Synthesis and Micellization of pH/Temperature-Responsive Double-Hydrophilic Diblock Copolymers Polyphosphoester-block-poly[2-(dimethylamino)ethyl methacrylate] Prepared via ROP and ATRP

Abstract

Novel pH- and temperature-responsive double-hydrophilic diblock copolymers, poly(ethylethylene phosphate)-block-poly[2-(dimethylamino)ethyl methacrylate] (PEEP-b-PDMAEMA), have been synthesized via the combination of ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The PEEP block with a bromine-terminated end (PEEP-Br) was first prepared by ROP of 2-ethoxy-2-oxo-1,3,2-dioxaphospholane (EEP) using 2-hydroxyethyl 2-bromoisobutyrate as a bifunctional initiator and stannous octoate as a catalyst. ATRP was then used to polymerize DMAEMA monomer in a methanol/water mixture with PEEP-Br as a macroinitiator, resulting in diblock copolymers of PEEP-b-PDMAEMA. Their chemical structures were respectively characterized by 1H NMR, 13C NMR, 31P NMR, and FT-IR. Their molar mass distributions were determined by gel permeation chromatography (GPC). The critical aggregation concentration (cac) of PEEP-b-PDMAEMA in aqueous solution, which was measured by the fluorescence probe technique, de...