Encapsulation of Clay by Ad-Miniemulsion Polymerization: The Influence of Clay Size and Modifier Reactivity on Latex Morphology and Physical Properties

Abstract

The influence of clay platelet size and type of organic modifier (reactive or nonreactive) on highly filled hybrid latex morphology and physical properties of the resultant polymer/clay nanocomposites (PCNs) were investigated. The hybrid latexes, containing clay loadings between 30 and 50 wt % clay, were prepared using ad-miniemulsion polymerization. These materials have potential use in the packaging and coating industry since clay platelets are well-known for barrier property improvements. Comparative studies on the use of montmorillonite (MMT), a large clay platelet (average size: 50-500 nm), and Laponite (Lap), small-sized clay platelets (average size: 25-40 nm), were conducted. Two different clay modifiers were used to modify the clays, i.e., a conventional nonreactive modifier (cetyltrimethylammonium bromide (CTAB)) and a reactive modifier (vinylbenzyldodecyldimethylammonium chloride (VBDAC)). Transmission electron microscopy (TEM) imaging of the hybrid latexes clearly showed strong morphological dependency on both the type of modifier and the clay platelet size. Furthermore, TEM together with small-angle X-ray scattering (SAXS) showed that the extent of clay exfoliation was strongly dependent on the reactivity of the clay modifier, irrespective of the clay platelet size. Both the type of modifier and clay platelets size were found to have an influence on different physical properties of the resultant PCNs. The influence of clay size was clearly indicated by storage modulus and thermal stability behaviors, while that of the clay modifier was indicated by the T(g). Lap-based PCNs exhibited constant or increasing storage modulus and no change in thermal stability with increasing clay content, while MMT-based PCNs showed a decreasing trend in both storage modulus and thermal stability. PCNs based on clay modified with CTAB showed a decreasing T(g) with increasing clay content, while those based on clay modified with VBDAC showed an increasing trend. It was concluded that the clay platelet size and the type of modifier play a crucial part of both the latex morphology and the physical properties of the resultant PCNs.

Novel Polymer Clay‐Based Nanocomposites: Films with Remarkable Optical and Water Vapor Barrier Properties

“…Sodium dodecyl sulfate (SDS, 99%), 4‐vinyl benzyl chloride (99%), N , N ‐dimethyl dodecylamine (99%), hexadecane (HD, 99%) and silver nitrate (AgNO 3 ) were supplied by Sigma‐Aldrich and used as received. Vinylbenzyldodecyldimethylammonium chloride (VBDAC), a polymerizable surfactant used for MMT modification, was synthesized using a method reported elsewhere …”

A review on borehole instability in active shale formations: Interactions, mechanisms and inhibitors

“…A common strategy is to use long chain polymers, such as Partially Hydrolysed Polyacrylamide (PHPA), that adhere to the cuttings surfaces, slow the imbibition of water and allow them to maintain their sizes. If the encapsulation polymer is successful, the cuttings coming over the shakers are firm and not sticky (Zengeni et al, 2012). However, application is limited to those shales producing medium to hard cuttings during drilling.…”

Tunable Morphology and Hydrophobicity of Polyfluoroacrylate/Clay Nanocomposite Prepared by In Situ RAFT Polymerization in Miniemulsion

“…Increase in particle size with increase in clay content also supported the fact of encapsulation as reported by Samakande et al for the polymerization of styrene in presence of modified nanoclay. Zengeni et al reported encapsulation of laponite nanoclay by using reactive modifier VBDAC. Here in our case, PEGMEMA acted as a polymerizable modifier, i.e., a reactive modifier for nanoclay.…”

“…The nanoclay‐armored morphology can be obtained by using reactive modifiers like a cationic initiator or a cationic monomer, which penetrates into the clay galleries by ion‐exchange process. Some authors used cationic initiators, like 2,2‐azobis(2‐methylpropioamidine) hydrochloride (AIBA) or cationic monomers like (vinylbenzyldodecyldimethylammonium chloride (VBDAC), 2‐(methacryloyloxy) ethyl trimethyl ammonium chloride (MADQUAT) to obtain latex particles with nanoclay‐armored morphology . Hydrophilic sodium montmorillonite (NaMMT) can be easily dispersed in water and subsequently the emulsion polymerization of hydrophobic monomers can be carried out.…”