Mechanical and Electrochemical Properties of New Nanocomposite Polymer Electrolytes Based on Poly(vinylidene fluoride-co-hexafluoropropylene) and SiO<Subscript>2</Subscript> Addition

Nanocomposite polymer electrolytes based on the system poly(vinylidene fluoride-co-hexafluoropropylene)–liquid electrolyte 1 mol/L LiBF₄ in gamma-butyrolactone which is modified by introducing up to 10 wt % of SiO₂ nanopowder (an average particle size of 7 nm) are synthesized and characterized. The introduction of SiO₂ nanoparticles worsens the elasticity of films but increases their fracture stress to 24 MPa. The conductivity of the nanocomposite electrolytes containing SiO₂ nanoparticles is higher than that without SiO₂ and attains 3.7 mS/cm at 20°C for the electrolyte containing 1.25 wt % SiO₂. Upon the introduction of SiO₂ nanoparticles, the electrochemical stability of electrolytes grows by 0.50–0.85 V and attains 6.7 V relative to Li/Li⁺.     

Study on parylene/SiO<Subscript>2</Subscript> composite films for protection of KDP crystals

In this paper, parylene/SiO₂ composite films were reported to protect KDP crystals, indispensable cells in ICF experiments, from moisture. FTIR, UV-NIR spectra and XPS were used to analyze the properties of films. Laser damage threshold of films was also measured. With porous silica coating on surface of parylene film, the transmittance of dual layers can be raised to more than 91%. KDP crystals with poly(p-xylylene)/SiO₂ coating could work well in ambient atmosphere for more than half a year.     

Preparation and stability of strongly luminescent CdSe/Cd(OH)<Subscript>2</Subscript>/SiO<Subscript>2</Subscript> nanocomposite particles in aqueous solution

Cadmium hydroxide-deposited cadmium selenide nanoparticles were prepared by the addition of cadmium sulfate solution to cadmium selenide nanoparticles in a weak alkaline solution at room temperature. The photoluminescence measurements displayed that the luminescence intensity was greatly increased by the addition of cadmium ions due to the formation of cadmium hydroxide on the surfaces of the cadmium selenide nanoparticles. Then, CdSe/Cd(OH)₂/SiO₂ nanocomposite particles were synthesized using 3-mercatopropyl trimethoxysilane by Stöber method. After the formation of CdSe/Cd(OH)₂/SiO₂ nanocomposite particles, the emission ability was mostly stabilized. Additionally, the stabilization of the composite particles against dilution with the physiological saline was checked. The results showed that the photoluminescence stability was promoted after the deposition of silica on the surfaces of the CdSe/Cd(OH)₂ nanoparticles. Comparison of the stability of CdSe/SiO₂ nanoparticles with that of CdSe/Cd(OH)₂/SiO₂ ones showed that Cd(OH)₂ shell could enhance the photoluminescence effectively.     

Nanocomposite scaffolds based on gelatin and alginate reinforced by Zn2SiO4 with enhanced mechanical and chemical properties for tissue engineering

Hydrogels have been employed in regenerative treatments for decades because of their biocompatibility and structural similarity to the native extracellular matrix. Injectable hydrogels with interconnected porosity and specific internal structures are momentous for tissue engineering. Here, we develop a group of injectable hydrogels comprised of oxidized alginate (OA)/gelatin (GEL) strengthened by modifying the amount of Zn₂SiO₄ nanoparticles. The physicochemical characteristics of OA/GEL/Zn₂SiO₄ hydrogels were studied by mechanical strength, swelling ratio, and morphology. The outcomes revealed that the mechanical characteristics of hydrogels containing a higher amount of Zn₂SiO₄ (0.12 wt%) improved more than five times than the hydrogels fabricated without Zn₂SiO₄. The in vitro degradation outcomes manifested the degradation of the hydrogel comprising 0.12 wt% Zn₂SiO₄ NPs was slower than one without NPs, and remaining masses of hydrogels depend on different contents of Zn₂SiO₄ NPs. The hydrogel containing Zn₂SiO₄ NPs exhibited less cytotoxicity and good cell attachment than the hydrogels prepared without the nanoparticles. The cell viability and attachment show that the nanocomposite hydrogels are biocompatible (>96%) with great cell adhesion to osteosarcoma cell line MG63 depending on the presence of Zn₂SiO₄. The superior physical, chemical as well as mechanical characteristics of the hydrogels containing Zn₂SiO₄ NPs along with their cytocompatibility suggest that they can introduce as good candidates as scaffolds in tissue engineering.     

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     

Fabrication and characterization of TiO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript> composite nanoparticles and polyurethane/(TiO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript>) nanocomposite films

TiO₂–SiO₂ composite nanoparticles were prepared by a sol–gel process. To obtain the assembly of TiO₂–SiO₂ composite nanoparticles, different molar ratios of Ti/Si were investigated. Polyurethane (PU)/(TiO₂–SiO₂) hybrid films were synthesized using the “grafting from” technique by incorporation of modified TiO₂–SiO₂ composite nanoparticles building blocks into PU matrix. Firstly, 3-aminopropyltriethysilane was employed to encapsulate TiO₂–SiO₂ composite nanoparticles’ surface. Secondly, the PU shell was tethered to the TiO₂–SiO₂ core surface via surface functionalized reaction. The particle size of TiO₂–SiO₂ composite sol was performed on dynamic light scattering, and the microstructure was characterized by X-ray diffraction and Fourier transform infrared. Thermogravimetric analysis and transmission electron microscopy (TEM) employed to study the hybrid films. The average particle size of the TiO₂–SiO₂ composite particles is about 38 nm when the molar ratio of Ti/Si reaches to1:1. The TEM image indicates that TiO₂–SiO₂ composite nanoparticles are well dispersed in the PU matrix.     

Conducting properties of nanocomposite polymer electrolytes based on polyethylene glycol diacrylate and SiO<Subscript>2</Subscript> nanoparticles at the interface with a lithium electrode

Nanocomposite polymer electrolytes based on polyethylene glycol diacrylate and 1 M LiBF₄ solution in γ-butyrolactone with addition of SiO₂ nanoparticles were synthesized and studied. Resistance measurement at the Li/electrolyte and Li/nanocomposite electrolyte interface by the time-resolved electrochemical impedance showed its significant decrease in the presence of SiO₂ nanoparticles. Charge-discharge cycling of prototypes of Li/LiFePO₄ batteries for 50 cycles also showed the advantage of using nanocomposite polymer electrolytes over electrolytes without SiO₂ additives.     

In situ synthesis of plate-like Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> nanoparticles in porous cellulose films with obvious magnetic anisotropy

Nanocomposite cellulose films with obvious magnetic anisotropy have been prepared by in situ synthesis of plate-like Fe₂O₃ nanoparticles in the cellulose matrix. The influence of the concentrations of FeCl₂ and FeCl₃ solutions on the morphology and particle size of the synthesized Fe₂O₃ nanoparticles as well as on the properties of the composite films has been investigated. The Fe₂O₃ nanoparticles synthesized in the cellulose matrix was γ-Fe₂O₃, and its morphology was plate-like with size about 48 nm and thickness about 9 nm, which was totally different from those reported works. The concentration of FeCl₂ and FeCl₃ solution has little influence on the particle size and morphology of the Fe₂O₃ nanoparticles, while the content of Fe₂O₃ nanoparticles increased with the increase of the concentration of the precursor solution, indicating that porous structured cellulose matrix could modulate the growth of inorganic nanoparticles. The unique morphology of the Fe₂O₃ nanoparticles endowed the composite films with obvious magnetic anisotropy, which would expand the applications of the cellulose based nanomaterials.     

Vanillin cross-linked hydrogel membranes interfacial reinforced by carbon nitride nanosheets for enhanced antibacterial activity and mechanical properties

Biopolymer based hydrogels are highly adaptable, compatible and have shown great potential in biological tissues in biomedical applications. However, the development of bio-based hydrogels with high strength and effective antibacterial activity remains challenging. Herein, a series of Vanillin-cross-linked chitosan nanocomposite hydrogel interfacially reinforced by g-C₃N₄ nanosheet carrying starch-caped Ag NPs were prepared for wound healing applications. The study aimed to enhance the strength, sustainability and control release ability of the fabricated membranes. Starch-caped silver nanoparticles were incorporated to enhance the anti-bacterial activities The fabricated membranes were assessed using various characterization techniques such as FT-IR, XRD, SEM, mechanical testing, Gel fraction and porosity alongside traditional biomedical tests i.e., swelling percentage, moisture retention ability, water vapor transmission rate, oxygen permeability, anti-bacterial activity and drug-release of the fabricated membranes. The mechanical strength reached as high as 25.9 ± 0.24 MPa for the best optimized sample. The moisture retention lied between 87–89%, gel fraction 80–85%, and water vapor transmission up to 104 ± 1.9 g/m²h showing great properties of the fabricated membrane. Swelling percentage surged to 225% for blood while porosity fluctuated between 44% ± 2.1% and 52.5% ± 2.3%. Oxygen permeability reached up to 8.02 mg/L showing the breathable nature of fabricated membranes. The nanocomposite membrane shown excellent antibacterial activity for both gram-positive and gram-negative bacteria with a maximum zone of inhibition 30 ± 0.25 mm and 36.23 ± 0.23 mm respectively. Furthermore, nanoparticles maintained sustainable release following non-fickian diffusion. The fabricated membrane demonstrated the application of inorganic filler to enhance the strength of biopolymer hydrogel with superior properties. These results envisage the potential of synthesized membrane to be used as wound dressing, artificial skin and load-bearing scaffolds.     

Preparation and characterization of luminescent cellulose–Y<Subscript>4</Subscript>Si<Subscript>2</Subscript>O<Subscript>7</Subscript>N<Subscript>2</Subscript>:Ce<Superscript>4+</Superscript> hybrid hydrogels

Novel luminescent bio-based hydrogels comprising cellulose and Y₄Si₂O₇N₂:Ce⁴⁺ (YC) were prepared in an alkali/urea aqueous system using epichlorohydrin as a cross-linker. The structure, characteristics and properties of the hydrogels were investigated by various techniques, including FTIR spectroscopy, wideangle X-ray diffraction, scanning electron microscopy, etc. The results showed that when the content of YC was less than 0.05 g, the YC particles were tightly embedded in the macro porous of cellulose matrix, which not only supplied cavities for YC immobilization, but also supplied the pore wall to protect the structure and character of YC. Hence, the cellulose–YC hybrid hydrogels exhibited strong cyan fluorescence under a UV lamp. However, excess of YC particles were enshrouded in the cellulose matrix resulted in smaller pores, weaker fluorescence intensity, lower swelling ratio and higher mechanical properties.     

Rapid dissolution of spruce cellulose in H<Subscript>2</Subscript>SO<Subscript>4</Subscript> aqueous solution at low temperature

Dissolution of cellulose is the key challenge in its applications. It has been discovered that spruce cellulose with high molecular weight (4.10 × 10⁵ g mol^?1) can be dissolved in 64 wt% H₂SO₄ aqueous solution at low temperature within 2 min, and the cellulose concentration in solution can reach as high as 5 % (w/v). FT-IR spectra and XRD spectra proved that it is a direct solvent for cellulose rather than a derivative aqueous solution system. The cold H₂SO₄ aqueous solution broke the hydrogen bonds among cellulose molecules and the low temperature dramatically slowed down the hydrolysis, which led to the dissolution of cellulose. The resultant cellulose solution was relatively stable, and the molecular weight of cellulose only slightly decreased after storage at ?20 °C for 1 h. Due to the high molecular weight of cellulose, cellulose solution could form regenerated films with good mechanical properties and transparency at low concentration (2 % w/v). This work has not only provided the new evidence of cellulose dissolution which facilitated the development of cellulose solvent, but also suggested a convenient way to directly transfer cellulose with high molecular weight into materials without structure modifications.     

UV-degradation effect on optical and surface properties of polystyrene-TiO<Subscript>2</Subscript> nanocomposite film

Thin films of polystyrene and polystyrene-TiO₂ nanocomposite were prepared by spin coating from a polystyrene solution in which TiO₂ nanoparticles were dispersed by mechanical mixing. Thin films of polystyrene (PS) and polystyrene-TiO₂ nanocomposite were exposed to UV irradiation for varied time intervals. The effect of UV radiation on the optical properties, crystallinity, surface energy and degradation of PS-TiO₂ nano-composite has been studied. X-Ray diffraction analysis (XRD), UV-Vis and FTIR spectroscopy, Atomic Force Microscopy (AFM) and contact angle measurement were used to study the induced changes of the properties of the irradiated PS-TiO₂ nanocomposite. Optical band gaps and hydrophilicity in UV-irradiated samples were altered by destruction processes. The optical band gap values were found to reduce from 4.54 eV in pure PS to 4.45 eV for PS-TiO₂ nanocomposite prior to irradiation. This value is further reduced to 3.46 after UV irradiation for 45 h.     

Nanocomposite films based on cellulose reinforced with nano-SiO2: microstructure, hydrophilicity, thermal stability, and mechanical properties

Microcrystalline cellulose/nano-SiO₂ composite films have been successfully prepared from solutions in ionic liquid 1-allyl-3-methylimidazolium chloride by a facile and economic method. The microstructure and properties were investigated by Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, scanning electron microscopy, transmission electron microscopy, water contact angle, thermal gravimetric analyses, and tensile testing. The results revealed that the well-dispersed nanoparticles exhibit strong interfacial interactions with cellulose matrix. The thermal stability and tensile strength of the cellulose nanocomposite films were significantly improved over those of pure regenerated cellulose film. Furthermore, the cellulose nanocomposite films exhibited better hydrophobicity and a lower degree of swelling than pure cellulose. This method is believed to have potential application in the field of fabricating cellulose-based nanocomposite film with high performance, thus enlarging the scope of commercial application of cellulose-based materials.     

TiO2 nanoparticles/poly(butylene adipate‐co‐terephthalate) bionanocomposite films for packaging applications

In this present study, biodegradable PBAT nanocomposites containing different weight percentages (1, 3, 5, 7, and 10% w/w) of TiO₂ nanoparticles were prepared by using solvent casting technique, chloroform as a solvent. The microstructure and morphology of the as‐synthesized poly(butylene adipate‐co‐terephthalate) (PBAT)/TiO₂ nanocomposite films were characterized by Fourier‐transform infrared, X‐ray diffraction, scanning electron microscopy, and transmission electron microscope. The thermal degradation of PBAT composites was studied by using thermogravimetric analysis. The mechanical strength of the films was improved by increasing TiO₂ concentration. Tensile strength increased from 32.60 to 63.26 MPa, respectively. Barrier properties of the PBAT/TiO₂ nanocomposites were investigated by using an oxygen permeability tester. The oxygen permeability (oxygen transmission rate) decreased with increasing the TiO₂ nanoparticle concentrations. The PBAT/TiO₂ nanocomposite films showed profound antimicrobial activity against both Gram‐positive and Gram‐negative foodborne pathogenic bacteria, namely, Escherichia coli and Staphylococcus aureus, to understand to the zone of inhibition. These results indicated that filler–polymer interaction is important and the role of the TiO₂ as a reinforcement in the nanocomposites was evident. Copyright © 2017 John Wiley & Sons, Ltd.     

Preparation and characterization of ternary composite films of polyvinyl alcohol/sodium alginate/TiO<Subscript>2</Subscript>

Nano-TiO₂ with anionic surface active agent sodium dodecylsulfate (SDS) modified, the poly(vinyl alcohol)/sodium alginate/TiO₂ composite films were prepared by method of solution blending representing. The structure of the films was analyzed by XRD and SEM. In addition, air permeability rate, swelling ratio, light transmittance, mechanical properties, and antibacterial properties were tested. The results showed that in compound membrane there was a strong force between poly(vinyl alcohol)/sodium alginate and TiO₂ particles, indicating that there was good compatibility between the sodium alginate and the poly(vinyl alcohol). The mixed membranes were of good water resistance, tensile strength, and closure. When the titanium dioxide content increased appropriately, they had very good mechanical properties. In addition, the antibacterial properties of composite membrane gradually increased with the increase in the TiO₂content.     

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.     

On the nature of the processes occurring in silver doped SiO<Subscript>2</Subscript> films under heat treatment

The processes taking place on air-heating of SiO₂−Ag⁺ films and xerogels produced from the SiO₂ sols of different pH (3.7 or 9.5) were investigated. Silver nanoparticles 10–40 nm in size tolerant to oxidation at temperatures above 600 °C were found to be formed in the systems whatever the pH value of the starting sol. SiO₂ crystallization giving the cristobalite phase in the temperature range from 500 to 800 °C was shown to proceed only in the films produced from the acidic sol, while in those formed from the alkali one SiO₂ remained amorphous. A mechanism by which the formation of Ag nanoparticles and the cristobalite phase occurs in the films at the oxidative conditions is suggested.     

The synthesis and characterization of polyorganosiloxane nanoparticles from 3-mercaptopropyltrimethoxysilane for preparation of nanocomposite films via photoinitiated thiol-ene polymerization

This article describes the synthesis of modified silica nanoparticles (SiO₂-MPTMS) via the condensation reaction carried out between silanol moieties of silica nanoparticles and the trialkoxy silyl groups of (3-mercaptopropyl) trimethoxysilane (MPTMS). Then, SiO₂-MPTMS nanoparticles in certain amounts (0.5 wt %, 1 wt %, 2.5 wt % and 5 wt %) were incorporated into thiol-ene resins consisting of bisphenol A glycerolate dimethacrylate and trimethylolpropane tris(3-mercaptopropionate) to prepare nanocomposite films via the photoinitiated thiol-ene polymerization in presence of 2,2-Dimethoxy-2-phenylacetophenone 99% as a photoinitiator. Fourier transform infrared spectroscopy, dynamic light scattering, scanning transmission electron microscopy, thermal gravimetric analyzer, and X-ray photoelectron spectrometer were employed to characterize SiO₂-MPTMS nanoparticles. It was revealed that the nanosilica surface was successfully grafted by MPTMS with the grafting ratio of 22.9%. Properties of the nanocomposite films such as decomposition temperature, thermal glass transition temperature, tensile strength, hardness, and particle distribution were investigated and the results were compared with each other and neat film. The addition of MPTMS-modified silica particles did not improve the thermal stability of the films. In scanning electron microscopy study, it was seen that 2.5 wt % of these nanoparticles used as additives were about 200 nm in size and dispersed homogeneously in the polymer matrix. The increase in tensile strength of nanocomposite films compared to the neat film was measured as 77.3% maximum.     

Cellulose scaffolds modulated synthesis of Co<Subscript>3</Subscript>O<Subscript>4</Subscript> nanocrystals: preparation,characterization and properties

Magnetic Co₃O₄ nanoparticles were prepared by using microporous regenerated cellulose films as sacrificial scaffolds. The cellulose macromolecules and the porous structure of the films made them used as spatially confined reacting sites where Co(OH)₂ nanoparticles could be synthesized in situ. When the cellulose matrix was removed by sintering at 500 °C, Co₃O₄ nanoparticles were obtained. XRD and XPS indicated that the prepared nanoparticles were pure Co₃O₄ without any impurity. TEM and SEM images revealed that the particle size of the nanoparticles was smaller than 100 nm. The nanoparticles had weak ferromagnetic properties at 25 °C. Furthermore, the pronounced quantum confinement effects of the synthesized nanoparticles have been observed, the optical bandgap energies determined were about 1.92 ~ 2.12 and 2.74 ~ 2.76 eV for O²⁻ → Co³⁺ and O²⁻ → Co²⁺ charge-transfer processes, respectively. Furthermore, the resulted Co₃O₄ nanoparticles behaved stable electrochemical performance with promising applications in the electrode for lithium ion battery.     

pH/temperature double responsive behaviors and mechanical strength of laponite‐crosslinked poly(DEA‐co‐DMAEMA) nanocomposite hydrogels

A nanocomposite (NC) hydrogel crosslinked by inorganic Laponite XLG was successfully synthesized via in situ free radical polymerization of monomers N,N‐diethylacrylamide and (2‐dimethylamino) ethyl methacrylate (DMAEMA). Polymerization was carried out at room temperature due to the accelerating effect of DMAEMA. The as‐prepared hydrogels displayed controlled transformation in optical transmittance and volume in response to small diversification of environmental factors, such as temperature and pH. The compressive strength of swollen D_6:1G₆ hydrogels was as high as 2219 kPa while compressive strain was 95%. Cyclic compression measurement exhibited good elastic properties of NC hydrogels. This work provides a facile method for fabricating stimuli‐responsive hydrogels with superior mechanical property. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 876–884