Stimuli-responsive polymers can change their physical and/or chemical properties in response to external stimuli. These polymers have found great success in a number of important areas including molecular gels and biomedical engineering, as well as success in applications such as targeted drug delivery and biosensors. We have been working toward the development of programmable polymers that remember the response after a stimulus is withdrawn. To this end, we set out to synthesize specific functional monomers. While different types of reactions could potentially result in the desired target monomer, we studied the ring-opening metathesis–cross-metathesis reaction (ROM-CM). Previous work of ours synthesized monomer 1a, a cis-norbornene-2,3-dicarboxylic imide precursor to functional monomer 2a. We report herein the attempts to prepare the target monomers 2a and 3 via alternative ROM-CM routes that varied in starting materials, solvent systems, reaction temperatures, and catalyst amounts. We discovered that methanol based solvent systems resulted in a higher production of oligomers and other side products. In addition, one promising route using the new maleic acid starting material in place of ethyl acrylate was found to effectively undergo the ROM-CM reaction with monomer 1b. This reaction appeared to produce the desired product 2b which is currently being converted to the diester monomer 3 for further characterization. Future efforts will involve further examination of the ROM-CM reaction of maleic acid and other olefins with the norbornene-dicarboxylic imide precursor, dilute conditions in norbornene reactions, and alternative synthetic routes.
Dziewior, Courtney S.; Strickland, Sharon M. S.; Li, Ping; and Shimizu, Ken D.
"Synthesis of Stimuli-Responsive Programmable Polymers Through Ring-Opening–Metathesis Cross-Metathesis (ROM-CM),"
Journal of the South Carolina Academy of Science: Vol. 17
, Article 2.
Available at: https://scholarcommons.sc.edu/jscas/vol17/iss2/2