Polystyrene Clay Nanocomposites Research Articles

Comparative Study of Protection Efficiency of C-Steel Using Polystyrene Clay Nanocomposite Coating Prepared from Commercial Indian Clay and Local Khulays Clay

This work aimed to compare the coating protection efficiency of C-steel using two kinds of clay: a local Khulays clay (RCKh) from Saudi Arabia and a commercial clay (CCIn) from India. Clay-based polymer nanocomposites have a unique layered structure, rich intercalation chemistry, and availability at low cost. They are promising reinforcements for polymers. The raw clay for both clay types was washed before being treated with NaCl to produce sodium clay (NaC). The cationic surfactant cetylpyridinium chloride (CPC) was then used to convert the NaC into the organoclay (OC) form. Polystyrene/organoclay nanocomposites (PCNs) were prepared by combining different concentrations of organoclay (1%, 3%, and 5% OC) in toluene solvent and polystyrene (PS) as the matrix. To ensure the success of the PCN modification process, the organoclay and PCN films were characterized using a variety of techniques, including Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The shifts in the FT-IR spectra after the CPC treatment of NaC confirmed the presence of CPC in the organoclay samples and the presence of OC in the PCNs. The exfoliated structure was obtained from the XRD spectrum for low clay loading (1–3% PCN), while the intercalated structure was the dominant form for the 5% PCN. The XRD results were confirmed by TEM images. To calculate the coating efficiency of the PCNs, various electrochemical methods were used. The electrochemical measurements included electrochemical impedance spectroscopy (EIS), the electrochemical frequency modulation (EFM) method, and Tafel plots. The PCN with a concentration of 1 wt.% OC has a fully exfoliated structure and higher coating efficiency than the PCNs with partially exfoliated structures (3 wt.% and 5 wt.%). It was found from the Tafel plots that commercial Indian clay has better corrosion protection (81.4%) than local Khulays clay (60.2%). A comparison with other studies using current density values shows that our results are superior to those of many studies.

Enhanced Coating Protection of C-Steel Using Polystyrene Clay Nanocomposite Impregnated with Inhibitors.

Polymer-Clay Nanocomposite (PCN) coatings were prepared using the solution intercalation method. The raw Khulays clay was treated with NaCl to produce sodium clay (NaC). Thereafter, Cetyl Pyridinium Chloride (CPC) was used to convert NaC into the organic clay form (OC). PCN was prepared by adding polystyrene as the matrix to different weights of OC to prepare 1 wt.% and 3 wt.% PCN. To enhance the coating protection of C-steel in NaCl solution, PCN coatings were added to microcapsules loaded with some corrosion inhibitors PCN (MC). The microcapsules are prepared by the encapsulation of rare-earth metal Ce+3 ions and Isobutyl silanol into polystyrene via the Double Emulsion Solvent Evaporation (DESE) technique. Characterization techniques such as FTIR, X-Ray Diffraction (XRD), and Transmission Electron Microscopy (TEM) were employed. FTIR confirmed the success of the preparation, while XRD and TEM revealed an intercalated structure of 1 wt.% PCN while 3 wt.% PCN has a fully exfoliated structure. Electrochemical Impedance Spectroscopy (EIS), Electrochemical Frequency Modulation (EFM), and Potentiodynamic Polarization showed an enhanced protection efficiency of PCN (MC) coatings. The results demonstrated that the corrosion resistance (RCorr) of 3% PCN (MC) coating was higher than all the formulations. These PCN (MC) coatings may provide corrosion protection for C-steel pipes in many industrial applications.

Capability of synthesized sulfonated aromatic cross-linked polymer covalently bonded montmorillonite framework in productivity process of biodiesel

Polystyrene clay nanocomposites represent a significant class of tailored materials that possess value-added properties based on their hybrid nature from organic and inorganic chemistry in their framework. Such materials had numerous applications extending from fire retardant properties, gas permeability, and catalysis. Herein, cross-linked polystyrene (CPS) and cross-linked polystyrene- organophilic montmorillonite (OMMT) nanocomposites (VO-MMT-PS) were prepared using 1,4-di(chloromethyl)benzene and ferric chloride as crosslinking agent and catalyst, respectively. The VO-MMT-CPS nanocomposites were prepared with 1, 3, and 5 wt% of MMT with respect to styrene to show the effect of the MMT layers on the properties of the polymer. The CPS and VO-MMT-CPS were post-sulfonated to create strong Brønsted acid sites on the surface of prepared materials. The prepared polymers are described by FTIR, N2–adsorption/desorption isotherms, TGA, and XRD techniques. The low angle XRD showed an increase in the OMMT layer after modification, and exfoliation structures are obtained after polymerization, whereas the entry of the OMMT layer in polymer structure increases the surface area of the polymer. The catalytic effects of the VO-MMT-CPS-SO3H nanocomposites were examined and compared to CPS-SO3H in the methanolysis of oleic acid to form the methyl oleate as a biodiesel model. The VO-MMT-CPS-SO3H that has a high OMMT ratio (5%) represented the highest catalytic performance in the methanolysis reaction with 89% conversion at 70 °C, 4% catalyst, 9:1 methanol: oleic acid molar ratio. Comparing 5% VO-MMT-CPS-SO3H to Amberlyst-15 as a commercial catalyst, the prepared catalysts exhibited better activity and higher thermal stabilities.

Functionalization-Induced Self-Assembly of Polystyrene/Kaolinite in Situ Nanocomposites into Giant Vesicles.

We report a facile functionalization strategy for fabrication of giant, inorganic-polymer hybrid vesicles by controlled aminosilyl/vinylsilyl functionalization (AS/VS) of the aluminol layer in kaolinite (Kaol) by intercalation and subsequent polymerization of styrene with the in situ polystyrene clay nanocomposite (PCN), followed by self-assembly in solvents. The synergistic effect of the AS/VS ratio on functionalization-assisted intercalation of Kaol was established in 1:3AS/VS-Kaol by the greater extent of formation of higher interlayer spacing corresponding to 1.12 nm compared to 1:1AS/VS-Kaol. As the AS/VS ratio was increased, the PCN synthesized showed an increase in molecular weight attributed to higher vinyl functionalization of Kaol. The PCN, 1:3AS/VS-Kaol/PS, showed self-assembly in tetrahydrofuran at 2.5 mg mL-1 into giant vesicles of 2-6 μm diameter with a wall thickness of 300-400 nm. This result is attributed to the functionalization-induced molecular mass-directed bilayer assembly of the delaminated, Janus-type, modified Kaol in a polar aprotic solvent by end-to-end hydrogen bonding involving terminal -OH groups along the wall and -NH2 groups laterally and further stabilized by the π-π interactions of the phenyl moiety along the periphery. Rhodamine-loaded vesicles showed a controlled release in buffer solutions of pH 7.0 and 9.0, attributed to the amino group-assisted pore formation. In a buffer solution of pH 4.0, rapid release of the dye was observed because of the collapse of the vesicle directed by protonation of the amino group. This study forms the first report on a novel method for the synthesis of rigid vesicles by functionalization-induced self-assembly of Kaol-based in situ PCN for possible applications in the cost-effective controlled delivery of drugs or cosmetics for topical applications.

Rheological and Thermal Analysis of Polystyrene –Kaolin Nanocomposite Prepared by Solution Intercalation Technique

Polymer-clay nanocomposite of commercial polystyrene (PS) and kaolin were prepared via solution intercalation technique. Organically modified kaolin was used to render kaolin miscible with hydrophobic PS. Vinyl modified kaolin was used for the study. The kaolin was well dispersed in PS solution. Different amounts of nanoclay was added to polystyrene, to analyse the effect of nanoclay concentration in nanocomposite prepared. SEM analysis provides information of the morphology of the polystyrene-clay nanocomposite. Intercalation occurs at low modified clay content, whereas aggregation and agglomeration occurs at high filler content. The thermal analysis and rheological analysis was carried on the PS-Kaolin nanocomposite. The results indicates the difference in property of polystyrene-nanoclay composite with filler loading.

Structure, permeability, and rheology of supercritical CO2 dispersed polystyrene-clay nanocomposites

Improvement in clay dispersion and clay-polymer interfacial interactions are keys to producing superior nanocomposites. A supercritical CO2 (scCO2) processing method was utilized to pre-disperse commercial organic clays, for further solvent mixing with polystyrene (PS) to form nanocomposites with significant dispersion and interfacial enhancement. The effect of scCO2 processing on clay pre-dispersion, and clay dispersion and interfacial interaction in nanocomposites were investigated. SEM and WAXD of the clays indicated that after scCO2 processing the clays lose their long region ordered layer structure appreciably, associated with reduction in particle size. WAXD and TEM of the PS/clay nanocomposites showed that the polymer penetrated into the pre-dispersed clay, leading to a disordered intercalated/exfoliated structure with improved interfacial interaction rather than a disordered intercalated structure as seen with as-received clays. Relationships between those structures, rheological and barrier properties were investigated. The scCO2-processed nanocomposites showed a plateau in the low-frequency storage modules and increased complex viscosity, each associated with significant clay dispersion in the nanocomposite. With only 1.09% volume fraction of clay, significant reduction (∼49%) of oxygen permeation was achieved.

폴리스티렌-클레이 나노 복합재료의 합성 및 차단 특성에 관한 연구

고성능 고분자/클레이 나노 복합재료의 제조 과정에는 친수성을 보이는 클레이 원료 물질인 $Na^+$ -MMT (sodium monmorilonite)를 친유성을 갖도록 유기화된 계면활성제로처리하여 개질하는 과정이 필수적이다. 이를 위하여 이 연구에서는 VDAC (vinylbenzyldimethyl-dodecylammonium chloride)를 간단한 화합물로부터 합성하였고 이를 이용하여 양이온 교환반응에 의하여 $Na^+$ -MMT를 개질한 후 $VDA^+$ -MMT를 제조하였다. 이를 스티렌과 혼합하여 in-situ 중합에 의하여 나노복합재료를 제조하였고 클레이의 분산성 및 차단특성을 연구하였다. 연구 결과 PS/ $VDA^+$ -MMT 나노 복합재료의 경우 클레이의 분산이 $Na^+$ -MMT와 비교할 때 현저히 증가함을 확인하였고 이로 인해 유기 용매에 대한 차단 특성이 매우 우수함을 확인하였다. 【In prepaparation of the high performance polymer/clay nanocomposite, it is essential to modify the hydrophillic $Na^+$ -MMT to hydrophobic alkyl ammonium-MMT via organic surfactant. The organic surfactant, VDAC (vinylbenzyldimethyl-dodecylammonium chloride) was synthesized from two primary chemicals and $VDA^+$ -MMT was prepared from $Na^+$ -MMT through a cation exchange reaction between $Na^+$ and $VDA^+$ (vinylbenzyldimethyl- $dodecylammonium^+$ ) cation. $VDA^+$ -MMT was then dispersed in styrene and polystyrene/ $VDA^+$ -MMT nanocomposite was fabricated by in-situ polymerization reaction. The clay dispersion and barrier property of the nanocomposite were investigated. From the investigations, it was confirmed that dispersion of the $VDA^+$ -MMT was enhanced compared with that of $Na^+$ -MMT and as a consequency of better dispersion, barrier property of organic solvent was improved in a great extent.】

Preparation of polystyrene–clay nanocomposite by solution intercalation technique

Polymer–clay nanocomposites of commercial polystyrene (PS) and clay laponite were prepared via solution intercalation technique. Laponite was modified suitably with the well known cationic surfactant cetyltrimethyl ammonium bromide by ion-exchange reaction to render laponite miscible with hydrophobic PS. X-ray diffraction analysis in combination with scanning electron microscopy gives an idea of structural and morphological information of PS–laponite nanocomposite for different varying organo-laponite contents. Intercalation of PS chain occurs into the interlayer spacings of laponite for low organo-laponite concentration in the PS–O-laponite mixture. However, aggregation and agglomeration occur at higher clay concentration. The molecular bond vibrational profile of laponite as well as PS–laponite nanocomposite have been explored by Fourier transform infrared spectroscopy. Thermogravimetric analysis along with differential scanning calorimetry results reveal the enhancement of both thermal stability and glass transition temperature of PS due to the incorporation of clay platelets.

Polystyrene-Organoclay Nanocomposites Prepared via In-Situ Emulsion Polymerization

In this study, polystyrene-clay nanocomposites (PSNC's) were prepared via in-situ bulk and in-situ emulsion polymerization. The effect of organoclay and the architecture of surfactant were investigated. For the investigation of the effect of surfactant, organoclays were synthesized containing clay modifiers having different structures. Trimethylhexadecyl ammonium chloride, dimethylbenzylhexadecyl ammonium chloride and dimethylbenzyl(4-vinyl) hexadecyl ammonium chloride, which is synthesized in laboratory, modified clays were synthesized. Pristine polystyrene (PS) was synthesized by bulk and emulsion polymerization for comparison, and PSNC's containing 3 wt.% organoclays were prepared by both these polymerization methods. Structural analysis of synthesized surfactant was identified by Nuclear Magnetic Resonance (NMR) Spectrometer. The interlayer spacing of silicate layers and the morphology of samples were examined by using the X-ray Diffraction (XRD) Spectrometer and Scanning Electron Microscopy (SEM) images, respectively. Thermal properties of nanocomposites were determined by Thermogravimetric analyzer (TGA) and Differential Scanning Calorimeter (DSC). It is observed that organoclays and PS were compatible to each other and each organoclay could form a nanocomposite structure with PS. PSNC's exhibited better properties than pristine PS. Nanocomposites prepared by in-situ emulsion polymerization resulted with better thermal properties and higher interlayer distances than that prepared by in-situ bulk polymerization. In order to improve some properties of PS such as thermal stability, preparation of PSNC's by in-situ emulsion polymerization has been suggested.

Preparation of polystyrene-clay nanocomposites via dispersion polymerization using oligomeric styrene-montmorillonite as stabilizer

This study describes the preparation of polystyrene–clay nanocomposite (PS-nanocomposite) colloidal particles via free-radical polymerization in dispersion. Montmorillonite clay (MMT) was pre-modified using different concentrations of cationic styrene oligomeric (‘PS-cationic’), and the subsequent modified PS-MMT was used as stabilizer in the dispersion polymerization of styrene. The main objective of this study was to use the clay platelets as fillers to improve the thermal and mechanical properties of the final PS-nanocomposites and as steric stabilizers in dispersion polymerization after modification with PS-cationic. The correlation between the degree of clay modification and the morphology of the colloidal PS particles was investigated. The clay platelets were found to be encapsulated inside PS latex only when the clay surface was rendered highly hydrophobic, and stable polymer latex was obtained. The morphology of PS-nanocomposite material (after film formation) was found to range from partially exfoliated to intercalated structure depending on the percentage of PS-MMT loading. The impact of the modified clay loading on the monomer conversion, the polymer molecular weight, the thermal stability and the thermomechanical properties of the final PS-nanocomposites was determined. Copyright © 2012 Society of Chemical Industry

Micropatterned Surfaces through Moisture-Induced Phase-Separation of Polystyrene−Clay Nanocomposite Particles

We report micropatterned polystyrene-clay nanocomposite (PCN) surfaces with concavities by moisture-induced phase separation of PCN particles. Micropatterned film with concavity size of 800 nm to 1.3 microm and a high number density of 2 x 10(8) features/cm(2) was obtained by drop-casting PCN solution (20 mg/mL PCN/THF) under ambient relative humidity of 70-80%. It is proposed that water droplets were channeled through the hydrophilic interfaces between the PCN particles, and the two-dimensional array of concavities was formed by spontaneous phase separation due to the presence of rigid clay platelets. The concavity size and number density can be tuned by varying the solvent for PCN. Micropatterned film with concavity size in the range of 650 nm to 1.1 microm with a number density of 5 x 10(7) features/cm(2) was obtained using chloroform as solvent, whereas a concavity size of 150-740 nm and number density of 10(8) features/cm(2) were obtained using carbon disulfide.

Processing of nanocomposite foams in supercritical carbon dioxide. Part I: Effect of surfactant

Polystyrene-clay nanocomposites were prepared by in situ polymerization to achieve the better dispersion of lamellar silicates i.e. montmorillonite and fluorohectorite and were used to process foams with supercritical CO2. Clay–Polymer interactions were modulated by varying the surface treatment of clays: a physical interface was formed with the compatible surfactant showing aromatic groups (MMT-benz) and a chemical interface was created after reaction of methacrylate group (MMT-MHAB) with the styrene monomer. The dispersion of nanocomposites and the microstructure of resulting foams are very dependent on the quality of the clay/matrix interface. With the compatible clay, exfoliation of aromatic clay in polystyrene matrix is obtained at all scales. On the other hand, with the reactive clay, intercalated primary particles are obtained but the size of foam cells is the smallest and cell density is the highest. Our results suggest that the nucleation occurs primarily on physico-chemical nucleation sites that are the carbonyl group of the tethered copolymers synthesized on reactive clay and that present a strong affinity for CO2. The relaxation times determined by using solid-state NMR spectroscopy are consistent with the formation of the in situ copolymers.

Microvesicles through Self-Assembly of Polystyrene−Clay Nanocomposite

Polystyrene-clay nanocomposite (PCN) particles, which exhibited concentration dependent self-assembling property in THF were synthesized by in situ intercalative polymerization of styrene with vinyl POSS amine-modified organoclay. While the particles from dilute solution of 0.001 mg mL(-1) showed a lateral dimension of 190-800 nm and thickness of 120 nm, microvesicles of diameter of 2.5-3.5 microm and average membrane thickness of 85 nm were produced from solution concentration of 2.5 mg mL(-1) by consuming the particles. The particle possessed a sandwich structure consisting of polystyrene(PS)-POSS-intercalated clay tactoid of thickness of 12.6 nm at the core and PS chains growing from the tactoid surfaces on either side, exposing the hydroxylated edges of the silicate layers. Vesicle was formed by edge-edge association of the silicate layers so that the layers lie flat along the vesicle membrane. Guest-encapsulated vesicles were obtained when prepared from solutions containing guest molecules.

Synthesis and characteristics of polystyrene–clay nanocomposites via in situ intercalative polymerization in a direct current electric field

AbstractPolystyrene (PS)/montmorillonite nanocomposites were prepared by the free‐radical polymerization of styrene‐containing dispersed clay in a direct current electric field. The intercalation spacing in the nanocomposites, the dispersion, and the orientation of these composites were investigated. The nanocomposites had higher Tg and better thermal stability when compared with the virgin PS. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Effect of organoclay on the mechanical / thermal properties of microcellular injection molded polystyrene–clay nanocomposites

An organically modified montmorillonite was compounded with polystyrene (PS) in a twin-screw extruder. The organoclay polystyrene nanocomposites were then injection molded by conventional and microcellular methods. Nitrogen was used as the blowing agent. The effect of organoclay content on the mechanical and thermal properties was investigated. The results showed that when the MMT content was 1 wt.%, the nanocomposites have maximum tensile strength, wear resistance, and cell density. Moreover, the addition of organoclay increases the glass transition and decomposition temperature of the nanocomposites. The XRD results showed that the layer spacing of the nanocomposites decreases by comparison with the organoclay. TEM pictures showed that MMT is well dispersed within the PS matrix.

High-throughput method for estimating the time to sustained ignition of polystyrene-clay nanocomposites based on thermogravimetric analysis

Polymer-modified clay nanocomposites were prepared by melt blending and the time to ignition was measured by cone calorimetry at various heat fluxes. Based on these experimental results, a critical mass flux and critical percentage mass loss (pmlcrit) for piloted ignition were identified and validated for both virgin polystyrene and its composites, across a wide range of heating fluxes. Based on the assumption that the polymer degradation kinetics in the heating segment of the cone calorimetry (up to the moment of ignition) and thermogravimetry experiments are similar, and using the pmlcrit, we hypothesized that the onset degradation temperature of the TGA samples (defined here as the temperature at pmlcrit) could be used to estimate the time to sustained ignition in cone calorimetry experiments. The onset degradation temperature and the time to sustained ignition showed a good correlation, regardless of the heating flux used in cone calorimetry experiments. Copyright © 2009 John Wiley & Sons, Ltd.

RAFT-mediated polystyrene-clay nanocomposites prepared by making use of initiator-bound MMT clay

The initiator 2,2′-azobis(2-(1-(2-hydroxyethyl)-2-imidazolin-2-yl)propane)dihydrochloride monohydrate (VA060) was used to surface-modify sodium montmorillonite clay (Na-MMT). The obtained organically modified clay was then used as a macro-initiator in the preparation of polystyrene-clay nanocomposites by in situ free radical polymerization of styrene in bulk. The polymerization was carried out in the presence of various reversible addition-fragmentation chain transfer (RAFT) agents: 1,4-phenylenebis(methylene)dibenzenecarbodithioate (PCDBDCP), didodecyl-1,4-phenylenebis(methylene)bistrithiocarbonate (DCTBTCD) and 11-(((benzylthio)-carbonothioyl)thio)undecanoic acid (BCTUA). All of the nanocomposites prepared were found to have intercalated morphologies. In the absence of RAFT agents, typical uncontrolled free radical polymerization occurred, giving polystyrenes with high molar masses and high polydispersity indices. In contrast, when the polymerization was conducted in the presence of any of the RAFT agents, the polymerization was found to occur in a controlled manner, as the polystyrene-clay nanocomposites obtained contained polymer chains of narrow polydispersities. The influences of clay loading and molar mass on thermal stability of the polystyrene-clay nanocomposites were investigated. Increases in the clay loading or the molar masses resulted in improvement of the thermal stability of the nanocomposites.

Encapsulated clay particles in polystyrene by RAFT mediated miniemulsion polymerization

AbstractRAFT grafted montmorillonite (MMT) clays [i.e., N,N‐dimethyl‐N‐(4‐(((phenylcarbonothioyl)thio)methyl)benzyl)ethanammonium‐MMT (PCDBAB‐MMT) and N‐(4‐((((dodecylthio)carbonothioyl)thio)methyl)benzyl)‐N,N‐dimethylethanammo‐nium‐MMT (DCTBAB‐MMT)] of various loadings were dispersed in styrene (S) monomer and the resultant mixtures emulsified and sonicated in the presence of a hydrophobe (hexadecane) into miniemulsions. The stable miniemulsions thus obtained were polymerized to yield encapsulated polystyrene‐clay nanocomposites (PS‐CNs). The molar mass and polydispersity index (PDI) of the PS‐CNs depended on the amount of RAFT agent in the system, in accordance with the features of the RAFT process. The morphology of the PS‐CNs ranged from partially exfoliated to an intercalated morphology, depending on the percentage clay loading. The thermomechanical properties of the PS‐CNs were better than those of the neat PS polymer, and were dependent on the molar mass, PS‐CN morphology and clay loading. The similarities and differences of the PS‐CNs prepared here by miniemulsion polymerization were compared to those prepared using the same RAFT agents and polymer system by bulk polymerization (as reported by us in a previous article). © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7114–7126, 2008

Use of acrylic based surfmers for the preparation of exfoliated polystyrene–clay nanocomposites

Two polymerizable cationic surfactants, (11-acryloyloxyundecyl)dimethyl(2-hydroxyethyl)ammonium bromide (hydroxyethyl surfmer) and (11-acryloyloxyundecyl)dimethylethylammonium bromide (ethyl surfmer), were used for the modification of montmorillonite (MMT) clay. The modification of MMT dispersions was carried out by ion exchange of the sodium ions in Na +-MMT by surfactants in aqueous media. Modified MMT clays were then dispersed in styrene and subsequently polymerized in bulk by a free-radical polymerization reaction to yield polystyrene–clay nanocomposites. An exfoliated structure was obtained using the ethyl surfmer-modified clay, whereas a mixed exfoliated/intercalated structure was obtained using the hydroxyethyl surfmer-modified clay. Nanocomposite structures were confirmed by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The nanocomposites exhibited enhanced thermal stability and an increase in glass transition temperature, relative to neat polystyrene. The nanocomposites also exhibited enhanced mechanical properties, which were dependent on the clay loading. Intercalated polystyrene–clay nanocomposites were obtained using the non-polymerizable surfactant-modified clay (cetyltrimethylammonium bromide). Nanocomposites made from mixtures of surfmer-modified and CTAB-modified clays were also prepared, showing intermediate properties. However, when the nanocomposites were prepared in solution only intercalated morphologies were obtained. This was attributed to the competition between the solvent molecules and monomer in penetrating into clay galleries. These nanocomposites also exhibited enhanced thermal stability relative to the virgin polystyrene prepared by the same method. Similar temperatures of degradation (at 50% decomposition) were found for these nanocomposites relative to those prepared by bulk polymerization.

Polystyrene nanocomposite materials by in situ polymerization into montmorillonite–vinyl monomer interlayers

AbstractA different series of new polystyrene–clay nanocomposites have been prepared by grafting polymerization of styrene with vinyl‐montmorillonite (MMT) clay. The synthesis was achieved through two steps. The first step is the modification of clay with the vinyl monomers, such as N,N‐dimethyl‐n‐octadecyl‐4‐vinylbenzyl‐ammonium chloride, n‐octadecyl‐4‐vinylbenzyl‐ammonium chloride, triphenyl‐4‐vinylbenzyl‐phosphonium chloride, and tri‐n‐butyl‐4‐vinylbenzyl‐phosphonium chloride. The second step is the polymerization of styrene with different ratios of vinyl‐MMT clay. The materials produced were characterized by different physical and chemical methods: (1) IR spectra, confirming the intercalation of the vinyl‐cation within the clay interlayers; (2) thermogravimetric analysis (TGA), showing higher thermal stability for PS–nanocomposites than polystyrene (PS) and higher thermal stability of nanocomposites with of phosphonium moieties than nanocomposites with ammonium moieties; (3) swelling measurements in different organic solvents, showing that the swelling degree in hydrophobic solvents increases as the clay ratio decreases; (4) X‐ray diffraction (XRD), illustrating that the nanocomposites were exfoliated at up to a 25 wt % of organoclay content; and (5) scanning electron microscopy (SEM), showing a complete dispersion of PS into clay galleries. Also, transmission electron microscopy (TEM) showed nanosize spherical particles of ∼ 150–400 nm appearing in the images. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3739–3750, 2007