Improvement of optical properties and thermal stability of poly vinyl alcohol using salicylic acid confined in nanohybrid material

This study aims to benefit from the confinement of salicylic acid in the nanoscale to convert poly vinyl alcohol to be UV absorber. Therefore, Zn–Al LDH was prepared and used as a host. It intercalated with salicylic acid which used as a guest to form nanohybrid material. This nanohybrid material was inserted inside poly vinyl alcohol to build nanocomposite material. X-ray diffraction results and electron microscopy images showed that the interlayer spacing of Zn–Al LDH increased from 0.77 to 1.55 nm after intercalation reaction with salicylic acid. The thermal analyses revealed the presence of a complex system of supra-molecular host–guest interaction. The optical properties of Zn–Al–salicylate nanohybrid material showed new absorption bands in the UV region comparing with the absorption bands of salicylic acid sodium salt. Nanocomposite based on both Zn–Al–salicylate nanohybrid and PVA were characterized by X-ray diffraction, Scanning electron microscopy, UV–Visible absorption spectra, and thermal analyses. The experimental results suggested that the nanocomposite was formed via exfoliated structure and the nanohybrid layers were completely and uniformly dispersed in a continuous polymer matrix. By comparing with the thermal and optical properties of the original PVA, the PVA nanocomposite became more stable and UV absorber.     

Electron beam‐induced piezoelectric phase in poly(vinylidene fluoride) nanohybrid: effect at the molecular level

A nanohybrid has been synthesized by incorporating organically modified layered silicate in a poly(vinylidene fluoride) (PVDF) matrix. Molecular‐level phenomena have been explored after exposing PVDF and its nanohybrid to an electron beam of varying doses. The electron beam interacts with polymer chains and thereby generates different free radicals, the number of which is quite high in nanohybrid as compared to pure PVDF. The stability of free radicals has been confirmed through density functional theory energy minimization, predicting stable β‐phase free radicals in the nanohybrid. Quantitative analyses of chain scission, crosslinking and double bond formation are reported and compared after irradiation for both PVDF and its nanohybrid using UV‐visible and Fourier transform infrared spectroscopies, sol–gel analyses and gel permeation chromatography, revealing both chain scission and crosslinking phenomena in irradiated PVDF and its nanohybrid, but at higher dose (>90 Mrad) crosslinking dominates in the nanohybrid due to more free radicals and proximity of radical chains on top of templated system in the nanohybrid as compared to pure PVDF. The enhanced crosslinking alters the nanostructure causing disappearance of the peak at 2θ ≈ 3°. Moreover, the electron beam induces significant piezoelectric β‐phase in the nanohybrid against only α‐phase in pure PVDF at a similar dose and raises the possibility for the use of electron‐irradiated nanohybrid as an electromechanical device. β‐Phase formation is also supported through solid‐state NMR, scanning electron microscopy and differential scanning calorimetry studies. The thermal properties in terms of heat of fusion and degradation temperature have been verified indicating steady decrease of melting point and heat of fusion for pure PVDF while considerably less effect is observed for the nanohybrid. The combined effect of chain scission and crosslinking makes both PVDF and its nanohybrid brittle, but with greater stiffness with respect to unirradiated specimens. © 2014 Society of Chemical Industry     

Noncovalent modified graphene sheets with ruthenium(II) complexes used as electrochemiluminescent materials and photosensors

Bi(2,2′-bipyridyl)-pyrene derivative functionalized ruthenium(II) complexes anchored on graphene sheets (B-Ru-P/GS nanohybrid) by π–π interaction were fabricated. The formation of the nanohybrid was verified by atomic force microscopy, fluorescence spectra and Raman spectroscopy. An obvious and stable electrochemiluminescence of the B-Ru-P/GS nanohybrid at the electrode was revealed. A typical photoelectrical response on the on/off light illumination was observed in a photoelectrochemical cell. The photocurrent of the B-Ru-P/GS nanohybrid was remarkable higher than that of Ru(II) complexes. Therefore, the B-Ru-P/GS nanohybrid is believed to have the potential use as for solid sensors, light emitting diodes and optoelectronic devices.     

Synthesis and characterization of novel UV-curable polyurethane–clay nanohybrid: Influence of organically modified layered silicates on the properties of polyurethane

Nanohybrids based on UV-curable polyurethane acrylate (PU) and cloisite 20B (C-20B) have been synthesized by solution blending method using different loading levels of C-20B. The structures of PU/C-20B nanohybrids were confirmed by Fourier transform infrared spectroscopy (FTIR) while X-ray diffraction and transmission electron microscopy (TEM) showed the intercalation of PU into layer silicates. The thermal properties of PU and PU/C-20B nanohybrids were investigated by thermal gravimetric analysis (TGA) and differential scanning calorimetric (DSC). TGA tests revealed that the thermal decomposition temperature (T_d10%) of the nanohybrid containing 5 wt% of C-20B increased significantly, being 61 °C higher than that of pure PU while DSC measurements indicated that the introduction of 5 wt% of clay increased the glass transition temperature from 89.7 to 101 °C. Accordingly, the mechanical and anti-water absorption properties proved also to be enhanced greatly as evidenced by nanoindentation anylsis and water absorptions data in which the nanohybrid containing 5 wt% of clay have highest elastic modulus (4.508 GPa), hardness (0.230 GPa) and lowest water absorption capacity. Thus the formations of nanohybrids manifests through the enhancement of thermal, mechanical and anti-water absorption properties as compared with neat PU due to the nanometer-sized dispersion of layered silicate in polymer matrix.     

Cellulose nanocrystals-organic montmorillonite nanohybrid material by electrostatic self-assembly

The hybridization based on various nanoparticles is an emerging technological field, involving the synergistic hybrid assembly of nanoparticles. In order to broaden the application of existing nanomaterials such as cellulose nanocrystals (CNC) and montmorillonite (MMT), a novel CNC–organic MMT (OMMT) nanohybrid material was constructed by electrostatic self-assembly. Morphology observations showed that one-dimensional needle-like CNC were adsorbed on the surface of two-dimensional flake-like OMMT, thereby forming a three-dimensional nanohybrid. In the nanohybrid, CNC and OMMT still maintained their original chemical structures. Zeta potential results indicated that there was a strong electrostatic adsorption between CNC and OMMT. Based on this, the lamellar structure of OMMT can hide sulfate groups on the CNC surface and had a shielding effect on heat transfer, thereby evidently improving the thermal stability of the nanohybrid. The nanohybrid with unique nanostructure is expected to achieve synergistic effects in polymer nanocomposites, which may provide a promising strategy for the fabrication of high-performance polymer nanocomposites.     

CSA doped polyaniline/CdS organic–inorganic nanohybrid: Physical and gas sensing properties

Camphor sulfonic acid (CSA) doped polyaniline/CdS nanohybrid materials were prepared by chemical oxidative polymerization method and characterized by field emission scanning electron microscopy (FESEM) and Fourier transform infrared (FTIR) spectroscopy. It is proved that there is a strong synergetic interaction between the CSA and polyaniline–CdS nanohybrid. Gas sensing measurements showed that the gas sensor based on the CSA doped PANi–CdS nanohybrid had high sensor response (75%), good selectivity (for H₂S) and stability (97.34%), as well as comparatively short recovery time to H₂S, operating at room temperature. The enhanced gas sensing performance of the nanohybrid is due to the high surface area of the CSA doped PANi–CdS hybrids and the p–n heterojunction formed between p-type polyaniline and n-type CdS nanoparticles.     

Increased optical nonlinearities of graphene nanohybrids covalently functionalized by axially-coordinated porphyrins

Two graphene oxide (GO)-based nanohybrid materials possessing covalent linkages to axially-coordinated tetraphenylporphyrin (TPP), GO–TPP, were prepared and were characterized by Fourier transform infrared (FT-IR), Ultraviolet–visible (UV–Vis) absorption, steady state fluorescence, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), thermogravimetric analysis (TGA), elemental analysis and Raman spectroscopic techniques. The nonlinear optical properties and optical limiting performance of GO, GO–TPP nanohybrids and the free porphyrins dihydroxotin(IV) tetraphenylporphyrin (SnTPP) and the phosphorus-cored porphyrin (PTPP) were investigated using nanosecond and picosecond Z-scan measurements at 532 nm. At the identical mass concentration of 0.2 mg mL⁻¹, GO–TPP nanohybrids exhibited enhanced nonlinear optical properties and optical limiting performance, ascribed to a combination of nonlinear scattering and/or two-photon absorption with reverse saturable absorption, and the photo-induced electron or energy transfer from the electron-donor porphyrin moiety to the acceptor graphene.     

Hydrothermal synthesis of micro-flower like morphology aluminum-doped MoS2/rGO nanohybrids for high efficient electromagnetic wave shielding materials

In this study, a three-dimensional (3D) micro-flower like morphology aluminum-doped molybdenum disulfide/reduced graphene oxide (Al@MoS₂/rGO) nanohybrids have been developed using a simple and sensitive hydrothermal approach. Their electromagnetic (EM) parameters (permittivity, permeability) and microwave shielding parameters (S₁₁, S₁₂) have been analyzed and reported for the first time in the microwave frequency range of 8.0–12.0 GHz. It is interesting to note that the electrical conductivity of the nanohybrids increases with the doping concentration of Al-ions, whereas skin-depth has a reverse trend. The 12% Al@MoS₂/rGO nanohybrid shows a higher total electromagnetic interference shielding effectiveness (EMI SE) value about SE_T ~33.38 dB, whereas undoped MoS₂/rGO nanohybrid exhibits a lower value around ~17.07 dB at the same thin thickness. The higher doping concentration of Al-ion creates lattice distortion and crystal defects with high charge carrier mobility between multiple interfaces and at defective sites. Hence, the Al-doping into MoS₂ lattice supported on the rGO surface can greatly enhance EM wave absorption and EMI SE value. The present work suggests that the 12% Al@MoS₂/rGO nanohybrid can be treated as a good microwave absorbing and shielding material and useful in various techno-commercial devices.     

3,4-Dichlorophenoxyacetate interleaved into anionic clay for controlled release formulation of a new environmentally friendly agrochemical

A new layered organic–inorganic nanohybrid material, zinc-aluminum-3,4-dicholorophenoxyacetate (N3,4-D) in which an agrochemical, 3,4-dichlorophenoxyacetic acid (3,4-D), is intercalated into zinc-aluminum-layered double hydroxide (ZAL), was synthesized by coprecipitation method. A well-ordered nanomaterial was formed with a percentage loading of 53.5% (w/w). Due to the inclusion of 3,4-D, basal spacing expanded from 8.9 Å in ZAL to 18.7 Å in N3,4-D. The Fourier transform infrared study shows that the absorption bands of the resulting nanohybrid composed of both the 3,4-D and ZAL further confirmed the intercalation episode. Thermal analysis shows that ZAL host enhances the thermal stability of 3,4-D. Controlled-release experiment shows that the release of 3,4-D in the aqueous media is in the order of phosphate > carbonate > sulfate > chloride. These studies demonstrate the successful intercalation of the 3,4-D and its controlled release property in various aqueous media.     

Surface modification of silica-graphene nanohybrid as a novel stabilizer for oil-water emulsion

The surface modification of silica-graphene nanohybrid through treatment with a mixture of nitric and sulfuric acid vapors to prepare a novel stabilizer for decalin-water emulsion was investigated. The nanohybrid was prepared through chemical vapor deposition using silica aerogel and acetylene as catalyst and carbon precursor at atmospheric pressure and 600 °C. The physicochemical properties of the modified nanohybrid were characterized by FT-IR, XPS, Raman spectroscopy, and TEM. The surface modification of nanohybrid was at various duration times (24, 48, and 72 hours) to optimize the surface modification conditions. Zeta potential of ?39.9 mV revealed that the surface modification of nanohybrid after 72 hours had an excellent stability in aqueous phase due to the presence of exceptional functional groups. The emulsion average droplet size decreased by increasing the nanohybrid concentration. The negative value of the zeta potential showed the proposed nanohybrid can be applied as an appropriate stabilizer for emulsion.     

Synthesis and characterization of nanohybrid of poly(octadecylacrylates derivatives)/montmorillonite as pour point depressants and flow improver for waxy crude oil

In this paper, a novel series of nanohybrid of poly(octadecylacrylate derivatives) montmorillonite (ODA/MMT) was prepared by successfully dispersing the inorganic nanolayers of MMT-clay on the organic polymer matrix via in situ free-radical polymerization by different ratios. The prepared nanohybrid polymers were characterized by FTIR and Raman spectroscopy, X-ray diffraction (XRD), HRTEM, GPC, DSC, and TGA instruments. The XRD confirmed the presence of an exfoliated/interacted clay structure in the prepared polymer. Moreover, the molecular weight of the prepared polymer nanohybrids is higher than the corresponding polymer. The results of applying the polymer as pour point depressants showed a considerable reduction from 27°C (initial pour point) to −3 °C, facilitating the process of oil flow at lower temperatures than earlier. The apparent viscosity of waxy crude oil was also decreased significantly by the addition of the (ODA/MMT) polymers, and the long-term stability of the prepared nanohybrid polymers was superior to that of a conventional polymer. The efficiency of polymers nanohybrid in reducing the pour point of crude oil associated with improved oil flow is one of the most important processes of charge and transportation process. The mechanism of enhancement of the flow properties by the polymers nanohybrid is predicted. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47333.     

Structure and electrically conductive properties of porous PAN-based nanocomposites prepared by Pickering emulsion template method

A carbon nanohybrid Pickering stabilizer was synthesized by the hydrothermal reaction of 2-ethyl-4-methylimidazole (EMI), graphene oxide (GO), and carbon nanotubes (CNTs). A water-in-oil (w/o) type Pickering emulsion was achieved using the mixed carbon nanohybrids/Span 80 to form a porous and conductive polyacrylonitrile (PAN) nanocomposites after polymerization. Contact angle and X-ray photoelectron spectroscopy (XPS) results show that the carbon nanohybrid stabilizer is amphiphilic. The effects of the composition and concentration of stabilizers were investigated. When the concentration of the carbon nanohybrid stabilizer is 4 mg ml⁻¹, the conductivity of the resulting material is 2.31 × 10⁻⁹ S m⁻¹, which is six orders of magnitude higher than that of porous PAN composites without carbon nanohybrid stabilizer. At the mass ratio of 6GO:1CNTs, the conductivity of porous PAN-based composites reaches 2.47 × 10⁻⁸ S m⁻¹. The significantly increased conductivity is the evidence for the three dimensional conductive network constructed by carbon nanohybrid stabilizer at the oil/water interface.     

Synthesis,characterization, and photophysical properties of covalent-linked ferrocene–porphyrin–single-walled carbon nanotube triad hybrid

The ferrocene–porphyrin–single-walled carbon nanotube (Fc–H₂P–SWCNT) triad hybrid was prepared by amidation reaction between carboxylated SWCNT and aminoporphyrin bearing an appended ferrocenyl substituent. The hybrid described here was fully characterized by a combination of analytical techniques such as Fourier transform infrared spectroscopy, Raman, absorption and emission spectroscopy, atomic force and scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The steady emission characteristics revealed the existence of the effective photoinduced electron transfer among ferrocene, excited porphyrin moiety and SWCNT, which was further confirmed by the results of time-resolved transient absorption spectra. The final lifetime of charge-separation state was observed to be 62.9 μs in N,N-dimethylformamide, which was significant increased compared to the reference nanohybrid porphyrin–SWCNT and the reported ferrocene–porphyrin–fullerene triad. Therefore, Fc–H₂P–SWCNT triad hybrid constructed by amidation is rationally expected to be an improved photon-to-electron conversion system.     

Oil-in-water Pickering emulsions stabilized with functionalized multi-walled carbon nanotube/silica nanohybrids in the presence of high concentrations of cations in water

Functionalized multi-walled carbon nanotube (MWCNT)/silica nanohybrid was synthesized and proposed as a stabilizer for oil-in-water Pickering emulsion. Carbon nanotube-to-silica weight ratio was a decisive factor influencing the performance of the synthesized nanohybrid. The results showed an appropriate value of such a ratio for a sol–gel synthesized nanohybrid structure was 28–33%. The emulsion formation time was dictated by the adopted mixing strategy such that without any mixing or ultrasonication it took 12 days for stabilization to be established. Conversely, the use of ultrasonication accompanied by mechanical mixing reduced this time to less than 4 h. Another key factor pertained to the type of the cation contained in water. Bivalent cations, such as magnesium and calcium, changed the hydrophilic–lipophilic balance more intensely than the sodium univalent cation. The nanohybrid holds a great promise to be adopted in enhanced oil recovery (EOR) processes as it does not require any emulsifier and mechanical treatment.     

Self‐assembly of novel architectural nanohybrid multilayers and their selective separation of solvent‐water mixtures

A new architectural nanohybrid multilayer has been explored and built on various substrates. The building blocks of positive and negative charged polyelectrolyte‐coated nanoparticles (NPs) could be obtained by tuning the electrical properties of the amphoteric oxide NPs in acid and basic environments. The nanohybrid films were, thereafter, formed by layer‐by‐layer (LbL) assembly of polycation‐ and polyanion‐coated NPs. It was demonstrated that this approach could incorporate single component NPs into both polycation and polyanion layers, and in turn improve the NP loading, maintain good dispersion of NPs within the film. For separation applications, a dynamic LbL assembly was attempted as a means of fabricating such nanohybrid multilayers on both 2‐D and 3‐D polymeric porous substrates. The nanohybrid multilayer membrane renders both much higher selectivity and flux in the separation of solvent‐water mixtures. Moreover, such assembly of nanohybrid multilayers allows us to efficiently simplify the procedures by reducing 30–40‐fold process cycles. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Preparation and properties of PVC/PMMA-g-imogolite nanohybrid via surface-initiated radical polymerization

Poly(methyl methacrylate) (PMMA) grafted imogolite clay nanotubes (PMMA-g-imogolite) were prepared through activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP) by developing a water soluble amphiphilic ATRP initiator, which carries both an initiator moiety and a surface-attachable phosphate group. Poly(vinyl chloride)/PMMA-g-imogolite nanohybrid was prepared by using this PMMA grafted imogolite. The structure and properties of the prepared nanohybrid were characterized by differential scanning calorimetry (DSC), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and tensile test. DSC and TEM results indicate that well-dispersed PMMA-g-imogolite dominates in the nanohybrid, in spite of some imogolite rich regions. SEM observation of the fracture surfaces and the fractured films reveals that the interfacial adhesion between PMMA grafted imogolite and the matrix may be weak or strong with respect to the cohesive energy of the poly(vinyl chloride) (PVC) matrix, depending on the environmental temperature. In liquid nitrogen or at room temperature, the interfacial adhesion between PMMA grafted imogolite and the matrix is weaker, while at 90 °C, is stronger than the cohesion of the PVC matrix. In accordance with the interfacial performance, the nanohybrid shows inferior tensile performance at room temperature; whereas, superior tensile performance at 90 °C compared with the pristine PVC.     

Novel chitosan‐TiO2 nanohybrid: Preparation,characterization, antibacterial,and photocatalytic properties

In this report, chitosan (CS) encapsulated titanium dioxide (TiO₂) nanohybrid was prepared by chemical precipitation method. Fourier transform infrared spectroscopy (FT‐IR) and X‐ray diffraction (XRD) confirmed the formation of nanohybrid. Transmission electron microscopy (TEM) analysis showed the immobilization of TiO₂ nanoparticles on the surface of CS. The nanohybrid was also characterized by thermogravimetric analysis (TGA) and zeta potential. The nanohybrid exhibited high photocatalytic activity as evident from the degradation of methylene blue (MB) dye. The result revealed substantial degradation of the MB dye (90%) under UV‐light illumination. The catalytic efficiency was unaltered even after five cycles of reuse. In addition, the nanohybrid exhibited a superior antibacterial activity of 100% within 24 h of treatment against Escherichia coli (E. coli) was measured by colony forming units (CFU). POLYM. COMPOS., 35:327–333, 2014. © 2013 Society of Plastics Engineers     

Facile one-step synthesis of cerium oxide-carbon quantum dots/RGO nanohybrid catalyst and its enhanced photocatalytic activity

Improvement in the catalytic activity of nanostructured cerium oxides (CeOx) was attained by incorporating in-situ generated heteroatom-(N and S)-doped carbon quantum dots/reduced graphene oxide (HDCQD@RGO) nanohybrid catalyst for the degradation of organic pollutants. The CeOx-HDCQD@RGO nanohybrid catalyst was synthesized by a facile, one-pot hydrothermal eco-friendly process. The HDCQD plays a vital role to improve the interaction between CeOx and RGO and function as a sensitizer for the electron-transfer process with CeOx. The size of CeOx and HDCQD are 10 nm and 5 nm, respectively. The nanostructured CeOx possesses multiple oxygen vacancies; this helps to generate the active oxygen and hydroxyl radicals. The active hydroxyl radical generation by the photocatalytic process with the help of nanostructured CeOx results in the improved photodegradation of organic pollutants. In addition, the prepared CeOx-HDCQD@RGO nanohybrid catalyst exhibits an improved water oxidation reaction. The CeOx-HDCQD@RGO nanohybrid performs as an excellent bifunctional catalyst for energy and environmental applications. The method presented here is a facile and environmentally friendly, scalable synthesis of the highly efficient catalyst.     

Synthesis and third-order nonlinear optical properties of a multiwalled carbon nanotube-organically modified silicate nanohybrid gel glass

We report the synthesis and characterization of multiwalled carbon nanotube (MWCNT)-organically modified silicate (ORMOSIL) nanohybrid gel glass, in which the incorporated MWCNTs are covalently bonded to the silica network. The structural properties of the 3-aminopropyltriethoxysilane functionalized MWCNTs and MWCNT-ORMOSIL nanohybrid gel glass are comprehensively characterized using spectroscopic and electron microscopy techniques. We find that the agglomeration of incorporated MWCNTs is effectively restrained and that the MWCNTs are dispersed homogeneously and individually in the gel glass matrix. Compared with the mother MWCNT suspension, the resultant nanohybrid gel glasses demonstrate sustained nonlinear optical properties at both 532 and 1064 nm laser wavelengths.     

Self-assembled peptide nanofibers on graphene oxide as a novel nanohybrid for biomimetic mineralization of hydroxyapatite

In this study, self-assembled peptide nanofibers (PNFs) were firstly created with a specially designed peptide molecule. Graphene oxide (GO) nanosheet, as a two-dimensional scaffold, was then modified with the prepared PNFs to fabricate a new type of GO–PNF nanohybrid, which was further utilized as a template for biomimetic mineralization. The produced GO–PNF nanohybrid and its minerals were characterized by atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, and thermogravimetric analysis. The obtained results indicate that the created GO–PNF nanohybrid facilitates the nucleation and growth of hydroxyapatite (HA) crystals. The created PNFs promote the formation of HA nanocrystals along the axis of PNFs within short-term incubation and the GO nanosheet mediates the formation of HA microsphere after long-term mineralization. The effects of the produced GO–PNF nanohybrid and biomimetic minerals (GO–PNF–HA) on the adhesion and proliferation of L-929 cells and MC3T3-E1 cells were further investigated. The cell culture result indicates that the produced GO–PNF–HA minerals have good biocompatibility and can enhance the proliferation ability of the studied cells. We believe this novel biocompatible nanohybrid will show great potentials in tissue engineering.