Dendritic Polystyrene with Hydroxyl-Functionalized Branch Points by Convergent Living Anionic Polymerization

Abstract

Dendritic polystyrene with hydroxyl functional groups at each branch point was synthesized using convergent living anionic polymerization. The polymer samples were formed by the slow addition of a 1/10 molar mixture of 4-vinylstyrene oxide/styrene to living polystyryllithium chains in a benzene/THF solution. The 4-vinylstyrene oxide contains both a vinyl group, which can undergo anionic vinyl addition polymerization, and an epoxide moiety, which can undergo a ring-opening addition reaction to result in an unreactive or terminated lithium alkoxide. The extent of generational growth for the dendritic polymers was calculated by molecular weight analysis and by titration of hydroxyl groups to determine generations as high as 3.8 and polymers with up to 14 hydroxyl groups situated at the branch points. Addition of LiCl to the benzene/THF solutions containing polystyryllithium chains resulted in the highest generational growth of the polymers. The polymers were characterized using gel permeation chromatography coupled with a MALLS detector, 1H NMR spectroscopy, and differential scanning calorimetry.