Polystyrene Discs as Barriers for Diffusion in Layered Organogels
Author:
Nicholas DeVita ’24Co-Authors:
Faculty Mentor(s):
Dr. Kenneth Mineart, Department of Chemical EngineeringFunding Source:
NSFAbstract
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. Our present work focuses on controlling the direction of diffusion in a polymer gel with an organic network. Organogels contain a diffusion probe, tri-block copolymer, and an organic solvent. 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. The main mechanism by which a probe maneuvers through a gel is time-dependent diffusion. Using Fourier Transform Infrared spectroscopy, the probe release rate can be tracked, and therefore, the fundamental parameter diffusivity can be determined. Controlling directionality allows for the delivery of probes to be tuned to our liking. Annealing external polystyrene was the main method employed to control diffusion. In particular, polystyrene pellets were annealed onto the face and walls of a gel. Sealed organogels were submerged in glass jars containing MO. Usually, gels submerged in MO gain in mass and thickness as a result of inward diffusion of oil into the gels. Our data shows that the mass transport of mid-block selective oil is limited based on how much Polystyrene covers the gel.