Novel strategy involving surfactant-polymer combinations for enhanced stability of aqueous teflon dispersions

Among various polymers, the Teflon surface possesses extreme hydrophobicity (low surface energy), which is of great interest to both industry and academia. In this report, we discuss the stability of aqueous Teflon dispersions (particle size range of 100-3000 nm) formulated by a novel strategy that involves distinct combinations of surfactant and polymer mixtures for dispersion stabilization. As a first step, the hydrophobic Teflon particles were wetted using a range of surfactants (ionic, Triton, Brij, Tween, and Pluronic series) bearing different hydrophobic-lipophilic balance (HLB) and further characterized by contact angle and liquid penetration in packed powder measurements. The interaction between hydrophobic chains of surfactants and the Teflon particle surface is the driving force resulting in wetting of the Teflon particle surface. Further, these wetted particles in aqueous solutions were mixed with various polymers, for example, poly(vinyl alcohol) (PVA), polyvinylpyrrolidone (PVP), hydroxyethyl cellulose (HEC), and hydroxypropyl methyl cellulose (HPMC). The rate of sedimentation for the final dispersions was measured using a pan suspended into the dispersion from a transducer recording the increase in weight with time. A significant stability was noticed for Teflon particles suspended in surfactant + polymer mixtures, which was linearly proportional to the concentration of added polymer. The observed phenomenon can be possibly explained by molecular interactions between the hydrophobic chains of surfactant molecules and polar groups in the polymer architecture. Brij-O10 + HEC mixture was found to be the best surfactant-polymer combination for decreasing the sedimentation of the Teflon particles in the final dispersion. As measured by dynamic light scattering (DLS), the hydrodynamic volume of the Teflon particles increases up to ∼55% in the final formulation. These dispersions could be further explored for various technological applications such as paints, inks, protective coatings, and so forth.