Formulating and Retaining the Structure of Polymerized Surfactant Phases Using a Microemulsion Curvature Framework.

Abstract

Nanostructured polymers contain features smaller than 100 nm that are useful in a wide range of areas, including photonics, biomedical materials, and environmental applications. Out of the myriad of nanostructured polymers, surfactant-templated polymers are versatile because of their ability to have tunable domain sizes, structure, and composition. This work addresses the gap between the formulation with industrial-grade polymerizable surfactants and the final structure of the polymer, using the hydrophilic-lipophilic difference (HLD) and net-average curvature (NAC) frameworks. HLD indicates the proximity of the formulation (surfactant and oil monomer selection, temperature, electrolyte concentration) to the phase inversion point, where HLD = 0. NAC uses the HLD to determine the curvature of the surfactant-oil-water interface, leading not only to the size and shape of micelles and bicontinuous isotropic (L3) systems but also to defining the most likely regions for lyotropic liquid crystal (LLC) existence and phase separation in ternary phase diagrams. Polymerizing LLC fluids produced nanostructured polymers with similar LLC structures that were highly swellable, but with low compressive strength. Polymerizing L3 fluids produced strong, but less water-swellable nanostructured polymers with a similar characteristic length to the parent L3 microemulsion. The relatively small scale of the parent LLC (∼6-8 nm) or L3 (∼3-4 nm) systems is consistent with the translucent nature of the polymers produced and the HLD-NAC predicted sizes.