Difference in Macroscopic Morphologies of Amylosic Supramolecular Networks Depending on Guest Polymers in Vine-Twining Polymerization

Abstract

Amylose, a natural polysaccharide, acts as a host molecule to form supramolecular inclusion complexes in its enzymatically formation process, that is, phosphorylase-catalyzed enzymatic polymerization using the α-d-glucose 1-phosphate monomer and the maltooligosaccharide primer, in the presence of appropriate guest polymers (vine-twining polymerization). Furthermore, in the vine-twining polymerization using maltooligosaccharide primer-grafted polymers, such as maltoheptaose (G7)-grafted poly(γ-glutamic acid) (PGA), in the presence of poly(ε-caprolactone) (PCL), the enzymatically elongated amylose graft chains have formed inclusion complexes with PCL among the PGA main-chains to construct supramolecular networks. Either hydrogelation or aggregation as a macroscopic morphology from the products was observed in accordance with PCL/primer feed ratios. In this study, we evaluated macroscopic morphologies from such amylosic supramolecular networks with different guest polymers in the vine-twining polymerization using G7-grafted PGA in the presence of polytetrahydrofuran (PTHF), PCL, and poly(l-lactide) (PLLA). Consequently, we found that the reaction mixture using PTHF totally turned into a hydrogel form, whereas the products using PCL and PLLA were aggregated in the reaction mixtures. The produced networks were characterized by powder X-ray diffraction and scanning electron microscopic measurements. The difference in the macroscopic morphologies was reasonably explained by stabilities of the complexes depending on the guest polymers.

Formation of Supramolecular Soft Materials from Amylosic Inclusion Complexes with Designed Guest Polymers Obtained by Vine-Twining Polymerization

“…To fabricate amylosic supramolecular soft materials comprising V-amylose segments, such as gels and films, by vine-twining polymerization, we have employed immobilized primers (maltoheptaose, G 7 ) or guest polymers as graft chains, which are covalently attached on suitable polymeric main chains. − With the progress of the vine-twining polymerization, amylosic inclusion complexes are formed with the graft chains among the main-chain polymers, which act as cross-linking points to construct supramolecular network structures, resulting in the formation of soft materials.…”

Vine-Twining Inclusion Behavior of Amylose towards Hydrophobic Polyester, Poly(β-propiolactone), in Glucan Phosphorylase-Catalyzed Enzymatic Polymerization

“…To initiate the GP-catalyzed polymerization, a maltooligosaccharide primer is required in the reaction system and the initiation and propagation occur at the nonreducing end of the α(1→4)-glucan chain, according to the following primary reaction; [α(1→4)-G] n + G-1-P → [α(1→4)-G] n+1 + inorganic phosphate. We have found that amylose, thus, enzymatically produced in the GP-catalyzed polymerization, includes polymeric guests with moderate hydrophobicity in its cavity, which are dispersible in the polymerization media, via the vine-twining process [ 19 , 20 , 21 , 22 ]. In the system, the enzymatically elongating amylosic chain gradually twines around the polymeric chains to directly construct amylosic supramolecular helical inclusion complexes with the polymers.…”

“…The enzymatically elongation of the shorter α(1→4)-glucan, i.e., maltooligosaccharide, into the longer α (1→4)-glucan, i.e., amylose, is conceived to provide appropriate dynamic field for easier inclusion complexation towards the polymeric guests, compared to the direct inclusion into the amylosic cavity. Because of schematic similarity of the present system to the growing plant vines that gradually twine around a support rod, it has been named ‘vine-twining polymerization’ [ 19 , 20 , 21 , 22 ].…”

Formation of microparticles from amylose-grafted poly(γ-glutamic acid) networks obtained by thermostable phosphorylase-catalyzed enzymatic polymerization

“…The resulting networks have formed different macroscopic structures, such as hydrogels and aggregates, in the reaction media depending on kinds of the guest polymers or guest polymer/primer feed ratios, because which strongly affected network sizes. 39,40 In these systems, therefore, PGA acted as frameworks, whereas the roles of amylose and guest polymers were cross-linking agents in the network structures.…”