Glycol Dimethacrylate Cross-linker Research Articles

Thermosensitive Micelle-Forming Block Copolymers of Poly(ethylene glycol) and Poly(N-isopropylacrylamide)

Thermosensitive Micelle-Forming Block Copolymers of Poly(ethylene glycol) and Poly(<i>N</i>-isopropylacrylamide)

Nanostructured Polymeric Materials from Microemulsion Polymerization Using Poly(ethylene oxide) Macromonomer

Transparent nanostructured polymeric materials have been produced from the direct polymerization of bicontinuous microemulsions using the macromonomer ω-methoxy−poly(ethylene oxide)40−undecyl−α-methacrylate (C1−PEO−C11−MA-40) as a polymerizable nonionic surfactant. Besides the PEO macromonomer, the system also consisted of methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), water, and the cross-linker ethylene glycol dimethacrylate (EGDMA). Most of the bicontinuous microemulsions investigated could be gelled within 10 min at 30 °C using a redox initiator. The transparent microemulsions were eventually transformed to transparent solid polymers. These polymeric materials were characterized by thermoporometry, SEM observation, and the pore size evaluation for the polymer films by PEG filtration. The pore size of these transparent polymeric materials ranges from about 1 to 10 nm in diameter. It was larger for the systems containing higher ratios of water to HEMA or water to C1−PEO−C11−MA-40 and smaller for higher ratios of HEMA to C1−PEO−C11−MA-40. The results from PEG filtration provide the direct evidence that bicontinuous nanostructured polymeric materials can readily be prepared via the polymerization of these nonionic bicontinuous microemulsions.

Synthesis and characterization of oxazoline-functional polymer particles by free radical nonaqueous dispersion polymerization

A novel oxazoline-functional methacrylate was prepared and employed as comonomer to produce nonaqueous dispersions of oxazoline-functional polymer particles. In nonaqueous free radical dispersion copolymerization of methylmethacrylate in the presence of oxazoline-functional methacrylate, ethyleneglycoldimethacrylate crosslinking agent, AIBN initiator, and polystyrene-block-poly(ethene-alt-propene) dispersing agent, the average polymer particle size, varying between 100 and 500 nm, was controlled by the dispersing agent contents. According to titration with HClO4 all oxazoline groups regardless of their location at particle surface or bulk, were accessible. Glass transition temperature decreased from 120 to 0°C when oxazoline functional methacrylate was increased from 0 to 95 mol %. As imaged by atomic force microscopy incorporation of the new oxazoline-functional methacrylate improved film formation. Oxazoline-functional polymer particles were easy to redisperse in a variety of other diluents. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2539–2548, 1997

Polymer Composites Obtained by Polymerization of Microemulsions Formed with Inorganic and Organic Monomers

Phase behavior studies of microemulsions containing the monomers methyl methacrylate (MMA), acrylic acid (AA), and tetraethoxysilane (TEOS), the cross-linking agent ethylene glycol dimethacrylate (EGDMA), and water (W), stabilized by the surfactant cetyltrimethylammonium bromide (CTAB), were carried out. An analagous surfactant-free system was also studied and compared with the surfactant-based system. Macroscopically single-phase, transparent microemulsions were formed over a considerable portion of the composition domain for the surfactant-based system. The effects of hydrochloric acid (HCl) and base (NH4OH) on the gel times were examined. Selected compositions in the surfactant-based system were chosen to examine the effect of the water to TEOS ratio (R) on the thermal stability and pore morphology of the polymer composite formed from the hydrolysis and condensation reactions of TEOS and the polymerization of organic-monomer-containing microemulsions. The polymer composites thus obtained exhibit high t...

Characterization of Some Polyacrylonitrile-Based Electrolytes

Polyacrylonitrile (PAN)-based electrolytes have been prepared by encapsulating Li salt solutions. The conductivity of these electrolytes is governed by a combination of factors including the relative amounts of PAN, EC, PC and the Li salt, and temperature. A conductivity of about 4.5 x 10{sup -3}{Omega}{sup -1} cm{sup -1} at 30 {degrees}C was exhibited by EC-rich electrolytes containing both LiN(SO{sub 2}CF{sub 3}){sub 2} and LiPF{sub 6}. The cationic transference numbers, measured using a dc polarization method coupled with impedance spectroscopy, were found to be between 0.2 and 0.3 for electrolytes containing LiN(CF{sub 3}SO{sub 2}){sub 2} and LiPF{sub 6}. The tensile strength of the electrolytes was observed to increase from 60 to 140 lb/in.{sup 2} upon incorporation of the thermally activated cross-linking agent ethylene glycol dimethacrylate. Cyclic voltammetry on Pt electrodes has shown that these electrolytes have an inherent oxidation stability window extending up to about 5 V versus Li{sup +}/Li. On Al, Ni, and Cu electrodes, however, oxidation was observed at lower potentials because of metal corrosion reactions. Copper was reversibly oxidized at 3.5 V, irrespective of the Li salt present in the electrolyte. On the other hand, the nature of the Li salt influenced the corrosion potentials of Al andmore » Ni. Nickel was found to be stable up to 4.2 V in the presence of LiAsF{sub 6}, whereas it was oxidized at about 3.5 and 4 V when the electrolyte contained LiN(SO{sub 2}CF{sub 3}){sub 2} and LiSO{sub 3}CF{sub 3} showing oxidation at {le}4 V. The electrochemical stability of the electrolytes was further verified in Li/LiMn{sub 2}O{sub 4} cells. 10 refs., 15 figs., 9 tabs.« less

A Novel Simultaneous Semi-Interpenetrating Polymer Network of Crosslinked Poly(Methyl Methacrylate) and Poly(2-Benzyl-2-Oxazoline)

Abstract The simultaneous cationic, ring-opening polymerization of 2-benzyl-2-oxazoline (BOX) with methyl tosylate in the presence of freeradical (benzoyl peroxide) initiated polymerization of methyl methacrylate (MMA), using ethylene glycol dimethacrylate (EGDMA) crosslinker produced transparent semi-interpenetrating polymer networks (semIPNs) with one glass transition temperature (T g), as shown by differential scanning calorimetry (DSC). The MMA/BOX ratios evaluated in the study were 70/30, 50/50, and 30/70. The simultaneous, free-radical, and cationic polymerization of MMA and 2-benzyl-2-oxazoline mixtures, without EGDMA and over the same monomer mixture ratio range, produced opaque plastics with two T g values, with both the PMMA and PBOX homopolymers soluble. The T g values of the two separated linear polymers were close to those previously reported for the two polymers. Over the monomers mixture range examined, the results clearly show that the simple blend of the PBOX and PMMA polymers are immiscible and that the PBOX/MMA polymers are miscible in the semi-IPN systems. Along with providing a new direction for IPN studies, the novel semi-IPNs of the type described may have utility in a variety of applications.

Kinetics of emulsifier-free emulsion polymerization of methyl methacrylate

The influences of polymerization temperature, initiator and monomer concentrations, ionic strength of the aqueous phase, as well as ethylene glycol dimethacrylate (EGDM) co-monomer, on the kinetics of the emulsifier-free emulsion polymerization of methyl methacrylate (MMA) and on the properties of the resulting poly(methyl methacrylate) (PMMA) lattices were studied. The polymerizations were carried out using potassium persulfate (KPS) as the initiator. Monodisperse PMMA lattices with particle diameters varying between 0.14–0.37 μm and polymer molecular weights of the order 0.4 × 106 to 1.2 × 106 g/mol were prepared. The initial rate of polymerization increases with increasing temperature, KPS-MMA mole ratio, EGDM content, or with decreasing ionic strength of the aqueous phase. It was shown that the bead size can be limited by reducing the monomer concentration or by using the cross-linking agent EGDM. The ionic strength of the aqueous phase has a dominant effect on final particle diameter and polymer molecular weight. The uniformity of the latex particles increases as the temperature increases or as the initiator concentration decreases. The experimental results can be reasonably interpreted by the homogeneous nucleation mechanism of the emulsifier-free emulsion polymerization of MMA. © 1996 John Wiley & Sons, Inc.

Kinetics of emulsifier‐free emulsion polymerization of methyl methacrylate

The influences of polymerization temperature, initiator and monomer concentrations, ionic strength of the aqueous phase, as well as ethylene glycol dimethacrylate (EGDM) co-monomer, on the kinetics of the emulsifier-free emulsion polymerization of methyl methacrylate (MMA) and on the properties of the resulting poly(methyl methacrylate) (PMMA) lattices were studied. The polymerizations were carried out using potassium persulfate (KPS) as the initiator. Monodisperse PMMA lattices with particle diameters varying between 0.14–0.37 μm and polymer molecular weights of the order 0.4 × 106 to 1.2 × 106 g/mol were prepared. The initial rate of polymerization increases with increasing temperature, KPS-MMA mole ratio, EGDM content, or with decreasing ionic strength of the aqueous phase. It was shown that the bead size can be limited by reducing the monomer concentration or by using the cross-linking agent EGDM. The ionic strength of the aqueous phase has a dominant effect on final particle diameter and polymer molecular weight. The uniformity of the latex particles increases as the temperature increases or as the initiator concentration decreases. The experimental results can be reasonably interpreted by the homogeneous nucleation mechanism of the emulsifier-free emulsion polymerization of MMA. © 1996 John Wiley & Sons, Inc.

Interpenetrating and pseudo-interpenetrating polymer networks of polyethylacrylate and zeolite 13X

Free radical polymerization of liquid ethylacrylate in the presence of zeolite 13X yielded PIPNs without crosslinker and IPNs if the crosslinker ethylene glycol dimethacrylate was present. We studied these materials both unextracted as well as partially extracted with a variety of solvents using DSC, SEM as well as Small Angle X-ray Scattering (SAXS). These studies suggest that in the composites polyethylacrylate chains entered the internal pores of the zeolite. These chains had an extended state and did not exhibit a bulk glass transition, a similar behavior to that previously reported for polystyrene/zeolite 13X composite. © 1996 John Wiley & Sons, Inc.

Preparation of Ultrafiltration Membranes by Direct Microemulsion Polymerization Using Polymerizable Surfactants

A novel method has been successfully used for the preparation of ultrafiltration (UF) membranes by direct polymerization of bicontinuous microemulsions. One of these microemulsions consisted of a polymerizable cationic surfactant of ((acryloyloxy)undecyl)trimethylammonium bromide (AUTMAB), methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), and water. The other was a zwitterionic microemulsion composed of a polymerizable surfactant of ((acryloyloxy)undecyl)dimethylammonio acetate (AUDMAA), MMA, HEMA, and water. In addition, a small amount of the cross-linker ethylene glycol dimethacrylate (EGDMA) was also included in each microemulsion polymerization for improving its UF membrane strength. The uniqueness of the microemulsion system is that all organic components can readily be copolymerized at room temperature using a redox initiator. The transparent membranes thus formed showed excellent strength and performance on the separation of different molecular weights of poly(ethylene glycol) (PEG). The pore sizes of the membranes were calculated to be within the range 1−5 nm in diameter, and they could be regulated by varying microemulsion compositions.

The film formation of acrylic latexes: A comprehensive model of film coalescence

AbstractA comprehensive model of film formation that was proposed in an earlier article by the present authors was evaluated for latexes having a wide range of physical properties. In this model, capillary force and interfacial forces act in tandem to promote film coalescence. The emulsion polymers studied were all based on poly(methyl methacrylate‐co‐butyl acrylate). The viscoelastic nature of the copolymer was varied by the addition of molecular weight modifiers (CBr4 chain‐transfer agent and ethylene glycol dimethacrylate cross‐linking monomer) during synthesis. In contrast to the simplifications of the previous analysis, the experimental system was well characterized. The effect of water plasticization was investigated. The surface energetics of the system were studied. Also, drying kinetics were considered. Results showed that the degree of coalescence ranged from complete fusion to superficial fusion. The minimum film temperature was found to increase with increasing polymer rigidity, as is expected. Comparison of the model predictions and experimental observations validated the model. © 1994 John Wiley &amp; Sons, Inc.

Sequential‐interpenetrating polymer networks from castor oil‐based polyesters. XXVI.

AbstractPolyesters were obtained from castor oil and dibasic acids for example, malonic, succinic, glutaric, adipic, suberic, and sebacic acids. These prepolyesters were characterized by infrared spectrometry, viscosimetric measurements, and molecular weight determinations (GPC). These prepolyesters were mixed with methyl methacrylate and were subsequently polymerized by free radical polymerization by benzoyl peroxide in the presence of the crosslinker ethylene glycol dimethacrylate. Polyester/poly(methyl methacrylate)‐interpenetrating polymer networks, PPE/PMMA IPNs, were obtained as soft and opaque elastomers by the transfer molding technique. These IPNs were characterized by static mechanical properties, differential scanning calorimetry (DSC), and thermogravimetry. © 1993 John Wiley &amp; Sons, Inc.

The effect of plasticization and pH on film formation of acrylic latexes

AbstractThe effect of several variables relevant to film formation in 49 : 49 : 2 poly(methyl methacrylate‐co‐butyl acrylate‐co‐methacrylic acid) latexes were studied.Plasticization of the terpolymer by both an anionic [sodium dodecyl benzene sulphonate (NaDBS)] and a nonionic [nonyl phenol ethylene oxide adduct (NP40), forty ethylene oxide units on average] surfactant were investigated. Dynamic mechanical measurements indicated that NP40 plasticized the polymer, whereas NaDBS did not. This was attributed to the compatibility of the nonionic emulsifier and the polymer. The influence of the surfactants on the film formation process was studied using minimum film temperature (MFT) measurements and scanning electron microscopy (SEM). As expected, the MFT was independent of NaDBS concentration. However, the MFT was also independent of NP40 concentration. Film formation was further investigated using SEM. The series of micrographs at varying NaDBS concentrations showed no effect on the degree of film fusion. However, surface exudates were observed. The micrographs revealed that increasing NP40 content resulted in an apparently greater degree of film coalescence. That is, there was bridging of the particles in the interstitial regions. This was attributed to localized plasticization of the polymer in these regions by NP40.The effect of water plasticization of the latex polymer was studied using dynamic mechanical measurements. The physical character of the terpolymer was varied using mol wt modifiers (CBr4 chain transfer agent and ethylene glycol dimethacrylate crosslinker). It was found that all of the polymers were plasticized by water.Finally, the film forming behavior was investigated as a function of latex pH. MFT measurements indicated an independence of pH. © 1993 John Wiley &amp; Sons, Inc.

Effect of crosslinking agent content, monomer functionality, and repeat unit chemistry on properties of unfilled resins

Seven mechanical/physical properties were used to evaluate 10 unfilled resins: eight aromatic dimethacrylates and two urethane dimethacrylates. Physical property tests included compressive strength, Young's modulus in compression, uniaxial tensile strength, intrinsic yield point, toothbrush abrasion, Knoop hardness, and water sorption. Controlled changes were made in the following four material parameters: amount of crosslinking diluent present in the uncured monomer, functionality of the monomer, repeat unit chemistry of the monomer (urethane vs. aromatic structure) and mode of activation (chemical vs. visible light). Polymers containing a high concentration of crosslinking agent (50 wt%) were found to be tougher and to possess lower hardness than materials containing lesser amounts of crosslinking agent. This was attributed to the flexible nature of the triethylene glycol dimethacrylate crosslinking molecule. Exposure to water plasticized the highly crosslinked materials to the degree that the yield point and elastic modulus were effectively lowered. Most of the tested properties were unaffected by differences in functionality except resistance to toothbrush abrasion, which was enhanced for polymers derived from high functionality monomers. The urethane-based polymers sorbed substantially more water than the aromatic-based materials, which presumably resulted in lower values for surface hardness. However, the urethane resins were very tough, and excellent resistance to toothbrush abrasion was observed. Property differences caused by differences in activation mode were small, although the visible light materials did sorb more water.

Microcellular polymeric materials from microemulsions: Control of microstructure and morphology

AbstractThe effect of a crosslinking agent on the formation of porous solids by polymerizing microemulsions formulated with monomers was investigated. Phenomenological studies were carried out to evaluate the possibility of controlling the morphology of the porous polymeric materials by using precursor microemulsions having a distinct microstructure. A microemulsion system, containing methyl methacrylate (MMA), acrylic acid (AA), the crosslinking agent ethyleneglycol dimethacrylate (EGDMA), water, and sodium dodecylsulfate (SDS) as surfactant, was studied. An identical surfactant‐free system, formed using the same monomers, crosslinking agent, and water, but without surfactant, was also studied. Microemulsion samples from both these systems, having a water in oil droplet microstructure and also samples exhibiting bicontinuous microstructural characteristics, were used as precursor systems for polymerization. The morphology of the polymeric solids obtained was examined using scanning electron microscopy and thermogravimetric analysis. The results of this study indicate the possibility of forming porous polymeric solids having specifically tailored morphology and microstructure by the polymerization of monomer containing microemulsions. © 1993 John Wiley &amp; Sons, Inc.

Surface energetics of films of surfactant free poly(methyl methacrylate-co-butyl acrylate) emulsion polymers

The surface energetics of poly(methyl methacrylate-co-butyl acrylate) emulsion polymer films was investigated using dynamic contact angle (DCA) analysis. From a series of Wilhelmy plate experiments using several probe liquids, the dispersive and polar components of the surface energy were determined to be 20.6 and 3.4 mJ · m −2, respectively. The surface energy was calculated from these values to be 24 mJ · m −2. It was found that addition of molecular weight modifiers (ethylene glycol dimethacrylate crosslinking agent and carbon tetrabromide chain transfer agent) during polymer synthesis had no effect on the surface tension of the polymer. The surface energy measured here was lower than expected for a poly(methyl methacrylate-co-butyl acrylate) system. This result was attributed to the exudation of oligomeric or polymeric pseudosurfactant to the surface of the films. The sulfate ion terminated pseudosurfactant is produced from the ammonium persulfate initiator used during the emulsion polymerization. The presence of these groups at the film surface was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy. In addition to the measurement of the polymer surface energy, the effect of water inhibition on the polymer—water contact angles was studied. The reduction of the contact angles after water exposure times of 1 week and 1 month indicated progressive orientation of the hydrophilic functionalities toward the water phase.

Studies on semi‐interpenetrating polymer networks from poly(vinyl chloride‐co‐vinyl acetate) and poly(butyl acrylate)

AbstractA series of semi‐interpenetrating polymer networks (semi‐IPN) based on linear poly(vinyl chloride‐co‐vinyl acetate) and cross‐linked poly(butyl acrylate) were synthesized. The copolymer was swelled in butyl acrylate monomer containing azobisisobutyronitrile (AIBN) initiator and tetraethylene glycol dimethacrylate cross‐linker and later polymerized in situ. Variation in composition of the IPN was achieved by varying the copolymer/monomer ratio. The semi‐IPN was found to exhibit two distinct glass transitions as measured by differential scanning calorimetry and dynamic mechanical analysis. The tan θ values were found to be dependent on the composition. The tensile strength was found to be higher for semi‐IPNs containing a higher percentage of copolymer.

Interpenetrating Polymer Networks from Castor Oil Based Polyurethanes and Poly(Methyl Methacrylate) XX

Abstract Two component interpenetrating polymer networks (IPNs) of castor oil based polyurethanes and poly(methyl methacrylate) were prepared by sequential polymerization. The liquid polyurethanes were formed by reacting the hydroxyl group of castor oil with diphenyl methane diisocyanate at different stoichiometric NCO/OH ratios. These polyurethanes were swollen in methyl methacrylate monomer and subsequently polymerized by radical polymerization initiated with benzoyl peroxide in presence of crosslinkers ethylene glycol dimethacrylate and 1,3-propanediamine. Novel interpenetrating polymer networks PU/PMMA IPNs were obtained as films by transfer molding technique. These IPNs were characterized in terms of crosslink density and mechanical properties. The morphology was studied by transmission electron microscopy. Thermal stability was assessed from the thermogravimetric data.

Interpenetrating polymer network from castor oil‐based polyurethanes and poly(methyl methacrylate). XV

AbstractThe polyurethanes have been prepared from 2.12 functional OH containing castor oil and diphenyl methane diisocyanate under identical experimental conditions with a varying NCO/OH ratio. These polyurethanes were swollen in methyl methacrylate and subsequently interpenetrated by free radical polymerization using benzoyl peroxide and crosslinker ethylene glycol dimethacrylate. A series of interpenetrating polymer network (IPN) PU/PMMA IPNs were obtained as films by a transfer moulding technique. These IPNs were characterized by their resistance to chemical reagents, thermal behavior, and mechanical properties. The morphology was shown by SEM and dielectric properties at different temperatures were measured.

Interpenetrating polymer networks from castor oil based polyurethanes and poly(ethyl acrylate)

Polyurethanes were obtained by the reaction of hydroxyl groups of castor oil with hexamethylene diisocyanate, isophorone diisocyanate or diphenylmethane diisocyanate using an NCO/OH ratio of 1.6. These polyurethanes were swollen in ethyl acrylate monomer and subsequently polymerized by radical polymerization initiated with benzoyl peroxide in the presence of the crosslinking agent ethylene glycol dimethacrylate. A series of interpenetrating polymer networks (PU/PEA IPNs) were obtained as tough films by casting in glass moulds. The characteristics of these films were determined: resistance to chemical reagents, thermal behaviour (DSC, TGA), tensile strength, Young's modulus, elongation at break (%) and Shore A hardness. The morphology was determined by scanning electron microscopy, and the dielectric properties such as electrical conductivity, dielectric constant (e′), dielectric loss (e″) and loss tangent (tan δ) were studied.