1404166-41-1Relevant academic research and scientific papers
Synthesis and liquid crystalline behavior of 2,5-disubstituted styrene-based random copolymers: Effect of difference in length of the rigid core on the mesomorphic behavior of mesogen-jacketed liquid crystalline polymers
Chen, Sheng,Shu, Xiang,Xie, He-Lou,Zhang, Hai-Liang
, p. 3556 - 3565 (2013)
A series of binary copolymers, poly{2,5-bis[(4-octadecyloxyphenyl) oxycarbonyl]-styrene-co-2,5-bis[(4′-octadecyloxybiphenyl)oxycarbonyl] -styrene} (poly(M-OC18-co-M-C18)), were synthesized via free radical polymerization. The random nature of the copolymers was expected on the basis of the assumed similar reactivities because of the analogous monomers. A combination of differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide-angle X-ray diffraction (WAXD) demonstrated that phase behavior of this series of copolymers were strongly composition dependent. The P-OC18 formed smectic A phase, re-entrant isotropic phase and column nematic phase, while the P-C18 only exhibited the stable smectic A phase. The comparison between P-OC18 and P-C18 indicates that the length of the rigid core is crucial to determine the liquid crystalline (LC) structures. After copolymerization, the glass transition temperature and the phase transition temperature of the copolymers from smectic phase to isotropic phase both increased with the molar fraction of 2,5-bis[(4′-octadecyloxybiphenyl)oxycarbonyl]-styrene (M-C18) in feed. In addition, when the feed was below 0.3, a column nematic phase was observed in high temperature. Namely, simply through copolymerization, we can greatly vary LC behavior of the mesogen-jacketed liquid crystalline polymers.
Influence of alkoxy tail length on the self-organization of hairy-rod polymers based on mesogen-jacketed liquid crystalline polymers
Chen, Sheng,Jie, Changkai,Xie, Helou,Zhang, Hailiang
, p. 3923 - 3935 (2012/11/07)
A series of hairy-rod polymers, poly{2,5-bis[(4-alkoxyphenyl)oxycarbonyl] styrenes} (P-OCm, m = 1, 2, 4, 6, 8, 10, 12, 14, 16, and 18) were designed and successfully synthesized via free radical polymerization. The chemical structure of the monomers was confirmed by elemental analysis, 1H NMR and 13C NMR. The molecular characterizations of the polymers were performed with 1H NMR and gel permeation chromatography. The phase structures and transitions of the polymers were investigated by the combination of techniques including differential scanning calorimetry, wide-angle X-ray diffraction, polarized optical microscopy, and rheological measurement. The experimental results revealed that the self-assembly behaviors of P-OCm changed with the increase in m. First, the P-OCm (m = 1, 2) showed only a stable liquid crystalline phase above Tg. Second, with the increasing length of alkoxy tails, the P-OCm (m = 4, 6, 8) presented a re-entrant isotropic phase above Tg and a liquid crystalline phase at higher temperature. Third, the P-OCm (m = 10, 12, 14, 16, 18) exhibited an unusual re-entrant isotropic phase which was separating SmA (in low temperature) and columnar phases (in high temperature). It was the first time that mesogen-jacketed liquid crystalline polymers formed smectic phase, re-entrant isotropic phase, and columnar phases in one polymer due to the microphase separation and the driving force of the entropy.
