Amphiphilic Model Conetworks Based on Combinations of Methacrylate, Acrylate, and Styrenic Units: Synthesis by RAFT Radical Polymerization and Characterization of the Swelling Behavior

Abstract

Reversible addition−fragmentation chain transfer (RAFT) polymerization was employed for the preparation of homopolymer and copolymer (co)networks based on four monomer units, belonging to three monomer types: methacrylates, acrylates, and styrenics. In particular, n-butyl methacrylate and 2-(dimethylamino)ethyl methacrylate (DMAEMA) (hydrophobic and hydrophilic-ionizable methacrylate monomers, respectively), n-butyl acrylate (hydrophobic) and styrene (hydrophobic) were used. Amphiphilic block copolymer conetworks were prepared by RAFT via the cross-linking of linear triblock copolymer precursors possessing two active polymer ends, which were subsequently interconnected by chemical cross-linking to a three-dimensional network, by using the appropriate cross-linker: ethylene glycol dimethacrylate for methacrylates, ethylene glycol diacrylate for acrylates, and 1,4-divinylbenzene for styrenics. The homopolymer and copolymer precursors to the (co)networks were characterized by gel permeation chromatography and 1H NMR spectroscopy for their molecular weights and compositions, respectively. The degrees of swelling (DSs) of all (co)networks were determined in tetrahydrofuran and, where the ionizable (DMAEMA) was present, the DSs were also measured in neutral and acidic water. The conetworks swelled more in acidic than in neutral water due to the ionization of their DMAEMA units.