pH-Responsive Vesicles with Tunable Membrane Permeabilityand Hydrodynamic Diameters from Self- Catalyzed Cross-Linkable Amphiphilic Block Copolymer
A series of cross-linked pH responsive vesicles with tunable diameters were prepared by self-assembly of poly (ethyleneoxide)-b-poly [2-(diethylamino) ethyl methacrylate-co-glycidyl methacrylate] [PEO-b-P(DEA-co-GMA)] inTHF/water mixture. The copolymers were synthesized by random copolymerization of DEA and GMA initiated by PEO-Br.With epoxy group and tertiary amine in its structure, self-catalyzed cross-linking was triggered easily by mild heating. The vesicles showed pH responsiveness as characterized by DLS and tunable permeability can be understood accordingly. As the pH of the solvent changed from 9.8 to 7.4, the diameters of the vesicles increased. It was observed that the diameters at pH = 6.0 were comparable to that at pH = 7.4. This alteration may have happened because of the protonation of PDEA segment.This particular property has great potential and applications since most drug loading and controlled release are conducted within this pH range.