Amphiphilic Conetworks Based on End-Linked Multiblock Copolymers of Different Numbers of Blocks and Constant Molecular Weight and Composition

Amphiphilic conetworks based on end-linked copolymers of the hydrophilic ionizable 2-(dimethylamino)ethyl methacrylate and the hydrophobic n-butyl methacrylate bearing 3, 5, 7, and 9 blocks were synthesized using group transfer polymerization, and employing a bifunctional initiator and sequential addition of monomers and ethylene glycol dimethacrylate cross-linker. All the linear precursors to the conetworks had the same molecular weight and composition, and differed only in their number of blocks. The aqueous degrees of swelling of the ionized conetworks increased with the number of blocks, manifesting the reduction of the driving force for nanophase separation, resulting from the reduction of the length of the hydrophobic segments. Reduction in the tendency for nanophase separation with increasing block number was also supported by atomic force microscopy on bulk conetworks, which indicated a decrease in the domain size as the number of blocks increased.