| Abstract
| - Amorphous copolymers with rigid azobenzene and ester side groupsform films in whichbirefringence can be induced using linearly polarized light. Whenboth the azobenzene and the estergroups are polar, cooperative motion occurs and high levels ofbirefringence can be achieved at relativelylow azobenzene content. With less polar ester groups, thiscooperative motion is significantly reduced,suggesting that the effect is not dictated by steric factors (as is thecase in liquid crystalline copolymers),but by electric interaction between the side group dipoles. Thedifferences in cooperative motion of twocopolymer systems: poly{4‘-[(2-(methacryloyloxy)ethyl)ethylamino]-4-nitroazobenzene(DR1M)-co-4-nitrophenyl4-[[2-[(2-methyl-1-oxo-2-propenyl)oxy]ethyl]oxy]benzoate(BEM)} (a polar azo/polar ester pair),and poly{DR1M-co-4-phenyl4-[[2-[2-(2-methyl-1-oxo-2-propenyl)oxy]ethyl]oxy]benzoate(NBEM)} (a polarazo/less polar ester) have been investigated using birefringencemeasurements and time dependent infraredspectroscopy. Thus, the “molecular addressing” conceptintroduced by Anderle and Wendorff for liquidcrystalline copolymers is real. Kinetic analysis usingtime-dependent infrared spectroscopy clearly showsthat the azobenzene groups move first and are followed by the estergroups, which move to a much greaterdegree when they have similar polarity (BEM with DR1M).
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