Preparation of Cu nanoparticles-modified PA6 composites using CuO as filler

This work focuses on the preparation of copper nanoparticles-modified polyamide 6 composites (denoted as nano-Cu/PA6) by in situ polymerization, with which cupric oxide as metallic copper source is directly reduced to metallic copper in the process of the opening-ring polymerization of ε-caprolactam only using the reducing atmosphere of reaction system. The obtained composites are characterized by means of transmission electron microscopy, X-ray diffraction, laser granulometry instrument, and ultraviolet–visible absorption spectroscopy. Moreover, the friction and wear resistance, mechanical strength, and antistatic performance of as-prepared composites are also readily evaluated. The results show that cupric oxide as filler is reduced to metallic copper and the as-reduced copper nanoparticles with 4–5-nm-size clusters separately disperse in polyamide 6 (PA6) matrix. Additionally, the addition content (mass fraction) of cupric oxide has significant effect on the crystalline form of PA6, and γ crystalline form of PA6 is predominant when higher dosage of CuO is introduced to fabricating nano-Cu/PA6 composites. Moreover, introducing a proper amount of CuO filler favors to generate nano-Cu/PA6 composites with improved mechanical properties and wear resistance. Particularly, nano-Cu/PA6 composite prepared at a CuO content of 0.5 % possesses the best tensile strength and wear resistance, showing promising application as a functional polymer–matrix composite.     

Preparation and Characterization of Copper Nanowire/Polyamide 6 Nanocomposites and Its Properties

Copper nanowire/polyamide 6 (denoted as nano-Cu/PA6) nanocomposites were readily prepared via in situ polymerization in reducing atmosphere. The microstructure, phase composition, and chemical state of typical elements of as-prepared nano-Cu/PA6 nanocomposites were analyzed by transmission electron microscopy, and X-ray diffraction, while their thermal stability and crystallization behaviors were evaluated by thermogravimetric analysis and differential scanning calorimetry. Moreover, the mechanical strength of as-prepared nano-Cu/PA6 nanocomposites was determined with a universal testing machine, and their friction and wear behaviors were evaluated with an MRH-3 high speed block-on-ring test rig. Findings indicate that copper nanowire is coated by surrounding molecular chains of PA6 and well disperses in the polymeric matrix. Besides, copper nanowire consists of metallic copper, which indicates that copper nanowire coated by PA6 matrix has good chemical stability and is not oxidized during the preparation of the title nanocomposites under high-temperature reactions. Furthermore, copper nanowire filler is able to remarkably improve the mechanical strength and wear resistance of polyamide 6. Particularly, nano-Cu/PA6 composite containing 0.5% (mass fraction) copper nanowire possesses the maximum tensile strength (its tensile strength is higher than that of pure PA6 by 77.41%); and its friction coefficient and wear scar diameter are also much smaller than those of PA6.     

Effect of Organoclays on Silicate Layer Structures and Thermal Stabilities of in-situ Polymerized Poly(D-lactide)/Clay Nanocomposites

Six kinds of organoclays were prepared through three kinds of polyols (PTMG, PEA and PCL) to investigate the effects of molecular weight and the chemical structure of organifiers. PTMG based organoclays showed higher ion-exchanged fraction than other organoclays and long chain organifier showed better efficiency in ion-exchanged fraction in the case of PTMG based organifiers. From WAXD and TEM analysis, it was confirmed that PTMG based organoclays formed partially exfoliated or fully exfoliated silicate layer structures. PDLA/clay nanocomposites were prepared by in-situ ring-opening polymerization of D-lactide with PTMG based organoclays as macro-initiators in the presence of equimolar Sn(Oct)₂/PPh₃ complex catalysts. The molecular weight of PDLA/clay nanocomposite decreased as increasing the feeding amount of organoclay because organoclay had hydroxyl terminal groups which can initiate the ring-opening polymerization of D-lactide. From TGA analysis, thermal stabilities of PDLA/clay nanocomposites improved with increasing organoclay content. From WAXD and TEM analysis, organoclay which was prepared by high molecular weight of PTMG based organifier was effective on the exfoliation of silicate layers in the in-situ polymerized PDLA/clay nanocomposite.     

Novel long-chain aliphatic polyamide/surface-modified silicon dioxide nanocomposites: in-situ polymerization and properties

A new kind of long-chain aliphatic polyamide (PA1218) with a relatively low melting point, high molecular weight, and stable mechanical properties at humid conditions was successfully developed via a polycondensation reaction between 1,18-octadecanedioic acid and 1,12-diaminodecane. Additionally, oleic acid-surfaced modified silicon dioxide (SSD) was prepared and employed to improve the properties of PA1218 through in-situ polymerization. FT-IR spectra and TGA thermograms confirmed the successful surface modification of nanoparticles, and consequently, 5% substitution of surface hydroxyl groups of SiO₂ nanoparticles with oleic acid molecules. Moreover, the thermomechanical and rheology tests revealed a significant improvement in nanocomposites’ properties compared to the pure PA1218; for instance, the tensile strength and storage modulus were increased by 22% and 40%, respectively in the sample containing 3% SSD nanoparticles. This improvement, along with SEM images, confirmed the uniform dispersion of SSD nanoparticles through the employed in-situ polymerization and excellent compatibility between inorganic and organic phases, which was achieved via surface modification. Finally, all the samples demonstrated a water uptake capacity of less than 0.6% attributed to the high methylene/amide ratio in their backbones, causing these newly developed nanocomposites to be notable candidates for specific engineering applications.     

Preparation and electrochemical properties of core-shell Si/SiO nanocomposite as anode material for lithium ion batteries

The Si/SiO nanocomposite was synthesized by a sol–gel method in combination with a following heat-treatment process. It was analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), cyclic voltammetry (CV) and capacity measurement as anode material for lithium ion battery. Si nanoparticles were coated with SiO and a core-shell structured nanocomposite was formed. The core-shell Si/SiO nanocomposite displays better reversibility of lithium insertion/extraction and higher coulomb efficiency than virginal Si nanoparticles. The SiO shell envelops the Si nanoparticles to suppress the aggregation of the nanoparticles during cycling. As a result, the core-shell Si/SiO nanocomposite exhibits better capacity retention than virginal Si nanoparticles, indicating that this is a promising approach to improve the electrochemical performance of nano anode materials for lithium ion battery.     

Silver nanoparticles immobilized on thin film composite polyamide membrane: characterization,nanofiltration, antifouling properties

Microbial biofouling is one of the major obstacles for reaching the ultimate goal of realizing a high permeability over a prolonged period of nanofiltration operation. In this study, the hybrid nanocomposite membranes consisting of silver (Ag) nanoparticles with antibiofouling capability on microorganism and polyamide (PA) were prepared by in situ interfacial polymerization and characterized by X‐ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). The hybrid membranes were shown to possess the dramatic antibiofouling effect on Pseudomonas. In addition, Ag nanocomposite membranes had little influence on the performances of the membrane such as on water flux and salt rejection. SEM analysis results showed that all Pseudomonas were dead on the PA/Ag nanocomposite membrane, indicating the effectiveness of silver nanoparticles. This investigation offers a strong potential for possible use as a new type of antibiofouling membrane. Copyright © 2007 John Wiley & Sons, Ltd.     

Transparent flexible ZnO/MWCNTs/pbma ternary nanocomposite film with enhanced mechanical properties

Functional organic-inorganic nanocomposites with high transparency show significant potential application in many fields. However, it is still a great challenge to prepare flexible transparent nanocomposites due to the intrinsic stiffness of the nanoparticles and the poor interaction between nanoparticles and organic matrices. In this work, a transparent ternary nanocomposite film with enhanced mechanical performance is fabricated by two-steps. First, the transparent ternary ZnO/MWCNTs/n-butyl methacrylate (BMA) nanodispersion is prepared by mixing the ZnO/BMA and MWCNTs/BMA dispersions directly. Then, the ternary nanocoposites film is fabricated via in-situ bulk polymerization of the above nanodispersions. As a result, the tensile strength of the ZnO/MWCNTs/poly-n-butyl methacrylate (PBMA) ternary film is enhanced by 42% and the elongation at break is three times that of ZnO/PBMA nanocomposite. The hardness of the film increases from 5B to 1H with 40 wt% ZnO. These results indicate that ZnO and MWCNTs can improve the mechanical properties of the composite significantly. Importantly, the ternary nanocomposite film still remains high transparency and exhibit excellent UV-shielding performance. The as-prepared transparent multifunctional nanocomposite films have promising applications in optical materials and devices, such as optical filters, contact lenses and protection packing.     

Mechanical property and corrosion resistance of zirconia/polydopamine nanocomposite multilayer films fabricated via a novel non‐electrostatic layer‐by‐layer assembly technique

Zirconia/polydopamine (ZrO₂/PDA) nanocomposite multilayer films were constructed on Si substrate via a novel nonelectrostatic layer‐by‐layer (NELBL) assembly technique. The building block of this technique is the newly reported dopamine molecule, which can be attached to almost all material surfaces and undergo oxidation‐polymerization to form PDA layers; more importantly, the outer hydroxyl groups of the PDA layer can chelated with certain inorganic oxide nanoparticles to generate oxide films. Thus, ZrO₂/PDA nanocomposite multilayer films were fabricated by sequential NELBL deposition of PDA and ZrO₂ nanoparticles. The formation of the ZrO₂/PDA nanocomposite multilayer films was monitored by the water contact angle (WCA) and ellipsometric thickness measurements, while the microstructure of the fabricated films was analyzed by means of atomic force microscope (AFM), field emission scanning electron microscope (FESEM), X‐ray photoelectron spectrum (XPS), and X‐ray diffraction (XRD) analysis. The mechanical and anticorrosion behaviors of the annealed ZrO₂/PDA nanocomposite multilayers were found to be greatly enhanced as compared with that of the annealed homogeneous ZrO₂ film. The better mechanical and anticorrosion behaviors of the annealed ZrO₂/PDA nanocomposite multilayers than the annealed homogeneous ZrO₂ film may be closely related to their special microstructure. Namely, the organic–inorganic hybrid microstructure of the annealed ZrO₂/PDA nanocomposite multilayers may largely account for the increased nanohardness and corrosion resistance. Copyright © 2010 John Wiley & Sons, Ltd.     

Polyaniline encapsulated silicon nanocomposite as high-performance anode materials for lithium ion batteries

Polyaniline encapsulated silicon (Si/PANI) nanocomposite as anode materials for high-capacity lithium ion batteries has been prepared by an in situ chemical polymerization of aniline monomer in the suspension of Si nanoparticles. The obtained Si/PANI nanocomposite demonstrates a reversible specific capacity of 840 mAh g^?1 after 100 cycles at a rate of 100 mA g^?1 and excellent cycling stability. The enhanced electrochemical performance can be due to that the polyaniline (PANI) matrix offers a continuous electrically conductive network as well as enhances the compatibility of electrode materials and electrolyte as a result of suppressing volume stress of Si during cycles and preventing the agglomeration of Si nanoparticles.     

Preparation and characterization of polymer/silica nanocomposites via double in situ miniemulsion polymerization

Polymer/SiO₂ nanocomposite microspheres were prepared by double in situ miniemulsion polymerization in the presence of methyl methacrylate, butyl acrylate, γ‐methacryloxy(propyl) trimethoxysilane, and tetraethoxysilane (TEOS). By taking full advantage of phase separation between the growing polymer particles and TEOS, inorganic/polymer microspheres were fabricated successfully in a one‐step process with the formation of SiO₂ particles and the polymerization of organic monomers taking place simultaneously. The morphology of nanocomposite microspheres and the microstructure, mechanical properties, thermal properties, and optical properties of the nanocomposite films were characterized and discussed. The results showed that hybrid microspheres had a raspberry‐like structure with silica nanoparticles on the shells of polymer. The silica particles of about 20 nm were highly dispersed within the nanocomposite films without aggregations. The transmittance of nanocomposite film was comparable to that of the copolymer film at around 70–80% from 400 to 800 nm. The mechanical properties and the fire‐retardant behavior of the polymer matrix were improved by the incorporation of silica nanoparticles. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3128–3134, 2010     

Synthesis and characterization of polyethylene/clay–silica nanocomposites: A montmorillonite/silica‐hybrid‐supported catalyst and in situ polymerization

A novel approach to the preparation of polyethylene (PE) nanocomposites, with montmorillonite/silica hybrid (MT‐Si) supported catalyst, was developed. MT‐Si was prepared by depositing silica nanoparticles between galleries of the MT. A common zirconocene catalyst [bis(cyclopentadienyl)zirconium dichloride/methylaluminoxane] was fixed on the MT‐Si surface by a simple method. After ethylene polymerization, two classes of nanofillers (clay layers and silica nanoparticles) were dispersed concurrently in the PE matrix and PE/clay–silica nanocomposites were obtained. Exfoliation of the clay layers and dispersion of the silica nanoparticles were examined with transmission electron microscopy. Physical properties of the nanocomposites were characterized by tensile tests, dynamic mechanical analysis, and DSC. The nanocomposites with a low nanofiller loading (<10 wt %) exhibited good mechanical properties. The nanocomposite powder produced with the supported catalyst had a granular morphology and a high bulk density, typical of a heterogeneous catalyst system. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 941–949, 2004     

强磁场作用对聚苯胺颗粒形貌及电性能的影响

聚苯胺的聚合掺杂条件对其颗粒结构及其导电性能有着很大的影响. 本文在10 T强磁场的作用下用化学氧化溶液原位聚合法得到聚苯胺并观察充分聚合后聚苯胺的颗粒结构、形貌特征及与其形成复合材料的电性能. 实验表明, 在没有强磁场作用下掺杂聚苯胺颗粒呈现礁石状, 而强磁场作用下的原位聚合聚苯胺颗粒呈现直径大约50 nm的棒状, 但其复合材料的电阻率与没有强磁场相比高出3个数量级; 本征态聚苯胺在强磁场下再掺杂得到20～30 nm的球状颗粒, 其复合材料电阻率却降低1个数量级. 分析认为这主要由于强磁场对聚苯胺晶粒的取向作用以及强磁场对聚合掺杂过程的影响所至.     

Structure and effective interactions in polymer nanocomposite melts: an integral equation theory study

The polymer reference interaction site model from integral equation theory is used to investigate the structure and effective interactions in polymer nanocomposite melts where strong nanoparticle-monomer interactions are principally considered in this work. For finite particle volume fraction, the compromise for the interference between polymers and nanoparticles results in an optimum particle volume fraction for nanoparticle dispersion in polymer melts. At constant particle volume fraction, the effects of degree of polymerization become insignificant when it reaches a threshold value, below which quantitative effects on the organization states of polymer nanocomposite melts are found and help nanoparticles to well disperse in polymer. The aggregation of large nanoparticles decreases with the increase of the nanoparticle-monomer attraction strength. These observations may provide useful information for the development of new polymer materials.     

Studies on Molecular Composites of Polyamide 6/Polyamide 66

Summary: A series of molecular composites of PA 6/PA 66 was synthesized via in situ polymerization. The impact resistance of PA 6 was improved dramatically by incorporating a minor amount of PA 66 (2–10 wt.‐%), without decreasing the tensile strength. Inserting PA 66 macromolecules at a molecular level into a PA 6 matrix may interfere with the arrangement of the hydrogen bonds of PA 6, in turn changing the crystalline structure and impeding the crystallization of PA 6.

SEM micrograph of the fractured surface of a PA 6/PA 66 composite containing 10 wt.‐% PA 66.     

In situ small-angle X-ray scattering studies during the formation of polymer/silica nanocomposite particles in aqueous solution

This study is focused on the formation of polymer/silica nanocomposite particles prepared by the surfactant-free aqueous emulsion polymerization of 2,2,2-trifluoroethyl methacrylate (TFEMA) in the presence of 19 nm glycerol-functionalized aqueous silica nanoparticles using a cationic azo initiator at 60 °C. The TFEMA polymerization kinetics are monitored using ¹H NMR spectroscopy, while postmortem TEM analysis confirms that the final nanocomposite particles possess a well-defined core–shell morphology. Time-resolved small-angle X-ray scattering (SAXS) is used in conjunction with a stirrable reaction cell to monitor the evolution of the nanocomposite particle diameter, mean silica shell thickness, mean number of silica nanoparticles within the shell, silica aggregation efficiency and packing density during the TFEMA polymerization. Nucleation occurs after 10–15 min and the nascent particles quickly become swollen with TFEMA monomer, which leads to a relatively fast rate of polymerization. Additional surface area is created as these initial particles grow and anionic silica nanoparticles adsorb at the particle surface to maintain a relatively high surface coverage and hence ensure colloidal stability. At high TFEMA conversion, a contiguous silica shell is formed and essentially no further adsorption of silica nanoparticles occurs. A population balance model is introduced into the SAXS model to account for the gradual incorporation of the silica nanoparticles within the nanocomposite particles. The final PTFEMA/silica nanocomposite particles are obtained at 96% TFEMA conversion after 140 min, have a volume-average diameter of 216 ± 9 nm and contain approximately 274 silica nanoparticles within their outer shells; a silica aggregation efficiency of 75% can be achieved for such formulations.

SAXS is used to study the formation of polymer/silica nanocomposite particles prepared by surfactant-free aqueous emulsion polymerization of 2,2,2-trifluoroethyl methacrylate in the presence of silica nanoparticles using a azo initiator at 60 °C.     

辐照法制备的醋酸乙烯酯/蒙脱土纳米复合材料与HDPE和PA6共混物的研究

利用γ射线辐射引发醋酸乙烯酯(VAc)在蒙脱土(MMT)中的原位插层聚合,X射线衍射测试与透射电子显微镜观察结果表明,PVAc/MMT复合材料为纳米复合材料.其与HDPE和PA6的共混物的扫描电镜测试结果表明,PVAc-MMT纳米复合物以微胶囊的形式存在于PVAc-MMT/HDPE/PA6共混物中,均匀分散的PVAc-MMT纳米复合物改变了复合材料的相结构.热失重测试结果显示,PVAc-MMT/HDPE/PA6的起始分解温度明显高于PVAc/HDPE/PA6,热失重过程差异较大,MMT纳米粒子的存在改变了材料的结构,使材料热性能得到了改善.在PVAc-MMT/HDPE/PA6共混物中,PVAc-MMT具有增强与增韧作用.     

Photo-oxidation behaviour of polyethylene/polyamide 6 blends filled with organomodified clay: Improvement of the photo-resistance through morphology modification

The impact of small amounts of organomodified clay (OMMT) on the photo-degradation behaviour of two blends obtained by mixing either low-density polyethylene (LDPE) or high density polyethylene (HDPE) with polyamide 6 (PA6) (LDPE/PA6 and HDPE/PA6 75/25 wt-%) was studied. The complex photo-degradation behaviour was followed by monitoring the main physical-mechanical properties of the blends. In particular, mechanical and spectroscopic tests were performed in conditions of accelerated artificial aging. An accurate mechanical and morphological characterization was previously carried out. The presence of the OMMT promotes the unexpected formation of a co-continuous morphology for the HDPE/PA6 blend without significantly improving the interfacial adhesion. Differently, the OMMT-filled LDPE/PA6 blend exhibits a finely distributed morphology, and some apparent improvement of the interfacial adhesion was noticed. Probably due to these differences in microstructure, a different impact of the nanoparticles on the photo-resistance behaviours was observed for the two families of samples. In particular, the HDPE-based nanocomposite blend exhibits an improved photo-resistance, while the opposite occurs for the LDPE-based system.     

Impact of Al nanoparticles upon the microstructure and wear properties of Ni-Cr-Al nanocomposite coatings

Ni–7Cr and Ni–7Cr–2Al (wt.%) nanocomposite coatings were fabricated by co-electrodeposition of Ni with Cr (40 nm) or and Al (75 nm) nanoparticles from a nickel sulfate bath, their microstructure, friction and wear performance were comparably evaluated in order to elucidate the effect of Al nanoparticles on the properties of nanocomposite coatings. The results indicated that the co-deposition of minor Al nanoparticles significantly increases the microhardness and wear resistance because Al nanoparticles with surface amorphous oxides layers exert the dispersion-strengthening effect like Al₂O₃ nanoparticles.     

Transparent and flame retardant cellulose/aluminum hydroxide nanocomposite aerogels

Cellulose-based nanocomposite aerogels were prepared by incorporation of aluminum hydroxide (AH) nanoparticles into cellulose gels via in-situ sol-gel synthesis and following supercritical CO₂ drying. The structure and properties of cellulose/AH nanocomposite aerogels were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, ultraviolet-visible spectrometry, N₂ adsorption, thermogravimetric analysis, and micro-scale combustion calorimetry. The results indicated that the AH nanoparticles were homogeneously distributed within matrix, and the presence of AH nanoparticles did not affect the homogeneous nanoporous structure and morphology of regenerated cellulose aerogels prepared from 1-allyl-3-methylimidazolium chloride solution. The resultant nanocomposite aerogels exhibited good transparency and excellent mechanical properties. Moreover, the incorporation of AH was found to significantly decrease the flammability of cellulose aerogels. Therefore, this work provides a facile method to prepare transparent and flame retardant cellulose-based nanocomposite aerogels, which may have great potential in the application of building materials.     

Preparation and characterization of the antibacterial Cu nanoparticle formed on the surface of SiO2 nanoparticles

Cu deposition on the surface of spherical SiO2 nanoparticles was studied to achieve the hybrid structure of Cu-SiO2 nanocomposite. SiO2 nanoparticles served as seeds for continuous Cu metal deposition. The chemical structure and morphology were studied with X-ray photoelectron spectroscopy (XPS), scanning electron microscope energy dispersive X-ray (SEM-EDX), and a transmission electron microscope (TEM). The antibacterial properties of the Cu-SiO2 nanocomposite were examined with disk diffusion assays. The homogeneously formed Cu nanoparticles on the surface of SiO2 nanoparticles without aggregation of Cu nanoparticles showed excellent antibacterial ability.