Synthesis and solar energy storage property of polymers containing norbornadiene moieties

Polymers having a pendant 3[(p-substituted phenyl)carbamoyl]-2,5-norbornadiene-2-carboxylate moiety were prepared by the reaction of poly(4-(chloromethyl)-styrene] with their corresponding potassium salts. The photochemical valence isomerization of pendant norbornadiene (NBD) to the quadricyclane (QC) moiety proceeded smoothly in the film state or polymer solution upon irradiation by sunlight. The rate of isomerization was strongly affected by the nature of the substituent. The resulting QC groups in the polymer film scarcely reverted to the original NBD without any catalyst if it were kept in dark at room temperature for a long time.