Abstract The structure of Langmuir-Blodgett (LB) diacetylene films CH3?(CH2)11?C≡C?C≡C?(CH2)8?COOCd1/2 (DA1) and CH3?(CH2)20?CO2?CH2?C≡C?C≡CH2OH (DA2) was studied by X-ray small angle scattering and electron diffraction methods prior to and upon their polymerization. It has been established that Langmuir films have layer packing. The periods of the constituent layers were determined as 58 Å (for DA1) and 69 Å (for DA2). This indicates the existence of a vertical bilayered packing of molecules. It has also been established that polymerization of LB diacetylene films due to the action of UV irradiation does not change the layer thickness appreciably and the structural rearrangement reduces to a slight redistribution of the electron density along the molecules which is explained by a break of the triple bonds during the UV irradiation. 相似文献
The polymerization of the cyclic tetradiyne monomer, [? (CH2) 2? C?C? C?C? (CH2)2? ]4, containing interstitial chloroform has been investigated using Raman and Fourier-transform infrared spectroscopy and x-ray diffraction techniques. A loss of crystallographic register between chains occurs during the polymerization reaction, although crystalline order in the chain-axis projection is retained. These studies indicate that 50 Mrad of 60Co γ-ray irradiation produces 1,4-addition polymerization at most of the diacetylene functionalities. Unreacted diacetylene groups are present primarily, although not completely, in soluble oligomeric material. Infrared spectroscopy indicates that this low molecular weight material has a butatriene (cumulene) backbone structure rather than the acetylenic structure of the insoluble polymer. 相似文献
This article describes the synthesis and the cation-radical polymerization (Scholl reaction) of 1,3-bis[4-(1-naphthoxy) benzoyl] benzene ( 6 ) and 1,4-bis[4-(1-naphthoxy) benzoyl]- benzene ( 7 ) initiated by FeCI3. This polymerization produced poly(ether ether ketone ketone)s (PEEKK) of number average molecular weight (M?n) up to 5400 g/mol. The synthesis of bis[4-(1-naphthoxy) phenyl] methane ( 8 ), 1,3-bis[4-(1-napthoxy) phenylmethyl] benzene ( 9 ), and 1,4-bis[4-(1-naphthoxy) phenylmethyl] benzene ( 10 ) are also described. Polyethers of M?n up to 15400 g/mol at a FeCl3/monomer molar ratio of 2/1 were obtained. An increased polymerizability of the monomers 9 and 10 containing two CH2 groups versus that of the corresponding monomers containing two carbonyl groups ( 6 and 7 ) was observed. This enhanced polymerizability was explained based on the increased nucleophilicity of monomers 9 and 10 . 相似文献
The polar epoxides, glycidonitrile, dimethyl glycidonitrile, tetracyanoethylene oxide, epicyanohydrin, 4,4,4-trichlorobutylene-1,2-epoxide, and 1,1-dichloro-3,4-epoxy-1-butene were prepared, characterized by their infrared and nuclear magnetic resonance spectra and their polymerizations studied. Epicyanophydrin was found to be an unpolymerizable dimer, and those epoxides with a cyano group attached directly to the epoxide ring could not be polymerized. The halogenated epoxides, 4,4,4-trichlorobutylene-1,2-epoxide and its dehydrochlorination product, 1,1-dichloro-3,4-epoxy-1-butene were polymerized to high polymers with a complex catalyst from aluminum alkyl, acetyl acetone, and water. The polymerization of these monomers gave low conversions and required large amounts of catalyst. Higher conversions were obtained by copolymerization with propylene oxide or terpolymerization with propylene oxide and allyl glycidyl ether. The polymerizability of the substituted epoxide in (where X is CH3? , ClCH2? , Cl3CCH2? , and Cl2C? CH? ) was found to follow the order: CH3? > ClCH2? > Cl3C? CH2? > Cl2C?CH. The polymers of 4,4,4-trichlorobutylene-1,2-epoxide and its dehydrochlorination products were not vulcanizable through the chlorine functionality or the olefinic unsaturation of the type Cl2C?CH? . The presence of an active third monomer such as allyl glycidyl ether was necessary to facilitate vulcanization. Properties of such vulcanizates are reported. 相似文献
A solution of AlCl3 in CH2Cl2 prepared in advance was used 18 days after the mixing of the components as an initiation system in the polymerization of isobutylene performed in CH2Cl2 in the temperature range between ?10 and ?20°C. The 1H-NMR analysis of polyisobutylene (PIB) samples synthesized to low and high conversion showed that it is the initiation reaction and not the transfer reaction to dichloromethane that is responsible for the ? CH2Cl endgroup in the polymer chain. In case of the transfer to monomer formation of PIB with internal terminal unsaturation [PIB? CH?C(CH3)2] is preferred to external unsaturation [PIB? CH2(CH3)C?CH2]. The solutions of AlCl3 in CH2Cl2 showed an absorption band at λmax = 302 nm. 相似文献
The molecular aggregation of acrylic and methacrylic acid esters containing long-fluorocarbon chains: 2-(perfluoroalkyl)ethyl acrylate (FFnEA) and 2-(perfluoroalkyl)ethyl methacrylate (FFnEMA) (F(CF2)nCH2CH2OCOC(X)=CH2, where X=H, CH3 and n=6, 8, 10) was investigated by differential scanning calorimetry (DSC) and temperature controlled X-ray powder diffraction measurement. These compounds exhibited some characteristic polymorphic behaviors depending on the length of fluorocarbon chain and the -position methyl group. The solid-state polymerization by -ray irradiation was studied for these compounds in the various crystal forms. In the solid-state polymerization, highest polymerizability was observed in the crystal form that exists in the highest temperature region for each compound.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
A series of exo-olefin compounds ((CH3)2C(PhY)−CH2C(=CH2)PhY) were prepared by selective cationic dimerization of α-methylstyrene (αMS) derivatives (CH2=C(CH3)PhY) with p-toluenesulfonic acid (TsOH) via β-C−H scission. They were subsequently used as reversible chain transfer agents for sulfur-free cationic RAFT polymerization of αMS via β-C−C scission in the presence of Lewis acid catalysts such as SnCl4. In particular, exo-olefin compounds with electron-donating substituents, such as a 4-MeO group (Y) on the aromatic ring, worked as efficient cationic RAFT agents for αMS to produce poly(αMS) with controlled molecular weights and exo-olefin terminals. Other exo-olefin compounds (R−CH2C(=CH2)(4-MeOPh)) with various R groups were prepared by different methods to examine the effects of R groups on the cationic RAFT polymerization. A sulfur-free cationic RAFT polymerization also proceeded for isobutylene (IB) with the exo-olefin αMS dimer ((CH3)2C(Ph)−CH2C(=CH2)Ph). Furthermore, telechelic poly(IB) with exo-olefins at both terminals was obtained with a bifunctional RAFT agent containing two exo-olefins. Finally, block copolymers of αMS and methyl methacrylate (MMA) were prepared via mechanistic transformation from cationic to radical RAFT polymerization using exo-olefin terminals containing 4-MeOPh groups as common sulfur-free RAFT groups for both cationic and radical polymerizations. 相似文献
Polymerization of 2-methyl-1-vinylimidazole (MVI) and 2-ethyl-1-vinylimidazole (EVI) was found to be markedly photosensitized in the presence of oxidizing metal salts such as UO2(NO3)2, Ce(NH4)2(NO3)6, Hg(CH3COO)2, AgNO3; non-oxidizing metal salts such as ZnII did not act as photosensitizers. The interaction of monomer with a metal salt is discussed on the basis of infrared and electronic spectroscopy. This photopolymerization is very specific with respect to the kind of monomer. The polymerization of noncomplexing monomer (styrene) is not photosensitized by these metal salts. Consequently, photosensitized electron transfer between monomer and metal salt via complex formation is considered to be the most probable initiation mechanism. Cupric acetate and sodium chlorolaurate, which have been reported as efficient initiators for the polymerization of vinylpyridine and N-vinylcarbazole, respectively, act as linear terminators of growing radicals. The radical polymerizability of the zinc complex of MVI was studied by means of copolymerization with styrene. The reduction of the reactivity of MVI on complexing was explained by correlating with the spectroscopic observations. Because the polymerization system is heterogeneous, a detailed discussion was not possible. 相似文献
Based on our recent discovery of the isomerization polymerization of β-(2-acetoxyethyl)-β-propiolactone into poly-δ-ester,1,2 we examined the generality of this phenomenon by using two related monomers. The catalysts were (EtAlO)n and Et(ZnO)2ZnEt. The side-chains in the monomers selected were the (CH3)2CHCOO? CH2CH2? (2) and (CH3)CICHCOO? CH2CH2? (3) groups in which steric effects are almost identical but electronic effects are in opposition. The monomers yielded isomerized poly-δ-ester units, depending on the terminal substituent groups in the side-chain. These observations can be interpreted with the bicyclic intermediate proposed in the earlier work. Monomer (2) was reactive and produced a poly-δ-ester structure most readily, probably because of the higher electron density at the side-chain ester group which coordinated with the catalyst. In contrast, monomer (3) was less reactive, and the probability of isomerization was the lowest, i.e., the electron deficient side-chain ester group apparently interfered with the formation of the intermediate, especially in the Zn-catalysis. Equibinary random copolymers were prepared from (2) and (3) according to the catalyst and polymerization conditions chosen. 相似文献
The polymerization activity of several allenes under the influence of Al-i-Bu3-VOCl3, and structure and properties of the solid polymers obtained, have been studied. Allene; butadiene-1, 2; hexadiene-1, 2; 3-methylbutadiene-1, 2; 3-methylpentadiene-1, 2; and pentadiene 2, 3 could be converted into soluble, solid polymers. 2-Methylpentadiene-2, 3; tetramethylallene; and tetraphenylallene did not react under the polymerization conditions applied. The following order of polymerization activity seems to be valid: CH2?C?CH2 > R1CH?C?CH2 > R1R2C?C?CH2 ≥ R1CH?C?CHR2, > R1R2C?C?CHR3 ≥ R1R2C?C-CR3R4. The polymers of the homologues of allene were obtained as amorphous solids with the exception of poly(3-methyl-butadiene-1, 2), which was fairly crystalline. 相似文献