Available at: https://digitalcommons.calpoly.edu/theses/978
Date of Award
MS in Polymers and Coatings
Chemistry & Biochemistry
Philip J. Costanzo
The goal of this thesis was to design thermally responsive polyol resins that would be compatible with isocyanates. Two approaches were made to reach this goal, the first involved functionalizing soybean oil and the second involved post-polymerization modification of a methacrylate based resin.
A soybean based coating with thermally responsive Diels-Alder linkages has been prepared following an automotive two-component formulation. The resulting coatings displayed the capability to be healed following physical deformation by a thermal stimulus, and such a material has significant potential for end users. Various curing agents were employed, and resulted in variation of scratch resistance and re-healablity. Different thermally responsive soybean resins were synthesized to have varying amounts of reversible and nonreversible linkages when incorporated into the coating.
Additionally, different isocyanates were added at differing ratios of NCO:OH in search of the optimum coating. It was found through the analysis of re-healabilty, hardness, gloss, and adhesion that the optimal combination was an acetylated resin (no irreversible crosslinks) with 54% reversible Diels Alder linkages at an NCO:OH ratio of 5:1 using isophorone diiscocyanate. Materials were evaluated via differential scanning calorimetry (DSC), scratch resistance, Koenig hardness, gloss measurements, and topographical analysis.
In the second project, copolymerization of methyl methacrylate and 2-isocyanatoethyl methacrylate via free radical polymerization was done to synthesize a polymer with pendant isocyanates. The isocyanate was used as a chemical handle to incorporate Diels-Alder linkages into the PMMA resin. The PMMA resin with Diels-Alder linkages was successfully synthesized and incorporated into a polyurethane gel as proven via 1H NMR and IR. The gel showed thermal reversibility at 120°C due to retro-DA reaction via DSC as well as thermally reversible bulk properties.