End-Linked Amphiphilic Polymer Conetworks: Synthesis by Sequential Atom Transfer Radical Polymerization and Swelling Characterization

Conetworks based on end-linked homopolymers and amphiphilic gradient copolymers were synthesized by the atom transfer radical polymerization (ATRP) of 2-(dimethylamino)ethyl methacrylate (DMAEMA, hydrophilic monomer), methyl methacrylate (MMA, hydrophobic monomer), and ethylene glycol dimethacrylate (EGDMA, hydrophobic cross-linker). Sequential, rather than step-wise polymerizations, were performed to enhance the livingness of the polymerization, particularly for the end-linking step, and to ultimately obtain conetworks based on gradient rather than pure block copolymers. Amphiphilic conetworks based on end-linked MMA-DMAEMA-MMA gradient copolymers of different compositions were successfully synthesized as confirmed by the narrow molecular weight distributions of the linear precursors, the rigidity of the amphiphilic conetwork products and the low sol-fraction extracted from the conetworks. Similarly successful was the ATRP synthesis of an end-linked conetwork based on a DMAEMA-MMA statistical copolymer and of a randomly cross-linked conetwork that resulted from the simultaneous terpolymerization of DMAEMA, MMA and EGDMA. An amphiphilic conetwork based on an end-linked DMAEMA-MMA-DMAEMA gradient copolymer presented a less rigid, mucous-like, texture. The degrees of swelling (DS) in tetrahydrofuran of all the conetworks were higher than those measured in pure water, whereas the aqueous DS values increased by lowering the pH and increasing the DMAEMA content of the conetworks. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1878-1886, 2010