Synthesis and photochemical reaction of polymers containing norbornadiene residues both in the main chain and side chain

The polyaddition of 2,5-norbornadien-2,3-dicarboxylic acid diglycidyl ester (NDGE) with adipoyl chloride gave a polyester (P-1) containing norbornadiene (NBD) residues in the main chain and pendant chloromethyl groups in the side chain. Polyesters containing NBD resides both in the main chain and side chains were synthesized by the polymer reaction of P-1 with certain NBD derivatives. When substitution reactions of P-1 with potassium 3-phenyl-2,5-NBD-2-carboxylate (PNC), potassium 3-phenyl-2,5-NBD-2-(4′-hydroxyphenyl)ketone (PNHK), potassium 3-(N, N-dipropylcarbamoyl)-2,5-NBD-2-carboxylate (DPNC), and potassium 3-(N-methyl-N-phenylcarbamoyl)-2,5-NBD-2-carboxylate (MPNC) were carried out using tetrabutylammonium bromide (TBAB) as a phase transfer catalyst in NMP for 48 h, corresponding NBD polymers (P-2 to approximately P-5) containing PNC, PNHK, DPNC, or MPNC groups were obtained in good yields. When the photochemical valence isomerization of NBD residues in polymers was performed in the film state, the rate of the photochemical reaction of NBD residue in the main chain of P-2 was higher than that of P-1. This result indicates that the NBD residues in the main chain of P-2 were sensitized by the pendant PNC moieties. It was also found that the photo-irradiated P-2 film containing QC moieties both in the main chain and side chain released 331 J/g of thermal energy, which is the highest record as compared with other NBD polymers synthesized before.