Structural and Adhesive Properties of Cellulosic Mucilage: A Molecular-Level Investigation

Several plant seeds release a mucilaginous envelope upon hydration, rich in pectin and stabilized by cellulose fibers, generating adhesion. However, the mechanisms governing mucilage adhesion remain unclear. Using a multibody dissipative particle dynamics (MDPD) model, we investigated the roles of cellulose, pectin, and water in seed adhesion. The softer pectin polymers exhibit stronger adhesion than stiffer cellulose chains. Adhesion decreases with increasing polymer stiffness but plateaus beyond a threshold. The presence of water enhances cellulose adhesion. As water content decreases, the adhesive force initially increases due to more cellulose contact with the substrate. As the polymer aggregates, however, adhesion primarily depends on water since reduced cellulose mobility limits its contribution. As a result, the adhesion goes through a maximum and then decreases with lower water content. For pectin, adhesion consistently increases as water content decreases, driven by enhanced pectin-substrate contact.