Understanding the Effects of Electric Field on Polyelectrolytes

About This Grant

PART 1: NON-TECHNICAL SUMMARY Charged polymers, or polyelectrolytes, are ubiquitous in nature and can be found in many day-to-day products. For example, negatively charged alginates obtained from brown algae are used in food products as thickening and stabilizing agents. Likewise, positively charged chitosan can be found in wound-healing bandages as a blood coagulation agent. The combination of oppositely charged polyelectrolytes in aqueous media can form polyelectrolyte complexes (PECs). The proposed research investigates the application of electrochemical processes to control the complex formation, a phenomenon not widely reported in the literature. Furthermore, the proposed research will explore how the application of an electric field can cause the adhesion of two oppositely charged ionic gels of polyelectrolytes. The factors that control the properties of PECs, the adhesion between oppositely charged ionic gels, and the disintegration of ionic gels and complexes will be investigated by changing the nature of charged polymers, both of synthetic and natural origin. The ability to control the properties of PECs will advance their applications in many areas, including biomedical, adhesives, food, and personal care products. The electric field-induced dissociation of ionic gels can provide pathways for the degradation and reuse of polymer gels. The understanding of the electric field-induced adhesion of ionic gels can be translated into development of adhesives for demanding applications such as biomedical adhesives. The proposed research results will be widely disseminated in peer-reviewed journals and through conference presentations. The new generation workforce will be trained through active participation in cross-disciplinary research activities and coursework related to this research and overall polymer science. New K-12 students will be inspired to pursue STEM education through laboratory demonstrations. PART 2: TECHNICAL SUMMARY This project aims to understand how natural and synthetic polyelectrolytes respond to an applied electric field in both solution and gel form. The underlying factors that dictate i) the electroformation of complexes of oppositely charged polyelectrolytes and their electrodeposition on electrodes through electrochemical processes and ii) the electric field-induced dissociation of ionic gels and adhesion between two oppositely charged ionic gels will be assessed by using state of the art characterization techniques and theoretical frameworks. The underlying mechanisms for electroformation, electrodeposition, electroadhesion, and degradation will be understood and linked to the physicochemical properties of PEs, including their molecular weight and charges per chain. For the electroformation processes, the impact of various factors that dictate the outcome of the process and properties of the resulting PECs, such as the polymer concentration, the ratios of molecular weight and charges of oppositely charged polyelectrolytes, and environmental conditions used, (e.g. doping with salts) will be investigated. The structure of PECs will be determined by using different microscopy and scattering techniques. For the electroadhesion between oppositely charged ionic gels, how the network properties and applied field in tandem affect the adhesion strength via control of the gel-gel interface will be elucidated. The scientific outcomes of this project will be (i) a new pathway for PEC formation via electrochemical processes and (ii) design principles for adhesives through electroadhesion between oppositely charged ionic gels. Overall, a fundamental structure-property relationship for polyelectrolytes subjected to an electric field will be achieved. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.