Abstract: A process for polymerization in the presence of nanoparticles of a mineral filler for obtaining polymer nanocomposites which includes the steps of (a) mixing a mineral filler with a swelling agent in a liquid state or near a critical state or supercritical state; (b) subjecting the swelling agent of the mixture obtained in step (a) to an endoenthalpic or isoenthalpic phase change, by altering the conditions of temperature and/or pressure; and (c) polymerizing a monomer, in a continuous or a batch process, in the presence of the mixture of step (b); wherein the swelling agent is a saturated or unsaturated hydrocarbon, a polar or vinylic organic compound, the same monomer used in the polymerization reaction or an inert compound present as a component of the reaction medium.

Abstract: The present invention refers to a process for the preparation of high performance polymer nanocomposites by means of an in situ continuous or batch polymerization process. More specifically, in this process, the sheet-like (layered) or spherical-like mineral filler is previously swollen with a swelling agent consisting in a saturated or unsaturated hydrocarbon or a polar or vinylic organic compound, in liquid state or near the critical point or in supercritical state, in a stirred continuous flow or batch type reactor, prior to being introduced into a polymerization reactor. The swelling agent is subjected to an endoenthalpic or isoenthalpic phase change upon being mixed with the mineral filler, in order to exfoliate and disperse the same at the nanometric level prior to the polymerization.