SYNTHESIS AND PROPERTIES OF POLYACETYLENES HAVING SUBSTITUTED AZOBENZENE PENDANT GROUPS

ABSTRACT

Azobenzene-containing polyacetylenes, poly[(4-butoxyphenyl)(4 -ethynylphenyl)diazene] [poly(BuOEAB)] and poly[4-(4-ethynylphenylazo)benzoic acid hexyl ester] [poly(HexOCOEAB)] with number-average molecular weights ranging from 2,800 to 104,000 were synthesized by the polymerization of the corresponding acetylene monomers by [RhCl(norbornadiene)]₂ catalyst in conjunction with Et₃N, Ph₂C˭C(Ph)Li, and PPh₃ as cocatalysts in toluene and THF in good yields. The polymers exhibited thermogravimetric curves with inflection points corresponding to cleavage of butyl ether and hexyl ester groups. The trans-azobenzene moiety of poly(BuOEAB) isomerized into cis-form upon UV-irradiation at the wavelength of 300–400 nm both in solution and in the filmy state. On the other hand, poly(HexOCOEAB) did not isomerize under the same condition.

Keywords:

• Polyacetylene
• Azobenzene
• UV-irradiation
• Isomerization

Acknowledgments