Encapsulation of a Biobased Lignin–Saponite Nanohybrid into Polystyrene Co-Butyl Acrylate (PSBA) Latex via Miniemulsion Polymerization

Abstract

In this study, lignin recovered from a biorefinery waste stream was used to modify a clay saponite to form a lignin–clay nanohybrid. Approximately 32 wt % of lignin was associated into a lignin–clay nanohybrid, which could be well dispersed into an organophilic monomer phase. This nanohybrid was then encapsulated into polystyrene co-butyl acrylate (PSBA) particles to form stable latex via in situ miniemulsion polymerization. The final latex had a broad size distribution and a narrow window of the nanohybrid (1.9–5.3 wt %) loading level. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) analysis of latex films indicated successful encapsulation of intercalated nanohybrids inside a co-polymer matrix. The introduction of lignin–clay nanohybrids greatly improved PSBA properties. The nanocomposite with a 5.3% nanohybrid had a 13.75 times increase in tensile strength, an approximate 50 °C increase in degradation temperature, and a 42% decrease in oxygen permeability.