Ring-opening metathesis polymerization with [2+2]-crosslinking to create new materials

There are almost no examples of Grubbs’-type ring-opening metathesis polymers that have been [2+2]-crosslinked. Two new monomers, 6 and 10, were used to construct two novel linear soluble polymers 7 and 11, bearing photochemically labile moieties for [2+2]-cycloaddition reactions. These soft polymers were photocrosslinked into very hard polymers, 8 and 12. Potential advantages of these new bioinspired materials include: (1) ready processing into flat, round, and cylindrical shapes; (2) reasonably low toxicity due to trace amounts of catalyst needed; and (3) rapid rate of polymerization and crosslinking that avoids acids and bases.