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

STUDIES ON CHITIN- BASED LIQUID CRYSTALLINE POLYMERSⅠ INFLUENCE OF SIDE CHAIN LENGTH ON THE LIQUID CRYSTALLINE BEHAVIOR OF ACYLATED CHITIN

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．

Methanesulfonic acid method was used to prepare five acylated chitins. Exceptheptanoyl chitin , four of them ,i.e .acetyl chitin ,propionyl chitin ,butyryl chitin andhexanoyl chitin ,had high degree of substitution(from 1 5 to 2 0)and exhibited lyotropicliquid crystalline behavior and cholesteric phase . Asthelength oftheside chain increased thecritical concentration ( W/ W)somewhat increased from 0 21 to 0 26 because the chainrigidity dropped . The criticalconcentration valuesofallthefour derivatives were much higherthan that of chitin(0 12) due to the decrease of intramolecular hydrogen bonds. The fouracylated chitin can form typical banded texture after being sheared . There minimumconcentrations to form banded texture of them were evidently different,varied from 0 25(for acetylchitin)to 0 37 (for hexanoyl chitin) . These results further indicated that liquidcrystallinity decreased while thelength offlexible side substituentsincreased .