Alan Aguirre1, Brian Adzima2, Timothy F. Scott3, Christopher J. Kloxin3, and Christopher N. Bowman3. (1) Chemical Engineering, Tecnologico de Monterrey, Monterrey, Mexico, (2) Chemical Engineering, University of Pittsburgh, Department of Chemical and Petroleum Engineering, Pittsburgh, PA 15261, (3) Chemical and Biological Engineering, University of Colorado, Campus Box 424, Boulder, CO 80309
Polymers are widely used in areas such as composites, marine, aerospace and car industry, being irreversibly damaged by high stresses. The research's objective is characterizing the thermo-rheological properties of a new cross-linked polymeric structure, which can potentially be crack-healed multiple times by forming new covalent bonds. A re-mendable maleimide/furan cross-linked polymer was synthesized through Diels-Alder thermo-reversible reaction between 1,1(methylenedi-4,1-phenylene) bismaleimide: multi-functional dienophile, and pentaerythritol propoxylate tris(3-(furfurylthio)propionate): multi-functional diene, then cured without solvent at 145C (agitation) for 30 minutes showing a fast chemical equilibrium with unique consistency in mechanical properties. Multi-functional furan was synthesized through Michael's addition of pentaerythritol propoxylate triacrylate and furfuryl mercaptan obtaining a pure product (C-NMR) by evaporation of unreacted thiol. It can transition from a glassy to a liquid state from ~85C to ~103C. It follows the theory of cross-linked polymers scaling and has a gel point at 95C indicated by Winters-Chambon criteria. It follows in a very particular way the Law of Rubber Visco-elasticity with inverse relation between the storage and the loss modulus to temperature. Thermo-reversibility allows cross-link density and hence modulus manipulation. Chemical equilibria and cross-link density are being studied. Findings could be applied to other systems, developing new crack-healing polymers with different applications.