Measurement of the adhesion between single melamine-formaldehyde resin microparticles and a flat fabric surface using AFM

Understanding adhesion of micro-particles particularly microcapsules containing a functional active on fabric surface is crucial to effective delivery of the active to the latter. Fabric surface is very rough, and direct measurement of the adhesion of single micro-particles on surfaces with roughnesses greater than the particle diameter can be difficult. In this work cotton films were successfully generated by dissolving cotton powder in an organic solvent and their properties including surface roughness, thickness, contact angle and purity were characterised. The adhesive forces between single melamine formaldehyde (MF) micro-particles and a cotton film under ambient condition with a relative humidity (RH) above 40% were measured using atomic force microscopy (AFM), which was considered to be dominated by capillary forces. It was also found that there was little adhesion between MF microparticle and cotton film in aqueous solution of surfactant sodium dodecylbenzenesulfonate (SDBS). Instead, repulsion between them was observed and reduced with the increase of surfactant concentration and the decrease in solution pH. The repulsion contributions are thought to originate mainly from electrostatic repulsion. It is believed that the studies on the adhesion between single MF micro-particles and a cotton film under ambient conditions or in the surfactant solutions are beneficial in attempts to enhance the adhesion of microcapsules on fabric surface via modification of their surface composition and morphology.