Doubly dendronized chiral polymers showing thermoresponsive properties

Abstract

ABSTRACTThe dendronization of linear polymers by dendrons with different cores and peripheries provides a convenient strategy to fuse distinct properties in one matter. By combining thermoresponsive properties with chirality, a series of doubly dendronized polymers possessing interior chiral proline units and peripheral oligoethylene glycol (OEG)‐based dendrons are synthesized and characterized. The chirality of proline moieties are varied to check potential effects on thermoresponsiveness and chiroptical properties, and the terminal groups in the OEG periphery are changed to tune the hydrophilicity of the resulting polymers. The macromonomer route is applied to obtain polymers with well‐defined structures. Free radical polymerization in bulk results in polymers with surprisingly high molar masses. Their thermally induced phase transition processes are monitored by UV–vis spectroscopy, and chiroptical properties are monitored by optical rotation measurements and circular dichroism spectroscopy. These doubly dendronized polymers show characteristic thermoresponsive behavior, and their phase transition temperatures are dominated by the peripheral structures. Polymerization accompanies weak chiral amplification, but the chirality of the proline interior contributes significantly to the thermal stability of chiroptical properties of the resulting polymers. In vitro cytotoxicity measurements are carried out to check the biocompatibility of these thermoresponsive polymers. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 5143–5152