Inclusion Complexes Between Polytetrahydrofuran-b-Amylose Block Copolymers and Polytetrahydrofuran Chains

Amylose inclusion complexes are prepared by complexation of synthetic amylose having a covalently attached PTHF block (PTHF-b-amylose) with guest polytetrahydrofuran of molecular weights of 650 and 1000 g · mol(-1) (PTHF650 and PTHF1000). Differential Scanning Calorimetry (DSC) analysis of the products shows a characteristic melting peak of the complexes at 140 °C. Compared to PTHF650, the PTHF1000 displays lower complexing ability with PTHF-b-amylose which is indicated by visible amylose retrogradation. The possible structures of the resulting products are estimated from Thermo Gravimetric Analysis (TGA) which reveals differences between PTHF-b-amylose and the corresponding complexes. In addition, X-Ray Diffraction (XRD) analysis demonstrates that the resulting structures of the complexes consist of 6-fold V-amylose helices. The results are confirmed further with Small Angle X-Ray Scattering (SAXS) diffractions which show that formation of inclusion complexes increases the crystalline size and regularity of the complex. There is a strong indication that the covalently attached PTHF block also induces the formation of V-amylose by residing in between the amylose blocks. In this case, the resulting structure of the complex is likely affected by both the complexation between amylose block and the added PTHF and by the in situ self-assembly of the block copolymers.