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.     

Photoinduced graft copolymerization of 2-hydroxyethyl methacrylate on cotton cellulose in the presence of triethyleneglycol dimethacrylate

The addition of a bifunctional monomer, triethylene glycol dimethacrylate (TEGDMA), to a grafting system containing 2-hydroxyethyl methacrylate (HEMA) and benzoin ethyl ether photoinitiator substantially increased the graft add-on of the unswollen and sodium hydroxide–swollen cotton cellulose. Grafting caused changes in the properties of the substrate such as moisture regain, the water of imbibition, and the dyeability with a direct and a reactive dye in accordance with the graft level. The observations have been explained in relation to structural changes in the grafted cotton. © 1994 John Wiley & Sons, Inc.     

Water sorption of poly(methyl methacrylate): 2. Effects of crosslinks

Glassy crosslinked networks were made by copolymerization of methyl methacrylate both with ethylene glycol dimethacrylate and with triethylene glycol dimethacrylate, using a redox initiator. Residual monomer was largely or wholly removed by extraction with water, by heating at 100°C, or by γ-irradiation. Water sorption conformed approximately to Fick's laws but with a retarded swelling component which increased with crosslink density. Approximate values were obtained for apparent diffusion coefficients both in sorption and desorption. The pattern of results was similar for both dimethacrylate systems. Values of diffusion coefficients were little influenced by crosslink density up to a dimethacrylate feed of 50 wt%. The saturation value for water uptake increased with increasing feed of dimethacrylate to more than twice the value for the linear polymer, i.e. poly(methyl methacrylate).     

Reducing volume shrinkage by low‐temperature photopolymerization

Low‐volume‐shrinkage poly(triethylene glycol dimethacrylate) was made by photopolymerization at a low temperature. The final double‐bond conversion and dynamic mechanical analysis indicated the optimal cure temperature to be ?40°C, at which a cured sample had less volume shrinkage than samples cured at room temperature but similar mechanical properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1126–1130, 2007     

Optical material having high refractive index,low specific gravity,and excellent impact resistance prepared by unsaturated nitrile-polyfunctional methacrylate-styrenic monomer copolymerization

A resin having a low specific gravity, an excellent impact resistance, and a high refractive index was produced by radical polymerization of a mixture of difunctional methacrylate, such as tetraethylene glycol dimethacrylate or triethylene glycol dimethacrylate, styrenic monomer such as styrene or α-methyl styrene, and acrylonitrile. We provide a totally balanced optical material composed of the said resin, especially a lens. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2247–2255, 1997     

Dilute gelling systems: copolymers of styrene and glycol dimethacrylates

Gelation properties of the copolymers of styrene with various proportions of ¹⁴C labelled ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and polyethylene glycol (MW = 400) dimethacrylate have been studied. The thermal copolymerizations were carried out in 15% (v/v) solution in toluene. The rates of polymerization were found to increase with larger proportions of dimethacrylate cross-linking agents. The conversion at the gel point was surprisingly constant over a wide range of crosslinker concentration. The fraction of crosslinker saturated at both ends was found to increase in the order ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and polyethylene glycol 400 dimethacrylate. The proportion of completely reacted crosslinker increased only slowly with conversion. At very high concentrations of crosslinker, the onset of inhomogeneity was observed as described previously by Storey³ and Dusek¹⁸.     

Ophthalmic lens material prepared by unsaturated nitrile–polyfunctional methacrylate–styrenic monomer copolymerization

A resin having excellent ophthalmic lens performance was produced by radical polymerization of a mixture of bifunctional methacrylate, such as tetraethylene glycol dimethacrylate or triethylene glycol dimethacrylate, a styrenic monomer such as styrene or α-methylstyrene, and acrylonitrile. We provide a totally balanced resin composition suitable for an ophthalmic lens, having a high refractive index, large Abbe number, high impact strength, low specific gravity, heat resistance, cutting processability, tintability, and durability. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1227–1235, 1998     

Prediction and comparison of textural properties of magnetic copolymer supports for enzyme immobilization

Magnetic polymers supports have proven to be valuable materials for enzyme immobilization, as they allow recovering the catalyst by magnetic separation, precluding the need for costly and time-consuming separation steps. In this study, magnetic copolymer supports were synthesized using styrene (STY) and different crosslinking agents (divinylbenzene, ethylene glycol dimethacrylate, or triethylene glycol dimethacrylate) and initiators (azobisisobutyronitrile or benzoyl peroxide) and used to immobilize Candida antarctica lipase B (CALB). The aim was to obtain biocatalysts with high enzymatic activity and satisfactory morphological properties for use in biotransformation reactions. Two morphological properties known to influence the immobilization yield were taken into consideration, specific surface area, and swelling index. Experimental data were compared to the predictions of a model based on molar balance, method of moments, numerical fractionation, and elementary gel structures. The high correlation (R² = 0.9974) between experimental and predicted values demonstrated the suitability of the model for estimating the textural properties of enzyme supports. CALB was successfully immobilized, showing high hydrolytic activity (500–700 U g⁻¹) and good thermal stability at 50°C. CALB/STY-EGDMA-M was 14 times more stable than free CALB. The results confirm the efficiency of the immobilization method and the suitability of the copolymers for enzyme immobilization.     

Preparation and properties of optical notch filters of cholesteric liquid crystals

We investigated the influence of preparative conditions of cholesteric-liquid-crystal (CLC) solid films on their cholesteric structures. They are made of poly[γ-butyl- (or )-glutamate] (PBuL(D)G and triethylene glycol dimethacrylate (TGDM), and have the ability to reflect the light in a specified wavelength region. When these films were combined with conventional colour filters, the colour reproduction region was enlarged by about 25% in the area of the CIE chromaticity diagram.     

4-烯丙氧基苯甲醇甲基丙烯酸酯厌氧单体的制备及其固化物耐热性能的研究

合成了4-烯丙氧基苯甲醇甲基丙烯酸酯(ABMA)厌氧单体,研究了单体的固化性能并探讨了其固化机理。ABMA的加入使二缩三乙二醇二甲基丙烯酸双酯(TEGMA)厌氧胶的耐热稳定性和热老化性能大大提高。当ABMA与TEGMA按质量比为1∶1作为主体树脂时,所制得的厌氧胶在300℃时的质量保持率可达96.7%;经300℃老化10h之后,螺纹粘接件的平均拆卸扭矩(Tp)仍能达到室温下强度的72%。     

Effects of diluent's concentration upon the properties of organically modified ceramics based composites for application in dentistry

Organically modified ceramic resin (ormoresin) mixed with triethylene glycol dimethacrylate (TEGDMA) was used as the binder resin for the preparation of visible light cured dental composite. Three different combinations of ormoresin and TEGDMA were used for the preparation of composites, and their properties were compared in terms of depth of cure, diametral tensile strength (DTS), flexural strength (FS), flexural modulus (FM), Vickers micro hardness (VMH), water sorption (WS), and solubility. It is found that an optimum amount of diluent is necessary for better crosslinking and properties of cured composites based on ormoresin. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 469–473, 2004     

J-213快速固化厌氧胶的研究

阐述了J-213快速固化厌氧型丙烯酸酯胶粘剂的基本组成、制备及主要性能。该胶选用乙氧化双酚A二甲基丙烯酸酯(SR348)、二缩三乙二醇二甲基丙烯酸酯(SR205)等为聚合单体，乙酰苯肼为促进剂，乙二胺四乙酸二钠(EDTA)为稳定剂，对苯醌为阻聚剂，异丙苯过氧化氢为引发剂，有机铜为活化剂。该胶定位时间短，几秒至几分钟即可定位；固化速度快，15min剪切强度即可达到最高值的80％以上；耐介质浸泡性能和耐高低温交变性能优异；与镍粉混合稳定性好，适用期长；对被粘接件无腐蚀。     

Strength and structure of glassy networks formed from dimethacrylates

Glassy networks were formed by copolymerization of methyl methacrylate (MMA) with both ethylene glycol dimethacrylate (EGDM) and triethylene glycol dimethacrylate (TGDM). The polymerization reaction was followed by estimation of vinyl group concentration from measurements of specific volume and infrared absorption. The sheets of polymer were cracked but gave fragments that were large enough to provide specimens suitable for a three-point bending test. Flexural strength decreased with increasing feed of dimethacrylate but, nevertheless, gave fairly strong products throughout the range of comonomer compositions c.f. PMMA, 144 ± 9 MPa; PTGDM, 132 ± 10 MPa; PEGDM, 66 ± 15 MPa. Examination of fracture surfaces indicated a predominantly brittle mode of fracture modulated by localized plastic deformation. In order to account for localized plastic deformation, it was postulated that the networks consist of highly crosslinked microgel particles in a much less crosslinked matrix.     

Preparation of porous polymeric structures for enzyme immobilization

Porous polymethacrylic acid‐co‐triethylene glycol dimethacrylate (MAA‐co‐3G) and polyacrylic acid‐co‐triethylene glycol dimethacrylate (AA‐co‐3G) were prepared by four different polymerization techniques, namely, suspension, dispersion, seed, and microemulsion polymerization using an inert diluent (n‐hexane and polystyrene). The morphology and porosity of the obtained polymers were examined by means of a scanning electron microscope. The surface areas of the obtained polymers were determined colorimetrically. The copolymers were modified by hydroximation and chlorination using hydroxyl amine and thionyl chloride, respectively. The effect of polymerization type, surface area, modification, and pH on the protease enzyme immobilization over poly(MAA‐co‐3G) and poly(AA‐co‐3G) was examined. The enzyme activity was measured by means of a spectrophotometer. The reactivity ratios of the two monomers MAA and 3G were determined by means of the elemental analysis method. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 594–601, 2000     

Characterization of Cure Profile of Anaerobic Adhesives by Real-Time FT-IR Spectroscopy. I. Effect of Transition Metal Dithiolate Complexes

A model acrylic adhesive formulation consisting of triethylene glycol dimethacrylate (TRIEGMA) monomer, cumene hydroperoxide (CHP), o-benzoic sulfimide (saccharin or BS) and with or without a metal dithiolate catalyst has been made to study kinetics and mechanism of the anaerobic polymerization. In these studies, a real-time FT-IR spectroscopic (RT/FT-IR) technique has been used to study anaerobic cure profiles at room temperature. The catalytic effect of several transition metal dithio complexes for redox-initiated acrylate polymerization has been studied. The dithiolates used in these studies include the dithiocarbamate, xanthate dithiophosphate complexes of copper, nickel and zinc systems. Copper diacetylacetonate was also studied for comparison of its catalytic reactivity. A syner-gistic effect of copper dithiolate catalyst and saccharin was observed. The effects of catalyst concentration, metal and ligand type, and co-initiator on cure profiles have been monitored in a real-time mode.     

Sorption and desorption parameters of water or ethanol in light‐cured dental dimethacrylate resins

Two cycles of sorption/desorption of water or ethanol by light‐cured dental resins of bisphenol A glycol dimethacrylate (Bis‐GMA), bisphenol A ethoxylated dimethacrylate (Bis‐EMA) urethane dimethacrylate (UDMA) triethylene glycol dimethacrylate and decanediol dimethacrylate (D₃MA) were studied. The experimental curves m_t = f(t) taken for the first water sorption by poly‐Bis‐GMA, poly‐Bis‐EMA and poly‐UDMA showed a maximum. A maximum was also observed in the curve obtained for first sorption of ethanol by poly‐Bis‐GMA. In all other cases, the curves for sorption or desorption of water or ethanol showed Fickian behavior. The experimental data obtained for first sorption of water or ethanol were perfectly fitted to a new proposed equation, which predicts water or ethanol sorption with simultaneous extraction of unreacted the monomer. This equation gave us the possibility for the determination of the diffusion coefficient of the extraction of the unreacted Bis‐GMA during the water and ethanol sorption, as well as the diffusion coefficient of the extraction of the unreacted Bis‐EMA and UDMA during the water sorption. The maximum water or ethanol absorbed at equilibrium and the diffusion coefficient are determined from the second sorption/desorption cycle during which the extraction of the monomer is negligible. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Filled interpenetrating networks: their formation and viscoelastic properties

The kinetics of curing, the microphase separation process (MPS) and the viscoelastic properties of interpenetrating polymer networks (IPNs) based on crosslinked polyurethane and linear poly(butyl methacrylate) were studied in the presence of two fillers—talc and polymeric fine-disperse triethylene glycol dimethacrylate. It was found that introducing filler into the reaction mixture changes the reaction kinetics and degree of microphase separation, which in turn affects the viscoelastic properties of the IPNs. The data obtained by dynamic mechanical spectroscopy and differential scanning calorimetry for filled semi-IPNs and calculations of the degree of segregation of the components show that filler introduction results in MPS inhibition on account of a local increase in viscosity near the solid interface, i.e. compatibility is increased.     

Evaluation of the light polymerization efficiency of copolymers used in dental formulations by differential scanning calorimetry

Different compositions of visible‐light‐curable triethylene glycol dimethacrylate/bisglycidyl methacrylate copolymers used in dental resin formulations were prepared through copolymerization photoinitiated by a camphorquinone/ethyl 4‐dimethylaminobenzoate system irradiated with an Ultrablue IS light‐emitting diode. The obtained copolymers were evaluated with differential scanning calorimetry. From the data for the heat of polymerization, before and after light exposure, obtained from exothermic differential scanning calorimetry curves, the light polymerization efficiency or degree of conversion of double bonds was calculated. The glass‐transition temperature also was determined before and after photopolymerization. After the photopolymerization, the glass‐transition temperature was not well defined because of the breadth of the transition region associated with the properties of the photocured dimethacrylate. The glass‐transition temperature after photopolymerization was determined experimentally and compared with the values determined with the Fox equation. In all mixtures, the experimental value was lower than the calculated value. Scanning electron microscopy was used to analyze the morphological differences in the prepared copolymer structures. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Performance of melamine modified urea–formaldehyde microcapsules in a dental host material

Urea–formaldehyde (UF) microcapsules filled with dicyclopentadiene (DCPD) show potential for making self‐healing dental restorative materials. To enhance the physical properties of the capsules, the urea was partially replaced with 0–5% melamine. The microcapsules were analyzed by different microscopic techniques. DSC was used to examine the capsule shell, and the core content was confirmed by ¹H NMR spectroscopy. Capsules in the range of 50–300 μm were then embedded in a dental composite matrix consisting of bisphenol‐A‐glycidyl dimethacrylate (Bis‐GMA) and triethylene‐glycol dimethacrylate (TEGDMA). Flexural strength, microhardness, and nanoindentation hardness measurements were performed on the light‐cured specimens. Optical microscopy (OM) examination showed a random distribution of the microspheres throughout the host material. The incorporation of small amounts of the microcapsules did not affect the performance of the matrix material. Scanning electron microscopy (SEM) analysis revealed excellent bonding of the microcapsules to the host material which is a characteristic of utter importance for maintaining the very good mechanical properties of a dental composite with self‐healing ability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Isobornyl methacrylate as diluent co-monomer on physical-mechanical properties of dental resin composites

The aim of this study was to evaluate the effects of isobornyl methacrylate (IBOMA) as a diluent co-monomer on the physical properties of experimental resins. Blends of bisphenol glycidyl methacrylate (Bis-GMA) were formulated with triethylene glycol dimethacrylate (TEGDMA) and IBOMA in different wt%. The degree of conversion, flexural strength, elastic modulus, and ultimate tensile strength were determined. Immediate and 24 h volumetric shrinkage were calculated. Data were submitted to ANOVA and Tukey's tests (α = 0.05). Blends of Bis-GMA and IBOMA showed the lowest ultimate tensile strength, flexural strength, elastic modulus, degree of conversion, and immediate and 24 h volumetric shrinkage results. However, when IBOMA was used together with TEGDMA in blends of Bis-GMA, the resin composites showed best curing performance and high physical-mechanical properties. Thus, the IBOMA is as diluent co-monomer that can be used in dental resin composites to reduce the volumetric shrinkage.