Supramolecular inclusion complexes of a star polymer containing cholesterol end‐capped poly(ε‐caprolactone) arms with β‐cyclodextrin

Abstract

ABSTRACT A novel hexa‐armed and star‐shaped polymer containing cholesterol end‐capped poly(ε‐caprolactone) arms emanating from a phosphazene core (N 3 P 3 ‐(PCL‐Chol) 6 ) was synthesized by a combination of ring‐opening polymerization and “click” chemistry techniques. For this purpose, the terminal OH groups of the synthesized precursor (N 3 P 3 ‐(PCL‐OH) 6 ) were converted into – Chol through a series of reaction. Both N 3 P 3 ‐(PCL‐OH) 6 and N 3 P 3 ‐(PCL‐Chol) 6 were then employed in the preparation of supramolecular inclusion complexes (ICs) with β‐cyclodextrin (β‐CD). The latter formed ICs with β‐CD in higher yield. The host–guest stoichiometry (ε‐CL:β‐CD, mol:mol) in the ICs of N 3 P 3 ‐(PCL‐Chol) 6 was found to be 1.2. The formation of supramolecular ICs of N 3 P 3 ‐(PCL‐Chol) 6 with β‐CD was confirmed by using Fourier transform infrared (FTIR) and 1 H nuclear magnetic resonance (NMR) spectroscopic methods, wide‐angle X‐ray diffraction (WAXD), and thermal analysis techniques. WAXD data showed that the obtained ICs with N 3 P 3 ‐(PCL‐Chol) 6 had a channel‐type crystalline structure, indicating the suppression of the original crystallization of N 3 P 3 ‐(PCL‐Chol) 6 in β‐CD cavities. Moreover, the thermal stabilities of ICs were found to be higher than those of the free star polymer and β‐CD. Furthermore, the surface properties of N 3 P 3 ‐(PCL‐Chol) 6 and its ICs with β‐CD were investigated by static contact angle measurements. The obtained results proved that the wettability of N 3 P 3 ‐(PCL‐Chol) 6 successfully increased with the formation of its ICs with β‐CD. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52 , 3406–3420