液晶聚苯胺及其衍生物

基于国内外最新研究文献 ,系统论述了新型液晶聚合物———液晶聚苯胺及其衍生物的合成及液晶性 ,并合理解释了它们的聚合物链伸展化、刚性化进而导致溶致或热致液晶性的原因 .指出对于乳液或水溶液化学氧化聚合制得的聚苯胺 ,大分子功能质子酸如樟脑磺酸、十二烷基苯磺酸掺杂是其获得溶致液晶性的唯一途径 .介晶基元邻位环取代聚苯胺是侧链型液晶聚合物 ,具有热致液晶性 .该液晶在 10T的外加磁场中沿磁场平行方向取向 ,有序度参数可达 0 .6 8.N -烷基磺酸取代聚苯胺实质上是自掺杂型聚苯胺 ,其水溶液在室温下显示溶致液晶性 ,具有类似近晶相的光学织构 .聚苯胺及其衍生物的液晶性主要来自于外掺杂或内掺杂后π电子的离域、对离子或侧链的拥挤效应 ,醌式链节的构象规整性也是维持液晶性的重要因素

Liquid Crystalline Polyaniline and Its Derivatives

The synthesis and liquid crystalline(LC) behavior of LC polyaniline and its derivatives,a new type of LC polymer,are systematically discussed based on the latest literature.Reasonable explanations for the extension and rigidity of the polymer chains,leading to their lyotropic or thermotropic liquid crystallinity,are provided and elaborated.It is pointed out that the only way to endow polyaniline prepared by chemical oxidization in emulsion or aqueous solution with LC properties is to dope polyaniline with functionalized protonic acids,such as camphor sulfonic acid or dodecylbenzene sulfonic acid.Polyaniline derivatives containing mesogenic core on the o-position of aniline unit belong to a side chain LC polymer,and possess thermotropic LC behavior.Their LC domains are aligned parallel to the magnetic field when applying an external magnetic field of 10 Tesla,and thus the order parameter is 0.68.Poly(aniline N-alkylsulfonate)s are substantially self-doped type polyanilines,whose aqueous solutions show lyotropic phase behavior at room temperature,and have an optical texture similar to that of a smetic phase.The sustaining of liquid crystallingity of polyaniline and its derivatives resulted from a combination of electronic delocalization after exterior or self-doping and the counter-ion or side chain crowding.The conformational regularity of quinoid moiety suggests the importance of quinoid rings for maintaining LC structure.