Poly(styrene‐co‐butyl acrylate)‐Brazilian Montmorillonite Nanocomposites, Synthesis of Hybrid Latexes via Miniemulsion Polymerization

Abstract

Summary: In this work hybrid latexes of poly(styrene-co-butyl acrylate)/montmorillonite were synthesized via miniemulsion polymerization using a Brazilian organically modified montmorillonite. The natural clay was previously treated with Cetyltrimethyl ammonium chloride (CTAC) in order to increase the interaction between the clay and the monomer phase. Three different methodologies to modify the clay and their influence on the final properties of the composites obtained were evaluated in this work. The modified clays were characterized by X-ray diffraction (XRD). The films obtained after drying the latexes were characterized by dynamicmechanical thermal analyses (DMTA), small amplitude oscillatory shear (SAOS), transmission electronic microscopy (TEM) and Cobb test. The X-ray diffractograms, showed an increase of basal spacing after organic treatment indicating the introduction of CTA þ within the clay interlamelar space. This interlamelar space was further increased after polymerization for all of the three differently modified clays studied, indicating that in situ polymerization occurred. The introduction of organically modified clays did not influence the kinetics of polymerization. Stable latexes were obtained. The DMTA presented improved mechanical properties for the materials charged with two of the modified clays studied when compared to a conventional composite. SAOS analysis revealed that an exfoliated structure might have been obtained when adding one of the modified clays to the reacting medium. Cobb tests showed that the permeability to water was reduced by the incorporation of clays to the copolymer.

Synthesis, characterization, and dynamic‐mechanical properties of styrene‐acrylate/nanoclay interpenetrating polymer network

“…However, the low amount of MMT present in the aqueous phase might not influence the particle size distribution. This is in agreement with the results presented by Diaconu et al and Moraes et al in studying the synthesis of polymer‐clay nanocomposite latexes.…”

Influence of granulometry and organic treatment of a Brazilian montmorillonite on the properties of poly(styrene‐co‐n‐butyl acrylate)/layered silicate nanocomposites prepared by miniemulsion polymerization

“…Clay‐containing polymer nanocomposites can be obtained using different techniques, these include exfoliation‐adsorption,7–10 in situ intercalative polymerization,11–14 and melt blending 15–17. In the case of materials to be used as surface coatings, the product needs to be dispersed in water.…”

“…These aqueous dispersions can be obtained either by emulsion8, 18–20 or miniemulsion polymerization 9–12. Two main processes have been used to produce those dispersions; (i) in situ intercalative polymerization: in this case, the layered silicate is modified organically by cation exchange11, 12, 14, 18, 21 or covalent bounding and later mixed with the reactants14, 20; (ii) exfoliation‐adsorption, when hydrophilic clays are delaminated in the aqueous phase prior to polymer intercalation. In the later case, the delaminated silicate layer may be attracted to the polymer particle surface by electrostatic8, 10 or physical‐chemical9 attraction.…”

Panorama da Pesquisa Acadêmica Brasileira em Nanocompósitos Polímero/Argila e Tendências para o Futuro

“…Espectros de RMN 13 C das amostras com argila revelaram modificações referentes ao empacotamento e ordenação das cadeias em relação à resina PP pura e difratogramas de raios X detectaram que somente a extrusão foi efetiva na formação de nanocompósitos [51,52] . Nanocompósitos de polímeros estirênicos [53] também foram extensamente estudados pelo grupo de Demarquette, especialmente no tocante às propriedades reológicas [54][55][56][57] . Em um destes trabalhos, estudou-se a influência do conteúdo de argila na resistência à luz ultravioleta de nanocompósitos preparados com PS e argila organofílica por injeção.…”