Synthesis of new photoresponsive polyesters containing norbornadiene residues by the polyaddition of donor-acceptor norbornadiene dicarboxylic acid diglycidyl ester with dicarboxylic acids and their photochemical properties

A donor-acceptor norbornadiene derivative, 5-(4-methoxyphenyl)-1,4,6,7,7-pe ntamethyl-2,5-norbornadiene-2,3-dicarboxylic acid diglycidyl ester (D-A NDG E), was synthesized by the reaction of the cesium salt of 5-(4-methoxypheny l)-1,4,6,7,7-pentamethyl-2,5-norbomadiene-2,3-dicarboxylic acid with epibro mohydrin in N-methyl-pyrrolidone (NMP). The polyaddition reactions of D-A N DGE with certain dicarboxylic acids were carried out with tetrabutylammoniu m bromide as a catalyst in NMP, producing corresponding polyesters containi ng D-A norbornadiene (NBD) residues in the main chain in fair to good yield s. The photoisomerization of the D-A NBD residues in the polyesters proceed ed very smoothly, forming the corresponding quadricyclane groups. The photo reactivities of the D-A NBD residues in the polymer were 50 times higher th an those of the NBD residues in the film state and 60 times higher than tho se in a tetrahydrofuran solution. The stored energy in the quadricyclane gr oups of the polymers was about 45-55 kJ/mol according to differential scann ing calorimetry analysis of the irradiated polymer films. (C) 2001 John Wil ey & Sons, Inc.