How Particle Deformability Influences the Surfactant Distribution in Colloidal Polymer Films

Abstract

The distribution of surfactants in waterborne colloidal polymer films is of significant interest for scientific understanding and defining surface properties in applications including pressure-sensitive adhesives and coatings. Because of negative effects on appearance, wetting, and adhesion, it is desirable to prevent surfactant accumulation at film surfaces. The effect of particle deformation on surfactant migration during film formation was previously investigated by Gromer et al. through simulations, but experimental investigations are lacking. Here, we study deuterium-labeled sodium dodecyl sulfate surfactant in a poly(butyl acrylate) latex model system. The particle deformability was varied via cross-linking of the intraparticle polymer chains by differing extents. The cross-linker concentration varied from 0 to 35 mol % in the copolymer, leading to a transition from viscoelastic to elastic. Ion beam analysis was used to probe the dry films and provide information on the near-surface depth distribution of surfactant. Films of nondeformable particles, containing the highest concentration of cross-linker, show no surfactant accumulation at the top surface. Films from particles partially deformed by capillary action show a distinct surfactant surface layer (ca. 150 nm thick). Films of coalesced particles, containing little or no cross-linker, show a very small amount of surfactant on the surface (ca. 20 nm thick). The observed results are explained by considering the effect of cross-linking on rubber elasticity and applying the viscous particle deformation model by Gromer et al. to elastically deformed particles. We find that partially deformed particles allow surfactant transport to the surface during film formation, whereas there is far less transport when skin formation acts as a barrier. With elastic particles, the surfactant is carried in the water phase as it falls beneath the surface of packed particles. The ability to exert control over surfactant distribution in waterborne colloidal films will aid in the design of new high-performance adhesives and coatings.

Diffusiophoresis-Driven Stratification in Pressure-Sensitive Adhesive Films from Bimodal Waterborne Colloids

“… a This value was obtained from the sol component in similar particles as reported by Palmer et al, which had a gel content of 63 wt %. b Because the gel content is 100%, the molecular weight of pBA 25 could not be measured. c As reported by van der Kooij et al., the gel content within pBA 25 is 100%. …”

“… a This value was obtained from the sol component in similar particles as reported by Palmer et al, which had a gel content of 63 wt %. …”

“…The other type of pBA particle contained 25 mol % ethylene glycol dimethacrylate (EGDMA) as a cross-linker (called pBA 25 ) Two mixtures were prepared: (1) a standard acrylic PSA copolymer (called PSA2) with pBA 25 and (2) PSA2 with pBA 0 . The PSA2 and pBA dispersions (both with a solids contents of 20 wt %) were mixed in a volume ratio of This value was obtained from the sol component in similar particles as reported by Palmer et al, 43 which had a gel content of 63 wt %. b Because the gel content is 100%, the molecular weight of pBA 25 could not be measured.…”

Film-Formation and Binder-Free Pigment Printing of Fluorosilicone-Modified Polyacrylate/Pigment Hybrid Latex: Effect of Cross-Linking Degree

“…In general, the three stages of latex film formation are water evaporation, deformation of latex particles, and polymer chains interdiffusion to coalesce latex particles. During film formation, the key to a controlled microstructure and homogeneity of latex film is the inhibition of “skin” formation. − The process referred to as skin formation results in a coalesced layer that can form at the top of a film while there is still water underneath the surface, which reduces the final properties of the latex film. , For example, Men et al tracked the dynamic drying process of latex particles across all stages at different temperatures and relative humidity (RH) conditions. They found that the skin weakened with decreasing temperature and increasing RH.…”

“…According to a review of recent literature, ,,− a thorough understanding of the drying and film-forming behavior of polymer latex particles has been investigated, which is useful in the design of novel or improved coatings. However, to the best of our knowledge, there are very few studies focused on the film formation of polymer-encapsulated Pigment Blue 15:3 (PB) hybrid latex to improve the performance of printed fabric.…”