Polymer/laponite composite colloids through emulsion polymerization: Influence of the clay modification level on particle morphology

A series of composite latexes have been synthesized by seeded emulsion (co)polymerization of styrene and butyl acrylate in the presence of Laponite clay particles previously functionalized by ion exchange with a free radical initiator: 2,2-azobis(2-methylpropionamidine) hydrochloride (AIBA). Since the AIBA/Laponite intercalation complexes settled down in water immediately after cation exchange, a set of experiments was first carried out in order to establish the conditions required to obtain stable aqueous dispersions of organically modified Laponite. Dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) were used to monitor the evolution of particle size and analyze the properties of the aqueous suspensions as a function of the amount of intercalated cation. A series of composite latexes were then prepared by emulsion polymerization using the organoclays as seeds. The composite particles were characterized by cryo-transmission electron microscopy (cryo-TEM), and a particular effort was devoted to analyze the effect of the Laponite modification level on particle morphology.