Hydrophilic CO2-based biodegradable polycarbonates: Synthesis and rapid thermo-responsive behavior

Common CO2-based biodegradable polycarbonates like poly(propylene carbonate) or poly(cyclohexene carbonate) are generally hydrophobic, leading to slow biodegradation rate and poor cell adhesion, which limit their applications in the biomedical field. Here hydrophilic polycarbonates were prepared by one-pot terpolymerization of CO2, propylene oxide (PO), and 2-((2-(2-(2-methoxyethoxy)ethoxy)ethoxy)methyl)oxirane (ME3MO) using binary Salen Co(III)-Cl/PPNCl catalyst system. The resultant terpolymers showed one glass transition temperature (Tg), which decreased with the increase of ME3MO units in the terpolymers (FME3MO). Water contact angles of the resultant terpolymers with FME3MO of 4.2-23.6% were 68-25 degrees, while that of poly(propylene carbonate) was 90 degrees, indicating that the terpolymers became hydrophlilic. Furthermore, the terpolymers with FME3MO more than 25.8% exhibited reversible and rapid thermo-responsive property in water, and the lower critical solution temperature (LCST) was highly sensitive to FME3MO. In particular, aqueous solution of the terpolymer with FME3MO of 72.6% showed a LCST around 35.2 degrees C, close to body temperature, which was promising for biomedical applications, especially for in vivo applications. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2834-2840.