Functional polymers and sequential copolymers by phase transfer catalysis. XXVIII. Synthesis and characterization of alternating block copolymers and polyformals of polyisobutylene and aromatic polyether sulfone

Alternating—i.e., -(A-B)_n- type—block copolymers of polyisobutylene (PIB) and aromatic polyether sulfone (PSU) have been prepared by phase transfer catalyzed Williamson polyetherification of α,ω-di(phenol)PIB with α,ω-di(chloroallyl)- or -(bromobenzyl)PSU. Block copolymers of the two prepolymers were also synthesized by the phase transfer catalyzed polyetherification of methylene chloride with α,ω-di(phenol)PIB and α,ω-di(phenol)PSU (bisphenol-A-terminated PSU). This method leads to -(A)_x-(B)_y]_n- block copolymers with formal linkages between segments. At sufficiently high segment lengths, both types of block copolymers exhibit two distinct T_gs, indicating phase separation into rubbery PIB and glassy PSU domains.