Inclusion Complexes with Amylose

The so-called V-amylose has a helical cavity in which some polymers can be included. The formation of this host-guest inclusion complexes leads to a versatile approach to prepare block copolymers capable of self-organizing with an additional hierarchical level, resulting in highly ordered supramolecular structures. Furthermore, as the molecular recognition between amylose and the guest polymers is not covalent-based, the resulted self-assembly of the complexes is expected to be reversible and responsive to temperature or solvent change. These tailored properties open possibility for the complexes to be applied in many areas, such as adhesives, printings, and coatings.

As a hydrophobic polymer, polytetrahydrofuran (PTHF) can act as a guest molecule for amylose inclusion complexes. This complexing ability can be used as a non covalent approach to synthesize block copolymers, in combination with conventional method. For this purpose, PTHF-b-amylose is prepared via cationic ring opening polymerization (CROP) of THF which results in PTHF. Maltoheptaose, which acts as a recognition unit for the enzymatic synthesis of amylose, is attached covalently to the synthesized PTHF via reductive amination. The resulting product, PTHF-b-maltoheptaose, is used as a primer for the subsequent enzymatic polymerization of amylose using glucose-1-phosphate (G1P) as monomer. Potato phosphorylase is used as catalyst to transfer glucose units from G1P to the non-reducing end of the attached primer forming α-(1 à 4) glycosidic linkages, resulted in PTHF-b-amylose. PTHF-b-amylose can be further complexed with free PTHF to yield in PTHF-b-[amylose-PTHF complex], as depicted in Figure 1.