Effect of siloxane backbone length on the physicochemical properties of gluconamide-modified polysiloxane surfactants

Three isostructural gluconamide-modified polysiloxane (GL@Si) surfactants of varying siloxane backbone lengths (molecular weights) were designed and synthesized via an amidation reaction. Their physicochemical properties and potential applications are discussed herein. Each of the three GL@Sis exhibits good surface activity. The critical aggregation concentrations (CAC) of GL@Sis solutions decrease with increasing siloxane backbone length. Surface tension at the CAC (γ CAC ) increases with molecular weight. Dynamic surface tension results indicate that lower molecular weight GL@Sis exhibit improved diffusion ability compared to larger GL@Sis. Contact angle measurements indicate that lower molecular weights and higher concentrations of GL@Sis produce smaller equilibrium contact angles. Emulsifying measurements reveal that GL@Sis forms better emulsions with soybean oil than liquid paraffin, with lower molecular weight GL@Sis demonstrating superior emulsifying capabilities. Moreover, GL@Sis exhibit good foamability and foam stability. GL@Sis possess smoothness, softness, and anti-yellowing properties. The fiber surface is visually smooth after finishing with GL@Si4-8.