Synthesis of amphiphilic ABA triblock copolymer bearing PIB and perfluorocyclobutyl aryl ether-containing segments via sequential living carbocationic polymerization and ATRP

A series of amphiphilic ABA triblock copolymers containing polyisobutylene (PIB) and poly(p-(2-(4-biphenyl)perfluorocyclobutoxy)phenyl methacrylate) (PBPFCBPMA) segments was synthesized via sequential living carbocationic polymerization and atom transfer radical polymerization (ATRP). Living carbocationic polymerization of isobutylene was initially performed at −78 °C in n-hexane–CH3Cl followed by end-capping with 1,3-butadiene to provide a well-defined diallyl-Cl-terminated PIB with a narrow molecular weight distribution (Mw/Mn = 1.26). The PIB functionalized at both ends was further transformed into Br-PIB-Br, an ATRP macroinitiator bearing one ATRP initiating group at each end. The target triblock copolymers of PBPFCBPMA-b-PIB-b-PBPFCBPMA with a relatively narrow molecular weight distribution (Mw/Mn ≤ 1.42) were obtained via ATRP of BPFCBPMA at 70 °C in tetrahydrofuran initiated by Br-PIB-Br. The self-assembly behavior of these triblock copolymers in n-hexane, acetone, and 1,1,1-trifluoroacetone was investigated by transmission electron microscopy. It was found that large spherical compound micelles with PIB blocks as coronas were formed in n-hexane, whereas large compound micelles with fluorine-containing PBPFCBPMA blocks as coronas were formed in acetone and 1,1,1-trifluoroacetone.