In this project funded by the Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division, Kevin Cavicchi of the University of Akron will study the fundamental physical chemistry of supramolecular assembly by organogelators. The approach is to prepare tris-amide gelators and nonvolatile, liquid polymer solvents. The phase behavior of these two component systems will be determined, and for combinations that form organogels their structures and physical properties will be characterized using thermal methods, x-ray scattering techniques, dynamic mechanical analysis, and microscopy techniques. The ultimate goal is to correlate qualitative gelation behavior with the chemical details of supramolecular assembly by the gelator. The broader impacts involve training graduate students, a research experience for teachers internship in the PI's laboratory, and broad dissemination of results through publications and presentations at national meetings.
This work will enhance our fundamental understanding about how supramolecular assembly of small organic molecules can lead to the gelation of organic solvents. The results of these studies could have many important long term impacts on many applications including oil recovery from aqueous media, drug delivery, cosmetics and tissue engineering.
The objective of this research was to investigate the phase behavior of low molecular mass organogelators (LMOGs) to better understand the relationships between the thermodynamic parameters of these systems and the resulting gelation behavior. It was hypothesized that understanding the phase behavior would improve the design of LMOGs for specific applications. LMOGs are small molecules that are able to self-assemble in a fluid to form a three-dimensional load, bearing network that gels the surrounding fluid. LMOGs are used in a variety of applications including cosmetics, foodstuffs, plastics processing, and materials synthesis. A central finding of this research is that the phase behavior of crystalline LMOGs could be accurately described using thermodynamic solution models employed for other systems, such as solvents and polymers. Relationships between the thermodynamic features, including the undercooling, solution state structure, and molecular size of the gelling fluid, and the gelation efficiency were found. More complex thermodynamic behavior, such as solution state aggregation, were found to strongly impact gelation behavior and improve LMOG gelation efficiency. These relationships will aid in the design of new LMOGs. Based on these findings responsive shape memory polymers were generated by swelling commercial rubber bands in stearic acid. Shape memory polymers have potential utility in biomaterials, aerospace, and consumer products applications. This simple approach to prepare a functional material should have broad impact as it will allow scientists and engineers to study shape memory polymers without the need of extensive chemistry to produce material systems. The results of this research have been broadly disseminated in seven peer-reviewed publications and nine presentations at national technical meetings of different scientific societies. Seven graduate students, six undergraduate students (three from underrepresented groups), three high school students, and two high school teachers have participated in this project. The high school teachers participated as part of an effort to expose teachers to cutting-edge research through summer research experiences. The goal of these experiences was to expose teachers to scientific research, which they used to develop a new, exciting lesson plan for their classroom. These lessons are used to engage their students and encourage them to pursue careers in STEM fields. The interaction among the different participants in this project was found to be very beneficial for generating exciting research directions. For example, the shape memory elastomers developed in this project was a direct result and solution of the challenge faced by a teacher in translating research from the laboratory to the classroom setting.
