied. Several poly(ethylene glycol) dimethacrylate (PEGDMA) crosslinkers were considered. The results show that introducing higher molecular weight crosslinkers into polyHIPEs produces a more open structure, with significantly increased compression strength and deformation at breakage. This eliminated the undesirable brittleness and chalkiness commonly found in polyHIPE materials. The Young's modulus of GMA‐based polyHIPEs containing 40% poly(ethylene glycol) dimethacrylate increased by 50% and the crush strength by 400% when compared with traditional GMA/ethylene glycol dimethylacrylate polyHIPEs. This improvement in mechanical properties is expected to improve the suitability of polyHIPEs for use in a wide range of applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46295.     

Photopolymerization of hydroxypropyl acrylate and tetraethylene glycol dimethacrylate initiated by uranyl ion

Uranyl nitrate, acetate, sulfate, and dibutyl phosphate were used in solution for the photoinitiation of homopolymerization and copolymerization of hydroxypropyl acrylate and tetraethylene glycol dimethacrylate. Solvents used included water, water-ethylene glycol mixtures, and dimethylformamide. Polymer yields in excess of 90% can readily be obtained by exposing solutions containing 0.014M UO₂²⁺ to light from a tungsten bulb for 1 hr. The rigidity of the polymers varied directly, the affinity for water in-versely, with the concentration of tetraethylene glycol dimethacrylate in the monomer mixture. Poly(hydroxypropy1 acrylate) contained 52% water and poly(tetraethy1ene glycol dimethacrylate) 34% water, a t equilibrium.     

Swelling 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 application. The copolymer was crosslinked at different concentrations of ethylene glycol diacrylate (EGDA) and ethylene glycol dimethacrylate (EGDMA) crosslinkers via catalytic initiation or by electron-beam irradiation at dose rate 80 kGy. The concentration of both crosslinkers was varied from 0.5% to 2%. The effect of crosslinking conditions, such as crosslinker concentration, method of polymerization and monomers concentration on conversion and gel fraction was examined through an oil-absorption test 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 polymer and swelling capacity were determined at 298 K. The effective crosslinking density V_e, the average molecular weight between the crosslinks M_c and the polymer-toluene interaction parameter were determined from stress–strain measurements. The crosslinking efficiencies of EGDA and EGDMA towards copolymers were determined.     

Separation of the effects of pH and polymer concentration on the swelling pressure and elastic modulus of a pH-responsive hydrogel

The elastic shear modulus G and swelling pressure ω are studied for a basic, pH-responsive hydrogel synthesized by crosslinking copolymerization of co-monomers hydroxypropyl methacrylate and N,N-dimethylaminoethyl methacrylate with crosslinker tetraethylene glycol dimethacrylate. Under normal conditions of use as a “smart” material, hydrogel swelling ratio Q and pH vary simultaneously, but here G and ω values are presented as a function of pH with Q held constant and vice versa. At fixed pH, G decreases with increase in Q in a power law dependence, as predicted by the Flory-Rehner model. However, at fixed Q, G increases with decrease in pH (i.e., increase in degree of ionization). The pH effect is more pronounced than the volume effect, thus the hydrogel stiffens as it swells in response to pH change. At high pH, ω values of the uncharged hydrogel obey the Flory-Rehner model, whereas explicit ionic contributions can be identified at lower pH values.     

Temperature-dependent transparency of poly(HPMA-co-DMA) hydrogels: effect of synthesis parameters

The acrylic comonomers hydroxypropyl methacrylate (HPMA) and N,N-dimethylaminoethyl methacrylate (DMA) have been used in several earlier studies to produce pH-responsive hydrogels. However, these same monomers can also be used to prepare hydrogels that are highly responsive to temperature. One manifestation of this temperature sensitivity is a sharp decrease in hydrogel optical transparency that occurs when the temperature exceeds a critical transition value. For example, a hydrogel that exhibits a swelling transition at the physiological pH value of 7.4 has a transition temperature of about 45 °C when the environmental salt concentration is 0.15 M. The value of the transparency transition temperature is shown to depend on hydrogel synthesis parameters such as comonomer mole ratio, crosslinker mole ratio, and even initiator concentration. By reducing the mole ratio of the crosslinker tetraethylene glycol dimethacrylate (TEGDMA), the transition temperature can be lowered by as much as 15 °C. Environmental salt concentration and solvent polarity are also shown to influence the transition temperature.     

Novel hexamethylene diamine‐functionalized macroporous copolymer for chromium removal from aqueous solutions

Macroporous copolymers of poly[(glycidyl methacrylate)‐co ‐(ethylene glycol dimethacrylate)] (PGME ) with various crosslinker (ethylene glycol dimethacrylate) concentrations and porosity parameters and additionally functionalized with hexamethylene diamine (PGME‐HD ) were tested as potential Cr(VI ) oxyanion sorbents from aqueous solutions. Kinetics of Cr(VI ) sorption was investigated in the temperature range 298–343 K and the results were fitted to chemical reaction and particle diffusion models. The Cr(VI ) sorption obeys the pseudo‐second‐order model with definite influence of pore diffusion. A temperature rise promotes chromium removal, with a maximum experimental uptake capacity of 4.21 mmol g^?1 at 343 K for the sample with the highest amino group concentration. Equilibrium data were analysed with Langmuir, Freundlich and Temkin adsorption isotherm models. Thermodynamic parameters, i.e. Gibbs free energy (ΔG ⁰), enthalpy (ΔH ⁰) and entropy change (ΔS ⁰) and activation energy of sorption (E _a), were calculated. The Cr(VI) adsorption onto PGME‐HD was found to be spontaneous and endothermic, with increased randomness in the system. Desorption experiments show that chromium anion sorption was reversible and the PGME‐HD sample GMA 60 HD was easily regenerated with 0.1 mol L^?1 NaOH up to 90% recovery in the fourth sorption/desorption cycle. In the fifth cycle, a substantial sorption loss of 37% was observed. © 2016 Society of Chemical Industry     

Adsorptive removal of technetium‐99 using macroporous poly(GMA‐co‐EGDMA) modified with diethylene triamine

The possibility of sorption of technetium‐99 in the form of pertechnetate anion (TcO₄^?) and the sorption kinetics for removing TcO₄^? from aqueous solution by chelating polymers based on glycidyl methacrylate (GMA) were investigated. Two samples of macroporous crosslinked poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) (PGME), with different amount of the crosslinker (ethylene glycol dimethacrylate, EGDMA), were synthesized by suspension copolymerization and functionalized with diethylene triamine (deta). We propose that nonspecific sorption of pertechnetate anion via electrostatic interactions takes place at the protonated amino groups of macroporous crosslinked copolymer. The results of batch experiments performed at pH 1–14 showed fast sorption kinetics for removing TcO₄^? by amino‐functionalized PGME‐deta in a wide range of pH, that is, from 1.0 to 9.0. Almost complete removal of TcO₄^? (91–98%) was reached within 180 min in the stated pH range (1.0–9.0), with the sorption half‐times of under 25 min. The partitioning coefficients of linear adsorption isotherms, with 180‐min equilibrium time, reach the high values of 2130 mL g^?1 and 1698 mL g^?1 for the two samples of synthesized PGME‐deta. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of oligomer on dye-sensitized solar cells employing polymer electrolytes

The effect of oligomer (M _n =400–500 g/mol) on dye-sensitized solar cells (DSSC) employing polymer electrolytes consisting of poly(epichlorohydrin-co-ethylene oxide) (Epichlomer), LiI, 1-methyl-3-propylimidazolium iodide (MPII) and I₂ is investigated. Five kinds of oligomer, poly(ethylene glycol) (PEG, M _n =400 and 1,000 g/mol), poly(ethylene glycol) dimethyl ether (PEGDME), poly(propylene glycol) (PPG) and poly(ethylene glycol) diglycidyl ether (PEGDGE), were introduced to elucidate the role of terminal groups and chain length. The coordinative interactions and structures of polymer electrolytes were characterized by FT-IR spectroscopy and X-ray diffraction (XRD). The improved interfacial contact between the electrolytes and the electrodes by the oligomer addition was confirmed using a field-emission scanning electron microscope (FE-SEM). The electrolytes exhibited ionic conductivities on the order of 10^?4 S/cm, but PEGDGE electrolyte showed much lower value (～10^?8 S/cm). As a result, the energy conversion efficiency of DSSC was significantly affected by the oligomer. For example, the DSSC employing PEGDME with methyl terminal groups exhibited 3.95% at 100 mW/cm², which is 200-fold higher than that employing PEGDGE.     

Removal of nonionic surfactant by systems based on chloromethylated polystyrene–poly(ethylene glycol)

For the purpose of obtaining compounds which can remove nonionic surfactants in water, chloromethylated polystyrene (CMPS) was allowed to react with triethylene glycol monomethyl ether (3EGMME), tetraethylene glycol (4EG), poly(ethylene glycol) (PEG) 200, 400, 600, 1000, and 1500. The amount of PEG groups combined with CMPS decreased with an increase in the molecular weight of PEG. The ability of the product to remove polyethylene glycol mono-p-nonyl phenyl ether (NP, n = 10), a nonionic surfactant, solutes in water was greater in the product with PEG of greater MW than that with PEG of smaller MW, and in the product with more PEG groups (mol/g prod.) than in that with less PEG groups. The removal behavior of the products conformed to Freundlich's adsorption formula. Constants of the formula, the effect of temperature on the constants, the effect of combined PEG groups on the removed amount, and the removal manner were studied.     

Relaxational behavior and swelling‐pH master curves of poly[(diethylaminoethyl methacrylate)‐graft‐(ethylene glycol)] hydrogels

Poly[(diethylaminoethyl methacrylate)‐graft‐(ethylene glycol)] hydrogels were prepared with a molar ratio of 10:1 of diethylaminoethyl methacrylate to poly(ethylene glycol) of number‐average molecular weights (M_n) 200, 400 and 1000 g mol^?1 using tetra(ethylene glycol) dimethacrylate to give a crosslinking ratio between 0.5 and 4.0 %. Glucose oxidase and catalase were immobilized in the matrix during polymerization. The maximum enzyme loading used was 6.6 × 10^?4 g of glucose oxidase per g of polymer. The equilibrium and dynamic swelling properties of these hydrogels were investigated. The pH‐dependent equilibrium swelling characteristics showed a sharp transition between the swollen and the collapsed state at pH 7.0. The dynamic response of the hydrogel discs to pH was analyzed in pulsatile pH conditions. The effects of particle size, crosslinking and molecular weight of poly(ethylene glycol) (PEG) on the dynamic swelling response were investigated. The pulsatile nature of the response was analyzed using Boltzmann superposition. Swelling–pH master curves were obtained. Copyright © 2004 Society of Chemical Industry     

NMR study of the early stages of gel formation in the PEG/poly(AMPS‐co‐NIPA) semi‐interpenetrating network system

The rate of conversion of the monomers and crosslinker in the formation of a novel semi‐interpenetrating poly(ethylene glycol)/ poly(2‐acrylamido‐2‐methylpropane sulfonic acid‐co‐N‐isopropylacrylamide) copolymer hydrogel was determined by using ¹H‐NMR spectrometry. It was established that poly(ethylene glycol) does not participate in the polymerization reactions and that crosslinking by methylenebisacrylamide occurs predominantly in the early stages of copolymer chain growth. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3635–3641, 2004     

Synthesis of conductive microspheres by radiation polymerization

A conductive monodisperse microspheres consisting of poly(ethylene glycol)dimethacrylate and methyloxycarbonyl-bicyclo[2.2.1]hepta-2,5-diene was synthesized by radiation induced polymerization. Ionic conductivity and relative dielectric constant were found to be greatly dependent on the content of poly(ethylene glycol)methacrylate in the copolymer. The diameter of the microspheres was 0.48-0.86 μm, in which the irradiation was carried out without stabilizer at a dose rate of 20 kGy/h with ⁶⁰Co γ-ray.     

Drying process in vapor swollen heterogels

Disk-shaped heterogels were prepared by combining methyl methacrylate (MMA) and styrene (S) with ethylene glycol dimethacrylate (EGDM) as a crosslinker agent in the presence of 2,2′-azobisisobutyronitrile (AIBN). Swelling experiments were performed under chloroform vapor and the swollen gels are then allowed to dry under room temperature. Gravimetric technique was used to study drying processes. It is observed that two different regimes are present in the drying processes of these heterogels. Fickian diffusion model was used to determine desorption coefficients for each drying step in both regimes. Desorption coefficients, D _d, of heterogels were found to be strongly correlated with the mixture composition of polymeric materials in the heterogel system for both regimes. Heterogels with high S content dry much slower than the heterogels with low S content.     

Studies on the kinetics of free-radical bulk polymerization of multifunctional acrylates by dynamic differential scanning calorimetry

The course and kinetics of nonisothermal bulk polymerization of multifunctional acrylates were studied by dynamic differential scanning calorimetry (DSC). Measurements were carried out for four straight-chain monomers, diethylene glycol diacrylate (DEGDA), triethylene glycol diacrylate (TEGDA), tetraethylene glycol diacrylate (TTGDA), and poly(ethylene glycol)diacrylate (PEGDA) (mol. wt. 600), to study the effect of the backbone chain length, atmosphere, and type of initiator on the crosslinking kinetics. 4,4′-Azobis(4-cyanovaleric acid) (1.0%, w/w) was used as a free-radical initiator. From the dynamic scanning of polymerization of DEGDA at five heating rates (2–30°C/min), the average heat of polymerization (ΔH_p) was found to be 524.2 J/g. An activation energy of 108.8 kJ/mol and preexponential factor 5.34 × 10¹² s^?1 were obtained from the Arrhenius plot, In dα/dt. The rate of polymerization was found manyfold greater at 20–60% conversion than at the initial stage (2–8% conversion). Polymerization was studied under both nitrogen and air atmosphere. The results corresponded well with the theory of oxygen inhibition. Different types of initiators, e.g., 4,4′-azobis(4-cyanovaleric acid) (ABCVA), 2,2′-azobisisobutyronitrile (AIBN), and benzoyl peroxide (BPO) were used for polymerization and ABCVA was found to be the most efficient among all. © 1995 John Wiley & Sons, Inc.     

Properties of chelating resins prepared by addition of 1,4,8,11-tetraazacyclotetradecane-5,7-dione to epoxy groups of poly(glycidyl methacrylate)s crosslinked with oligoethylene glycol dimethacrylates

In order to improve Cu(II) adsorption ability of chelating resins based on a macrocyclic ligand 1,4,8,11-tetraazacyclotetradecane-5,7-dione (L) bound to crosslinked copolymers, the resins were prepared by reaction of L with poly(glycidyl methacrylate)s crosslinked with ethylene glycol dimethacrylate (1G), tetraethylene glycol dimethacrylate (4G) or nonaethylene glycol dimethacrylate (9G). By systematically changing the amounts of each crosslinker (degree of crosslinking) and of isobutyl acetate (IBA) as diluent in the suspension polymerization of the monomers, precursory copolymers with various degrees of crosslinking as well as with different specific surface areas (SSAs) were prepared, and then L was introduced into them. Ligand contents, SSAs, and Cu(II) adsorption abilities of the resulting resins were evaluated, and it was clarified that resins derived from precursors (prepared by using 4G or 9G in the presence of 120–160 vol % of IBA) exhibit high capacities for Cu(II), whereas the capacities of resins crosslinked with 1G are not so high. Further detailed study on the uptake of metal ions using the resins RG4D(10)-140 and RG9D(10)-140 (derived from the precursors prepared by using 10 mol % of the respective crosslinkers 4G and 9G in the presence of 140 vol % of IBA) showed that RG9D(10)-140 is much superior to RG4D(10)-140 in the column-mode adsorption of Cu(II). These results indicate that not only the selection of the suitable crosslinker but also the use of a pertinent amount of the diluent are very important in improving the complexing abilities of the polymer-bound L. © 1996 John Wiley & Sons, Inc.     

Swelling of heterogels in good solvents; a fast transient fluorescence study

The swelling of disc-shaped heterogels were studied using Fast Transient Fluorescence Technique (FTRF). Disc-shaped heterogels were prepared by combination of methyl-methacrylate (MMA) and styrene (S) with ethylene glycol dimethacrylate (EGDM) as a crosslinker agent in the presence of 2,2′-azobisisobutyronitrile (AIBN). Pyrene (P_y) was introduced as an extrinsic floroprobe during polymerisation. Lifetimes of P_y were measured during in situ swelling processes of heterogels in good solvents to determine the relation between the diffusion and solvent quality. An equation is derived for low-quenching efficiencies to interpret the behavior of lifetime of P_y during swelling. Li-Tanaka equation was employed to determine the cooperative diffusion coefficients, D_c in heterogels, which were found to be strongly correlated with the chosen solvent and the polymeric material in the heterogel system.