Organic–Inorganic Hybrid Brushes Consisting of Macrocyclic Oligomeric Silsesquioxane and Poly(e-caprolactone): Synthesis, Characterization, and Supramolecular Inclusion Complexation with a-Cyclodextrin

摘要

Organic–inorganic hybrid brushes comprised of macrocyclic oligomeri csilsesquioxane (MOSS) and poly(e-caprolactone) (PCL) were synthesized via the ringopening polymerization of e-caprolactone (CL) with cis-hexa[(phenyl) (2-hydroxyethylthioethyldimethylsiloxy)] cyclohexasiloxane as the initiator. The MOSS macromer bearing hydroxyl groups was synthesized via the thiol-ene radical addition reaction between cis-hexa[(phenyl)(vinyldimethylsiloxy)]cyclohexasiloxane and b-mercaptoethanol. The organic–inorganic PCL cyclic brushes were characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). These MOSS–PCL brushes were then used to prepare the supramolecular inclusion complexes with a-cyclodextrin (a-CD). The X-ray diffraction (XRD) indicates that the organic–inorganic inclusion complexes (ICs) have a channel-type crystalline structure. It is noted that the molar ratios of CL unit to a-CD for the organic–inorganic ICs are quite dependent on the lengths of the PCL chains bonded to the silsesquioxane macrocycle. While the PCL chains were short, the efficiency of inclusion complexation was significantly decreased. The decreased efficiency could be attributed to the repulsion of the adjacent PCL chains bonded to the silsesquioxane macrocycle and the restriction of the bulky silsesquioxane macrocycle on the motion of PCL chains; this effect is pronounced with decreasing the length of the PCL chains.