Date of Award
MS in Polymers and Coatings
Chemistry & Biochemistry
The corrosion of infrastructure imposes a significant monetary cost, and at times human cost, upon society. Methods to improve corrosion resistance of materials are described herein which utilize the reversibility of the Diels-Alder reaction to impart thermal responsiveness upon materials. Such stimuli responsiveness can potentially play a role in self healing properties which lead to reduced cracking and thus increased corrosion protection.
Reversible Diels-Alder chemistry was utilized to manipulate the surface energy of glass substrates. Hydrophobic dieneophiles were prepared and attached to glass slides and capillaries to yield a nonwetting surface. Thermal treatment of the surfaces cleaved the Diels-Alder linkage, and resulted in the fabrication of a hydrophilic surface. Preliminary analysis utilized contact angle (CA) measurements to monitor the change in surface energy, and observed a hydrophilic state (CA - 70±3°) before attachment of the dieneophile to a hydrophobic state (CA - 101±9°) followed by regeneration of the hydrophilic state (CA - 70±6°) upon cleavage of the Diels-Alder linkage. The treatments were then applied to glass capillaries, with effective treatment confirmed by fluid column measurements. Patterned treatments were also demonstrated to provide effective fluid flow gating.
Reversible Diels-Alder linkages were incorporated into polymer thermoset binding resins in order to provide a means by which a crosslinked thermoset could undergo stimuli responsive reversible crosslinking. The binder systems which were utilized included two types of amine curing agents, polydimethylsiloxane (PDMS) and Jeffamine® polyetheramines (PEA), and two types of epoxy resins, EPON resin based on diglycidyl ether of Bisphenol-A and epoxidized soybean oil. Various dienes and dienophiles were employed to functionalize the selected binder systems and were met with various degrees of success. The synthetic technique which proved to be the most promising was the Diels-Alder modification of the epoxidized soybean oil.