Effect of the plasticizer on the self-healing properties of a polymer coating based on the thermoreversible Diels-Alder reaction

A self-healing polymer for coating application was developed based on thermoreversible Diels-Alder (DA) reactions. The polymer network is formed by reacting a mixture of trifunctional and difunctional furanized resins (3F and 2F) with a bismaleimide (2M). The DA reaction occurs at temperature above 50 °C whilst retro-DA reaction occurs at about 120 °C. FTIR spectra were taken in order to monitor the reaction progress, and the thermal reversibility of the reaction was proved by DSC and DMA tests. A significant improvement of both the mechanical properties and the self-healing behaviour was achieved by introduction of small amount of a suitable plasticizer like benzyl alcohol. Self-healing properties of the plasticized polymer resulted in complete scratch recovery after retro-DA and DA reaction, whilst tensile testing reveals a 48% restoring of the pristine mechanical strength.