Thermal Optical Analysis of Cholesteryl Methacrylate and Methyl Methacrylate CopolymersShoji, Kikuo; Nakajima, Yukio; Ueda, Eiichi; Takeda, Masatami
doi: 10.1295/polymj.17.997pmid: N/A
As side chain types of liquid crystalline polymers, cholesteryl methacrylate (ChMA) homopolymer and ChMA–methyl methacrylate copolymer (p-ChMA–MMA) were synthesized. The copolymer was a type of direct coupling side chain, a mesogenic side group directly bonded to the main chain without a flexible spacer. Since the observation of the transition temperature with polarized microscopy was not effective in this case, the mesomorphic behavior of the copolymers was studied by thermal optical analysis (TOA). Moreover, the effect of the casting method on the mesomorphic behavior was studied. It became clear that the isotropic temperature of the copolymer with a large fraction of ChMA was particularly effected by the casting method. The correlation between the thermotropic nature and stereoregularity of p-ChMA–MMA was also studied. The copolymers containing more than 72 mol% of ChMA were syndiotactic rich and exhibited a remarkable thermotropic mesophase.
Tris(2,2′-bipyridine)Ruthenium(II)-Sensitized Photopolymerization of AcrylamideIwai, Kaoru; Uesugi, Maki; Takemura, Fukuo
doi: 10.1295/polymj.17.1005pmid: N/A
Photopolymerization of vinyl monomers sensitized by tris(2,2′-bipyridine)ruthenium(II) complex (Ru(bpy)3
2+) was studied in polar solvents. No vinyl monomer tested was photopolymerized in the presence of sensitizer Ru(bpy)3
2+ alone under irradiation of visible light. Acrylamide (AA) was found to be photopolymerized in the presence of both the sensitizer and an electron donor triethylamine. The photopolymerization of AA did not occur in the presence of the sensitizer and methylviologen as an electron acceptor, but did in the coexistence of KSCN. In these systems the photosensitizer Ru(bpy)3
2+ was not consumed during the polymerization. The photopolymerization mechanisms for the Ru(bpy)3
2+-sensitized systems are discussed.
Evaluation of Concentration Dependence of χ-Parameter, Flory Temperature and Entropy Parameter for Polymer–Solvent System from Their Critical Solution Temperature and Concentration DataKamide, Kenji; Matsuda, Shigenobu; Saito, Masatoshi
doi: 10.1295/polymj.17.1013pmid: N/A
The critical polymer volume fraction v
p
c and the critical solution temperature T
c were estimated from the threshold cloud point (tcp) for polystyrene (PS) and polyethylene (PE) solutions in literature. The critical points thus obtained, together with those directly determined in literature, of PS in ten solvents and PE in sixteen solvents were analyzed, according to the Shultz–Flory (SF), Koningsveld et al. (KKS), and Kamide–Matsuda (KM) methods, to evaluate the Flory temperature θ and the entropy parameter ψ. The concentration dependence parameters p
1 and p
2 of the χ-parameter, as given by χ=χ0(1+P
1
v
p+P
2
v
p
2)(χ0, a concentration-independent parameter, v
p, polymer volume fraction) were determined by KKS and KM methods, which gave almost the same values of p
1 and p
2. Except for few solvents, p
1 value for PS solutions can be regarded as constant, which is near to 2/3, theoretically predicted when A
2=A
3=0 at θ (A
2 and A
3, second and third virial coefficients). For lower critical solution point (LCSP), p
2 is always negative, except for PS/cyclopentane and for upper critical solution point (UCSP) p
2 is positive. The very wide variation of p
1 and p
2 with solvents was observed for PE. Application of KM method to the most reliable data on PE/diphenylether by Koningsveld et al. led to p
1=0.61, which is not so far from the theoretical value. θ, obtained by three methods, is practically independent of the method used, if ψ estimated by KM method coincides with that by KKS method for a given polymer–solvent system, if ψ was found to be positive for UCSP and negative for LCSP, suggesting that the polymer solution should be athermal at a temperature between UCSP and LCSP. The effect of solvent nature on p
1, p
2 , θ, and ψ are discussed in some detail.
Thermal Optical Analysis of Cholesteryl Methacrylate and Butyl Methacrylate CopolymersShoji, Kikuo; Nakajima, Yukio; Ueda, Eiichi; Takeda, Masatami
doi: 10.1295/polymj.17.1029pmid: N/A
As a side chain type of liquid crystalline polymer, the copolymers of cholesteryl methacrylate and butyl methacrylate were synthesized. When the mesomorphic behavior of the copolymers was examined with a polarized microscope, the observed transition temperatures were so much varied that the mesomorphic behavior had to be studied by thermal optical analysis (TOA). TOA curves with a single peak were obtained by a sandwich-type film prepared by interposing the casting solution between two cover glasses and drying sufficiently. The mesomorphic temperature region increased with increasing mole fraction of cholesteryl methacrylate (ChMA) in the copolymers. The appearing and clearing temperatures of birefringence shifted to the higher temperature side with increasing mole fraction. The effect of pretreatment of the cover glasses with trimethyl chlorosilane was examined. The relation between the maximum intensity of the TOA curve and the film thickness was studied for both films prepared with the treated and untreated glasses. The intensity remarkably increased with increasing film thickness for the treated glasses, but no such correlation was found for the untreated glasses. A sandwich cell was prepared by the same casting method of a TOA sample with tin coated glasses. The cell was heated up to the mesomorphic temperature under a dc field of 40 V. Although no electro-optical effect was observed in the first heating step, the apparent flow instability, similar to William’s domain, appeared in the cooling step from the isotropic state. Small angle X-ray diffraction patterns were obtained for the samples of both cast and annealed films. A sharp peak at 2θ=2.5° corresponding to 35.5 Å of periodicity was observed only for annealed film.
Crystal Structure of meso-(2R,4r,6S)-2,4,6-Heptanetriol as a Model Compound for Syndiotactic Poly(vinyl alcohol)Kuribayashi, Shunsuke
doi: 10.1295/polymj.17.1037pmid: N/A
The crystal structure of meso-(2R,4r,6S)-2,4,6-heptanetriol as a model compound for syndiotactic poly(vinyl alcohol) was determined. The crystal belongs to a triclinic system with dimensions of a=10.950(9), b=9.904(11), c=14.199(13)Å, α=104.47(11), β=114.10(8), and γ=70.34(7)°. The space groupis P1 and D
x=1.125, D
m=1.122 Mgm−3, and Z=6. The final R factor was 0.080 for 3348 observed reflections. There are three crystallographically independent molecules in the unit cell. The seven carbon atoms of these three molecules have TTTT sequences and the OH groups form intermolecular hydrogen bonds. The best planes composed of seven carbon atoms of the three independent molecules are nearly parallel to each other and the molecular axes of the all molecules are nearly parallel to each other and point in the direction of the a-axis.
Vinylbenzyl-Type Polyamide Macromer Synthesized from Bicyclic Oxalactam. Preparation and Characterization of Graft Copolymer Composed of Polystyrene as a Stock and Hydrophilic Polyamide as BranchesHashimoto, Kazuhiko; Sumitomo, Hiroshi; Kawasumi, Masaya
doi: 10.1295/polymj.17.1045pmid: N/A
Vinylbenzyl-type polyamide macromers (1) of various average molecular weights (M
n; 3900, 5400, and 8400) were prepared by the anionic ring-opening polymerization of a bicyclic oxalactam, 8-oxa-6-azabicyclo[3.2.1]octan-7-one (abbreviated as BOL, 2) followed by a reaction with p-vinylbenzylamine. The relative reactivity of the macromer (M1) in the radical copolymerization with styrene (M2) was found to be lower than that of p-methylstyrene from the estimation of the reciprocal monomer reactivity ratio (1/r
2). The resulting graft copolymer composed of a polystyrene stock and polyamide branches was characterized by structural analysis, solubility test, and determination of moisture sorption. Two kinds of transparent binary blend films, which were i) the graft copolymer and homopolystyrene and ii) the graft copolymer and polyBOL, were cast on a glass plate from the corresponding chloroform and chloroform-methanol (9:1) solutions, respectively. In the case of the former film comprising mainly polystyrene, the hydrophilic polyamide segment of the graft copolymer as a really minor component was found to be located on the glass-side surface from the contact angle measurement and the attenuated total reflection-infrared spectroscopy.
Preparation and Properties of Thermotropic Mesogenic PolyestersMakaruk, Leszek; Polanska, Hanna; Ksiezakowska, Elzbieta; Wazynska, Barbara
doi: 10.1295/polymj.17.1055pmid: N/A
The effect of the chemical structure and stereogeometry of mesogen on the liquid crystalline properties of thermotropic main-chain polyesters was studied by means of DSC and polarized microscopy for three series of polymers. The polyesters obtained from modified 4,4′-dihydroxybenzophenone (DHBP) and sebacoyl (SEB) or suberoyl (SUB) dichlorides did not exhibit the mesogenic properties. Modification of DHBP in this case consisted in replacement of ketone linkage by [InlineEquation not available: see fulltext.] between two aromatic rings. The same bisphenol, however, when mixed with another (showing mesogenic behaviour) enhanced the liquid crystalline properties of the copolyesters, namely increasing the temperature range of liquid crystalline phase. The condensation of SEB or SUB with DHBP modified by lateral substitution (at various positions) of one aromatic ring with CH3 group lead to polyesters of lower temperatures of the transition from crystal to nematic phase and mesophase to isotropic liquid, as compared to parent polymers (i.e., polyesters of DHBP+SEB or SUB). Different shifts of those temperatures with the position of substitution have been observed and it was found less pronounced for 3-substituted than 2-substituted bisphenols. Temperature ranges of mesophases also depended on the structure of bisphenols and were broader for 3-substituted DHBP. Therefore, the stereogeometry of the polymer molecules and the bulkiness of their substituents are considered the most important parameters in controlling the mesogenic properties of thermotropic, rigid-flexible polyesters with mesogens incorporated in the main chain.