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

Abstract

ABSTRACTA novel hexa‐armed and star‐shaped polymer containing cholesterol end‐capped poly(ε‐caprolactone) arms emanating from a phosphazene core (N3P3‐(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 (N3P3‐(PCL‐OH)6) were converted into –Chol through a series of reaction. Both N3P3‐(PCL‐OH)6 and N3P3‐(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 N3P3‐(PCL‐Chol)6 was found to be 1.2. The formation of supramolecular ICs of N3P3‐(PCL‐Chol)6 with β‐CD was confirmed by using Fourier transform infrared (FTIR) and 1H nuclear magnetic resonance (NMR) spectroscopic methods, wide‐angle X‐ray diffraction (WAXD), and thermal analysis techniques. WAXD data showed that the obtained ICs with N3P3‐(PCL‐Chol)6 had a channel‐type crystalline structure, indicating the suppression of the original crystallization of N3P3‐(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 N3P3‐(PCL‐Chol)6 and its ICs with β‐CD were investigated by static contact angle measurements. The obtained results proved that the wettability of N3P3‐(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