Preparation and characterization of inclusion complexes of biodegradable amphiphilic poly(ethylene oxide)-poly[(R)-3-hydroxybutyrate]-poly(ethylene oxide) triblock copolymers with cyclodextrins

Abstract

Inclusion complexes (ICs) of biodegradable amphiphilic poly(ethylene oxide)-poly[(R)-3-hydroxybutyrate]-poly(ethylene oxide) triblock copolymers with α-cyclodextrin (α-CD) or γ-cyclodextrin (γ-CD) were prepared from aqueous medium. The ICs were characterized by XRD, DSC, 13C CP/MAS NMR, 1H NMR, FTIR, and TGA. The results of XRD and 13C CP/MAS NMR indicated that the ICs formed channel structure, and the α-CD or γ-CD molecules in the ICs adopted a more symmetric conformation compared with their uncomplexed states. As to the triblock copolymers, while the poly(ethylene oxide) blocks were included in the channel structure, the poly[(R)-3-hydroxybutyrate] block was partially threaded by α-CD or γ-CD, which was confirmed by the results of XRD, DSC, 1H NMR, and FTIR. The formation of ICs led to an increase in the thermal stability of both cyclodextrins and the triblock copolymers.