Soy Protein/Dialdehyde Starch Sizes with Responsive Coating and Removability via a Dual-Zone Dynamic Imine Strategy for Ecofriendly Textile Processing

Warp sizing constitutes an indispensable preparatory process in weaving production, with an annual consumption of sizing agents exceeding one million tons. However, current sizing agents face difficulty in balancing the conflicting requirements of strong yarn adhesion and easy desizability. Inspired by stimulus response characteristics of dynamic covalent bonds, we developed a dual-zone dynamic imine-mediated controllable soy protein/dialdehyde starch (DAS-SP) sizing agent. Imine cross-linking within the film was achieved by incorporating DAS, which led to obvious enhancements in both the mechanical properties and thermal stability of the sizing films. Tensile strength and fracture energy of the film increased by 34.8% and 112.90%, respectively. The formation of interfacial imine “switches” between the DAS-SP sizing agent and oxidized cellulose yarns endowed the DAS-SP sizing agents with enhanced adhesion to the yarn, representing an improvement of 84.76% compared to the original yarn. Moreover, leveraging the pH-responsive nature of the imine bonds, desizing with a trigger solution at pH 6 achieved over 90% removal efficiency with a water-to-fabric mass ratio of 60:1, thereby reducing water consumption by more than 50%. Collectively, the incorporation of green-based dynamic covalent bonds into the sizing agents provides a promising approach for promoting sustainable and high performance of textile processing.