Thermo-reversible self-healing polymeric coatings derived from gum rosin

The growing demand for the development of bio-based, greener and more sustainable polymeric systems was the inspiration to develop two bio-based thermo-reversible polymers derived from gum rosin, a product of pine trees, being reported in this article. The Diene moieties were inserted into the backbones of rosin-based polymers, and thermo-reversible Diels-Alder (DA) bonds were formed between the diene moieties of the polymers and the bismaleimide crosslinkers. The introduction of thermo-reversible linkages to the polymer improves the durability of the material by extending its life span and improving its mechanical properties as well. After damage, the material shows self-healing due to the thermo-reversibility, which causes the DA bonds to de-crosslink, allowing the material to reflow to the wounded site and seal the fracture. The DA and Retro-Diels-Alder (r-DA) reactions are analyzed by differential scanning calorimetry. The scanning electron microscope (SEM) was used to evaluate the self-healing capabilities of polymeric materials that were applied on glass surface, mild steel, and concrete specimens. Artificial scratches were created, and the repairing process was examined.