Date of Thesis

Summer 2023

Description

Organogels are often considered for transport-based applications such as transdermal drug delivery vehicles and gel actuators due to their unique properties. Recent consideration of styrenic block copolymer based organogels’ application in transdermal drug delivery requires an extensive investigation of drug diffusion behavior through these gels to assess their applicability. Temperature is a major influencing parameter on diffusion. The goal of this research is to better understand the impact of temperature on diffusion in styrenic triblock copolymer organogels. To accomplish this goal, we focused on three specific objectives: (i) accurately measure the diffusivities of a solute – AOT reverse micelles – through organogels made with one of the three mineral oil solvents – Squalane, Hydrobrite 200 and Hydrobrite 380 – at different temperatures, (ii) establish a meaningful understanding of these data by interpreting them with preexisting models, and (iii) explore the possibility of composition-diffusion superposition in these materials. Gels for each oil solvent were formulated with five different copolymer concentrations, and Fourier Transform Infrared (FTIR) spectroscopy was used to track the diffusion of AOT reverse micelle through the gels. Diffusivity values are interpreted using two theoretical models – a general Arrhenius model and the detailed model developed by Petit et al. Ultimately, both of the models represent our data well and provide diffusion activation energy of the solute through gels. The diffusion activation energy is shown to increase with an increase in gel solvent viscosity. Lastly, we observe that diffusivity through gels composed of different solvents can be superimposed into a single master series at a specified reference composition using viscosity data. The master data set can be used to extend the temperature range over which diffusivity can be assessed in gels.

Keywords

Arrhenius model, diffusion activation energy, composition-diffusion superposition, model of Petit et al., block copolymer, temperature-dependent diffusion

Access Type

Masters Thesis

Degree Type

Master of Science in Chemical Engineering

Major

Chemical Engineering

First Advisor

Kenneth P. Mineart

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