Synthesis of precisely diphenyl ether-functionalized polyethylene via acyclic diene metathesis polymerization

We demonstrated the facile synthesis of a new class of functionalized polyethylene containing precisely sequenced diphenyl ether moieties via acyclic diene metathesis (ADMET) polymerization of a series of α, ω-diene monomers (M1-M3) with central diphenyl ether segments and subsequent exhaustive hydrogenation. 1H and 13C NMR spectroscopy have provided unambiguous evidence for precise primary architectures of the synthesized monomers and the resulting polymers. The thermal behaviors of all polymers were systematically investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicate that the introduction of diphenyl ether segments significantly enhanced the thermal stability of the polyethylenes. Ring-opening insertion metathesis polymerization (ROIMP) of M1-M3 with cis-cyclooctene was also performed, and after exhaustive hydrogenation, a series of irregularly sequenced copolymers with less regular chain structure and lower diphenyl ether content were yielded. Those copolymers possess a broad and ill-defined melting transition compared with the precisely-defined saturated homopolymers.