4 - Dynamic fabrication of amylosic supramolecular composites in an enzymatic polymerization field

Abstract

This chapter reviews dynamic fabrication of supramolecular composites by means of inclusion complexation by amylose in a phosphorylase-catalyzed enzymatic polymerization field. Amylose is a well-known polysaccharide and forms an inclusion complex with various hydrophobic small molecules. A pure amylose is produced by the enzymatic polymerization using α-d-glucose 1-phosphate as a monomer and maltooligosaccharide as a primer catalyzed by phosphorylase. The author has found that a propagating chain of amylose in the enzymatic polymerization dynamically twines around hydrophobic polymers present in the reaction system to form supramolecular inclusion composites. The author named this polymerization system as “vine-twining polymerization” because the formation process is similar as the way that a vine plant grows twining around a rod. Amylosic supramolecular composite materials such as hydrogel and film were dynamically fabricated by means of the vine-twining polymerization approach in the presence of copolymers covalently grafting with hydrophobic guest polymers. The enzymatically produced amyloses induced complexation with guest polymers in intermolecular graft copolymers, which acted as crosslinking points to form a supramolecular composite hydrogel. By using the graft copolymer having a film-formable main-chain, a supramolecular composite film was also obtained through hydrogelation. Supramolecular polymeric composites were dynamically fabricated by the vine-twining polymerization using primer-guest conjugates. The products in the vine-twining polymerization system formed a polymeric continuum of an inclusion composite, where the enzymatically produced amylose chain elongated from the conjugate included the guest segment in the other conjugate.