Preparation of polyurethane/hectorite,polyurethane/montmorillonite,and polyurethane/laponite nanocomposites without organic modifiers

Polyurethane (PU) nanocomposites were prepared from hectorite (HEC) and laponite without adding any organic modifier. PU‐montmorillonite nanocomposites were prepared for comparison. The structure of the composites were investigated by transmission electron microscopy, X‐ray diffraction spectroscopy, and Fourier transform infrared spectroscopy. Thermal gravimetric analysis and dynamic mechanic analysis were used for determination of the thermal and viscoelastic behaviors, respectively. Tensile tests were conducted for characterization of the mechanical properties. The results showed a 113.5% increase in the tensile strength of PU containing 7 wt % HEC compared to that of neat PU. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of microphase‐separated solvent‐free solid polymer electrolyte nanocomposite films using amphiphilic urethane acrylate precursors

A new solvent‐free solid polymer electrolyte (SPE) films could be fabricated through bulk copolymerization process of amphiphilic urethane acrylate nonionomer (UAN). Amphiphilic UAN chain having polypropylene oxide‐based hydrophobic segment and polyethylene oxide‐based hydrophilic segment can not only dissolve lithium salt by complex formation with lithium cations but also be copolymerized with various monomers to form microphase‐separated polymeric matrix. Unlike conventional SPE systems showing higher conductivity with polar polymers and polar solvents, our SPE films prepared by copolymerization of UAN and hydrophobic monomers exhibited relatively higher conductivity. Dissolving lithium salts in UAN/hydrophobic monomer mixtures caused hydrophilic/hydrophobic microphase separation, which was more favorable for ionic conduction of lithium ions, resulting in the higher ionic conductivity than the SPE films fabricated using UAN/hydrophobic monomer mixture. This microphase‐separated structure of SPE films could be also confirmed by transmission electron microscope (TEM) images. Ionic conductivity of our SPE films could be also improved by dispersing clay minerals within SPE films. Three types of clay having different surface properties were used to fabricate clay/SPE nanocomposite films. Ionic conductivity of nanocomposite films depended on dispersibliity of clay nanoparticles with a SPE film, which was confirmed by measuring X‐ray diffraction and TEM. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Characterization and anticorrosive properties of poly(2,3‐dimethylaniline)/Na+‐montmorillonite composite prepared by emulsion polymerization

Composites of Poly(2,3‐dimethylaniline) and inorganic Na⁺‐montmorillonite clay were synthesized by emulsion polymerization. The as‐synthesized composites (PDMA) were characterized by Fourier Transform Infrared Spectroscopy, X‐ray diffraction, and scanning electron microscopy. The protective performance against corrosion of the samples was evaluated by Tafel and electrochemical impedance spectroscopy measurements. The results showed that the composite containing 5 wt. % of clay loading (PDMA‐5%) displayed a better anticorrosive performance than other samples. The Epoxy(E) blend with PDMA‐5% (EPM5) coating was founded to have a higher corrosion potential and a lower current density than that of Epoxy blend P(2,3‐DMA) (EP) coating. The impedance value of EPM5 coating was about 6.68×10⁶Ω·cm² in 5 wt. % NaCl solution even after 288 h, compared to EP (4.26×10⁵Ω·cm²) coating, which went to show that the corrosion inhibition of P(2,3‐DMA) could be effectively enhanced by incorporating MMT into the P(2,3‐DMA) matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4528–4533, 2013     

Synthesis of poly(butyl acrylate‐co‐methyl methacrylate)/montmorillonite waterborne nanocomposite via semibatch emulsion polymerization

Poly(butyl acrylate‐co‐methyl methacrylate)‐montmorillonite (MMT) waterborne nanocomposites were successfully synthesized by semibatch emulsion polymerization. The syntheses of the nanocomposites were performed in presence of sodium montmorillonite (Na‐MMT) and organically modified montmorillonite (O‐MMT). O‐MMT was used directly after the modification of Na‐MMT with dimethyl dioctadecyl ammonium chloride. Both Na‐MMT and O‐MMT were sonified to obtain nanocomposites with 47 wt % solids and 3 wt % Na‐MMT or O‐MMT content. Average particle sizes of Na‐MMT nanocomposites were measured as 110–150 nm while O‐MMT nanocomposites were measured as 200–350 nm. Both Na‐MMT and O‐MMT increased thermal, mechanical, and barrier properties (water vapor and oxygen permeability) of the pristine copolymer explicitly. X‐ray diffraction and transmission electron microscope studies show that exfoliated morphology was obtained. The gloss values of O‐MMT nanocomposites were found to be higher than that of the pristine copolymer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42373.     

Polyacrylate‐core/TiO2‐shell nanocomposite particles prepared by in situ emulsion polymerization

We report the preparation of polyacrylate‐core/TiO₂‐shell nanocomposite particles through in situ emulsion polymerization in the presence of nano‐TiO₂ colloid obtained by the hydrolysis of titanium tetrachloride. The resultant colloidal system can be stable for months without any precipitation. In a typical sample, the diameter of nanocomposite particles was about 150 nm, and the thickness of TiO₂‐shell was 4–10 nm. Only cetyltrimethylammonium bromide was employed to provide the latex particles with positive charge, which was enough for the formation of fine TiO₂ coatings. Three initiators were tested. Ammonia persulfate was the most suitable one, because the cooperative effect was formed by the negatively charged TiO₂ particles and the terminal anionic group (SO₄^2?, the fraction of Ammonia persulfate) of the polymer chain on the surface of latex particles to maintain the stability of nanocomposite system. The pH value played a vital role in obtaining a tight TiO₂ coating. Transmission electron microscopy, X‐ray diffraction and Atomic force microscopy were used to characterize this nanocomposite material. It was found that rutile and anatase coexisted in the nanocomposite film. This may suggest a potential application in the field of photocatalytic coating. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1466–1470, 2006     

In situ polymerization and characterization of polyester‐based polyurethane/nano‐silica composites

Polyester‐based polyurethane/nano‐silica composites were obtained via in situ polymerization and investigated by Fourier‐transform infrared spectroscopy (FTIR), or FTIR coupled with attenuated total reflectance (FTIR‐ATR), Transmission electron microscopy (TEM), atomic force microscopy (AFM), an Instron testing machine, dynamic mechanical analysis (DMA) and ultraviolet‐visible spectrophotometry (UV‐vis). FTIR analysis showed that in situ polymerization provoked some chemical reactions between polyester molecules and nano‐silica particles. FTIR‐ATR, TEM and AFM analyses showed that both surface and interface contained nano‐silica particles. Instron testing and DMA data showed that introducing nano‐silica particles into polyurethane enhanced the hardness, glass temperature and adhesion strength of polyurethane to the substrate, but also increased the resin viscosity. UV‐vis spectrophotometry showed that nano‐silica obtained by the fumed method did not shield UV radiation in polyurethane films. Copyright © 2003 Society of Chemical Industry     

Sound absorption properties of polyurethane/nano‐silica nanocomposite foams

In this study, polyurethane (PU)/nano‐silica nancomposite foams were prepared. The effects of isocyanate index, cell size, density, and molecular weight of polyols on the sound absorption ratio of PU/nano‐silica foams were investigated. With increasing nano‐silica content, the sound absorption ratio of PU/nano‐silica foams increases over the entire frequency range investigated in this study. Decrease of isocyanate index, cell size, and increase of density leads to the increase of sound absorption ratio of PU/nano‐silica foams. PU/nano‐silica foams have a broad T_g centered around room temperature by decreasing molecular weight of polyol resulting in good sound absorbing ability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

水性聚氨酯/蒙脱土复合乳液的合成及性能表征

本文通过蒙脱土插层聚合法制备了水性聚氨酯/蒙脱土复合乳液。通过单体插层于蒙脱土中,与聚氨酯聚合反应,均匀分散于水性聚氨酯中。用FTIR和TEM测试表征,观察到蒙脱土均已聚合入聚氨酯包裹。研究结果表明:当蒙脱土含量在5%左右时,该乳液涂膜具有较好的耐热性、10%分解温度比普通聚氨酯提高了大约20℃,拉伸强度和断裂强度达到最高值,分别为2.31Mpa和17.94N/mm。随着蒙脱土含量的增大,乳液粒子粒径增大,耐水性增强。蒙脱土含量达到5%时,乳液粒径为108nm,吸水率降至31.9%。     

Nanocomposites of urethane and montmorillonite clay in emulsion: In situ preparation and characterization

Nanocomposites of polyurethane‐montmorillonite (PU‐MMT) were successfully prepared by in situ emulsion polymerization. The PU‐MMT particles size in emulsion was controlled in nanolevel, which was confirmed by laser scattering size distribution analyzer. The morphology of MMT in PU‐MMT composites was observed by transmission electron microscopy (TEM). Wide angle x‐ray diffraction (WAXD) was also used to detect the dispersion of MMT in composites. The thermal property was evaluated by dynamic mechanical analysis. Mechanical and fracture properties were also been tested. Gas barrier property was discussed on the basis of testing oxygen permeability of PU‐MMT films. The permeability coefficient of the films is found to reduce after composing with MMT, which indicates that the potential application of PU‐MMT could be realized as coating materials to prevent metal rusting. It is also found that dimethyl distearylbenzyl ammonium chloride (DMDSBA) is a better modifier for MMT in PU than dimethyldistearyl ammonium chloride (DMDSA). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis of novel amphiphilic pH‐sensitive polyurethane networks through W/O soap‐free emulsion polymerization process. II. Mechanical property and biphasic swelling behaviors

Amphiphilic urethane acrylate anionomer (UAA) chains exhibited very different solution properties in various solvents, such as water, dioxane, and dimethyl sulfoxide (DMSO). UAA chains showed a polyelectrolyte effect in a highly polar solvent, DMSO, but gave constant viscosity at various concentrations in aqueous solution, because of the microstructural difference of the UAA chain formed in solvents. In polar solvents (water and DMSO), the swelling of UAA networks prepared with water and dioxane strongly depended on the properties of the hydrophilic domains. In low and nonpolar solvents (dioxane and methylene chloride), the swelling of UAA networks was only dependent on the property of the hydrophobic segments. In the polar solvent medium, UAAG networks prepared with water exhibited greater swelling than UADG networks prepared with dioxane. Concerning swelling in a nonpolar solvent, however, UADG networks showed greater swelling than UAAG networks. This is because of the microstructural difference between these networks, which was confirmed by the mechanical property measurement. UAAG networks, having highly microphase‐separated structures, had higher modulus and transition temperatures than the UADG networks, because of the microstructural difference between UADG and UAAG networks. Both the UAAG and UADG networks take up two immiscible solvents simultaneously within their hydrophobic and hydrophilic domains. Equilibrium swelling ratio of these networks in two immiscible solvents strongly depends on their hydrophilic/hydrophobic balance that is controlled by the type of solvent used in the network synthesis. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 621–630, 2001     

Preparation of poly(styrene‐co‐butyl acrylate)/montmorillonite nanocomposite by emulsion polymerization: Characterization and nanoscratch behavior

Organic–inorganic hybrid poly(styrene‐co‐butyl acrylate)/organically modified montmorillonite (PSBA/organo‐MMT) latex particles have been prepared by in situ emulsion polymerization. The effects of modifier variety and the level of organo‐MMT have been investigated on the basis of the characteristics and mechanical properties of the resulting hybrid emulsion polymers. Although the more hydrophilic intercalated organic modifiers increased the latex particle size, the hydrophobic ones decreased the particle size. A more heterogeneous copolymer chain intercalation was seen by widespread XRD reflection as the organo‐MMT (organoclay) level increases. The tapping mode atomic force microscopy (AFM) and transmission electron microscopy (TEM) were used to determine the dispersion state of organoclay particles inside the nanocomposite copolymer films. Dynamic mechanical thermal analysis (DMTA) showed that adding the organoclay to the copolymer decreased the maximum loss tangent (tanδ) value and caused the shift to a lower temperature. Interestingly, the incorporation of organoclay decreased the glass storage modulus of the copolymer, while increased the rubbery storage modulus to some extent. In addition, a standard indenter for the nanoscratching of copolymer nanocomposite films was used under low applied loads of 150 and 250 μN. The nanoscratch results showed that incorporation of a 3 wt % hydrophobic organoclay, e.g., Closite15A, in the copolymer matrix enhanced considerably the near‐surface hardness and grooving resistance of the nanocomposite film at room temperature. In fact, copolymer nanocomposite films with higher near‐surface hardness and tanδ curve broadening exhibited more nanoscratch resistance through a specific variety of viscoelastic deformation, which did not create a bigger groove. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis of novel amphiphilic pH‐sensitive polyurethane networks through water‐in‐oil soap‐free emulsion polymerization process. I. Microstructural differences and swelling behaviors

pH‐sensitive amphiphilic networks are synthesized from urethane acrylate anionomer (UAA) precursor chains. The microstructures of these networks are very sensitive to the nature of and the amount of solvent used during crosslinking. Whereas dioxane forms relatively homogenous solution, water preferentially interacts with hydrophilic segment of UAA chains, causing the microphase separation between hydrophilic moieties and hydrophobic main chains. This microphase separation was locked‐in by crosslinking reaction, enhancing largely the hydrophilicity of UAA networks and the hydrophobic aggregation. The UAA gels, prepared with water (UAAG) and/or dioxane (UADG), exhibit quite different swelling behaviors in the same dissolution medium because of their completely different microstructures. The improved hydrophilicity of UAAG gels due to the hydrophilic/hydrophobic microphase separation is confirmed by measuring the contact angle to water. These microphase‐separated hydrophilic domains on UAA gel matrix, which are observed by scanning electron microscopy measurement, influence the mechanical property of dried UAA gels as well. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 2115–2127, 2000     

Synthesize and characterization of styrene‐N‐phenyl maleimide/montmorillonite nanocomposites prepared through emulsion polymerization

Composites of organomodified (OMMT) and pristine montmorillonite (MMT) intercalated by styrene‐N‐phenyl maleimide (PMI) copolymer were prepared by emulsion intercalative polymerization. X‐ray diffraction (XRD) and transmission electron microscopy results show that the dispersability of clay in the matrix was greatly improved by the incorporation of polar moiety PMI. The dispersability of OMMT in the matrix is better than MMT. XRD patterns of the extracted nanocomposites showed that d₀₀₁ of the clay are much larger than that of the original OMMT and MMT, which indicates that the interaction of copolymer with the clay layers was greatly improved by incorporation with polar monomer PMI. The thermal property of the composites was greatly improved by the intercalation with clay. The DSC results showed that the glass transition of the composites became inconspicuous, which indicated that the movement of the polymer segment was extremely confined by the clay layer. The consistency factor of the melts of the composites increased monotonically with a decreasing flow index showing stronger shear thinning property of the composites. The rheological activity energy of the composites decreased more than that of the pure copolymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1010–1015, 2005     

Mechanical properties of polyurethane/montmorillonite nanocomposite prepared by melt mixing

Nanocomposites from polyurethane (PU) and montmorillonite (MMT) were prepared under melt‐mixing condition, by a twin screw extruder along with a compatibilizer to enhance dispersion of MMT. MMT used in this study was Cloisite 25A (modified with dimethyl hydrogenated tallow 2‐ethylhexyl ammonium) or Cloisite 30B (modified with methyl tallow bis‐2‐hydroxyethyl ammonium). Maleic anhydride grafted polypropylene (MAPP) was used as the compatibilizer. XRD and TEM analysis demonstrated that melt mixing by a twin‐screw extruder was effective in dispersing MMT through the PU matrix. The PU/Cloisite 30B composite exhibited better interlayer separation than the PU/Cloiste 25A composite. Nanoparticle dispersion was the best at 1 wt % of MMT and improved with compatibilizer content for both composites. Properties of the composites such as complex viscosity and storage modulus were higher than that of a pure PU matrix and increased with the increase in MMT content, but decreased with the increase in compatibilizer content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Poly(N‐vinylcarbazole)–clay nanocomposite materials prepared by photoinitiated polymerization with triarylsulfonium salt initiator

A series of polymer–clay nanocomposite (PCN) materials that consist of poly(N‐vinylcarbazole) (PNVC) and layered montmorillonite (MMT) clay are prepared by effectively dispersing the inorganic nanolayers of MMT in an organic PNVC matrix via in situ photoinitiated polymerization with triarylsulfonium salt as the initiator. Organic NVC monomers are first intercalated into the interlayer regions of the organophilic clay hosts, followed by one‐step UV‐radiation polymerization. The as‐synthesized PCN materials are typically characterized by Fourier transform IR spectroscopy, wide‐angle X‐ray diffraction, and transmission electron microscopy. The molecular weights of PNVCs extracted from the PCN materials and the bulk PNVC are determined by gel permeation chromatography analysis with tetrahydrofuran as the eluant. The morphological image of the synthesized materials is observed by an optical polarizing microscope. The effects of the material composition on the optical properties and thermal stability of PNVCs and a series of PCN materials (solution and fine powder) are also studied by UV–visible absorption spectra measurements, thermogravimetric analysis, and differential scanning calorimetry, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1904–1912, 2004     

Synthesis and characterization of polyurethane/montmorillonite nanocomposites by in situ polymerization

In this paper, a new type of organophilic montmorillonite, co‐treated with cetyltrimethyl ammonium bromide (CTAB) and 4,4′‐diphenymethylate diisocyanate (MDI), was modified and applied to prepare polyurethane/montmorillonite nanocomposites via in situ polymerization. The nanoscale montmorillonite layers were exfoliated and dispersed relatively homogeneously in the polyurethane matrix, and characterized by X‐ray diffraction and transmission electron microscopy. The thermal degradation temperature of the nanocomposites increased, as compared with pristine polyurethane. Dynamic mechanical analysis confirmed the constraining effect of exfoliated montmorillonite layers on polyurethane chains, which benefited the increased storage modulus and increased glass transition temperature. Tensile tests showed that the exfoliated nanocomposites were reinforced and toughened by the addition of nanometer‐size montmorillonite layers. Copyright © 2006 Society of Chemical Industry     

Pyrene‐anchored ZnO nanoparticles through click reaction for the development of antimicrobial and fluorescent polyurethane nanocomposite

This work demonstrates the development of a multifunctional, antimicrobial and fluorescent polyurethane–ZnO hybrid nanocomposite coating with the aid of azide–alkyne click chemistry. Firstly, the surface of ZnO nanoparticles was successfully modified with 3‐azidopropyltriethoxysilane coupling agent. The azide‐terminated nanoparticles were then reacted with separately synthesized propargylpyrene in order to obtain pyrene‐anchored ZnO nanoparticles. The size of the modified nanoparticles was measured using dynamic light scattering and field emission scanning electron microscopy. Thermogravimetric analysis showed that the thermal stability of the nanoparticles decreased with surface modification. The intensities of UV absorption and fluorescence emission were improved with an increase of pyrene units on the ZnO surface. These nanoparticles were incorporated into a triazole‐rich hyperbranched polyurethane matrix in various weight percentages. It was observed that thermal stability and the intensity of UV absorption and fluorescence emission of the resulting polyurethane nanocomposite hybrid films were improved with loading of the modified nanoparticles. These hybrids are extremely resistant towards various bacterial and fungal attacks, which is attributed to the presence of the ZnO nanoparticles in the coatings. © 2014 Society of Chemical Industry     

Structure and property characterization of nanograde core‐shell polyurethane/polyacrylate composite emulsion

Anionic aqueous polyurethane dispersion was synthesized through self‐emulsifing method from cycloaliphatic isophorone diisocyanate (IPDI) and dimethylolpropionic acid (DMPA). The carboxyl acid group in DMPA was used to make the polyurethane dispersible. The polyurethane/polyacrylate (PU/PA) composite particles were also prepared by seeded surfactant‐free emulsion polymerization; the cycloaliphatic polyurethane aqueous dispersion was used as seed particles. The structures and properties of the composite emulsion as well as the physical mixture of polyurethane dispersion and polyacrylate emulsion were characterized by FTIR, DSC, dynamic light scattering, TEM, X‐ray photoelectron spectroscopy (ESCA), and electronic tensile machine. The results showed that the synthesized PU/PA composite emulsion was found to form inverted core‐shell structure with polyacrylate as the core and with polyurethane as the shell, and its diameter of particles is in the range of nanograde, the crosslinking reaction was existed in composite emulsion. The intimate molecular mixing of crosslinking polymers are also claims to result in a superior balance of properties compared to physical blends of polyurethane dispersion and acrylate emulsion. The crosslinking mechanism of PU/PA composite emulsion was also discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Structure and property study of nylon‐6/clay nanocomposite fiber

The crystal structures of nylon‐6 and nylon‐6/clay fibers were investigated on annealing and drawing. Annealing increased the γ‐crystalline form of both fibers, as indicated by the DSC curves, and its effect was dominant in nylon‐6/clay fiber. On drawing, the γ‐crystalline form was easily converted into the α form in nylon‐6, whereas it was still observed at a relatively high spin‐draw ratio in nylon‐6/clay fiber. However, although the α‐crystal form was dominant in nylon‐6, the γ‐crystal form was dominant in nylon‐6/clay with annealing and drawing, on the basis of the XRD data. The fast crystallization rate of nylon‐6/clay compared with pure nylon‐6 was confirmed, on the basis of the Avrami exponent. The initial modulus of nylon‐6/clay fiber was 30 % higher than the neat nylon‐6 fiber. The reinforcing effect of clay on the dynamic storage modulus was observed. Copyright © 2004 Society of Chemical Industry     

γ‐Crystalline form of nylon‐10,10 in nylon‐10,10–montmorillonite nanocomposite

Wide‐angle X‐ray diffraction (WAXD) and variable temperature WAXD spectroscopy and Fourier‐transform infrared (FTIR) spectrometry were used to identify the γ‐crystalline form of nylon‐10,10 in the nanocomposite of nylon‐10,10 and montmorillonite. A new diffraction peak at 2θ = 22° was observed in the WAXD pattern of the nanocomposite as compared with nylon‐10,10, and the data of variable temperature WAXD indicated that it was the characteristic peak of γ‐crystalline form of nylon‐10,10. The amide VI band at 624 cm^?1 was also observed in the FTIR spectrum of the nanocomposite, which is characteristic of γ‐crystalline nylon. In addition, the shoulder peak at 1553 cm^?1 can be assigned to the amide II band of γ‐crystalline form of nylon‐10,10. Copyright © 2003 Society of Chemical Industry