Aqueous Phase Separation Behavior of Highly Syndiotactic, High Molecular Weight Polymers with Densely Packed Hydroxy-Containing Side Groups

Herein we describe the Rh-catalyzed C1 polymerization of silyl-protected diazoacetates of the general formula HC(═N₂)C(═O)O(CH₂)_xOSiR₃, where x = 2–5. After polymerization and subsequent desilylation, syndiotactic polymers bearing a hydroxy-containing side group on every backbone carbon are obtained. The molecular weight of the desired polymers can be controlled via chain transfer with methanol during the polymerization. The produced polymers are compared to atactic analogues formed by [(η³-C₃H₅)PdCl]-catalyzed polymerization of silyl-protected diazoacetates with the same general formula. While the polymers produced by the Rh and Pd catalysts have the same hydrophilic/hydrophobic balance, the stereoregularity of the polymers formed by the Rh catalyst was found to be of influence on the thermoresponsive behavior of the polymer. The effect of this stereoregularity on the thermoresponsive phase separation behavior of the produced polymers in aqueous solution was investigated.