Abstract
There is an urgent need for coatings that exhibit both self-healing as well as self-cleaning properties as they can be used for a wide range of applications. Herein we report a novel approach toward fabricating polyurethane thermosets possessing both self-cleaning and self-healing properties. The desired coating was achieved via casting a bottom layer of self-healable polyurethanes comprised of reversible phenolic urethane bonds followed by a subsequent dip-coating of the prepared layer in a solution of bis(3-aminopropyl)-terminated polydimethylsiloxane (PDMS-NH2). The PDMS was used to impart self-cleaning properties to the coating. While the self-healing behavior of the bottom polyurethane layer is achieved through phenolic urethane chemistry, via the exchange of phenolic urethane moieties. The prepared coatings were tested for their optical, mechanical, self-healing, and self-cleaning properties using a variety of characterization methods, which confirmed the successful fabrication of novel self-cleaning and self-healing clear urethane coatings.
Highlights
Polymeric materials are prone to surface damage during their life cycle
The water contact angle hysteresis values were measured based on the difference between the receding and advancing angle according to Equation (1)
Biobased and low-cost propyl gallate was selected as a self-healing agent from the sustainability perspective
Summary
Polymeric materials are prone to surface damage during their life cycle. If this damage is left unaddressed, it can propagate with the passage of time and can cause a loss of structural integrity, environmental degradation of the substrate, as well as functional and mechanical failure. Due to the harmful and persistent nature of fluorine-containing compounds in the environment, fluorine-free alternatives are highly desirable In this regard, PDMS has recently been employed by our group and others to introduce self-cleaning properties [38,39,40,41,42,43,44,45]. Polydopamine (PDA) coated fabric was treated with stearic acid to impart excellent water repellency These coatings were non-repellent for oil as evident from their use in water and oil separation [46] fluorine-free rough surfaces were recently reported with very high contact angles for water, but these surfaces are neither oil-repellent nor self-healing [47]. The prepared coatings were tested for their optical, mechanical, self-healing, and self-cleaning properties
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