RAFT preparation and the aqueous self-assembly of amphiphilic poly(octadecyl acrylate)-block-poly (polyethylene glycol methyl ether acrylate) copolymers

Reversible addition-fragmentation chain transfer (RAFT) polymerisation was used to prepare novel amphiphilic poly(octadecyl acrylate)-block-poly(polyethylene glycol methyl ether acrylate) (P(ODA)-b-P(PEGA-OMe)) copolymers. These polymers were reduced to remove the dodecyl RAFT end-group, via radical-induced reduction using a hypophosphite salt, N-ethylpiperidine hypophosphite (EPHP). The resulting brush-like diblock copolymers were characterised by proton nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC). Investigation of the self-assembly behaviour of both the reduced and RAFT-group functional polymers in excess water determined by dynamic light scattering (DLS), cryo-transmission electron microscopy (cryo-TEM) and cross-polarised light microscopy (CPLM), indicated that all the copolymers form micellar aggregates in excess water. The hydrophobic dodecyltrithiocarbonate RAFT end-group, which is located on the terminal end of the hydrophilic domain, was found to influence the self-assembly behaviour of the copolymers in water.