High molecular weight diblock and ABA/ABC triblock copolymers of tert-butyl (meth)acrylate

AB diblock copolymers were prepared by use of poly(tert-butyl (meth)acrylate) (PtBA/PtBMA) as monofunctional macroinitiator in atom transfer radical polymerization of various (meth)acrylates (methyl, butyl) in the presence of the CuBr/N, N, N′, N′, N″-pentamethyldiethylenetriamine catalyst system. Then using the diblock copolymer as macroinitiator with a bromine atom at the chain end, ABC and ABA triblock copolymers containing at least one PtBA or PtBMA segment were synthesized via polymerization of the selected (meth)acrylic monomer. Gel permeation chromatography was applied to determine molecular weights and polydispersity indices. The latter, for block copolymers prepared without deactivator addition, were in the range 1.2-1.6 with a high degree of polymerization (150-500). The chemical compositions of the block copolymers were characterized with ¹H nuclear magnetic resonance. The kind of combined segments and their lengths influenced the glass transition temperature (T _g) determined by differential scanning calorimetry.