134 - Self-repariable polymer and copolymer networks that change color
Marek W Urban, email@example.com, School of Polymers and High Performance Materials, The University of Southern Mississippi, Hattiesburg, MS 39406, United States
Although the last decade has brought self-healing materials on the forefront of scientific interests, combining repair and sensing attributes into one material entity have not been addressed. These studies report the development of poly(methyl methacrylate/n-butylacrylate/2-[(1,3,3-trimethyl-1,3-dihydrospiro[indole-2,3'-naphtho[2,1-b][1,4]oxazin]-5-yl)amino]ethyl-2-methylacrylate) [p(MMA/nBA/SNO)] copolymer films that upon mechanical scratch undergo color changes from clear to red in the damaged area, but upon exposure to sunlight, temperature and/or acidic vapors, the damaged area is self-repaired and the initial colorless appearance is recovered. The process is reversible and driven by the ring-opening-closure of spironapthoxazine (SNO) segments to form merocyanine (MC), which are recovered back to the SNO form. Upon mechanical damage, SNO segments of the neighboring copolymer segments form inter-molecular H-bonding that stabilizes copolymer backbone, that remains in an extended conformation. External stimuli, such as light, temperature, or acidic environments cause a dissociation of the H-bonded MC pairs, which are converted back to SNO. This process is associated with the p(MMA/nBA/SNO) backbone collapse, thus pulling entangled neighboring copolymers to fill removed mass and repair a scratch. Mechanical nano-indentation analysis combined with molecular modeling and spectroscopic measurements confirm this behavior. The enclosed video clip illustrates molecular repair processes induced by visible light monitored by in-situ Raman imaging spectroscopy. These materials may find numerous future applications, where coupling of simultaneous color changes and reversible self-repair responses may lead to new technological paradigms.
Monday, March 26, 2012 01:30 PM
Polymers in Organized Assemblies (01:30 PM - 04:35 PM)
Location: Manchester Grand Hyatt
Room: Annie A