Crack Healing in Polymeric Materials via Photochemical [2+2] Cycloaddition

Several novel aromatic polymers have been prepared through palladium-catalyzed cross-coupling reactions involving two single phenyl ring units, one containing two bromo substituents and the other containing either two boronic ester moieties or two tributyltin moieties. These sets of reactions were carried out under different conditions (catalyst, solvent, and base) in order to optimize the yield, the degree of polymerization, and the polydispersity. Following optimization of the reaction conditions, a series of novel, substituted polymers were prepared to show the scope of the methodology. The synthesis of the polymerizable aromatic intermediates proved interesting and challenging, particularly those with many substituents. The novel polymers generated are discussed in terms of their synthetic methods, degree of polymerizations, and polydispersities