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Pure Appl. Chem., 2012, Vol. 84, No. 12, pp. 2559-2568

Published online 2012-11-06

Syntheses of hyperbranched liquid-crystalline biopolymers with strong adhesion from phenolic phytomonomers

Siqian Wang, Daisaku Kaneko, Kai Kan, Xin Jin and Tatsuo Kaneko*

School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan

Abstract: A novel thermotropic liquid-crystalline (LC) biocopolymer, poly{trans-3-methoxyl-4-hydroxycinnamic acid (MHCA: ferulic acid)-co-trans-3,4-dihydroxycinnamic acid (DHCA: caffeic acid)}, was synthesized by a thermal acidolysis-polycondensation of MHCA and DHCA, efficiently catalyzed by Na2HPO4. When the MHCA composition of poly(MHCA-co-DHCA) was 60, 75, and 90 mol %, the copolymers showed a nematic LC phase although individual homopolymers such as polyMHCA and polyDHCA did not exhibit LC phase. Poly(MHCA-co-DHCA)s showed high molecular weight (Mw) ranged between Mn 2.6 × 104 to 3.7 × 104 and Mw 8.2 × 104 to 13.1 × 104, respectively, high glass-transition temperature (Tg) with the range of 115 to 140 °C and high degradation temperature T10, from 315 to 356 °C. In the adhesive test of copolymers against the surface of carbon substrate, the copolymers showed high shear strength at fracture.