Facile fabrication of anti-fouling polymeric membrane potentiometric ion sensors based on biocide 1,2-dichloro-4-octylisothiazolin-3-one-containing self-adhesive waterborne polyurethane coatings

Polymeric membrane ion-selective electrodes (ISEs) are a powerful tool for ion sensing. However, their applications in complicated environmental water samples are still a challenge owing to the occurrence of electrode biofouling. To address this issue, we propose a facile and effective method for enhancing the anti-biofouling properties of these sensors. A self-adhesive coating based on waterborne polyurethane and biocide 1,2-dichloro-4-octylisothiazolin-3-one is prepared. The anti-fouling potentiometric ion sensor can be obtained by simply drop-casting of such self-adhesive coating. The classical poly(vinyl chloride) membrane-based Ca2+-ISE is chosen as a model. Compared to the unmodified pristine Ca2+-ISE, the obtained anti-fouling sensor exhibits remarkable improved anti-fouling properties such as much lower adhesion rate of bacteria (96.8% reduction after modification), higher anti-microbial rate and more superior anti-algal properties. More importantly, the proposed potentiometric sensor displays excellent long-term response stabilities even immersion in real seawater or high levels of alga solution for 30 days. It is anticipated that this simple and flexible approach could be extended to fabricate other anti-fouling electrochemical or optical membrane sensors. This work may lay an important foundation for development of anti-fouling chemical sensors for environmental water monitoring.