New Molecular Chain Extenders for Self-Healing Polyurethanes

Abstract

Novel low-molecular-weight chain extenders based on aromatic bismaleimides were synthesized, and their effect on the properties of polyurethanes was investigated. The bismaleimides were prepared from symmetric aromatic diamines with various donor–acceptor properties and reacted with furfuryl alcohol via the Diels-Alder reaction to yield diols (DA-diols). Corresponding polyurethanes were obtained based on the synthesized novel compounds as well as a benchmark DA-diol synthesized for comparison. The structure and molecular weight characteristics of the polyurethanes were investigated by infrared (IR) spectroscopy and gel permeation chromatography (GPC), while the thermochemical parameters of the Diels–Alder reaction within the polyurethanes were determined by differential scanning calorimetry (DSC). The mechanical properties of the new materials were evaluated by uniaxial tensile testing and compared with the characteristics of the polyurethane based on the reference DA-diol. It was established that the Young’s modulus was 20‒30 MPa, the tensile strength at break was 20 MPa, and the elongation at break was 928‒1037 %. The property recovery efficiency after heat treatment reached 77‒89 %. Scanning electron microscopy (SEM) of the film surfaces demonstrated the ability of the materials to heal defects upon thermal treatment. The results demonstrate the feasibility of using the synthesized DA-diols based on novel aromatic bismaleimides as chain extenders to develop self-healing polyurethanes with an extended service life.