659 research outputs found
Surface modification of UV Cured epoxy resins by click Chemistry
No full textA novel method for surface modification of UV-cured epoxy network was described. Photoinitiated cationic copolymerization of a bisepoxide, namely 3,4-epoxy cyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (EEC) with epibromohydrine (EBH) by using a cationic photoinitiator, [4-(2-methylpropyl)phenyl]4-methylphenyl-iodonium hexafluorophosphate, in propylene carbonate solution was studied. The real-time Fourier transform infrared spectroscopic, gel content determination and thermal characterization studies revealed that both EEC and EBH monomers take part in the polymerization and epoxy network possessing bromomethyl functional groups was obtained. The bromine functions of the cured product formed on the glass surface were converted to azide functionalities with sodium azide. Independently prepared alkyne functional poly(ethylene glycol) (PEG) was subsequently anchored to azide-modified epoxy surface by a "click" reaction. Surface modification of the network through incorporation of hydrophilic PEG chain was evidenced by contact angle measurements. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2862-2868, 201
Photopolymerization kinetics and dynamic mechanical properties of silane hydrolysed without evolution of byproducts. I. Tetrakis(methacryloyloxyethoxy)silane-diethylene glycol dimethacrylate
No full textThe temperature dependence of photopolymerization kinetics of tetrakis[(methacryloyloxy)ethoxy]silane (TetMESi) was compared with an analogue, diethylene glycol dimethacrylate and their copolymers. In all cases, the kinetics are controlled by the temperature dependence of the propagation step, the effect of diffusion on radical termination, the effect of rising glass transition during cure, and topological restraint on complete conversion. The glass transition regions of these polymers were very broad, suggesting their use in high temperature applications. NMR of the TetMESi monomer, and FTIR and water sorption measurements during exposure to water of the TetMESi-based polymers showed that the Si−O−C bond was slowly hydrolyzed, resulting in water-swollen polymers containing poly(hydroxyethyl methacrylate) which reduced the glass transition temperature and narrowed the glass transition region. UV−vis spectroscopic studies showed that during exposure to water, SiO2 nanoparticles or nanostructures were formed from the condensation of the silanol groups formed during the hydrolysis of TetMESi.Fil: Uygun, Mustafa. Monash University; AustraliaFil: Cook, Wayne D.. Monash University; AustraliaFil: Moorhof, Cornelis. Monash University; AustraliaFil: Chen, Fei. Monash University; AustraliaFil: Vallo, Claudia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Yagci, Yusuf. Istanbul Technical University; TurquíaFil: Sangermano, Marco. Politecnico Di Torino; Itali
In situ synthesis of gold-cross-linked poly(ethyleneglycol)nano composites by photoinduced electron transfer and free radical polymerization processes
No full textDegradable epoxy coatings by photoinitiated cationic copolymerization of bisepoxide with epsilon-caprolactone
No full textPhotoinitiated Curing of Mono- and Bifunctional Epoxidesby Combination of Active Chain End and ActivatedMonomer Cationic Polymerization Methods
No full textVisible Light Induced Cationic Polymerization of Epoxides by Using Multiwalled Carbon Nanotubes
No full textThe visible light induced cationic polymerization of epoxides can be achieved by means of multiwalled carbon nanotubes (MWCNTs), which act as visible light photoinitiators via a radical-induced cationic photopolymerization process. When MWCNTs are irradiated with longer wavelengths (above 400 nm), they generate carbon radicals, by means of hydrogen abstraction from the epoxy monomer; these radicals are oxidized in the presence of iodonium salt to a carbocation that is sufficiently reactive to start the cationic ring-opening polymerization of an epoxy monomer. These mechanisms have been supported by electron paramagnetic resonance analysis.Fil: Sangermano, Marco. Politecnico di Torino; ItaliaFil: Rodriguez, Damian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Gonzalez, Monica Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Laurenti, Enzo. Università di Torino; ItaliaFil: Yagci, Yusuf. Istanbul Technical University; Turquí
Synthesis of H-Shaped Complex Macromolecular Structures by Combination of Atom Transfer Radical Polymerization, Photoinduced Radical Coupling, Ring-Opening Polymerization, and Iniferter Processes
No full textThree controlled/living polymerization processes, namely atom transfer radical polymerization (ATRP), ring opening polymerization (ROP) and iniferter polymerization, and photoinduced radical coupling reaction were combined for the preparation of ABCBD-type H-shaped complex copolymer. First, a-benzophenone functional polystyrene (BP-PS) and poly( methyl methacrylate) (BP-PMMA) were prepared independently by ATRP. The resulting polymers were irradiated to form ketyl radicals by hydrogen abstraction of the excited benzophenone moieties present at each chain end. Coupling of these radicals resulted in the formation of polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) with benzpinacole structure at the junction point possessing both hydroxyl and iniferter functionalities. ROP of e-caprolactone (CL) by using PS-b-PMMA as bifunctional initiator, in the presence of stannous octoate yielded the corresponding tetrablock copolymer, PCL-PSPMMA- PCL. Finally, the polymerization of tert-butyl acrylate (tBA) via iniferter process gave the targeted H-shaped block copolyme
Synthesis of hybrid liquid crystalline block copolymers by combination of cationic or promoted cationic and free-radical polymerizations
No full textA novel poly(p-phenylene) containing alternating poly(perfluorooctylethyl acrylate-co-methyl methacrylate) and polystyrene grafts by combination of atom transfer radical polymerization and Suzuki coupling processes
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