Nanoparticle Fillers Research Articles

Mechanical Properties of Thebes Limestone Treated by Nano Filler Particles

Composite material nowadays has a competitive role in controlling other material. Therefore, coating other material using such composite material help to enhance the mechanical compressive and failure strength of deteriorates ancient materials Thebes limestone is attractive source for a lot of researcher. Natural weathering like rains, rockslides, moisture, salty groundwater absorption and changing temperature can damage or even may weaken the strength of such deteriorates ancient buildings. Compression Samples of ancient Thebes limestone are coated with Nano calcium carbonate and Nano Calcium Hydroxide. While single edge notch bending samples are treated cracked face using Nano calcium carbonate. The results showed an enhancement in both compression and fracture strength.

Bio‐Inspired Multiple Cycle Healing and Damage Sensing in Elastomer–Magnet Nanocomposites

AbstractDamage‐sensing and healing are biological functions which are urgently required in structural health monitoring and remediation of engineering structures. The development of a bio‐inspired multiple cycle damage sensing and triggered healing magnet–polymer nanocomposite (Magpol) is reported. Magpol is comprised of an acrylonitrile butadiene co‐polymer (NBR) matrix and a magnetic nanoparticle (MNP) filler. Magpol nanocomposites in a range of MNP filler concentrations are studied. NBR is selected as the matrix due to its extensive use in industrial coatings, for example, in the automotive industry. Mn‐Zn ferrite MNP is chosen due to its appropriate Curie temperature and good specific absorption rate. Exposure of damaged Magpol to a remote external alternating magnetic field results in MNP heating. The MNP heats the surrounding NBR matrix, resulting in triggered healing. Fractured Magpol samples are successfully healed over several cycles. Incorporation of rhodamine b mechano‐chromophore in Magpol results in multicycle damage sensing by photo‐luminescent absorption. Thus, the developed Magpol is attractive for structural health monitoring and remediation application.

Graphite/UPE Nanocomposite: Transport, Thermal, Mechanical and Viscoelastic Properties

This chapter presents the preparation and characterization of some unique properties of nanocomposites by dispersing graphite flakes in commercial unsaturated polyester (UPE) matrix. The composite was prepared by a novel method with the use of solvent swelling technique. Three different specimens of UPE/graphite nanocomposites were fabricated with addition of 1, 2 and 3 wt% of graphite flakes. Except mechanical, viscoelastic and thermo gravimetric properties, transport properties like electrical conductivity, thermal conductivity and water transport properties were studied for the first time. Graphite flakes propose enhanced properties to the composites suggesting homogeneous distribution of the nanofiller in the matrix and strong interaction with the matrix. 2wt% nanofiller loading showed superior essential characteristics and after that the properties reduced may be due to the nucleating tendency of the nanofiller particles. The XRD pattern showed the compatibility of the graphite flakes by introducing a peak around 26.550 in the nanocomposites. SEM Properties are also in agreement with the compatibility. Nanocomposite with 2wt% graphite also showed remarkable enhancement in transport, mechanical, viscoelastic and thermo gravimetric properties. So by introduction of a small quantity of graphite endow the new class of multiphase nanocomposites with inimitable structure and tremendous application.

Chitosan Grafted Carbon Nanotubes Reinforced Vinyl Ester/UPE Blend Based Partially Bio-Nanocomposite

This work represents the preparation and characterization of some unique properties of vinyl ester (VE) and unsaturated polyester (UPE) blend based nanocomposites by introducing biopolymer chitosan grafted multi-walled carbon nanotubes (MWCNTs). Initially, surface grafting of MWCNTs with chitosan was performed by utilizing glutaraldehyde as a cross linking reagent through covalent deposition method and are successfully characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy(SEM). Then 50:50 wt % of vinyl ester and unsaturated polyester blend was prepared by simple sonication method. Three different specimens of VE/UPE/CS-g-MWCNTs nanocomposites were fabricated with addition of 1, 3 and 5 wt % of functionalized bionanofiller. Chitosan grafting of MWCNTs offered enhanced properties to the nanocomposites suggesting homogeneous distribution of the nanofiller in the matrix with minimum corrosion and swelling properties. 3 wt % of functionalized bionanofiller loading showed superior essential characteristics and after that the properties reduced may be due to the nucleating tendency of the nanofiller particles.

Impact of PVDF/PEO blend composition on the β-phase crystallization and dielectric properties of silica nanoparticles incorporated polymer nanocomposites

Polymer nanocomposite (PNC) films consisted of varying weight composition polymer blends of poly(vinylidene fluoride) (PVDF) and poly(ethylene oxide) (PEO) as host organic matrices incorporated with 5 wt% amorphous silica (SiO2) nanoparticles as inorganic nanofiller have been prepared by solution casting method. The alterations in morphology, PVDF polymorphism and relative fraction of β-phase crystals, degree of crystallinity, and the polymer-polymer and polymer-nanoparticle interactions with change of polymer blend compositional weight ratio (i.e., PVDF/PEO = 100/0, 75/25, 50/50, 25/75, and 0/100) have been investigated by the SEM, EDX, XRD, and FTIR measurements. The frequency dependent complex dielectric permittivity, ac electrical conductivity, and electric modulus of the PNC films are studied at room temperature by employing the DRS technique. The SEM images reveal that the spherulite morphology of PVDF/PEO blend structures incorporated with SiO2 nanoparticles is altered enormously with the change of polymers blend compositions in the PNC films. The XRD results of these PNC films confirm that the β-phase crystallization is considerably enhanced in the PVDF-rich PNC film but it decreases almost linearly with the increase of PEO amount in the host matrices of these films, and remains higher for the PNC films in comparison to that of the pristine polymer blend films. The degree of crystallinity of these PNC films enhances non-linearly with the increase of PEO concentration but it is found low as compared to that of the PVDF/PEO blend films without nanofiller. Dielectric dispersion in the frequency range from 20 Hz to1 MHz reveals that the interfacial polarization significantly contributed to the enhancement of dielectric permittivity in the audio frequency range of dielectric spectra of these PNC films. The addition of 5 wt% amount of SiO2 nanoparticles in the pristine PVDF and PEO matrices reduces the dielectric permittivity over the entire frequency range, whereas the presence of these nanofiller particles in the PVDF/PEO blend matrices based PNC films increases at radio frequencies which is predominantly due to enhancement of the β-phase crystals. The relaxation time values determined from the relaxation peaks exhibited in the loss part of electric modulus spectra confirm that there is an increase in hindrance to the PEO chain segmental dynamics with the increase of PVDF amount in the polymer blend compositions of these PNC films, whereas the dc electrical conductivity is found independent of the blend composition. The polymer blend compositional ratio dependent promising structural, dielectric, and electrical properties of these PNC films offer their suitability as tunable novel nanodielectric materials of multifunctionality for the flexible electronic devices.

Room temperature ac conductivity, dielectric properties and impedance analysis of polypyrrole-zinc cobalt oxide (PPy/ZCO) composites

Zinc-cobalt oxide nanoparticles were fabricated by hydrothermal method. The polypyrrole and zinc cobalt oxide (PPy/ZCO) composites were synthesized by using in-situ chemical polymerization method. These composites were characterized by x-ray diffraction (XRD) which confirmed the crystalline nature of the PPy/ZCO composites. The scanning electron microscopy and energy dispersive x-ray diffraction (EDX) confirmed the spherical structured particles of composites and the chemical composition, respectively. Electrical characterizations of PPy/ZCO composites were analyzed as a function of ZCO concentration in the frequency range of 102–106 Hz. The alternating current (ac) conductivity versus frequency graph for PPy/ZCO composites showed a direct current (dc) plateau in the frequency range of 102–104 Hz, indicating an isolated network within the composites. At the higher frequencies, there was an increase in ac conductivity obeying the universal dynamic response (UDR). The UDR suggested that the conduction in the PPy/ZCO composites was due to hopping along the polymer chains due to filler nanoparticles. The nature of response of real and imaginary part of impedance (Nyquist plot) revealed that the conduction has attribution from the effects of grains and grain boundaries.

Investigation on SPEEK/PAI/SrTiO3-based nanocomposite membrane for high-temperature proton exchange membrane fuel cells

Optimization of an alternative proton exchange membrane fuel cell (PEMFC) instead of Nafion membrane electrolyte with sulfonated poly(ether ether ketone) (SPEEK) is regarded as the most promising alternative to commercial membranes. In this work, facile composite membranes consisting of SPEEK/poly (amide imide) (PAI) and SrTiO3-based nanocomposite electrolyte are prepared by solvent casting technique. The prepared samples are characterized by FT-IR, thermo-mechanical stability, electrochemical impedance spectroscopy (EIS), water uptake capacity, swelling ratio, and ion transport capacity tests. The incorporation of PAI in the membrane structure has increased the mechanical strength, increased water uptake, and restricted swelling ratio. Incorporation of SrTiO3 nanoparticle fillers are easily bounded into the polymer membrane matrix via ionic interaction due to presence of sulfonic acid groups moieties in SPEEK. The addition of SrTiO3 filler in the blend membranes provided enhanced protonic conductivity, ion exchange capacity with restricted swelling capacity, and inhibit water loss at high temperatures. The highest proton conductivity of 10.78 × 10−3 S cm−1 at 150 °C is obtained by the SPEEK (90 wt%)/PAI (10 wt%)/SrTiO3 (06 wt%) coded membrane in electrochemical impedance spectroscopy. This study shows that nanocomposite blend membrane seems to be a promising alternative membrane for PEMFC application. The SPEEK and SPEEK/PAI/SrTiO3(06 wt%) nanocomposite membrane obtained the current density and power density values of 277 mA cm−2, 56 mW cm−2 and 379 mA cm−2, and 75 mW cm−2, respectively.

Tuning mechanical reinforcement and bioactivity of 3D printed ternary nanocomposites by interfacial peptide-polymer conjugates

We present a study on ternary nanocomposites consisting of medical grade poly(ε-caprolactone) (mPCL) matrix, hydroxyapatite nanopowder (nHA) and compatibilized magnesium fluoride nanoparticle (cMgF2) fillers. MgF2 nanoparticles were compatibilized by following a design approach based on the material interfaces of natural bone. MgF2-specific peptide-poly(ethylene glycol) conjugates were synthesized and used as surface modifiers for MgF2 nanoparticles similarly to the non-collagenous proteins (NPC) of bone which compatibilize hydroxyapatite nanocrystallites. Different compositions of mPCL/nHA/cMgF2 composites were blended together and processed into three dimensional (3D) scaffolds using solvent-free techniques including cryomilling and melt extrusion-based additive manufacturing. The use of two different inorganic fillers in mPCL resulted in nanocomposite materials with enhanced mechanical and biological properties. In particular, cMgF2 nanoparticles were found to be the primary constitent leading to the significant improvements in the mechanical properties of these composites. The scaffolds of the ternary nanocomposites provided the best in vitro performance in terms of osteogenic differentiation and stimulated mineralization. In summary, we demonstrated that the concept of bioinspired interface engineering facilitates the development of homogeneous ternary nanocomposites with increased processability in additive biomanufacturing. Additionally, the concept leads to scaffolds exhibiting enhanced mechanical and biological properties. Overall, these multicomponent nano-interfaced building blocks add a new group of advanced functional materials with tunable mechanical properties, degradation and bioactivity.

Stone consolidation with SiO2 nanoparticles: Effects on a high porosity limestone

This study deals with the effect of a water colloidal suspension of nanosilica applied as a consolidant on a porous limestone. The stone performances were investigated by several analyses and tests. They fulfilled basic requirements such as consolidating effectiveness and compatibility with the original colour and water transport properties. A point of weakness was found in the behaviour under the salt crystallisation test, showing a decreased durability for the treated stone. The modification of the porous structure accounts for this result, suggesting that the distribution of the nanoparticle fillers into the stone substrate should be improved.

A new permeation model in porous filler–based mixed matrix membranes for CO2 separation

AbstractIn this paper, a novel comprehensive permeation model for mixed matrix membranes (MMMs) is introduced. This model shows the importance of understanding and developing a more reliable model for the permeation behavior of MMMs containing porous filler nanoparticles. A new method is established to provide a more precise/large‐scale three‐dimensional MMMs geometry. The required number of spherical porous fillers in random/nonuniform positions in the polymer matrix is calculated. Interfacial equilibrium constant (K) at the polymer/filler interfaces was adjusted as the concentration ratio of the diffusing penetrants (C2 and C1) at the interface, respectively. In this case, the K values are changed by varying the intended gaseous concentration due to their permeation through the MMM. Hence, its effect on penetrants effective diffusion coefficient was examined. Then, the obtained results were evaluated with similar experimental data, which showed much consistency. Therefore, the accurate calculation method for MMMs permeability was governed for the entire range of the operating pressures in MMMs. The results showed that the permeability of MMMs increases with increasing filler particle size. On the other hand, variations that occur in the MMM permeability at various particle size were much more distinct at higher loadings. Moreover, some well‐known analytical permeation models were used to compare and validate the model's permeability results. It can be concluded that this model provides a method for more precise and realistic design of MMMs as well as to better construe the large number of related experimental data. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

Modeling of Entangled Polymer Diffusion in Melts and Nanocomposites: A Review.

This review concerns modeling studies of the fundamental problem of entangled (reptational) homopolymer diffusion in melts and nanocomposite materials in comparison to experiments. In polymer melts, the developed united atom and multibead spring models predict an exponent of the molecular weight dependence to the polymer diffusion very similar to experiments and the tube reptation model. There are rather unexplored parameters that can influence polymer diffusion such as polymer semiflexibility or polydispersity, leading to a different exponent. Models with soft potentials or slip-springs can estimate accurately the tube model predictions in polymer melts enabling us to reach larger length scales and simulate well entangled polymers. However, in polymer nanocomposites, reptational polymer diffusion is more complicated due to nanoparticle fillers size, loading, geometry and polymer-nanoparticle interactions.

Polymer engineering by blending PIM-1 and 6FDA-DAM for ZIF-8 containing mixed matrix membranes applied to CO2 separations

The preparation of mixed matrix membranes (MMMs) for post-combustion CO2 capture and biogas upgrading from PIM-1 (10–90 wt%)/6FDA-DAM heterogeneous blends with ZIF-8 as filler (3–20 wt% with regard to the polymer blend) is described. The heterogeneity of the blend, considered here as an advantage for the dispersion of the filler within the MMMs, has been confirmed by the existence of a single glass transition temperature, consistent with that of 6FDA-DAM. The segregation between the two polymeric phases and the filler dispersion has been studied by Raman spectroscopy, SEM microscopy and EDX analysis. Increasing the amount of PIM-1 in the blend makes the d-spacing of the polymer chains higher and increases gas permeability. When embedding filler nanoparticles of ZIF-8, a better compatibility with 6FDA-DAM than with PIM-1 is observed. The filler locates near the interphase between polymers helping its dispersion. The use of small loadings of ZIF-8 enhances the gas separation performance of the MMMs in terms of permeability and selectivity for 50/50 CO2/CH4 and 10/90 CO2/N2 mixtures. The best performing membranes are the blends PIM-1/6FDA-DAM 10/90 (w/w) with 10 wt% of ZIF-8, showing a CO2 permeability of 2891 Barrer, a CO2/CH4 selectivity of 26.6 and 2802 Barrer of CO2 with a CO2/N2 selectivity of 18.1. Importantly, the CO2, N2 and CH4 permeabilities of the pure polymeric blends can be predicted using both the logarithmic and the Maxwell models. A new coupled Maxwell model has also been developed able to calculate the flow through the blends containing ZIF-8 and to predict the gas separation properties of the filler itself.

The Effect of Uniaxial Extrusion on the Degree of Reinforcement of Nanocomposites Polyvinyl Chloride/Boron Nitride

The influence of uniaxial extrusion on the structure, molecular characteristics, and properties of polymer/2D nanofiller nanocomposites is elucidated by example of polyvinyl chloride/boron nitride nanocomposites. The extrusion is found to cause a drastic (by 2.5 times) increase in statistical rigidity of polymer chains in the nanocomposite matrix determined by their characteristic ratio. The characteristic ratio for unoriented samples is less than that for a polymer precursor, but exceeds the values for oriented specimens. Nanofiller particles (or their aggregates) form a fractal network (“skeleton”) in the polymer matrix, whose dimension increases upon uniaxial extrusion. This effect leads to a linear reduction of the percolation index in the percolation model of reinforcement of nanocomposites, which significantly affects the degree of their reinforcement. When the dimension reaches its threshold of 2.8, the percolation index changes values from positive to negative values, meaning the transition from the “ant” to the “termite” limit. This yields an abrupt (to ~150) increase in the degree of reinforcement of polymer nanocomposites at low nanofiller contents. The characteristic ratio of polymer chains of the nanocomposite matrix is closely related to the aggregation level of the 2D nanofiller, which depends on the number of boron nitride slabs in a “package” (tactoid). The relative fraction of interfaces serving as reinforcing elements in a nanocomposite structure by analogy with nanofillers is also a function of statistical rigidity of polymer chains in the matrix and increases with the characteristic ratio. The theoretical estimates in the context of the percolation model of reinforcement reveal the prospects in the improvement of the properties of polymer/2D nanofiller nanocomposites.

The improvement of thermal conductivity in silica gel composite employing graphene nano-particles

Heat conducting gel sheets were fabricated with graphene nano-particles (GNPs) filler which was prepared by ball-milling method. The thermal conductivity of GNPs gel sheets (GNPs-GS) with 10 wt.% reaching 0.38 W/(m⋅K) at [Formula: see text] increased by 90% compared with the pure gel sheets (Pure-GS). The conduction of heat-sink device which was made of GNPs-GS with 10 wt.% is much faster than the one which was made of Pure-GS. FE-SEM images show that the GNPs are layered and uniformly distributed in the matrix, which demonstrated the actual exfoliation of GNPs in the process of ball-milling. This handy and cost-efficient method of ball-milling to exfoliate GNPs and further for fabricating heat conducting gel sheets is a feasible program in industrial production.

A conductive mechanism of PVA (Mowiol 10-98) filled with ZnO and MWCNT nanoparticles

Polyvinyl alcohol (PVA) hybrid nanocomposites are prepared via an ex situ approach with ZnO and MWCNT nanoparticle fillers and their conductive mechanisms have been investigated. The tailored hybrid nanocomposite conformation and their microstructural disparities for different filler concentrations were studied using an X-ray diffractometer. The direct current (DC) conductivity studies show an increase in the conductivity from \(1.0528\times 10^{-11}\) to \(2.1514\times 10^{-8}\hbox { S cm}^{-1}\) up to a percolation threshold filler concentration of \(x=7.5\) wt%. The dielectric constant substantially indicates a decreasing trend with increasing frequency. The exaggerated dielectric constant values of 11.8 at 5 kHz, 6.3 at 100 kHz, 5.86 at 500 kHz and 2 at 1 MHz are observed for 7.5 wt% filler hybrid nanocomposites, which indicates their potential application as a gate material in metal-oxide-semiconductor field-effect transistors (MOSFETs). The alternating current (AC) electrical conductivity demonstrates an increasing behaviour up to \(x=7.5\) wt% filler concentration. The smaller values observed in the real part of the electric modulus (\({M}^{\prime })\) indicates a riddance in electrode polarization. The observed higher frequency shift in the imaginary part of the electric modulus for increasing the filler concentration up to \(x=7.5\) wt%, decreases the relaxation time of the dipole orientation thereby increasing the conductivity mechanism of the hybrid nanocomposites. Apart from these, its small relaxation time with high electrical conductivity favours this material PVA/(x)MWCNT(\(15-x\))ZnO to have prospective application in microwave absorption appliances. The increase in the surface roughness of the film seen from the AFM images up to \(x=7.5\) wt% concentration supports an enhancement in the crystalline nature of the filler. Differential scanning calorimeter studies show an enhancement in glass transition temperature (\(T_{\mathrm{g}})\), melting temperature (\(T_{\mathrm{m}})\) and decomposition temperature (\(T_{\mathrm{d}})\) for PVA filled with MWCNTs and ZnO composites for optimum filler concentration \(x=7.5\) wt%.

Nanostructural Properties of Fe3-xZnxO4-PEG/Carboxymethyl Cellulose/Polyvinyl Alcohol Magnetic Hydrogel by Using SAXS

The Fe3-xZnxO4-PEG/Carboxymethyl Cellulose/Polyvinyl Alcohol (Fe3-xZnxO4-PEG/CMC/PVA) magnetic hydrogel has been successfully synthesized through the freezing-thawing process. The filler of Fe3-xZnxO4 nanoparticles has been successfully fabricated using the coprecipitation method. The investigation of nanostructural characteristic of Fe3-xZnxO4-PEG/CMC/PVA magnetic hydrogel was conducted using X-Ray Diffractometer (XRD), TEM, and Small Angle X-ray Scattering (SAXS) spectrometer to analyse the structure of crystal, morphology of Fe3-xZnxO4-PEG/CMC/PVA nanoparticles, and nanostructural behaviour of Fe3-xZnxO4 distribution in the Fe3-xZnxO4-PEG/CMC/PVA magnetic hydrogel The addition of Zn doping into Fe3-xZnxO4 nanoparticles with the variation of compositions of x = 0.65, 0.75, and 0.85 has been done and caused the shifting of the peak of diffraction angle to the smaller diffraction angle as the addition of x composition. Through the X-ray analysis, it can be found that the sizes of Fe3-xZnxO4 nanoparticles crystal in the Fe3-xZnxO4-PEG/CMC/PVA magnetic hydrogel were around 10 - 12 nm. These data were in line with the data analysis using SAXS, especially the value of secondary particles from the Fe3-xZnxO4 magnetic filler with the values of about ∼ 9 nm. Meanwhile, the values of Fe3-xZnxO4 primary particles were about ∼ 2 nm. The data of the distribution of Fe3-xZnxO4-PEG magnetic nanoparticles in the Fe3-xZnxO4-PEG/CMC/PVA magnetic hydrogel were also supported by the characterization of the nanoparticles filler morphology using TEM showing the number of about 9 - 11 nm. The tissue of PEG/CMC/PVA polymer was effective enough in inhibiting the aggregation of Fe3-xZnxO4 filler nanoparticles so that they could be equally distributed in the Fe3-xZnxO4-PEG/CMC/PVA magnetic hydrogel.

Polymer-particulate composites with differential interfaces: synthesis, characterization, and mathematical modeling to evaluate interface-yield strength correlations

Polymer particulate composites (PPC) are extensively used in numerous mechanical and aviation applications, which take advantage of their synergistic properties such as superior yield strength. This work combines experimental and theoretical approaches to evaluate yield strength of thermosetting PPC made of pristine p-TiO2 or surface-grafted g-TiO2 nanoparticles and an epoxy thermoset. Accordingly, p-PPC and g-PPC sheets containing different volume fraction (ϕf = 0.0234–0.0936) of p-TiO2 or g-TiO2 nanoparticles exhibit variable yield strength. A mathematical model is used to evaluate the effects of nanoparticles aggregation on the relative yield strength of PPC. The interfacial parameters “B” and “Bagg” give a quantitative measure of the ability of stress dispersion by the agglomerated nanoparticles. The higher “B” and “Bagg” values for g-PPC reveal its greater interfacial strength. The experimental data show good correlation with the theoretical predictions. However, these models truly predict PPC’s yield strength only at low volume fraction (ϕf ≤ 0.09) of filler nanoparticles.

The Size Effect of Strenthening for Dispersion-Filled Polymer Nanocomposites

In the case of dispersion-filled polymer nanocomposites, it is assumed that a decrease in the size of dispersed nanoparticles leads to a strong increase in their degree of amplification. However, it is known that reducing the size of nanofiller particles intensifies the process of their aggregation, which ultimately dramatically increases the effective size of the nanofiller in the polymer matrix. Therefore, the question arises which nanofiller is more effective from a practical point of view – one having a small size of the initial particles, but highly aggregated, or another having a relatively large size of nanoparticles, but poorly aggregated. The aim of this work is to answer the above question. We have used two dispersion-filled polymer nanocomposites having the same polymer matrix, but filled with a dispersed filler, which size of the original particles differed by about 15 times. It is shown that the level of aggregation of dispersed nanofiller particles in the polymer matrix of the nanocomposite is controlled by two main factors: the size of its initial particles and the conditions for obtaining the nanomaterial, and the influence of the first factor prevails. The process of nanofiller aggregation significantly affects the level of interfacial adhesion and, as a consequence, the final properties of nanocomposites.

Structural and dynamic study of block copolymer – Nanoparticles nanocomposites

Nanocomposites based on block copolymer (BCP) and gold nanoparticles (NPs) filler were measured in terms of their structure and polymer chain molecular dynamics. NPs were functionalized in order to gain selective affinity to one specific type of BCP domain. BCP directed NPs assembly was monitored using atomic force microscopy. Thin nanocomposite films were fabricated via spin-coating technique, annealed and subsequently subjected to reactive ion etching in order to expose inorganic NPs location within the BCP matrix. Selective NPs incorporation was confirmed. Furthermore, interesting NPs distribution in quasi-2D crystallites was revealed. Spectroscopic methods (nuclear magnetic resonance and dielectric spectroscopy) enabled investigation of polymer chain reorientations and estimation of the impact of nano-filler on polymer dynamics. Nanocomposite crystallinity was assessed via thermal analysis and supported by spectroscopic techniques.

Graphene-Augmented Polymer Stabilization: Drastically Reduced and Temperature-Independent Threshold and Improved Contrast Liquid Crystal Device.

Polymers reinforced with nanofillers, especially graphene in recent times, have continued to attract attention to realize novel materials that are cheap and also have better properties. At a different level, encapsulating liquid crystals (LCs) in polymer networks not only adds mechanical strength, but could also result in device-based refractive index mismatch. Here, we describe a novel strategy combining the best of both these concepts to create graphene-incorporated polymer-stabilized LC (PSLC) devices. The presence of graphene associated with the virtual surface of the polymer network besides introducing distinct morphological changes to the polymer architecture as seen by electron microscopy brings out several advantages for the PSLC characteristics, which include 7-fold lowered critical voltage, its temperature invariance, and enhanced contrast ratio between field-off scattering/field-on transparent states. The results bring to fore the importance of working at very-dilute-concentration limits of the filler nanoparticles in augmenting the desired properties. These observations open up a new vista for polymer–graphene composites in the area of device engineering, including substrate-free smart windows.