含冠醚环的席夫碱型液晶高分子的合成与表征

以 4 ,4′ (α ,ω 烷亚甲基二酰氧 )二苯甲醛和二氨基二苯并 14 冠 4为单体 ,采用溶液缩聚方法 ,首次合成了一类新的含冠醚环的席夫碱型液晶高分子 .一种单体采用脂族二酰氯和对羟基苯甲醛反应制备 ,另一种新的单体采用二硝基二苯并 14 冠 4 ,在钯 碳催化剂存在下 ,水合肼还原制备 .通过1H NMR、13 C NMR和分子力学计算方法研究了二氨基二苯并 14 冠 4的两种异构体的空间立体结构 ,发现能从1H NMR谱图上区分它们的立体结构 .它们的立体结构近似属于Cs 和C2 群 .聚合物的分子量不高 ,Mn 在 130 0 0～ 2 4 0 0 0之间 .单体的结构通过元素分析、IR、1H NMR和MS等方法确证 .聚合物的性质采用GPC、DSC、TG和POM等方法进行了研究 .发现所有的聚合物加热到各自的熔融温度 (Tm)以上都能形成液晶态 ,在液晶态可以观察到向列相的丝状织构和纹影织构 .聚合物的玻璃化转变温度 (Tg)、熔融温度和各向同性温度 (Ti)随聚合物分子中柔性间隔基的变化而变化 ,它们有较高的清亮点温度和宽的液晶态温度范围 .WAXD的研究进一步证实了聚合物的液晶性

SYNTHESIS AND CHARACTERIZATION OF SCHIFF BASE TYPE LIQUID CRYSTALLINE POLYMERS WITH CROWN ETHER CYCLE

A novel series of Schiff base type liquid crystalline polymers with cr own ether cycle was synthesized for the first time by solution polycondensation from 4,4′ (alkylene dioyloxy)dibenzaldyhyde (M 1),cis diamino dibenzo 14 crow n 4 (M 2) and trans cis diamino dibenzo 14 crown 4(M 3) as the mono mers.Monomer M 1 h as been synthesized by esterification reaction of aliphatdiyl chloride and 4 hy d roxybenzaldehyde.Monomers M 2 and M 3 have been synthesized by reduction react i on of cis dinitrodibenzo 14 crown 4 and trans dinitrodibenzo 14 c rown 4 in the pres ence of 10% Pd/C catalyst and hydrazine hydrate.The stereo structures of cis (trans) dinitrodibenzo 14 crown 4 have been investigated by 1 H NMR, 13 C NMR and molecular mechanics theory.It was found that t he s tereo structures of cis trans and dinitrodibenzo 14 crown 4 can be differentiated by 1H NMR spectrum,appro ximately belonging to groups C s and C 2,respectively .The molecular w eights of th e polymers are not high,and the M n of the polymers ranges from 13000 to 24 000.The monomer structures were identified by using elementary analysis,IR, 1H NMR and MS etc.The properties of polymers were investigated by using GPC,DSC,TG, WAXD and POM.It was found that all the polymers went into liquid\|crystal phase when they were heated over their melting temperature (T m).The threaded texture and schlieren texture can be observed.The glass transition temperature (T g),melting temp eratur e and isotropization temperature (T i) change with varing of the flexible s pacer unit in the polymers.All the polymers have high clearing points and wide mesophase range.The WAXD study illustrated that the polymers of PI b,PI d,PII b and PI I d are liquid crystalline with a nematic phase.A dispersive peak at 2θ ne ar 20° appeared in their WAXD patterns,which is a typical character for quenche d nematic liquid crystal polymers.