| Summary: | 碩士 === 國立成功大學 === 化學工程研究所 === 82 === In this article, the main purpose is to use the bezene-1,2,4,
5-tetracarboxylic acid(BTA) to modify the polyester of main
chain thermotropic liquid crystal. We investigate the structure
of liquid crystals and its beha- viors.In our studies, we use
the 4,4'-dioxy-2,2'-dimethy azoxy benzene (Azoxy) as mesogenic
unit, 1,12-dodecandionicaid (DDA) as spacer to synthesize the
liquid crystal of poly(4,4'-dioxy-2,2'- dimethy azoxy benzene
dodecandioyl), and indroduce the BTA, which has four reactive
groups,to become four-arm star azoxy polyester. We perform
polymerization reaction using the method of two-phase reaction.
The phase transtfer catalyst is (C4H9)4N+HSO4-. Utiliz- ing the
difference of the reactivity of BTA and DDA in the oil phase,
the monomers in the oil phase will compete to copolymerize with
azoxy in the water phase by appropriate molar feed ratio and
produce the liquid crystal of BTA-[(Azoxy-DDA)n]4 or BTA-[(
Azoxy- DDA)m]2 . Theses two copolymers both lower the
transition temper- ature of liquid crystal Ti, Tm and order.
But the alignment type of the liquid crystal would be affected
by the benzene ring in the center. According to the increment
of the average repeated unit n of the liquid crystal,the Ti,Tm
and ΔS will be decreased. (the following is omitted)
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