pH-Responsive Hyperbranched Copolymers from One-pot RAFT Copolymerization of Propylacrylic Acid and Poly(Ethylene Glycol Diacrylate)

pH-Responsive polymers have attracted much attention for biotechnology applications as carriers or matrix to facilitate intracellular or extracellular therapeutic drug delivery and release. In this paper, we report the development of new pH-responsive and hyperbranched copolymers with potential for such applications. These pH-responsive hyperbranched copolymers were synthesized via one pot reversible addition-fragmentation chain transfer (RAFT) copolymerization of propylacrylic acid (PAA) and a branching co-monomer poly(ethylene glycol diacrylate) (PEGDA) (Mn=258 Da) at the monomer feed molar ratios [PAA](0)/[PEGDA](0) = 99/1, 90/10 and 80/20. The resultant poly(PAA-PEGDA) copolymers were characterized by Proton Nuclear Magnetic Resonance (H-1 NMR) and Gel Permeation Chromatography (GPC) to obtain the molecular weight, copolymer composition and degree of acrylate functionality. The hydrodynamic dimensions of these copolymers at pH range between 5.0 and 7.4 were studied using Dynamic Light Scattering technique (DLS). Moreover, these hyperbranched copolymers demonstrated composition- and size-dependent membrane disruptive properties by red blood cell hemolysis assay. Poly(PAA-PEGDA) with the copolymer composition [PAA]/[PEGDA]= 68/32, obtained from the copolymerization at the monomer feed molar ratio [PAA](0)/[PEGDA](0) = 99/1, demonstrated significant membrane disruptive activity.