Dual-Role Mechanism of Dimethyl Sulfone in the Preparation of Surface Layer Membrane of Superfine Fiber Veneer Synthetic Leather

In this study, the characteristics of water solubility and self-crystallization of dimethyl sulfone (DMSO2) are adopted to design a dope solution system with waterborne polyurethane and additive DMSO2. A supersaturated salt solution is used as a coagulation bath to induce the unidirectional diffusion effect of the membrane formation system. Surface layer membranes of superfine fiber veneer synthetic leather with high water vapor permeability (WVP) are prepared. The role mechanism of DMSO2 during the membrane formation process is studied. The results show that the synergistic effect of the dual-role mechanism of dimethyl sulfone (dissolution and self-crystallization in the dissolution channel) leads to the increase of the microporous channel size of the membrane. The WVP of the membrane reaches 67.41 g m–2 h–1 (more than 2.4–23.1 times higher than the membranes reported) when the DMSO2 content relative to the total dope solution is 15%. Meanwhile, the membrane shows excellent mechanical properties.