Nanocomposites In Solid State Research Articles

Carbon dots as building blocks for the construction of functional nanocomposite materials

Carbon dots (CDs) are carbon-based quasi-spherical fluorescent nanoparticles with unique physical and chemical properties. Due to their complexity and diversity, CDs are applied in analytics, sensors, bio-imaging and diagnostics. Stabilizing CDs as well as improving their performances can extend their range of applications; it is desirable to combine them in an appropriate solid matrix or prepare solid-state nanocomposites. In this review, a summary of the research of CD nanocomposites is given. Describes the loading methods of CDs on polymers, metals and their compounds, non-metals and their compounds, and metal organic frameworks, which including electrostatic interactions, covalent bonds, non-covalent bonds or hydrogen bonds. In addition, the working mechanism and application of CD nanomaterials are also introduced. The challenges encountered, potential and prospects with CD nanocomposite are discussed at the end of the article.

Restricting Molecular Mobility in Polymer Nanocomposites with Self-Assembling Low-Molecular-Weight Gel Additives.

Multiscale investigation of molecular gel additives in polymer matrices guides understanding of how solution-state assemblies result in mechanically enhanced, solid-state nanocomposites. Model polymers, poly(ethylene oxide- co-epichlorohydrin) (EO-EPI) and poly(vinyl acetate) (PVAc), were utilized as matrices and reinforced by cholesterol-pyridine (CP) nanofiber networks. The CP nanofillers suppress ethylene oxide segment melting for EO-EPI composites, whereas for PVAc nanocomposites, cause a polymer-gel dissociation transition. Incorporation of crystalline CP fiber networks led to an order of magnitude increase in tensile storage modulus due to restrictions on polymer chain mobility. This decrease in molecular mobility was confirmed by decreased loss moduli for both EO-EPI and PVAc composites. Excitingly, PVAc nanocomposites display an additional relaxation mode caused by release of PVAc chains from the transient molecular gel assembly. For both EO-EPI and PVAc composites, bulk flow can be suppressed to temperatures up to 100 °C by simply increasing the CP concentration.

PREPARATION, CHARACTERIZATION, AND EVALUATION OF ANTI-INFLAMMATORY ACTIVITY OF ETORICOXIB LOADED SOLUPLUS® NANOCOMPOSITES

Objective: The objective of this study was to prepare and characterize etoricoxib (ECB) loaded Soluplus® nanocomposites to improve its physicochemical properties. The effect of polymer and surfactant concentration on particle size, in vitro percentage dissolution efficiency and the anti-inflammatory activity of nanocomposites were also investigated.Methods: The nanocomposites were prepared by using a freeze-drying technique. The analytical evidence for the formulation of lyophilized nanocomposites in solid state were generated and confirmed by differential scanning calorimetry (DSC), fourier transformation infrared spectroscopy (FTIR), x-ray powder diffractometry (XPRD) and scanning electron microscopy (SEM). The in vitro drug release profile of nanocomposites was compared with pure ECB powder.Results: The nanocomposites of ECB were contained in a nano range with particle size and zeta potential of 63.5 nm and 46.5 mv, respectively. The solubility and dissolution of the nanocomposites were significantly (p<0.001) improved as compared to ECB alone, evidenced by decreased log P values (1.90±0.002) of the nanocomposites. The characterization studies revealed the formation of amorphous nanocomposites of ECB with existence of physical interactions between drug and polymer. The anti-inflammatory activity of nanocomposites evaluated by carrageenan-induced rat paw edema model demonstrated nonsignificant (p>0.05) increase in anti-inflammatory activity as compared to pure ECB.Conclusion: From the results, it could be concluded that the formation of ECB nanocomposites with Soluplus® could be an effective and alternative approach to modify the physicochemical properties of ECB.

Photochromism of Diarylethene Composite Organometallic Nanostructures. I. Spectrophotometry and Scanning Probe Microscopy Studies

Methods for fabricating solid-state Ag- and Au-containing nanostructured composites with shells of photochromic diarylethenes (DAEs) were developed. The obtained nanocomposites exhibited photochromic properties similar to photochromic transformations of DAEs in solutions and solid-state layers without metal nanoparticles. Chemical interaction between the nanoparticles and S-containing DAE derivatives were detected in the solid-state nanocomposites.

Morphological studies and thermo‐mechanical behavior of polypropylene/sepiolite nanocomposites

This article describes the effect of natural Sepiolite nanofibers on the properties of polypropylene (PP) in the absence/presence of compatibilizer (maleic anhydride grafted‐polypropylene (PP‐g‐MA)). For this purpose, PP/Sepiolite and PP/PP‐g‐MA/Sepiolite nanocomposites were prepared by melt blending using twin‐screw extruder. The morphology and dispersion of Sepiolite in PP composites characterized using scanning electron microscope (SEM) and transmission electron microscope (TEM) revealed that the dispersion of Sepiolite in PP matrix was better in the presence of PP‐g‐MA. Thermogravimetric analysis (TGA) was used to study the effect of Sepiolite on the thermal stability of PP in absence/presence of PP‐g‐MA. X‐ray diffraction (XRD) and differential scanning calorimetric (DSC) techniques were employed to assess the effect of Sepiolite on the crystallinity of PP matrix. Dynamic mechanical analysis (DMA) was used to evaluate the viscoelastic properties of PP/Sepiolite nanocomposites in solid state. Mechanical properties evaluated as per ASTM methods showed ∼65% increase in flexural modulus, 60%–70% increase in tensile modulus and 10%–20% increase in impact strength on addition of 10% Sepiolite in PP. Addition of compatibilizer has further improved the flexural modulus close to 85% when compared to neat PP without compromising other properties like impact strength and tensile strength. POLYM. COMPOS., 38:E285–E294, 2017. © 2015 Society of Plastics Engineers

Thermophysical and rheological behavior of polystyrene/silica nanocomposites: Investigation of nanoparticle content

In this work, solvent blending in combination with extruding are applied to provide polystyrene/silica nanocomposite specimens. Transmission electron microscope (TEM) and scanning electron microscope (SEM) show same nanoparticle dispersion in PS matrix in low to high filler loadings. Differential scanning calorimetry (DSC), dynamic mechanical thermal analyzer (DMTA) and thermogravimetric analyzer (TGA) were used to study the thermophysical characteristic of the nanocomposites in solid state. In addition, the melt state rheological behavior of the samples was investigated under constant and zero shear rates. Interestingly, different behaviors were detected in nanocomposites in low and high nanoparticle loadings. In addition, rheological characteristics of molten polymer are dramatically affected in samples with low nanosilica concentration while stabilized in high filler loadings.

A method to produce two-phase nanocomposites in solid state

We demonstrate that full-density, bulk, two-phase nanocomposites can be produced stoning from a powder mixture of two coarse-grained individual phases in equilibrium. Instead of going through liquid or vapor phase precursors, mixing is achieved through mechanical milling, a highly nonequilibrium driven process imposing external forcing. The precursor created is a supersaturated solid solution with nanocrystalline grain sizes. Upon subsequent hot consolidation to bulk samples, phase separation occurs on the scale of the nanograins, forming two-phase nanocomposites in situ. Transmission electron microscopy of the Cu 60Fe 40 sample presented in this paper confirm that, after full density processing using the sinter forging consolidation scheme, nanophase grains are maintained and a homogeneous twophase micro structure is obtained.