Series Of Nanocomposite Films Research Articles

Fabrication and enhanced dielectric constant of nanocomposite films based on polyimide and core–shell structured Al2O3@0.4mol%Nb-(Ba0.87Sr0.04Ca0.09)(Ti0.86Zr0.08Sn0.06)O3 nanoparticles

A series of nanocomposite films loaded with various concentrations of fillers were successfully synthesized by solution casting method (BSCTZS nanoparticles (NPs) as filler and polyimide (PI) as polymer matrix). To improve the dispersion and the physical–chemical properties of (Ba0.87Sr0.04Ca0.09)(Ti0.86Zr0.08Sn0.06)O3 (BSCTZS) NPs surface, BSCTZS NPs were modified by Al2O3 coating and modified Al2O3@Nb-BSCTZS NPs/PI nanocomposite films were prepared. The prepared modified Al2O3@Nb-BSCTZS NPs were characterized by X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM), and the dielectric properties of these composites were characterized in details. As a result, the nanocomposite films filled with 5 vol% Al2O3@0.4mol%Nb-BSCTZS nanoparticles exhibit an excellent energy density of 2.11 J cm−3 at 298 kV/mm, which is 48% over the original pristine PI (1.42 J cm−3 at 313 kV/mm). This work can provide a prospective solution for the preparation of composite film materials with high dielectric constant and high energy density.

Preparation and properties of super hydrophobic films from siloxane-modified two-component waterborne polyurethane and hydrophobic nano SiO2

Nanocomposite films with super hydrophobic surface were prepared by building rough micro/nano structure on the surface of siloxane-modified two-component waterborne polyurethane (2K-WPU) with hydrophobic nano SiO2. Firstly, nano SiO2 prepared by StÖber method with tetraethoxysilane (TEOS) as precursor was modified with trimethylethoxysilane (TMES), in order to cover a layer of hydrophobic methyl groups on the surface of nano SiO2. Then, a series of nanocomposite films with different water contact angles were obtained by adding different contents of TMES modified SiO2 into the siloxane-modified 2K-WPU. The effects of the content of nano SiO2 on the morphology and hydrophobicity of film surface were investigated. The results showed that the surface structures of the nanocomposite films became rougher and the water contact angle of nanocomposite films was increased obviously with the increase of the content of hydrophobic nano SiO2. Super hydrophobic nanocomposite film with water contact angle over 150° was successfully fabricated by using polysiloxane as low surface energy material and hydrophobic nano SiO2 as micro/nano rough structure builder on the polymer surface. Moreover, incorporating nano SiO2 into the 2K-WPU matrix could increase the glass transition temperature and thermal stability of the nanocomposite films.

Sulfonic Acid-Functionalized Fe3O4 Reinforced Soluble Polyimide: Synthesis and Properties

ABSTRACTIn this study, a series of nanocomposite films based on an aromatic polyimide and sulfonic acid-functionalized magnetic nanoparticles was successfully prepared via an in situ technique. For this purpose, new soluble aromatic polyimide containing sulfone group as a polymeric matrix of the nanocomposites was synthesized. The surfaces of MNP were grafted with 3-mercaptopropyl trimethoxysilane. Then sulfonic acid-functionalized magnetic nanoparticle was obtained by oxidation of the thiol group. Effects of sulfonic acid-functionalized magnetic nanoparticles on thermal, tensile, and magnetic properties of the prepared nanocomposite films were studied. The magnetic nanoparticles containing the sulfonic acid groups could have strong intermolecular bond interactions between the hydroxyl groups of SO3H and the sulfone and carbonyl groups of the polyimide matrix which caused the better dispersion of nanoparticle and exhibited superior mechanical properties, good magnetic properties, and high thermal stability.

Preparation, characterization, mechanical and barrier properties investigation of chitosan–clay nanocomposites

In the current study the effect of dilution of chitosan acetate solution and of the use of a reflux-solution method on the morphology, the mechanical and water barrier properties of chitosan based nanocomposites is being investigated. Two series of nanocomposite films from two chitosan acetate solutions with 2w/v% and 1w/v% in chitosan were prepared, with 3, 5 and 10wt% Na-montmorillonite (NaMMT) and/or 30wt% glycerol. Intercalation of NaMMT was more effective in films based on 2w/v% solutions which presented decreased hydrated crystallinity. Upon NaMMT addition an enhancement was found in stiffness and strength (up to 100%) and a remarkable decrease in the elongation at break (up to 75%) and water vapor permeability (WVP) (up to 65%). This enhancement was less pronounced in 1w/v% systems. Addition of glycerol had a negative effect on the stiffness, strength and WVP, and a positive effect on the elongation at break and the absorbed water. Compared with the conventional solution cast method, the reflux treatment led to a significant improvement of the tested properties of nanocomposite films.

PH-dependent structure and photochromic properties of phosphomolybdic acid/polyacrylamide composite films

A series of nanocomposite films with different pH were constructed by entrapped phosphomolybdic acid (PMoA) into polyacrylamide (PAM) networks. The structure, photochromic properties and mechanism of composite films were studied with transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible spectra (UV–vis) and X-ray photoelectron spectroscopy (XPS). The results indicated that pH had a significant effect on the microstructure and photochromic properties of composite films. The TEM image showed that PMoA particles changed from well dispersed sphere-shape to irregular similar ball-shape with the increase of pH. XRD pattern showed that PMoA changed from crystal phase to amorphous phase with pH increased. The FT-IR results revealed that the octahedral structure of PMoA was destroyed with the increase of pH. PMoA/PAM films with pH 2 had higher photochromic efficiency than those films with other pH value. According to XPS, the different photochromic properties were caused by the microstructure change of the heteropoly compound with different pH value.

Non-covalently functionalized multiwalled carbon nanotubes by chitosan and their synergistic reinforcing effects in PVA films

Multiwalled carbon nanotubes (MWCNTs) were regarded as ideal candidates for fillers in a polymer matrix due to their outstanding mechanical, electrical and thermal properties. A series of nanocomposite films were prepared by a solution casting method introducing chitosan (CS) treated MWCNTs into a poly (vinyl alcohol) (PVA) matrix. The nanocomposites were characterized by field emission scanning electron microscopy and Fourier Transform Infrared Spectroscopy. The results indicated that MWCNTs treated by chitosan dispersed well in the PVA matrix, and the tensile properties and water resistance of nanocomposites were improved greatly compared with neat PVA.

A chitosan/poly(vinyl alcohol) nanocomposite film reinforced with natural halloysite nanotubes

AbstractBiodegradable polymer/clay nanocomposites have attracted tremendous attentions because of their excellent properties and ecofriendly advantages. In this article, a series of nanocomposite films were prepared by introducing of halloysite nanotubes (HTs) into chitosan (CS)/poly(vinyl alcohol) (PVA) matrix using the solution casting method, and the effect of HT as nanofillers on the properties of polymer/HT nanocomposites was explored. The results indicated that the tensile strength of CS/PVA/HT3 and elongation at break of CS/PVA/HT2 sharply increased by 39.72% and 26.14% in comparison with the pure CS/PVA film, respectively. The water resistance and thermal stability of polymer/HT nanocomposites were also improved compared with the pure CS/PVA film, but the optical property of the nanocomposite films was not affected by introducing HT into the CS/PVA matrix. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

Preparation and Characterization of Nanocomposite Films from Chitin Whisker and Waterborne Poly(ester-urethane) With or Without Ultra-Sonification Treatment

Two series of nanocomposite films were prepared from waterborne poly(ester-urethane) and chitin whisker with and without ultrasound treatment coded as CW/WPU and CHW/WPU, respectively. The effects of ultra-sonification method and chitin whisker content on the chemical compositions, crystallization behavior and miscibility were studied by attenuated total reflection Fourier transform infrared (ATR-FTIR), wide-angle X-ray diffraction (WXRD), dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). Thermal stability and mechanical properties of the films were measured by thermogravimetric analysis (TGA) and tensile test, respectively. The results revealed that both nanocomposite films exhibited a certain degree of miscibility when chitin whisker content was lower than 30 wt%, resulting in higher thermal stability and tensile strength than the pure waterborne poly(ester-urethane) film. Interestingly, the composite films CW/WPU with ultrasound treatment possessed better miscibility, storage modulus, thermal stability and tensile strength than those without ultrasound treatment over the entire composition range studied here. The difference can be attributed to the relatively higher dispersion level of whisker within poly(ester-urethane) matrix resulting in relatively stronger entanglement and interaction between both components. The ultrasound treatment can effectively improve the miscibility and mechanical properties of the casting nanocomposite films with nano-meter size chitin whisker added. This indicated that the structure, miscibility and mechanical properties of the nanocomposite films depended significantly on the preparation method.

Nanocomposites Derived from a Low-Color Aromatic Polyimide (CP2) and Amine-Functionalized Vapor-Grown Carbon Nanofibers: In Situ Polymerization and Characterization

Vapor-grown carbon nanofibers (VGCNF) were functionalized with amine-containing pendants via a Friedel−Crafts acylation reaction with 4-(3-aminophenoxy)benzoic acid. The resulting H2N−VGCNF with relatively high degree of functionalization was in attendance during the synthesis of a polyimide (previously designated as CP2) from 2,2-bis(phthalic anhydride)-1,1,1,3,3,3-hexafluoroisopropane (6FDA) and 1,3-bis(3-aminophenoxy)benzene (APB) in N,N-dimethylacetamide (DMAc). Thus, a series of CP2-based nanocomposite films, which contained 0.18−9.19 wt % of H2N−VGCNF (corresponding to 0.10−5.0 wt % of basic VGCNF) were obtained using the conventional poly(amic acid) precursor method. For comparison purposes, the pristine VGCNF (0.10−5.0 wt %) was also used in the in situ polymerization of 6FDA and ABP. These two series of nanocomposite films were cast from the respective poly(amic acid)/VGCNF/DMAc solutions, followed by thermal imidization at curing temperatures up to 250 °C. The benefit and limitation of functiona...

Ferromagnetic Nanocomposite Films from Thermally Labile Nitride Precursors

ABSTRACTA series of nanocomposite films containing nickel or cobalt nitride dispersed in a ceramic matrix of aluminum nitride, boron nitride or silicon nitride, were prepared by reactive sputtering of selected alloys or compounds such as nickel aluminide or cobalt suicide. Thermal treatment of the nitride composites in vacuum at ≤ 500 °C leads to selective loss of nitrogen from CoN or Ni3N to generate dispersions of the metal in the ceramic matrix. This treatment may be performed in a localized manner by means of a focused laser beam to generate microscopic features that are imaged by magnetic force microscopy. The films are potentially useful for data storage with superior chemical and mechanical stability provided by the ceramic matrix and high encoding density made possible because of the size of the magnetic particles of less than 10 nm generated in the thermal treatment. The films were characterized by chemical and physical means including FTIR, TEM, MFM and magnetic measurements. Preliminary results on similar iron composites are also described.