Erik Fréchette, Charles de Lannoy (2022). Antifouling and Oxygen Permeability Properties of Zwitterionic Polymer Coatings for Long-Term Dissolved Oxygen Surface Water Monitoring. Proceedings of the GWF Annual Open Science Meeting, May 16-18, 2022.

The assurance of global water security has become a crucial aim for humanity in the 21st century. Although Canada’s freshwater reserves are among the world’s largest, many Indigenous communities lack reliable means to access clean water. A variety of factors such as community remoteness, fiscal mismanagement, archaic environmentally racist policies, and improper pollutant disposal have all played a role in the precarity of Indigenous water management. During the implementation of a community based participatory research approach to monitor the surface water of Six Nations of the Grand River (SNGR), a series of water quality monitoring stations (WQMS) were developed, each monitoring five common water quality parameters. However, these sensors are prone to fouling, which can significantly reduce the reliability of their collected data after extended operation in the field. In this research, a series of antifouling zwitterionic polymer coatings is investigated for use on a cheap, commercially available dissolved oxygen (DO) sensor. Zwitterions are being investigated as these polymers are tuneable for improved antifouling ability, are relatively easy to fabricate, and are environmentally friendly. However, research is lacking as to whether zwitterionic coatings would degrade the sensor signal strength by inhibiting oxygen transfer across a dense polytetrafluoroethylene (PTFE) membrane at the sensor’s surface. As such, the zwitterionic copolymer sulfobetaine methacrylate-co-glycidyl methacrylate was prepared via free radical polymerization and was grafted to a series of PTFE membranes via polydopamine (PDA) and branched polyethyleneimine (PEI). The antifouling properties of these surfaces were examined following two-week immersion in nonspecific bacterial solutions and in bovine serum albumin (BSA) solutions. Preliminary tests confirm lower foulant adhesion to the coated membranes compared to the non-coated ones, as suggested in literature. A dissolved gas diffusion cell was constructed using two 1-litre vessels connected by a central channel in which sits a sample PTFE membrane. Pure O2 gas is bubbled into a DO rich aqueous environment to observe the oxygen transfer rates from the vessel of oxygen rich water (~35 ppm) to the vessel of oxygen poor water (~5 ppm), testing zwitterionized and non-zwitterionized membranes, as well as fouled and unfouled membranes. Preliminary results indicate a lack of a statistically significant difference of DO transfer between zwitterionized and non-zwitterionized membranes, which points to using zwitterionic antifouling coatings as a viable option for long-term environmental endeavours on DO sensors.

First Author: Erik Fréchette, Department of Chemical Engineering McMaster University
Additional Authors: Charles de Lannoy, Department of Chemical Engineering McMaster University