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Thermal Polymerization (thermal + polymerization)
Selected AbstractsMonitoring ultrathin film photopolymerization of tetra-alkylepoxyporphyrin by UV-Vis spectroscopyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2009Kalle Lintinen Abstract Cationic photopolymerization is a convenient in situ polymerization method for organic thin film preparation. In this work, the polymerization mechanisms is applied for highly viscous cross-linking monomers, using tetra-alkylepoxyporphyrin (TAEP) as a case study. By comparing the UV-Vis spectra of the polymerized sample before and after the unreacted monomers have been dissolved, it is possible to estimate the polymerization yield. An IR spectrum of a reference thick film confirms full polymerization. Scanning fluorescence lifetime microscopy and AFM show the uniformity of the polymer. It was shown that photopolymerization is highly dependent on the substrate nature and requires at best case a 10 min illumination at 90 °C. Thermal polymerization of the same sample requires 10 min heating at 150 °C in dark. It was also shown that TAEP works as a self-sensitizer for cationic photopolymerization. The proposed method is a mild and versatile technique for in situ preparation of thin polymeric films directly from chromophore monomers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6095,6103, 2009 [source] Synthesis and Characterization of the Nitrogen-Rich Hyperbranched Polymers , Poly([1,2,3]-Triazole-[1,3,5]-Triazine)sPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 6 2008Georgiy Abstract Novel hyperbranched poly([1,2,3]-triazole-[1,3,5]-triazine)s (HBP TT) were synthesized by a 1,3-dipolar cycloaddition reaction from AB2 monomer , 2-azido-4,6-bis-prop-2-yn-1-yloxy- [1,3,5]-triazine (ABPOT). The monomer contains one azide group A and two terminal alkyne units B. Thermal polymerization of ABPOT in bulk or in DMF solution leads to hyperbranched polymers containing both 1,4- and 1,5-disubstituted [1,2,3]-triazoles. The monomer was also polymerized catalytically in the presence of Cu(I) salts under mild reaction conditions in DMSO solution and in bulk affording hyperbranched poly-[1,2,3]-triazoles 1,4-disubstituted only. The reactions lead to the products soluble in aprotic polar solvents like DMSO or DMF. Side reactions can proceed in a few cases, particularly: (i) homocoupling of alkyne groups, leading to the formation of insoluble products as a result of cross-linking, (ii) isomerization of propynyloxytriazine fragments to propynyl- or propadienyltriazinone ones, and (iii) hydrolysis of triple bonds without the loss of solubility. Heats of formation of monomer and synthesized polymers were calculated from their combustion heats. All products were characterized by NMR-, IR-spectroscopy, and size exclusion chromatography (SEC) data. The obtained results open the prospect for the use of HBP TT as the high-enthalpy modifiers for energetic and non-energetic binders. [source] Determination of Diclofenac in Urine Samples by Molecularly-Imprinted Solid-Phase Extraction and Adsorptive Differential Pulse VoltammetryELECTROANALYSIS, Issue 15 2007Laura Fernández-Llano Abstract A molecularly imprinted polymer for diclofenac (DCF) was prepared by thermal polymerization over silica beads using 2-(dimethylamino)ethyl-methacrylate as functional monomer. After silica elimination by HF treatment, the polymer was applied to the selective solid-phase extraction of the drug from urine followed by its quantification by adsorptive differential pulse voltammetry. Results indicate that the drug could be selectively extracted from the sample and quantified at clinically relevant concentrations (,g/mL). [source] Synthesis and Chemical Properties of Diacetylenes with Pyridinium and 4,4,-Bipyridinium GroupsHELVETICA CHIMICA ACTA, Issue 5 2010Isao Yamaguchi Abstract Diacetylenes (DAs) having a dipolar D- , -A structure (D=donor: amino group; ,=, -conjugation core; A=acceptor: pyridinium (Py) and bipyridinium (BPy) groups), i.e., 4 (APBPyDA) and 5 (APPyPyDA), or an A- , -A structure, i.e., 7 (DBPyDA) and 8 (PyDA(Cl)), were obtained by 1,:,1 and 1,:,2 reactions of 4,4,-(buta-1,3-diyne-1,4-diyl)bis[benzenamine] (APDA; 3) with 1-(2,4-dinitrophenyl)-1,-hexyl-4,4,-bipyridinium bromide chloride (1,:,1,:,1) (1), 1-(2,4-dinitrophenyl)-4-(pyridin-4-yl)pyridinium chloride (2), or 1-(2,4-dinitrophenyl)pyridinium chloride (6) (Schemes 1 and 2). The anion-exchange reactions of 8 with NaI and Li(TCNQ) (TCNQ,=2,2,-(cyclohexa-2,5-diene-1,4-diylidene)bis[propanedinitrile] radical ion (1,)) yielded the corresponding I, and TCNQ, salts 9 (PyDA(I)) and 10 (PyDA(TCNQ)). Compounds 10 and 4 exhibited a UV/VIS absorption due to a charge transfer between the TCNQ, and the pyridinium groups and a strong solute,solvent interaction of a dipolar solute molecule in the polar environment, respectively. Compounds 8,10 exhibited photoluminescence in solution, whereas 4 and 7 did not because of the presence of the 4,4,-bipyridinium quenching groups. Differential-scanning-calorimetry (DSC) measurements suggested that the DAs obtained in this study can be converted into poly(diacetylenes) by thermal polymerization. [source] Preparation and characterization of PDLC films formed using a two-step procedureADVANCES IN POLYMER TECHNOLOGY, Issue 1 2007Yu-Che Hsiao Abstract A novel polymer-dispersed liquid crystal composite film was prepared using liquid crystal and dual resins, namely, UV-curable urethane diacrylate and thermo-curable epoxy, with a fixed LC content of 50 wt%. A combination treatment of UV irradiation and heat was performed in sequential steps. At first, the urethane diacrylate resin was cross-linked through UV irradiation and a pre-UV-cured film was formed. Then, the pre-UV-cured film was heat treated for curing the thermo-curable epoxy resin. As the thermal polymerization continued, LC droplets were formed and became embedded within the polymer matrix. PDLC films obtained from the polymer matrix with refractive indices in a range from 1.511 to 1.523 (1.517 ± 0.006) have optimal electro-optical properties. Films with a refractive index higher than 1.523 have high contrast ratio (CR), threshold voltage (Vth), and V90, whereas those with a low refractive index of 1.508 have low CR, Vth, and V90. In this study, we found that PDLC composite films with optimal compositions prepared by dual resins (UV/thermal) have good electro-optical properties. © 2007 Wiley Periodicals, Inc. Adv Polym Techn 26:14,20, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20087 [source] Grafting of polymers onto and/or from silica surface during the polymerization of vinyl monomers in the presence of ,-ray-irradiated silicaJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2006Akiko Tsuchida Abstract The effects of radicals on silica surface, which were formed by ,-ray irradiation, on the polymerization of vinyl monomers were investigated. It was found that the polymerization of styrene was remarkably retarded in the presence of ,-ray-irradiated silica above 60 °C, at which thermal polymerization of styrene is readily initiated. During the polymerization, a part of polystyrene formed was grafted onto the silica surface but percentage of grafting was very small. On the other hand, no retardation of the polymerization of styrene was observed in the presence of ,-ray-irradiated silica below 50 °C; the polymerization tends to accelerate and polystyrene was grafted onto the silica surface. Poly(vinyl acetate) and poly(methyl methacrylate) (MMA) were also grafted onto the surface during the polymerization in the presence of ,-ray-irradiated silica. The grafting of polymers onto the silica surface was confirmed by thermal decomposition GC-MS. It was considered that at lower temperature, the grafting based on the propagation of polystyrene from surface radical ("grafting from" mechanism) preferentially proceeded. On the contrary, at higher temperature, the coupling reaction of propagating polymer radicals with surface radicals ("grafting onto" mechanism) proceeded to give relatively higher molecular weight polymer-grafted silica. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2972,2979, 2006 [source] Synthesis and Characterization of Thermally Curable Benzoxazine-Functionalized Polystyrene Macromonomers,MACROMOLECULAR RAPID COMMUNICATIONS, Issue 10 2005Baris Kiskan Abstract Summary: Thermally curable benzoxazine ring-containing polystyrene macromonomers were synthesized and characterized. 1,4-Dibromo-2,5-bis(bromomethyl)benzene and 1,4-dibromo-2-(bromomethyl)benzene were used as initiators in the atom transfer radical polymerization of styrene. The resulting polymers were used in combination with 3-aminophenylboronic acid hemisulfate, for a Suzuki coupling. The obtained polymers, with amino groups in the middle or end of the chains, were reacted with formaldehyde and phenol to yield benzoxazine ring-containing macromonomers. In addition to the glass transition temperature of the polystyrene segment observed at ca. 105,°C, differential scanning calorimetry thermograms exhibit an exotherm at ca. 276,°C corresponding to the oxazine thermal polymerization. Both macromonomers undergo thermal curing with the formation of thermosets having polystyrene segments. Structure of the benzoxazine-functionalized polystyrene. [source] Photo-induced polymerization of methyl methacrylate/cyclodextrin complex in aqueous solutionPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 11 2008Jianping Deng Abstract Polymerization of hydroxypropyl- , -cyclodextrin (HP- , -CD) complex of methyl methacrylate (MMA) (MMA/HP- , -CD) was carried out under UV irradiation in aqueous solution with Irgacure 2959 (4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone) as a photoinitiator at room temperature. The effects of some principal factors, including UV irradiation intensity, initiator concentration, and the ratio of HP- , -CD to MMA, on the polymerization were investigated in detail. Compared to the corresponding thermal polymerization, photo-induced polymerization of the MMA/HP- , -CD complex could be accomplished at a higher speed; the polymerization conversion in photo-induced polymerization reached 94% within 30,min, while it was only 62% for the thermal polymerization of 16,hr at 70°C. The number-average molecular weight (Mn) and polymerization conversion decreased with the increase in UV intensity and initiator concentration. The resulting PMMA precipitated spontaneously from the solution during polymerization in the absence of any precipitator. About 95,wt% of the HP- , -CD remained in the solution after polymerization and the reusability of the residual HP- , -CD was experimentally demonstrated. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||