Rigid Hyperbranched Polycarbonate Polyols From Co2 And Cyclohexene-Based Epoxides

Hyperbranched, multifunctional polycarbonate polyols based on CO2, cyclohexene oxide (CHO), and the inimer (initiator-monomer) (4-hydroxymethyl)cyclohexene oxide (HCHO) were prepared in one-pot syntheses. The related linear poly(hydroxymethyl cyclohexene carbonate) structures based on protected HCHO and postpolymerization deprotection were also synthesized as model compounds. The content of hydroxyl functionalities was adjustable for both linear and hyperbranched terpolymer systems. All CO2/epoxide polymerizations were catalyzed by the (R,R)-(salcy)-Co(III)Cl complex. The polycarbonates obtained were comprehensively investigated using various 1D and 2D NMR techniques, SEC, FT-IR, UV-vis spectroscopy, and contact angle measurements. Rigid polyols with molecular weights between 3600 and 9200 g mol(-1) and moderate dispersity between 1.18 and 1.64 (Mw/Mn) were obtained. In addition, the materials were examined with respect to their thermal properties, intrinsic viscosity, and their three-dimensional structure. Glass transition temperatures in the range of 113-141 degrees C (linear) and 72-105 degrees C (hyperbranched) were observed. The intrinsic viscosity of the hyperbranched systems is in the range of 5.69-11.51 cm g(-1) and mirrors their compact structure. The hyperbranched polyols were also studied regarding their successful reaction with phenyl isocyanate to convert the free hydroxyl groups into urethanes.