Date of Thesis
Spring 2024
Description
Block copolymer gels are under consideration as drug delivery patches. Controlling and modeling the transport inside the gel is an important contribution to the successful delivery of pharmaceuticals. The diffusive transport of a solute – such as a therapeutic compound – within the gel can be described by the mesh size of the gel, which is defined as the distance between polymer chains. Existing experimental evaluations of mesh size do not work for block copolymer gels due to differences in the fundamental gel structure. As such, an experimental method of measuring mesh size of block copolymer gels using dynamic light scattering (DLS) is explored. While the mesh size of the studied system is not easily evaluated experimentally, the correlation length of gels can be determined by DLS. The correlation length of the gel is roughly the same size and scale as the mesh size of the gel, but they are fundamentally different parameters. The correlation length of the polymer can be theoretically calculated by blob scaling theory: a model for the distribution of polymer chains in a semidilute polymer solution. A semidilute polymer solution is present within the block copolymer gel matrix. In this study, the correlation length of physically crosslinked block copolymer gels is evaluated in different conditions by DLS. The results of DLS were shown to be consistent between measurements and do not change even after gels are aged several months. The concentration dependence of correlation length as resolved by DLS matched the correlation length predicted by blob scaling theory. At increasing temperatures, the results of DLS were inconsistent and inconclusive. Overall, DLS was shown to provide a reasonable approximation of the correlation length of a polymer gel at ambient temperature. A considerable amount of uncertainty present in DLS data leaves questions about the application of this method to extract precise values of correlation length.
Keywords
Polymers, Polymer Gels, Polymer Physics, Dynamic Light Scattering, Polymer Light Scattering, Transport Processes
Access Type
Honors Thesis
Degree Type
Bachelor of Science in Chemical Engineering
Major
Chemical Engineering
Minor, Emphasis, or Concentration
Mathematics
First Advisor
Kenneth Mineart
Recommended Citation
Hill, Duncan M., "Experimental Evaluation of Mesh Size in Physically Crosslinked Polymer Gels using Dynamic Light Scattering" (2024). Honors Theses. 678.
https://digitalcommons.bucknell.edu/honors_theses/678