Abstract
Copolymers of methyl methacrylate and 11-(4-ethoxyazobenzene-4′-oxy)undecyl methacrylate (azo-MA) were synthesized and characterized with respect to their photochemical and free volume properties. The isomerization yield at 360 nm was measured by UV spectroscopy. The cis yield after illumination was not significantly suppressed in the solid state when compared to the polymer solution. The free volume characteristics were measured by positron annihilation. The ortho-positronium (o-Ps) lifetime, which is associated with the intersegmental distance in the polymer, increased with increasing azo-MA content up to about 4 mol-% azo-MA. The results are consistent with density and DSC measurements, which show that both the density and glass transition temperature of the copolymers decrease with increasing azo-MA content.
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