A simple strategy for preparing anti-glare WPU coating and the influence of post-chain extender on the surface morphology of latex particles

Anti-glare coatings offer a promising solution for mitigating light pollution, with the construction of a rough surface being essential to their effectiveness. In this paper, a series of waterborne polyurethane (WPU) coatings with self-antiglare effect were successfully synthesized by adjusting the molar ratio of the post-chain extenders sodium N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonate (BES) and hydrazine hydrate (N2H4). This approach utilized BES as a post-chain extender for the first time, resulting in a double micro-rough surface structure that enabled the coating to achieve better anti-glare effect with relatively lower roughness. The effects of BES and N2H4 on particle size, morphology, gloss, zeta potential, transmittance, and hydrophilicity of WPU were investigated. When the BES content accounted for 30 mol% of the post-chain extenders, the average particle size of the emulsion was 1321.4 nm, and the 60° gloss of the coating was 36.1 GU. Additionally, we thoroughly analyzed the formation mechanism of the “worm-like” micro-rough structure on the surface of latex particles. The strongly hydrophilic -SO3−Na+ groups in the emulsion pulled the molecular chains to extend to the outer layer of the latex particles. Upon water evaporation, these molecular chains curled up on the particle surfaces, forming a "worm-like" micro-rough structure. XRD spectrum, FBI-SEM, and TEM images confirmed that this micro-rough structure was formed by self-assembly on the particle surface rather than internal crystallization. This finding provides novel insights into the development of self-antiglare WPU coatings characterized by intricate rough surfaces. Furthermore, it contributes to the advancement of surface and interface science through improved performance of WPU coatings. [Display omitted]