Novel a,a-bischolesteryl functional (Co)polymers: RAFT radical polymerization synthesis and preliminary solution characterization

Well-defined poly[pentafluorophenyl (meth)acrylate] (PPFP(M)A) homopolymers are prepared by RAFT radical polymerization mediated by a novel chain transfer agent containing two cholesteryl groups in the R-group fragment. Subsequent reaction with a series of small-molecule amines in the presence of an appropriate Michael acceptor for ?-group end-capping yields a library of novel bischolesteryl functional hydrophilic homopolymers. Two examples of statistical copolymers are also prepared including a biologically relevant sugar derivative. Specific examples of these homopolymers are examined with respect to their ability to self assemble in aqueous media - a process driven entirely by the cholesteryl end groups. In all instances evaluated, and under the preparation conditions examined, the homopolymers aggregate clearly forming polymersomes spanning an impressive size range. (Co)Polymers containing two cholesteryl groups at the a-terminus are prepared using RAFT polymerization in combination with pentafluorophenyl (meth)acrylate monomers. Subsequent reaction of the activated ester precursors with a range of amines gives a small library of hydrophilic (meth)acrylamido (co)polymers. Interestingly, these homopolymers are capable of undergoing self-directed assembly in aqueous media to form polymersomes.