Hydroxypropyl β‐Cyclodextrin Solubilizing Hydrophobic Initiator to Initiate Copper‐Mediated RDRP of NIPAM in Aqueous Media

Abstract

AbstractThe copper mediated reversible deactivation radical polymerization (Cu0‐RDRP) can realize the precise synthesis of vinyl polymers in aqueous media. To our best of knowledge, there are few hydrophobic initiators directly utilized to perform the aqueous Cu0‐RDRP because the heterogeneity usually causes the polymerization to go out of control. This article first describes a very small number of hydroxylpropyl β‐cyclodextrins (HP‐β‐CDs) enabling to solubilize a bifunctional hydrophobic initiator tetraethylene glycol bis(2‐bromoisobutyrate) (T2B) into water to initiate the homogeneous Cu0‐RDRP of N‐isopropylacrylamide (NIPAM) giving rise to well‐defined poly(N‐isopropylacrylamide) (PNIPAM). The solubilization action is arisen from the inclusion complexation of HP‐β‐CDs with T2B as evidenced by 2D NOESY and 2D DOSY NMR analyses. Furthermore these entrapped HP‐β‐CDs show little effect on the polymerization process as they all skip off the initiator at the very beginning of the polymerization as determined by GPC and 1H NMR measurements.