Poly(methyl methacrylate)−Poly(caprolactone) AB and ABA Block Copolymers by Combined Ring-Opening Polymerization and Atom Transfer Radical Polymerization

Chemical modification of α-hydroxy,ω-isopropylestertelechelic iPrO−PCL−OH, 1, and α,ω-dihydroxytelechelic HO−PCL−OH, 4, poly(ε-caprolactone) (PCL), synthesized from ring-opening polymerization using La(O i Pr)3 or Sm(BH4)3(THF)3, allows the synthesis of the corresponding α-bromoester end-functionalized polymers iPrO−PCL−Br, 2, and Br−PCL−Br, 5, respectively. This direct procedure consists in an esterification of the hydroxy group(s) of 1 and 4 using 2-bromoisobutyryl bromide. These bromopolyesters 2 and 5 have subsequently been used as macroinitiators to synthesize, via atom transfer radical polymerization of methyl methacrylate (MMA), the new set of di- and triblock polyester−polyacrylate copolymers PCL-b-PMMA, 3, and PMMA-b-PCL-b-PMMA, 6, respectively. All (co)polymers are well defined as characterized by NMR and size exclusion chromatography analyses. In addition, the thermal properties of copolymers 3 and 6 have been investigated by differential scanning calorimetry. The self-assembly of triblock PMMA-b-PCL-b-PMMA, 6, copolymers into nanoparticles has been investigated by dynamic light scattering, atomic force microscopy, and optical microscopy techniques.