Search results for "Methyl methacrylate"
showing 10 items of 162 documents
Preferential solvation of poly(methyl methacrylate) and a bisphenol A diglycidyl ether by size-exclusion chromatography
2004
The preferential adsorption coefficient, lambda, of poly(methyl methacrylate), PMMA, in solutions formed by an epoxy resin in tetrahydrofuran (THF), was studied by size-exclusion chromatography (SEC). Only PMMA of lowest molar mass was preferentially solvated by epoxy but at low concentrations of epoxy in the mixture. At higher epoxy content PMMA was preferentially solvated by THF. A simultaneous and competitive solvation between the specific interactions PMMA-epoxy and the self association of epoxy at high concentrations would be the responsible of this inversion point. The more compacted coil of PMMA of higher molecular weights in solution could explain the lack of interaction of these po…
Die thermische polymerisation von methylmethacrylat, 2. Bildung des ungesättigten dimeren
1980
The spontaneous thermal polymerization of methyl methacrylate (MMA) is accompanied by the production of serveral oligomers among which a linear unsaturated dimer H-1 (dimethyl 1-hexene-2,5-dicarboxylate) is predominant. The reaction kinetics of this dimer formation was investigated in bulk and in solution. The temperature dependence of the second order dimerization constant was determined as Reaction mechanisms for the thermal dimer formation of MMA are discussed.
Estimation of the Compatibility Between Poly(Methylmethacrylate) and Poly(Styrene Co Vinyl Phenol) Blends from Dilute Solution Measurements
2006
Abstract The compatibility of poly(methyl methacrylate) (PMMA) with poly(styrene‐co‐vinyl phenol) (PS‐VPh) with two different contents of vinyl phenol, 5.8 and 7.2%, in dilute tetrahydrofuran solutions has been investigated by size exclusion chromatography and fluorescence spectroscopy at 25°C. The chromatographic technique permits the evaluation of the preferential solvation at different PMMA/PS‐VPh ratios. Changes in the fluorescence properties of PS‐VPh, caused by its association with PMMA, were used to obtain the fraction of copolymer bound to PMMA at diverse PMMA compositions. Both techniques agree quantitatively in every system, indicating that the association increases when the PMMA …
Evolution of the “knitting pattern” morphology in ABC triblock copolymers
1996
A new morphology of ternary ABC triblock copolymers is presented which results from the asymmetric interaction between a centre block (poly(ethylene-co-butene)) to different end blocks (polystyrene and poly(methyl methacrylate)). This morphology with the appearance of a “knitting pattern” can be described as an intermediate of a morphology of A, B and C lamellae and a morphology of A and C lamellae with B cylinders at the A/C interface.
Dispersion polymerization of methyl methacrylate in supercritical carbon dioxide stabilized with poly(ethylene glycol)-b-perfluoroalkyl compounds
2004
Abstract In this work selected components of an easily synthesible class of poly(ethylene glycol)-perfluoroalkyl block compounds were tested as stabilizers for the dispersion polymerization of methyl methacrylate in scCO 2 . As already observed in the case of different block surfactants the anchor soluble balance (ASB) of the stabilizer is the crucial parameter affecting the efficacy of the stabilization and the kinetics of the polymerization process. When stabilizers with appropriate ASB were used, high molecular weight poly(methyl methacrylate) was synthesized under the form of microspherical polymer particles with yields ranging up to 80%. In these experiments the occurrence of a gel-eff…
Polymerization of methyl methacrylate through ionizing radiation in CO2-based dense systems
2000
Herein, we report the use of ionizing radiation to induce a dispersion polymerization reaction in dense CO2. As a model system, the polymerization of methyl methacrylate in the presence of poly(dimethylsiloxane) stabilizers was investigated. It was demonstrated that the dose plays the key role in the progress of the reaction and in the morphology of the resulting polymer. Dispersion polymerization carried out in the presence of mono- and bifunctionalized surfactants gave differently structured polymers. The polymers obtained have been characterized by scanning electron microscopy, solubility tests, and gel permeation chromatography, and the molecular structure has been related to dynamic me…
DFT exploration of [3 + 2] cycloaddition reaction of 1H-phosphorinium-3-olate and 1-methylphosphorinium-3-olate with methyl methacrylate
2018
A Molecular Electron Density Theory (MEDT) study of the regio- and stereoselectivity of the [3 + 2] cycloaddition (32CA) reaction of 1H-phosphorinium-3-olate and 1-methylphosphorinium-3-olate with methyl methacrylate was carried out using the B3LYP/6-31G(d) method. In order to test the method dependence for the most favorable reaction path leading to the 1H-substituted 6-exo cycloadduct (CA) various functionals using higher basis sets were taken into consideration in the gas phase. An analysis of the energetic parameters indicates that the reaction path leading to 6-exo CA are kinetically as well as thermodynamically favored in the gas phase, THF and ethanol. The calculated energetic parame…
New Photosensitive Polymers: Synthesis and Free Radical Polymerization of Oxypyridinium and Oxyisoquinolinium Functionalized Methacrylate and Styren…
2002
Polymerizable hydroxypyridinium and hydroxyisoquinolinium salts 1a−4a, 2d, and 3d have been prepared from vinylbenzyl chloride or glycidyl methacrylate and 3-hydroxypyridine (2), 4- or 5-hydroxyisoquinoline (1, 3), and 8-hydroxyquinoline (4). Radical homo- and copolymerization with styrene or methyl methacrylate of the salts 1a−3a, 2d, and 3d produced (co)polymers 1e, 2e, 2f, 3f, 1g, 2g, 2h, and 3h. The photosensitive dipolar oxypyridinium or oxyisochinolinium betaine structures were generated in solutions with triethylamine from the low molecular weight and polymeric salt precursors. For the model compounds 1b−4b and (co)polymers 1e, 2e, 2f, 3f, 1g, 2g, 2h, and 3h, the degradation of the l…
A refractive free-space microoptical 4 x 4 interconnect on chip level with optical fan-out fabricated by the LIGA technique
2002
A parallel purely refractive 4/spl times/4 optical data link has been built. The design is based on pairs of crossed cylindrical microlenses. The optical module is fabricated and monolithically integrated in. polymethyl methacrylate (PMMA) by the LIGA technique.
1980
Using a bifunctional initiator such as the tetrameric dianion of α-methylstyrene for the anionic polymerization of methyl methacrylate the rate constant is found to increase with conversion approaching that observed with a monofunctional initiator while the tacticity of the polymers obtained changes from that of an almost ideally atactic to a highly syndiotactic polymer. The results are explained by the assumption of an intramolecular association of the two terminal ion pairs yielding a new active species and gradually dissociating with increasing degree of polymerization of the chain. Using a polymeric dianion of α-methylstyrene as an initiator the association phenomenon is not observed.