甲壳素类液晶高分子的研究Ⅰ侧基长度对羧酰化甲壳素的液晶性的影响.pdfVIP

高分子学报990511 高分子学报 ACTA POLYMERICA SINICA 1999年 第5期 No.5 1999 甲壳素类液晶高分子的研究 * Ⅰ.侧基长度对羧酰化甲壳素的液晶性的影响 董炎明　汪剑炜　吴智福　梅雪峰　袁　清　刘晃南 摘　要　四种羧酰化甲壳素即乙酰化、丙酰化、丁酰化和己酰化甲壳素在二氯乙酸溶液中均呈现胆 甾型溶致液晶相.临界浓度随侧基长度增加而略有增加，衍生物的临界浓度明显都比原甲壳素高许 多，这些规律都可以用链刚性的变化来解释.四种羧酰化甲壳素在剪切时均能形成条带织构，而且能 形成条带织构的最低浓度有明显差别，随侧基长度增加而提高，进一步表明侧基较长，液晶性减少. 关键词　甲壳素，羧酰化甲壳素，合成，溶致液晶，胆甾相，临界浓度，条带织构 STUDIES ON CHITIN-BASED LIQUID CRYSTALLINE POLYMERS Ⅰ. INFLUENCE OF SIDE CHAIN LENGTH ON THE LIQUID CRYSTALLINE BEHAVIOR OF ACYLATED CHITIN DONG Yanming, WANG Jianwei, WU Zhifu, MEI Xuefeng, YUAN Qing, LIU Huangnan (Department of Materials Science,Xiamen University,Xiamen　361005) Abstract　Methanesulfonic acid method was used to prepare five acylated chitins.Except heptanoyl chitin, four of them,i.e.acetyl chitin,propionyl chitin,butyryl chitin and hexanoyl chitin,had high degree of substitution(from 1.5 to 2.0)and exhibited lyotropic liquid crystalline behavior and cholesteric phase.As the length of the side chain increased the critical concentration (W/W)somewhat increased from 0.21 to 0.26 because the chain rigidity dropped.The critical concentration values of all the four derivatives were much higher than that of chitin(0.12) due to the decrease of intramolecular hydrogen bonds.The four acylated chitin can form typical banded texture after being sheared.There minimum concentrations to form banded texture of them were evidently different,varied from 0.25 (for acetyl chitin)to 0.37 (for hexanoyl chitin). These results further indicated that liquid crystallinity decreased while the length of flexible side substituents increased. Key words　Chitin,Acylated chi