2022 Annual Meeting
Quantifying the Relationship between Probe Size and Diffusivity in Triblock Copolymer Organogels
Transdermal drug delivery is a vital mechanism for skincare, hormone replacement, and other biomedical applications. Organic polymer gels have been recently identified as candidates for this drug delivery mechanism. The present work investigates diffusion in gels composed of a triblock copolymer, a mid-block selective aliphatic mineral oil, and a diffusion probe.The tri-block copolymer forms a physically crosslinked network that consists of spherical polystyrene domains and a plasticized rubbery matrix consisting of ethylene-co-butylene and aliphatic mineral oil. The matrix phase is fluid-like and amenable to mass transport, which allows for probe diffusion. Using Fourier Transform Infrared spectroscopy, the probe release rate can be tracked, and therefore, the fundamental parameter diffusivity can be determined. Our work focuses on the diffusion of probes including AOT (sodium bis(2-ethylhexyl)sulfosuccinate), poly(hyrdoxystearic acid), oleic acid, Span 80 (sorbitan monooleate), and Span 85 (sorbitan trioleate). The AOT forms reverse micelles whereas the other probes are present as individual molecules. Reverse micelles are an aggregation of molecules that serve as larger probes. Our measurements show the diffusivity of the probes from slowest to fastest is as follows: AOT, poly(hyrdoxystearic acid), Span 85, Span 80, and oleic acid. We believe this is due to a variation in probe size. In this poster, we plan to describe this using existing solute diffusion theory.