Highly Effective Antiadhesive Coatings from pH‐Modified Water‐Dispersed Perfluorinated Acrylic Copolymers: The Case of Vulcanizing Rubber. Issue 13 (1st April 2016) - Radaelli, Greta
Abstract : A pH‐based method to tune the tribological and wetting properties of a coating obtained from water‐dispersed perfluorinated acrylic copolymer is demonstrated. The surface‐exposed fluorinated chains and chemical charges of the sprayed coatings can be controlled simply by tuning the pH of the initial water dispersion. The surface properties of the sprayed polymeric coatings remain unmodified when the pH of the water dispersion is reduced (addition of HCl). On the contrary, from dispersions with increased pH (addition of NaOH) a fluoroacrylic polyelectrolyte polymer is formed and clear variations in wetting and tribological properties of the polymeric coatings are observed. Interestingly, coatings' surface adhesion to vulcanizing rubber can be strongly reduced when the pH of the dispersions is in the range 4.5–6.0, which corresponds to a specific ratio between fluorinated chains and chemical charges. Consequently, such coatings can be proposed as low‐cost and easy‐to‐apply alternatives to aqueous release agents for the rubber tires demolding processes, thus having significant implications for the automotive tire industry. Abstract : Water‐based perfluorinated acrylic copolymer spray coated from dispersions with pH between 4.5 and 6.0 (NaOH addition to the initial dispersion) forms polyelectrolyte coatings of a specific ratio between fluorinated chains and carboxylate groups, with minimal adhesion to vulcanizing rubber. On the contrary, coatings from water dispersions with unmodified or reduced pH (HCl addition) show higher adhesion.