Synthesis and Characterization of Side-Chain Liquid-Crystal Polyurethanes Having Methoxyazobenzene as Mezogenic Unit
M. Brecl
Kemijski institut
Laboratorij za polimerno kemijo
in tehnologijo
1115 Ljubljana, Hajdrihova 19
T. Malavasic, KI Ljubljana
Iz 4-[omega[bis(2-hidroksietil)amino]alkoksi]-4'-metoksiazobenzenov
in heksametilen diizocianata v ekvimolarnem razmerju smo
sintetizirali stranskoverizne tekocekristalne poliuretane z
metoksiazobenzensko mezogeno enoto, vezano na polimerno verigo
preko gibljivih oligometilenskih stranskih verig razlicnih dolzin
n. Tekocekristalno obnasanje in temperature faznih prehodov
poliuretanov in diolov z razlicnimi dolzinami gibljivih stranskih
verig smo dolo~ili z DSC meritvami. Polimeri z n=8 in vec so
tekocekristalni.
Kljucne besede: teko~a kristalnost, fazni prehod, poliuretan
Side-chain liquid crystal polyurethanes having a
methoxyazobenzene mezogenic unit attached to the polymer backbone
via a flexible oligomethylene spacer of different length n were
synthesized from
4-[omega-[bis(2-hidroxyethyl)amino]alkoxy]-4'-methoxyazobenzenes and
hexamethylene diisocyanate in an equimolar ratio. Liquid
crystalline behavior and phase transition temperatures of the
polyurethanes and of the diols with different spacer lenght were
determined by DSC measurements. Polymers with n=8 and more were
found to exert liquid crystallinity.
Key words: liquid crystallinity, phase transition, polyurethane