Discipline: Chemistry & Chemical Sciences
Subcategory: STEM Research
Karina Chavez - Cornell University
Co-Author(s): Anil N. Netravali
Microcapsules (MCs) with poly(lactic-co-glycolic acid) (PLGA) shell and soy protein isolate (SPI) core were produced by using a water-in-oil-in-water (w/o/w) emulsion and solvent evaporation technique. A water-in-oil emulsion consisting of SPI in water and PLGA in ethyl acetate, created spherical micelles that were made to elongate by forcing the water-in-oil emulsion through a 25-gauge needle into an aqueous poly(vinyl alcohol) (PVA) bath while pulse stirring. The PVA served as a stabilizer and also provided hydroxyl groups on the MC surfaces and improved MC/resin interfacial bonding. This can be expected to improve the self-healing efficiency of the resin as well as the green composite. The resulting w/o/w emulsion containing micelles was then sheared between concentric cylinders (one cylinder was spun at 300 rpm while the other cylinder remained stationary) while allowing the ethyl acetate to slowly evaporate and solidify the PLGA shell. The effect of SPI solution pH on MC formation was also studied. Alkaline pH of 12 resulted in MCs sticking together to form clusters, particularly with excess PVA, while a higher pH of 14 led to a fine powder containing individualized MCs. The size and shapes as well as healant content of the SPI-PLGA MCs were confirmed using optical, electron and confocal laser scanning microscopy. The surface chemistry of MCs was characterized using attenuated total reflectance infrared spectroscopy. The MCs made with green materials will be used as the self-healing mechanism and to repair microcracks as they are created and, thus, increase the durability of green SPI based resins as well as cellulose fiber reinforced green composites.
Funder Acknowledgement(s): NSF-CREST
Faculty Advisor: None Listed,
NSF Affiliation: CREST