Synthesis of polymer/Laponite nanocomposite latex particles via emulsion polymerization using silylated and cation-exchanged Laponite clay platelets |
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Authors: | Norma Negrete-Herrera Jean-Luc Putaux Elodie Bourgeat-Lami |
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Affiliation: | aLaboratoire de Chimie et Procédés de Polymérisation – CNRS/CPE, UMR 140, Bât. F 308, 43 Bd du 11 Novembre 1918, BP 2177, 69616 Villeurbanne Cedex, France;bCentre de Recherches sur les Macromolécules Végétales – ICMG/CNRS, BP 53, F-38041 Grenoble Cedex 9, France |
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Abstract: | We report the synthesis and characterization of polymer/Laponite nanocomposite latex particles through emulsion polymerization using organically modified Laponite clay platelets as seeds. Two approaches were adopted for the organic modification of Laponite. The first one is based on the grafting of either γ-methacryloyloxy propyl dimethyl-methoxysilane (γ-MPDES) or γ-methacryloyloxy propyl triethoxysilane (γ-MPTES) on the clay edges. The other strategy consists in exchanging the clay interlayer sodium ions by either a free radical initiator, 2,2-azobis(2-methyl propionamidine)hydrochloride (AIBA) or a cationic vinyl monomer, 2-(methacryloyloxy)ethyl trimethyl ammonium chloride (MADQUAT). The grafting was characterized both qualitatively using FTIR and quantitatively using elemental analysis or UV analysis. The results show that the degree of functionalization depends on the nature of the organic modifier. Before performing the emulsion polymerization reaction, the functionalized clay platelets were successfully dispersed in water. Nanocomposite latexes were then synthesized using a mixture of styrene (Styr) and butyl acrylate (BA) and sodium dodecyl sulphate (SDS) as anionic surfactant. An important result of the present work is that clay redispersion in water is a key step of the overall process. The larger the size of the clay aggregates, the poorer the stability of the resulting latex suspension. The morphology and mechanism of formation of the nanocomposite particles are discussed. |
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Keywords: | Laponite Cation exchange Silylation Emulsion polymerization Nanocomposite latexes Cryo-TEM |
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