Cross-Linked Gel Concentrated Above the Overlap Concentration
Department: Chemical and Biomolecular Engineering
Advisor: Kelly Schultz
View: UGRS Research Poster (PDF)
Cross-linked hydrogels are significant within a variety of chemical industries, playing an important role in fields ranging from the petroleum industry to applications within biomaterials. The overall objective is to gain a better understanding of these gels at higher concentrations and study their functionality within different growth mechanisms. The polymer used for these experiments was poly(ethylene glycol) (PEG), and was applied to photo-polymerization reactions involving click chemistry. While characteristics of PEG have been previously studied at lower concentrations, this project aims to understand the material properties of the resulting gel when it is concentrated above its overlap concentration, c*. Since the overlap concentration reflects the solution’s viscosity, initial experiments increased the percentage of PEG in solutions to determine dilute, semi-dilute and entangled regions and their corresponding concentrations. Using this as a foundation, experiments used PEG precursor solutions from each of these viscous regions to study the effects on gelation and final material properties during polymerization by both chain and step growth mechanisms. These experiments applied bulk and microrheology to track particles and measure characteristics within the gelation reaction. Through multiple particle tracking microrheology (MPT), material properties of the gel were optically tracked and analyzed. Bulk rheology was then used to confirm these results and provide further material details. These experiments will provide important results regarding polymer interactions and long term stability that will improve the understanding of concentrated solution properties. By determining how different polymerization mechanisms effect cellular behavior and interact within solutions, concentrated gels can provide effective solutions and innovative improvements to processes within the chemical industry.
About Michelle Mazzeo:
Michelle S. Mazzeo is a junior Chemical Engineering Major with a biotechnology minor in the Department of Chemical and Biomolecular Engineering at Lehigh University. She received a Dean’s Merit Scholarship and has qualified for the Dean’s List each semester. Within the Chemical and Biomolecular Engineering department, she has gained experience in the Rheology laboratory of Professor Schultz, studying the material properties of cross-linked gels, particularly focusing on researching gels above their overlap concentration. She has obtained additional experiences in summer internships at Cincinnati Children’s Hospital in a Molecular Cardiovascular Biology lab, followed by an internship at Regeneron Pharmaceuticals in Purification Development Analytics this past summer. Some of her primary extracurricular leadership positions at Lehigh include AIChE ChEHH mentor; captain of the Lehigh Running Club’s morning running group; active member of the Lehigh University Choir. She also played an important role on the Choir Executive Board as Assistant Stage Manager when the choir sang at Carnegie Hall and Yankee Stadium last November, and on their international tour in Italy last May.