Synthesis and characterization of novel poly(o‐toluidine) montmorillonite nanocomposites: Effect of surfactant on intercalation

The investigation of clay based polymer nanocomposites has opened the door for the development of novel, ecofriendly advanced nano materials that can be safely recycled. Because of their nanometer size dispersion, these nanocomposites often have superior physical and mechanical properties. In this study, novel nanocomposites of poly(o‐toluidine) (POT) and organically modified montmorillonite (MMT) were synthesized using camphor sulfonic acid (CSA), cetyl pyridinum chloride (CPCl), and N‐cetyl‐N,N,N‐trimethyl ammonium bromide (CTAB) to study the role of surfactant modification on the intercalation. The in situ intercalative polymerization of POT within the organically modified MMT layers was analyzed by FTIR, UV–visible, XRD, SEM as well as TEM studies. The average particle size of the nanocomposites was found to be in the range 80–100 nm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effect of organic modifiers and silicate type on filler dispersion,thermal, and mechanical properties of ABS‐clay nanocomposites

Acrylonitrile–butadiene–styrene (ABS)–clay composite and intercalated nanocomposites were prepared by melt processing, using Na‐montmorillonite (MMT), several chemically different organically modified MMT (OMMT) and Na‐laponite clays. The polymer–clay hybrids were characterized by WAXD, TEM, DSC, TGA, tensile, and impact tests. Intercalated nanocomposites are formed with organoclays, a composite is obtained with unmodified MMT, and the nanocomposite based on synthetic laponite is almost exfoliated. An unintercalated nanocomposite is formed by one of the organically modified clays, with similar overall stack dispersion as compared to the intercalated nanocomposites. T_g of ABS is unaffected by incorporation of the silicate filler in its matrix upto 4 wt % loading for different aspect ratios and organic modifications. A significant improvement in the onset of thermal decomposition (40–44°C at 4 wt % organoclay) is seen. The Young's modulus shows improvement, the elongation‐at‐break shows reduction, and the tensile strength shows improvement. Notched and unnotched impact strength of the intercalated MMT nanocomposites is lower as compared to that of ABS matrix. However, laponite and overexchanged organomontmorillonite clay lead to improvement in ductility. For the MMT clays, the Young's modulus (E) correlates with the intercalation change in organoclay interlayer separation (Δd₀₀₁) as influenced by the chemistry of the modifier. Although ABS‐laponite composites are exfoliated, the intercalated OMMT‐based nanocomposites show greater improvement in modulus. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

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

The influence of granulometry and organic treatment of a Brazilian montmorillonite (MMT) clay on the synthesis and properties of poly(styrene‐co‐n‐butyl acrylate)/layered silicate nanocomposites was studied. Hybrid latexes of poly(styrene‐co‐butyl acrylate)/MMT were synthesized via miniemulsion polymerization using either sodium or organically modified MMT. Five clay granulometries ranging from clay particles smaller than 75 μm to colloidal size were selected. The size of the clay particles was evaluated by specific surface area measurements (BET). Cetyl trimethyl ammonium chloride was used as an organic modifier to enhance the clay compatibility with the monomer phase before polymerization and to improve the clay distribution and dispersion within the polymeric matrix after polymerization. The sodium and organically modified natural clays as well as the composites were characterized by X‐ray diffraction analysis. The latexes were characterized by dynamic light scattering. The mechanical, thermal, and rheological properties of the composites obtained were characterized by dynamical‐mechanical analysis, thermogravimetry, and small amplitude oscillatory shear tests, respectively. The results showed that smaller the size of the organically modified MMT, the higher the degree of exfoliation of nanoplatelets. Hybrid latexes in presence of Na‐MMT resulted in materials with intercalated structures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Liquid‐crystalline copolyester/clay nanocomposites

A series of novel polymer–clay nanocomposites, that is, liquid‐crystalline copolyester/montmorillonite (MMT) nanocomposites, were synthesized by the intercalation polycondensation of terephthalic acid, p‐acetoxy benzoic acid, and 1,2‐diacetoxy benzene in the presence of different organically modified montmorillonites (OMt's). The OMt's were prepared by the ion exchange of MMT with octadecylamine hydrochloride, p‐aminobenzoic acid hydrochloride, or lysine hydrochloride. X‐ray diffraction and transmission electron microscopy studies indicated that the inorganic cations in the MMT interlayers were already exchanged by organic onium ions and that the OMt intercalated with p‐aminobenzoic acid or lysine was good for obtaining more delaminated clay nanocomposites. The glass‐transition temperature and modulus of the nanocomposites increased compared with those of the pure polymer, whereas the isotropic temperature decreased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3155–3159, 2003     

Synthesis and characterization of hybrid clay/poly (N,N‐dimethylaminoethyl methacrylate) nanocomposites

Four quaternary ammonium salt monomers (2a–d) were synthesized from N,N‐dimethylaminoethyl methacrylate and subsequently polymerized to afford cationic polymers (3a–d). The synthesized monomers and polymers were characterized by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (¹H NMR) spectroscopy. Molecular weights of the synthesized polymers were determined using gel permeation chromatography. Polymer/clay nanocomposites (4a–d) were prepared using solution‐intercalation method and characterized by FTIR, X‐ray diffraction, high‐resolution transmission electron microscopy, energy dispersive X‐ray, and thermogravimetric analysis. Data analysis showed that polymer/clay nanocomposites have intercalated structure. The dielectric properties of the polymer/clay nanocomposites were studied as a function of both temperature and frequency. POLYM. COMPOS., 37:2950–2959, 2016. © 2015 Society of Plastics Engineers     

Polymerizable ionic liquids for the preparation of polystyrene/clay composites

Polymerizable ionic liquids (ILs) 1‐methyl‐3‐(4‐vinylbenzyl)imidazolium chloride, 1‐hexyl‐3‐(4‐vinylbenzyl)imidazolium chloride and 1‐dodecyl‐3‐(4‐vinylbenzyl)imidazolium chloride were prepared and used as new surfactants for the modification of montmorillonite (MMT). Functionalized MMTs were prepared by cationic exchange between sodium MMT and each of the ILs. Polystyrene (PS)/MMT composites were subsequently prepared by in situ intercalative free radical polymerization of styrene containing dispersed organophilic MMT. Exfoliation of MMT in the PS matrix was achieved only for MMT functionalized with the 1‐dodecyl‐3‐(4‐vinylbenzyl)imidazolium‐based IL as revealed by X‐ray diffraction and electron microscopy. The exfoliated composites showed good transparency and higher decomposition temperature than virgin polymer matrix, particularly pronounced under air atmosphere (ΔT_max = 66 °C), data comparable to or even greater than those reported in the literature for exfoliated PS nanocomposites. Copyright © 2012 Society of Chemical Industry     

Tri‐ammonium end functional polyethylene: facile synthesis and application as an intercalation agent

Organo‐modification of montmorillonite (MMT) is crucial for the promotion of a fine dispersion of MMT into an (often hydrophobic) polymer matrix. Ammonium‐terminated polymers are more efficient in modifying clay compared to small organic cations such as alkyl ammoniums or side functionalized polymers. Herein, tri‐amino end functional polyethylene (PE‐3 N) with low molecular weight was first synthesized via an efficient and robust epoxide ring‐opening reaction by treating epoxide‐terminated PE with diethylenetriamine. The chemical structure of PE‐3 N was unambitiously characterized by chromatographic and spectral methods. By reacting with excess HCl, PE‐3 N was subsequently converted to tri‐ammonium end functional polyethylene (PE‐3 N⁺), which serves as an intercalation agent of MMT. By adjusting the weight ratio of PE‐3 N⁺ to pristine MMT (R_P/M) applied in the static melt intercalation process, correlations between the extent of exfoliation and R_P/M were successfully established. XRD results revealed that complete exfoliation of MMT could be afforded with R_P/M as low as 1, which is the lowest value ever reported for ammonium‐terminated polymers applied as intercalation agents. SEM micrographs showed that MMT sheets were swollen by PE‐3 N⁺, affirming the successful modification of MMT. The PE modified MMT obtained may find application in preparing high‐performance PE/MMT nanocomposites. © 2017 Society of Chemical Industry     

Preparation of silicon dioxide/polyurethane nanocomposites by a sol–gel process

Aqueous emulsions of cationic polyurethane ionomers, based on poly(?‐caprolactone glycol) as soft segment, isophorone diisocyanate as hard segment, 3‐dimethylamino‐1,2‐propanediol as chain extender and potential ionic center, and hydrochloric acid as neutralizer, were mixed with tetraethoxysilane to prepare silicon dioxide–polyurethane (SiO₂/PU) nanocomposites by a sol–gel process during which the inorganic mineral is deposited in situ in the organic polymer matrix. The sizes and distributions of the particles were measured by dynamic light scattering, and the structure and morphology of the nanocomposites were observed by transmission electron microscope and FTIR spectrum. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2013–2016, 2004     

Preparation and properties of polyurethane/montmorillonite nanocomposites cured under room temperature

The polyurethane/C₁₆C₁₈‐MMT (the montmorillonite modified with cetyloctadecyldimethyl ammonium bromide) nanocomposites were synthesized by intercalative polymerization and cured under room temperature. The d‐spacing and the dispersion of the C₁₆C₁₈‐MMT in the nanocomposites were measured by X‐ray Diffraction (XRD) and Transmission Electron Microscope (TEM). The mechanical and thermal properties of the nanocomposites were measured by Universal Testing System, Electric Anti‐fold Instrument, Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC). It was found out that introducing C₁₆C₁₈‐montmorillonite (MMT) in the polyurethane (PU) displayed good mechanical properties and thermal stability. Rheology behavior in liquid state showed that the addition of the C₁₆C₁₈‐MMT to PU resulted in low gel time and high viscosity. POLYM. COMPOS. 27:470–474, 2006. © 2006 Society of Plastics Engineers.     

Efficient Dispersion of Magnetite Nanoparticles in the Polyurethane Matrix Through Solution Mixing and Investigation of the Nanocomposite Properties

Recent studies on inorganic/polymer nanocomposites have shown enhancements in thermal, mechanical, and chemical properties over the neat polymer without compromising density, toughness, and processibility. When nanoparticles are incorporated into the polymer matrix, significant enhancements in thermal and mechanical properties of the nanocomposite are observed. The present study is focused on the preparation and characterization of nanosize magnetite-reinforced PU composites, which induces magnetic properties to a specific thermoplastic polyurethane elastomer. The nanocomposites are prepared and the effects of magnetite content on thermal, mechanical, and magnetic properties of the nanocomposites are evaluated. Ultrasonication was used to disperse the nanoparticles and break up any large clumps and aggregates and followed by mechanical mixing. The magnetic nanocomposites were characterized by FT-IR spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). Characterization of the magnetic nanocomposite by FT-IR showed a successful incorporation of magnetite nanoparticles into the polymeric matrix. TGA and magnetometry of the magnetic nanocomposites revealed the amount of magnetite that was incorporated into the polymeric phase. Finally, the corresponding magnetization behavior of the nanocomposites was studied.     

Thermal aging and accelerated weathering of PVC/MMT nanocomposites: Structural and morphological studies

This work focuses on the influence of weathering factors—UV radiation, humidity, and temperature on the structure and morphology of poly(vinyl chloride)/montmorillonite (PVC/MMT) nanocomposites obtained by melt blending. It has been observed that organically modified MMT (OMMT) deteriorates the weathering resistance, the thermal behavior, as well as the long‐term stability of PVC. Decomposition of the organic modifier of MMT causes substantial color changes in the PVC nanocomposites as it facilitates the dehydrochlorination process of the polymer. However, the nonmodified MMT provides some stabilization during PVC weathering. The nanocomposites after annealing are characterized by higher glass transition temperature. The increase in heat capacity step (Δc_p) during glass transition suggests that in the PVC composites with nonmodified MMT stronger molecular interactions between the polymer and clay platelets occur than in PVC/OMMT nanocomposites. The scanning electron microscopy images on the surface and the cross section show that thermal aging and weathering proceed by different mechanisms. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42090.     

Preparation,structural characterization,and properties of poly(methyl methacrylate)/montmorillonite nanocomposites by bulk polymerization

Poly(methyl methacrylate) (PMMA)/montmorillonite (MMT) nanocomposites were synthesized by a simple technique of a monomer casting method, bulk polymerization. The products were purified by hot acetone extraction and characterized by Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), examination of their mechanical properties, and light transmittance testing. Although XRD data did not show any apparent order of the MMT layers in the nanocomposites, TEM revealed parallel MMT layers with interlamellar spacings of an average of 9.8 nm and the presence of remnant multiplets of nonexfoliated layers. Therefore, PMMA chains were intercalated in the galleries of MMT. DSC and TGA traces also corroborated the confinement of the polymer in the inorganic layer by exhibiting the increase of glass‐transition temperatures and mass loss temperatures in the thermogram. Both the thermal stability and the mechanical properties of the products appeared to be substantially enhanced, although the light transmittances were not lost. Also, the materials had excellent mechanical properties. Measurement of the tensile properties of the PMMA/MMT nanocomposites indicated that the tensile modulus increased up to 1013 MPa with the addition of 0.6 wt % MMT, which was about 39% higher than that of the corresponding PMMA; the tensile strength and Charpy notched impact strength increased to 88 MPa and 12.9 kJ/m², respectively. As shown by the aforementioned results, PMMA/MMT nanocomposites may offer new technology and business opportunities. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 348–357, 2005     

Synthesis,characterization, and ionic conductivity of nanocomposites: Polyelectrolyte systems

The synthesis, diffraction patterns, thermal stability, and ionic conductivity properties of methacrylate‐type polymers are analyzed here to assess their feasibility as polymer electrolytes. From the parent polymer, poly (N,N‐dimethylaminoethylmethacrylate), herein labeled PDMAEMA, a protonated derivative was used to prepare polymer/Montmorillonite nanocomposites with various clay contents (1, 3, and 5 wt %). AC spectroscopy provided the ionic conductivity data for the polymers and clay–polymer nanocomposites. Evidences of nanocomposite formation are shown using transmission electron microscopy and wide‐angle X‐ray diffraction. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The effect of clay modification on the mechanical properties of poly(methyl methacrylate)/organomodified montmorillonite nanocomposites prepared by in situ suspension polymerization

Poly(methylmethacrylate) (PMMA)/montmorillonite (MMT) nanocomposites were prepared by in situ suspension polymerization. MMT was previously organically modified by different modification agents [dioctadecyl dimethyl ammonium chloride (DODAC) and methacrylatoethyltrimethyl ammonium chloride (MTC)] and different modification method (cation‐exchange reaction and grafting reaction), ultimately giving rise to five kinds of organomodified MMT (OMMT). The structure of the OMMT was studied by Wide angle X‐ray diffraction (WAXD) and Fourier transform infrared spectroscopy (FTIR). Meanwhile, the structure of the PMMA/MMT nanocomposites microspheres was also investigated by WAXD. The molecular weight of the polymers extracted from PMMA/MMT nanocomposites was measured by gel permeation chromatograph (GPC). Finally, the mechanical properties of these PMMA/MMT nanocomposites were studied in detail. It was found that large interlayer spacing (d₀₀₁) of OMMT could not entirely ensure an exfoliated structure of resultant PMMA/MMT nanocomposites, while OMMT with relative small d₀₀₁ could still yield exfoliated structure as long as the compatibility between OMMT and polymer matrix was favorable. In addition, the results of mechanical investigation indicated that the compatibility between OMMT and PMMA matrix turned out to be the dominant factor deciding the final mechanical properties of PMMA/MMT nanocomposites. POLYM. COMPOS., 37:1705–1714, 2016. © 2014 Society of Plastics Engineers     

Preparation and thermal property of hybrid nanocomposites by free radical copolymerization of styrene with octavinyl polyhedral oligomeric silsesquioxane

The poly(styrene‐co‐octavinyl‐polyhedral oligomeric silsesquioxane) (PS–POSS) organic–inorganic hybrid nanocomposites containing various percent of POSS were prepared via one‐step free radical polymerization and characterized by FTIR, high‐resolution ¹H NMR, ²⁹Si NMR, GPC, DSC, and TGA technologies. The POSS contents in these nanocomposites were determined using FTIR calibration curve. The result shows that the POSS contents in nanocomposites can be tailored by varying the POSS feed ratios. On the basis of the POSS contents in the nanocomposites and the ¹H NMR spectra, the number of reacted vinyl groups of each octavinyl‐POSS macromonomer were calculated to be 6–8. DSC and TGA measurements indicate that the incorporation of POSS into PS homopolymer can apparently improve the thermal properties of the polymeric materials. The dramatic T_g and T_dec increases are mainly due to the formation of star and low cross‐linking structure of the nanocomposites, where POSS cores behave as the joint points and hinder the motion and degradation of the polymeric chains. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Preparation and characterization of polystyrene–clay nanocomposites by free‐radical polymerization

The polymerizable cationic surfactant, vinylbenzyldimethylethanolammouium chloride (VBDEAC), was synthesized to functionalize montmorillonite (MMT) clay and used to prepare exfoliated polystyrene–clay nanocomposites. The organophilic MMT was prepared by Na⁺ exchanged montmorillonite and ammonium cations of the VBDEAC in an aqueous medium. Polystyrene–clay nanocomposites were prepared by free‐radical polymerization of the styrene containing intercalated organophilic MMT. Dispersion of the intercalated montmorillonite in the polystyrene matrix determined by X‐ray diffraction reveals that the basal spacing is higher than 17.6 nm. These nanocomposites were characterized by differential scanning calorimetry (DSC), transmission electron micrograph (TEM), thermal gravimetric analysis (TGA), and mechanical properties. The exfoliated nanocomposites have higher thermal stability and better mechanical properties than the pure polystyrene. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1370–1377, 2002     

Study on the rheological behaviors of UHMWPE/CA‐MMT nanocomposite

In our previous study, we have prepared a novel antibacterial ultra‐high molecular weight polyethylene/chlorhexidine acetate‐montmorillonoid (UHMWPE/CA‐MMT) composites and examined its crystallization process and kinetics [1]. In this work, the rheological behaviors of pure UHMWPE, UHMWPE/MMT, UHMWPE/CA, and UHMWPE/CA‐MMT were characterized. The results showed that MMT can increase the viscosity of the polymer composites and CA can act as a plasticizer in the composites. Compared with UHMWPE/CA, UHMWPE/CA‐MMT had lower η*, G′, and G″. The TGA result indicated that CA‐MMT has higher thermostability than CA. Hence, CA‐MMT has the lower thermal decomposition ratio at high temperature than CA when it is blended with polymer. The TGA result could be used to explain that UHMWPE/CA‐MMT composites had better plasticizer effect than UHMWPE/CA composites. POLYM. COMPOS., 36:47–50, 2015. © 2014 The Authors Polymer Composites published by Wiley Periodicals, Inc.     

The effects of zwitterionic and anionic charge densities in polymer chains on the viscosity behavior of a pH‐responsive hydrophobically modified ionic polymer

Sulfur dioxide, N,N‐diallyl‐N‐carboethoxymethylammonium chloride, and the hydrophobic monomer N,N‐diallyl‐N‐octadecylammonium chloride were cyclocopolymerized in dimethyl sulfoxide using azobisisobutyronitrile (AIBN) as the initiator to afford water‐soluble cationic polyelectrolytes (CPE) having a five‐membered cyclic structure on the polymeric backbone. The CPE on acidic hydrolysis of the pendent ester groups gave the corresponding cationic acid salts (CAS), which, on treatment with sodium hydroxide, were converted to polybetaines (PB) and anionic polyelectrolytes (APE), as well as polymers PB/APE containing various proportions of zwitterionic (PB) and anionic fractions (APE) in the polymer chain. The solution properties of the CPE, APE, and PB/APE systems containing varying amounts of the hydrophobic monomers in the range 0–4 mol % were investigated by viscometric techniques. Treating the pH‐responsive CAS polymers 4 with different equivalents of NaOH varied the zwitterionic and anionic charge densities in the polymer chain. It was found that the PB/APE polymer with a ratio of 33 : 67 for the zwitterionic and anionic fractions in the polymer chain, respectively, gave the highest viscosity value. The polymers showed that concentration (C*_HA) of around 1 g/dL was required for the manifestation of significant hydrophobic associations. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1404–1411, 2005     

Dispersivity of modified ZnO and characterization of polyurethane/ZnO composites

The properties of inorganic nanoparticles/polymer composites depend on the dispersivity of nanoparticles in a polymer matrix. The effect of surface modification on the dispersivity of ZnO nanoparticles in a polyurethane (PU) resin matrix was investigated. The nanocomposites were characterized by scanning electron microscopy (SEM), thermogravimetric analysis, and X‐ray diffraction. The scanning electron micrographs show that ZnO nanoparticles (CDI–SA–APS–ZnO), which were modified by aminopropyltriethoxysilane (APS) and activated stearic acid (SA) by N,N′‐carbonyldiimidazole (CDI), can be homogeneously dispersed and had been encapsulated in the PU phase. The interfacial compatibility between ZnO nanoparticles and PU matrix was significantly improved by hydrophobically modifying ZnO nanoparticles with APS and SA. The tensile strength and elongation at break of PU/CDI–SA–APS–ZnO nanocomposites increased by 82 and 64% respectively, compared with the pure PU material. The thermal stability and ultraviolet‐shielding properties were also improved by incorporating ZnO nanoparticles into the PU matrix. POLYM. COMPOS., 35:237–244, 2014. © 2013 Society of Plastics Engineers     

Influence of organic montmorillonite nanoparticles on the microstructures and thermal and tribological properties of polyethersulfone and polytetrafluoroethylene composites

Because of high wear rate and low thermal deformation temperature, the generalization and application of polytetrafluoroethylene (PTFE) in the field of tribology is restrained to a certain extent. In order to improve the wear resistance and thermal stability of this self‐lubricating polymer, organic montmorillonite (OMMT) nanoparticle reinforced polyethersulfone (PES) and PTFE ternary composites were prepared by the cold molding and vacuum sintering technology. The effects of sodium montmorillonite (Na‐MMT) and OMMT on the microstructures, thermal stabilities and tribological properties of PTFE composites were comparatively studied. The results show that the thermal stability of the PES/PTFE composites is clearly improved by the incorporation of OMMT nanoparticles. Not only the friction coefficients but also the wear rates of OMMT/PES/PTFE composites are less than those of Na‐MMT/PES/PTFE composites under identical tribological tests. Of all these PTFE composites, the PES/PTFE composite containing 10.0 wt% OMMT nanoparticles exhibits the best friction and wear properties (μ = 0.14, k = 5.78 × 10^?15 m³ N^–1 m^?1). This can be attributed to the existence of a polymer multicomponent layer consisting of PTFE, PES and OMMT on the composite surface as well as the formation of uniform PTFE transfer film on the worn surfaces of metal counterparts.