Cellulosic, Water-Based, Flourine-Free, Superhydrophobic Coatings

Superhydrophobic surfaces have been extensively studied for fluid management across multiple industries. There is a trend to make such surfaces fluorine-free, water-based, and cellulosic, that they can be safer for disposal, for end-users, and manufacturers. This study explores that effort to meet all these requirements. Some importance was placed on using off-the-shelf materials, which could be spray cast, ensuring substrate independence and scalability of all formulations. The first chapter deals with reducing fluorine content while achieving superhydrophobicity. The second chapter of the thesis dwells on the advantage of reducing fluorine content in disposables, looking at achieving the necessary durability and repellency without the use of fluorine. Self-cleaning surfaces were achieved with as little as 1% fluorine present in dry coatings. In the latter half of this work, the motivation for fluorine-free surfaces is presented, along with an alternate hydrophobe to that end. By using cellulose for roughness and Alkyl Ketene Dimer (AKD) for low surface energy, the requirements for such a surface are met, and the advantage of using these surfaces for disposable products where low durability is acceptable are immediately apparent over fluorine. The solutions presented focus on producing superhydrophobic surfaces that incorporate cellulose, which is still not widely used in a facile manner for inducing water repellency. Cellulose is ideal as a biodegradable filler particle, and in unison with coatings that eschew fluorine and organic solvents, trends toward the green coatings that will have the least impact on the environment from fabrication to decomposition. Using cellulose filler to imbue roughness while another polymer provides hydrophobicity, allows that opportunity. Maintaining low solids content in cellulose dispersions ensures sprayable formulations that can be as versatile as needed. By making such solutions sprayable, the option remains in the future to screen-print, dip coat, or roll on the coating. This ensures the broadest array of possible applications.