厦门大学学报（自然科学版）2009，Vol.48Issue(4)：547-553,7.
取代基上官能团位置对苄基壳聚糖衍生物液晶性的影响
Influence of the Position of Functional Groups in Substituents on Liquid Crystalline Behavior of N-benzyl Chitosan Derivatives
摘要
Abstract
Four N-benzyl chitosan derivatives,i.e.N-(2-hydroxyl-benzyl)chitosan (NOCS), N-(3-hydroxyl-benzyl)chitosan (NMCS),N-(4-hydroxyl-benzyl)chitosan (NPCS) and N-(3-methoxyl-4-hydroxyl-benzyl)chitosan (NMPCS),were synthesized,the number and position of the functional groups in the substituents of which were different.The degrees of NOCS,NMCS,NPCS and NMPCS were close to each other,which were 0.72,0.62, 0.71 and 0.68,respectively.The lyotropic cholesteic liquid crystalline phase was observed in the formic acid solutions of the four chitosan derivatives.The critical concentrations of NOCS,NMCS,NPCS and NMPCS were measured to be 28%,37%,24% and 27%,respectively,by means of both polarized optical microscopy and refractive index method.These values were all much higher than chitosan itself (12%),because the very strong hydrogen bonding interactions of chitosan were broken by the substituent groups.The molecular simulation approach was used to compare the intra-molecular hydrogen bonding interaction and the inter-molecular hydrogen bonding interaction of these four derivatives respectively.In the aspect of the intra-molecular hydrogen bonding,NOCS was stronger,but NMCS,NPCS and NMPCS were weaker.In the aspect of the inter-molecular hydrogen bonding,NOCS was weaker,NMCS was middle,but NPCS and NMPCS were stronger.Relating the critical concentration with the hydrogen bonding interaction,it can be seen that if the derivative have a stronger intra-molecular hydrogen bonding (such as NOCS) or a stronger inter-molecular hydrogen bonding (such as NPCS and NMPCS),the rigidity of the molecular chain is significantly improved,the arrangment and orientation of the molecular chain are more regular,as a results,the values of the critical concentration decrease.These two factors require just only one.On the contrary,if both of the two interactions are weaker (such as NMCS),the rigidity of the molecular chain is smaller,the value of the critical concentration becomes evidently higher (37%).For this system,the influence of the strength of the hydrogen bonding on the liquid crystalline critical concentration is definitive.关键词
苄基壳聚糖/溶致液晶/取代基/临界浓度/氢键/分子模拟Key words
N-benzyl chitosan/lyotropic liquid crystalline/substituent/critical concentration/hydrogen bonding/molecular simulation分类
化学化工引用本文复制引用
曾志群,董炎明,曾海涛..取代基上官能团位置对苄基壳聚糖衍生物液晶性的影响[J].厦门大学学报（自然科学版）,2009,48(4):547-553,7.基金项目
国家自然科学基金(20774077),福建省自然科学基金(E0710025)资助 （20774077）
