Micellar Nanoreactors from Amphiphilic Copolymers for Thia-Michael Addition in Water

Micellar systems have been recognized as effective nanoreactors for performing chemical reactions in aqueous solutions. This research aims to develop nanoreactors from polymeric micelles in which organic substrates are encapsulated and stabilized within their hydrophobic pockets. An amphiphilic random copolymer, poly(N-(benzyl acrylamide))-ran-poly(N-(2-hydroxypropyl)acrylamide) or PBAM-ran-PHPAM, was first prepared by a simple post-polymerization modification of a polymer precursor, poly(pentafluorophenyl acrylate) (PPFPA), with benzylamine and 1-amino-2-propanol via nucleophilic acyl substitution. The micellar nanoparticles assembled from PBAM-ran-PHPAM were found to be spherical in shape, well-dispersed in water with a diameter of less than 170 nm, and low polydispersity. Thia-Michael addition (or sulfa-Michael addition) between beta-nitrostyrenes and thiol derivatives in the presence of the 0.5 wt % PBAM26-ran-PHPAM74 amphiphilic copolymer provide excellent conversions and high isolated yields (75-99%) of the Michael adducts over 20 substrates under ambient conditions. Moreover, the micellar nanoreactors can also be reused up to 10 times while maintaining a respectably high reaction conversion of 75%. This research suggests that the post-polymerization modification of the PPFPA polymer precursor by nucleophilic substitution is a versatile approach to developing customized nanoreactors for diversified chemical reactions in the future.