Semicontinuous microemulsion polymerization

Batch microemulsion polymerization is a process that allows the synthesis of oil-soluble and water-soluble nano particles, nanocomposites and nanogels smaller than ca. 50 nm with larger molecular weights (ca. 10(7) g/mol); however, the large amounts of surfactant required by this process to produce small amounts of polymer have hindered its industrial scaling. Semicontinuous O/W and W/O microemulsion polymerizations allow increasing the polymer content without adding more surfactant to the original reacting formulation. The several schemes of semicontinuous microemulsion polymerization that have been proposed, semibatch, semicontinuous feeding or lot additions of monomer to the reacting microemulsion, are reviewed here. Semicontinuous inverse microemulsion polymerization, which is a process to synthesized water-soluble polymer nanoparticles that have important applications as superabsorbents and flocculants, are also reviewed. Moreover, alternative processes, denoted by our group as normal and inverse semicontinuous heterophase polymerizations, which allows the synthesis of-even larger concentration of polymer employing smaller amounts of surfactant compared to microemulsion polymerization, are examined. (C) 2016 Elsevier Ltd. All rights reserved.