Collaborative research: Rates and Mechanisms of Biofouling and Mineral Scaling on Zwitterionic Amphiphilic Copolymer Surfaces

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This award from the Environmental Chemical Sciences Program in the Division of Chemistry supports Professors Ayse Asatekin from Tufts University, and Yandi Hu and Debora Rodrigues from University of Houston to investigate mechanisms of mineral scaling and biofouling on a new family of materials previously demonstrated to exhibit promising resistance to organic fouling. Fouling, or the deposition of unwanted materials on surfaces, is a severe problem in many applications where surfaces are in contact with seawater, affecting ship hulls, heat exchangers, and membranes. Therefore, there is an urgent need for developing materials that resist fouling when exposed to various environmental streams. Fouling can arise from the deposition of various components in water, including organic compounds, microorganisms, or inorganic minerals. This project focuses on a new family of materials having exceptional resistance to organic fouling. The main objective of this research is to determine if these materials also resist biofouling (i.e. adhesion of microorganisms) and mineral scaling (i.e. deposition of inorganic salts or minerals), understand how their chemical structure affects these different types of fouling processes, and eventually develop design rules for surfaces that resist multiple types of fouling. The research is conducted by a diverse team of graduate and undergraduate students in labs with a track record of recruiting and training members of underrepresented groups, and is incorporated into several university courses and K-12 outreach activities targeted at girls and underrepresented minorities. This project investigates processes of biofouling and mineral scaling on amphiphilic copolymers of zwitterionic and hydrophobic monomers, termed zwitterionic amphiphilic copolymers (ZACs), which can exhibit unprecedented resistance to organic fouling. The team is synthesizing ZACs with a range of monomer chemistries, hydrophobicities, and surface charges. Upon coating onto substrates, these materials are screened for organic fouling resistance. Promising ZACs are investigated in terms of the mechanisms and rates of gypsum scaling and biofouling. Scaling studies employ state-of-the-art techniques for in situ quantification of the heterogeneous nucleation of gypsum minerals onto surfaces as well as their aggregation and deposition. This project also develops a quantitative PCR array approach to identify the microbial genetic pathways of biofouling on ZAC coated surfaces. At the same time, advanced microscopic techniques are used to identify the unique properties of ZACs and connect them with initial microbial cell attachment rates and biofilm growth rates. Synergistic effects of biofouling and scaling are also considered. These results are compiled and correlated with ZAC chemistry (zwitterionic and hydrophobic groups), surface energy, surface charge, and other criteria. This work is expected to lead to a fundamental understanding of mechanisms and ZAC surface chemistry properties associated to organic fouling, biofouling, and scaling. The team's multidisciplinary and complementary expertise enables rational design of novel advanced materials to allow new scientific and transformative findings across disciplines of environmental chemistry, chemical and environmental engineering, environmental microbiology, and materials science.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.