Construction of durable and original color constancy photochromic cotton fabrics by a facile esterification strategy

Cotton-based photochromic textiles have emerged as a representative smart textile, yet constrained by the complicated process, deep original color and limited durability in practical applications. Here, spiropyran (SP) with a simple carboxy linking group was directly covalently immobilized onto cotton fabric through a facile and effective esterification strategy. Benefit from the simple structure, this modification process does not affect the basic properties and color of the fabric. In addition, the SP-cotton fabrics exhibited excellent reversible photochromic properties from colorless to violet and allowed to print exquisite patterns with long-distance control by switching light resource and photomasks. Moreover, the stable ester covalent bond endowed these SP-cotton fabrics with appropriate washing fastness and photo fatigue resistance. This study not only added value to cotton, but also paved a rational and general approach for the construction of durable and original color constancy photochromic textiles, providing a potential candidate for brand protection, anti-counterfeiting, and fashion textiles.