Synthesis of a novel star liquid crystal polymer using trifunctional initiator via atom transfer radical polymerization

• Published in: European polymer journal Vol. 41; no. 5; pp. 933 - 940
• Main Authors: Wang, Xing-Zhu, Zhang, Hai-Liang, Shi, Da-Chuan, Chen, Jian-Fang, Wang, Xia-Yu, Zhou, Qi-Feng
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.05.2005; Elsevier
• Subjects: Applied sciences; Atom transfer radical polymerization; Electrical, magnetic and optical properties; Exact sciences and technology; Mesogen-jacketed liquid crystal polymer; Organic polymers; Physicochemistry of polymers; Properties and characterization; Star-shaped polymer; Atom transfer radical polymerization; Star-shaped polymer; Mesogen-jacketed liquid crystal polymer; Monodispersed polymer; Liquid crystal polymers; Atom transfer polymerization; Preparation; Thermotropic state; Star polymer; Experimental study; Phase transitions; Styrene derivative polymer
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2004.11.015

In this paper, two types of three-arm star mesogen-jacketed crystal polymers (MJLCPs) with different core (that is hard core and soft core) were synthesized by 2,5-bis[(4-methoxyphenyl)oxycarbonyl]styrene (MPCS), which was initiated by two different trifunctional initiators 1,3,5-(2′-bromo-2′-methylpropionato)benzene (I a) and 1,1,1-tris(2-bromoisobutyryloxymethyl)propane (I b), respectively. Characterization of these polymers by 1H NMR and GPC clearly supported the formation of a three-arm star-shaped PMPCS. The resulting three-arm star PMPCS possessed narrow molecular weight distribution, and its molecular weight ( M n,NMR) agreed well with the theoretical value, which reveals the quantitative initiation efficiency. The liquid-crystalline behaviors of the two types of three-arm star polymer with different structure were also investigated by differential scanning calorimeter (DSC) and polarized optical microscope (POM). We found that the liquid-crystalline behavior was incorrelated with structure of core but correlated with the length of three-arm star polymer arm. Only each arm of the three-arm star-shaped polymers with a M n,GPC beyond 0.90 × 10 4 g/mol could form a liquid crystalline phase,which was found to be stable up to the decomposition temperature of these tri-arm MJLCPs.