CHROMIC TRANSITIONS IN CROSS-POLYMERIZED POLY(ALPHA,OMEGA-ALKYLDIYNE) MACROMONOMERS

Chromic transitions have been observed in poly(α,β-alkyldiyne) macromonomers that have been cross-polymerized by exposure to UV light. A solvatochromic transition can be induced by exposing the cross-polymerized material to liquids that are good solvents for the virgin macromonomer; similarly, a thermochromic transition can be induced by exposing the cross-polymerized material to temperatures greater than the melting point of the macromonomer. These transitions occur despite the fact that the cross-polymerized material is insoluble and infusible. The degree of chromic change has been found to be dependent upon the degree of conversion to the poly(diacetylene) form. Resonance Raman and UV-vis spectroscopic studies as well as X-ray diffractometry studies have shown that these chromic changes are due to order-disorder transitions. A study of the chromic behavior as a function of conversion for the macromonomer poly(l,8-nonadiyne) revealed that the cross-polymerization reaction is homogeneous and that the crosspolymerization process in the most highly ordered regions in the sample is virtually complete after about 3-6 min of UV exposure. © 1990, American Chemical Society. All rights reserved.