Modern personal care and detergent formulations should not just clean the surface but also, at a later stage, deliver certain benefit agents, such as perfumes or conditioning agents, onto the surface. At the next level of performance, these benefit agents should be deposited selectively at intended target surfaces. Using in-situ null-ellipsometry we have studied the surface deposition of hydrophilic or hydrophobic model particles from aqueous polymer– surfactant formulations onto anionic hydrophilic, or hydrophobized, model silica surfaces. The model particles were anionic silica particles or silicone oil droplets, respectively, both with hydrodynamic radii in the range 15-20 nm. The polymer-sufactant formulations contained anionic sodium dodecylsulfate (SDS) and a cationic polymer. Surface deposition from the formulations was induced by controlled dilution of the formulations into the coacervation region, and was monitored with time by ellipsometry. The dilution simulated a rinsing process in a typical application. In all cases a steady-state surface layer remained after extensive dilution. An enhanced deposition from the silica-containing formulations was found on the hydrophobized silica surface, indicating a substantial co-deposition of silica particles. The opposite trend, enhanced co-deposition onto hydrophilic silica, was found in similar experiments with hydrophobic silicone oil droplets as co-deposants. The amphiphilic cationic polymers evidently favor a ‘‘mismatched” co-deposition of anionic particles to hydrophobic surfaces, or vice versa. The findings suggest a strategy for surface-specific delivery of particles to surfaces.

Using coacervation to achieve surface-selective particle deposition

253rd National Meeting (2017)

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