Poly(arylenevinylene)s through Ring-Opening Metathesis Polymerization of an Unsymmetrical Donor-Acceptor Cyclophane

Reported are well-defined donor-acceptor alternating copolymers prepared using ring-opening metathesis polymerization (ROMP). Unsymmetrical cyclophanedienes comprising electron-donating (4-methoxy-1-(2-ethylhexyl)oxy)benzene (MEH) and electron-accepting benzothiadiazole (BT) rings were synthesized from the corresponding [3.3]dithiaparacyclophanes. ROMP of the strained unsymmetrical and “electronically-ambiguous” cyclophanedienes proceeded in a controlled manner in the presence of either Hoveyda–Grubbs II or Grubbs II initiator in wake of both steric and electronic encumbrance. The resulting polymers, comprising alternating BT and MEH-PPV units, are achieved in molecular weights exceeding 20k with Đ values ranging from 1.1–1.4. The living nature of the polymerization is verified through the formation of rod-coil and rod-rod block copolymers. Our strategy to develop previously unrealized polymers from functional building blocks featuring a locked-in D-A unit is significant in a field striving to achieve well-defined and sequence-specific materials.