Assessing the impact of interaction between starch and emulsifier on the performance of starch-based adhesive: Adjusting the alkyl chain lengths of sodium sulfonate

Interactions of emulsifiers/starch likely affect interfacial adsorption and migration behavior of emulsifiers, hence, altering the multi-scale structure of starch-based adhesive. Here, the interaction between starch and emulsifier was adjusted altering sodium sulfonate alkyl chain lengths ( Sodium dodecyl sulfate : SDS , Sodium hexane sulfonate : SHS , and Sodium octadecyl sulfonate: SOS ), and the resultant performance and structural change of starch-based adhesive were investigated. Studies demonstrated latex aggregation regardless of emulsifier addition. Notably, SHS exhibited low migration propensity and was preferentially embedded within starch molecules via hydrogen bonding, which accelerated fusion and enhanced molecular network strength, thereby improving adhesive strength. Besides, asymmetric adsorption of short-chain molecules altered latex self-assembly. SDS formed a V-type complex with starch and promoted uniform latex dispersion through interfacial adsorption. It reduced interfacial layer thickness, slowed fusion, and facilitated molecular migration to air-water interfaces, weakening internal strength. SOS moderately increased interparticle repulsion via hydrogen bonding and inclusion complexation. However, strengthened hydrophobic interactions of SOS promoted micelle formation, enhancing latex particle interactions. Consequently, interfacial fusion layer thickness and strength increased, enabling penetration into solid-liquid interfaces with reduced water migration. These findings provide essential insights for designing high-performance starch-based adhesives and understanding the mechanistic effects of emulsifiers. • Sodium sulfonate with different alkyl chain lengths were incoporated into starch-based adhesive. • The interaction between latex particles was altered by adding different emulsifiers. • The change in interactions between latex particles shows different film-forming process. • Bonding performance of starch-based adhesive can be improved by adding target sodium sulfonate emulsifiers.