Polyethylenes functionalized with ureidopyrimidone: synthesis, thermomechanical properties and shape memory behavior

Abstract

In this contribution, we reported an approach to functionalize polyethylene with quadruple hydrogen bonds. First, a poly(hydroxyether ester) (PHEE) was synthesized via step-growth polymerization of diglycidyl ether of bisphenol A with cis-butenedioic acid. The as-obtained PHEE was used as a macromolecular chain transfer agent to mediate the ring-opening metathesis polymerization (ROMP) of cyclooctene (COE) by using Grubbs second generation catalysis. By controlling the mass ratios of PHEE to COE, PCOEs bearing side hydroxyl groups (PCOE–OH) were obtained and then they were hydrogenated into polyethylenes bearing hydroxyl groups (PE–OHs). Finally, the PE–OHs were reacted with 2-(6-isocyanatohexylaminocarbonylamino)-6-methyl-4[1H]pyrimidinone to obtain PEs bearing ureidopyrimidone (denoted as PE–UPy). The introduction of UPy structural units did not affect the structure of PE crystals. Due to the introduction of quadruple hydrogen bonds, the mechanical properties of the materials were significantly improved. More importantly, the UPy-functionalized PEs significantly displayed shape memory properties. The shape memory properties are attributable to the formation of physically crosslinked networks via the dimerization of UPy moieties via quadruple hydrogen bonds. The stress relaxation tests showed that the UPy-crosslinked PE networks possessed self-adaptability.