Atom transfer radical polymerization of tert-butyl acrylate and preparation of block copolymers

Atom transfer radical polymerization (ATRP) of tert-butyl acrylate is reported. Controlled polymerizations were performed using a CuBr/N,N,N',N ",N "-pentamethyldiethylenetriamine catalyst system in conjunction with an alkyl bromide as the initiator. Low molecular weight polymers with narrow molecular weight distributions were obtained by the addition of a solvent to create a homogeneous catalytic system. The addition of the solvent was necessary to decrease the polymerization rate and afford low polydispersity materials. This differs from the ATRP of methyl or n-butyl acrylate using this catalytic system, which do not require the addition of a solvent to obtain well-defined polymers. Subsequent hydrolysis of the polymer in refluxing dioxane with addition of HCl afforded poly(acrylic acid). Characterization using H-1 NMR and FT-IR confirmed complete hydrolysis of the eater group. Further use of poly(tert-butyl acrylate) as a macroinitiator for block copolymerizations followed by hydrolysis of the cater group produced amphiphilic block copolymers. In addition, the preparation of an ABC triblock copolymer of poly(tert-butyl acrylate)-b-poly(styrene)-b-poly(methyl acrylate) by ATRP is reported.