Preparation and photo-responsive behavior of reversible photochromic polyurethane cement composites

A smart coating based on a polyurethane cement (PUC) substrate with photochromic behavior and anti-ultraviolet performance was obtained successfully by depositing photochromic sol–gel material on the PUC surface using a simple drop-coating method. The results revealed that the PM concentration considerably affected the photochromic properties. The total color change (ΔE*) was optimum (66) at a PM concentration of 20%. The chromogenic time of the photochromic PUC was 2.4 s, and the fading time was 30 s at room temperature. Furthermore, accelerated aging and abrasion tests suggested that the treated PUC composites had excellent anti-ultraviolet properties and mechanical stability. The results indicate that the proposed photochromic PUC is a promising candidate for many applications, such as road and bridge construction and green buildings.