Polymer Nanocomposites Research Articles

Fabrication and performance evaluation of polycarbonate/polyvinyl alcohol–titanium dioxide thin‐film nanocomposite membranes for water treatment

AbstractIn recent years, there has been growing interest in using polymer nanocomposite membranes as a more advanced method for removing pollutants from water and treating wastewater for various purposes. In this study, thin‐film nanocomposite (TFN) membranes of polycarbonate/polyvinyl alcohol–titanium dioxide thin‐film (PC/PVA–TiO2) were fabricated by dip‐coating a PC substrate in a PVA/TiO2 solution. Various methods, including attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR) spectroscopy, field emission scanning electron microscopy (FE‐SEM), atomic force microscopy (AFM), and water contact angle were utilized to assess the structural characteristics of the produced membranes. The PC/PVA thin‐film composite (TFC) and PC/PVA–TiO2 TFN membranes were then examined in a submerged membrane system to evaluate their effectiveness in filtering humic acid (HA) under various vacuum transmembrane pressure (0.3 and 0.6 bar) condition. The FTIR‐ATR results confirmed the formation of the active layer of PVA/TiO2 nanoparticles (NPs). It was observed that adding 1 wt.% of TiO2 NPs to the active layer of PVA/TiO2 significantly enhanced the water contact angle from 77.5° for PC support to 55.3° for PC/PVA–TiO2 (0.1) TFN membranes. Furthermore, the FE‐SEM results confirmed the formation of an active layer of PVA/TiO2 with a thickness of 237.87 nm. The pure water flux increased from 101.64 L/m2h for the PC/PVA TFC membrane to 144.02 L/m2h and 199.09 L/m2h for the PC/PVA–TiO2 (0.05) and PC/PVA–TiO2 (0.1) TFN membranes, respectively. Also, the results revealed that at lower transmembrane pressure, all membranes showed higher value in HA removal as compared to when higher transmembrane pressure was used.

Novel poly(2-ethyl-2-oxazoline) and poly(diallyldimethylammonium chloride) polymer functionalized montmorillonite: Physicochemical aspects and near-IR study of hydration properties

The novel functionalized montmorillonites (Mts) with non-ionic poly(2-ethyl-2-oxazoline) (PEtOx) and cationic poly(diallyldimethylammonium) (PDDA) were created via an intercalation method with different loading ratio of both polymers. A comprehensive investigation into their physicochemical properties was conducted using Carbon analysis (CA), Powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FTIR), Simultaneous thermal analysis (TGA/DSC) and BET-N2 adsorption analysis. The impact of hydration on PEtOx-Mts and PDDA-Mts was assessed through gravimetric analysis and near-infrared spectroscopy (NIR) spectroscopy. PXRD analysis revealed a significant increase in 001 diffraction of PDDA-Mt corresponding to a PDDA interlayer with a basal spacing ranging from 1.47 to 1.49 nm. Conversely, the basal spacing exceeding 2 nm for PEtOx suggested, that the PEtOx polymer was intercalated in a larger amount and packed in a less compact manner compared to PDDA. After modification of Na-Mt with PEtOx polymer, FTIR spectroscopy confirmed the presence of the carbonyl CO group (3265 and 1641 cm-1) and the stretching (2982, 2942 and 2883 cm-1) and bending (1480–1200 cm-1) vibrations of the CH2 and CH3 groups. The vibrations of CH groups were further verified following PDDA modification. NIR spectroscopy also confirmed the vibrational bands attributed to both modifiers after intercalation of PEtOx and PDDA. The results of BET-N2 adsorption revealed a significant decrease in the specific surface area (SSA) after intercalation with a non-ionic PEtOx polymer. On the contrary, in the case of saturation of Na-Mt with polycation PDDA, SSA increased slightly in two instances. TGA analysis confirmed greater weight loss for PEtOx-Mts compared to PDDA-Mts. Derivative thermogravimetry (DTG) revealed the release of physisorbed bound water around 100 °C, decomposition of the organic phase within the 250–550 °C range and dehydroxylation of OH groups around 550–800 °C in both cases. The results obtained from the gravimetry and NIR analysis indicated a greater hydrophobic nature for PEtOx-Mts compared to PDDA-Mts. These findings hold substantial potential for enhancing the properties of novel organo-montmorillonites, thereby facilitating their application as adsorbents for pollutants, surface coatings, biodegradable materials, fillers in polymer nanocomposites, drug carriers, anticancer agents and various other significant applications.

Plasticized PVC composites comprising MWCNT‐RGO hybrid filler–the synergetic effect of hybrids on the dielectric and mechanical properties

AbstractModification of polymers with hybrid fillers has sought much attention in the past few years. The addition of hybrid fillers will lead to a synergistic effect in reinforcing and is advantageous in polymer nanocomposites. One such attempt is presented here that explores the effect of incorporation of hybrid derived from reduced graphene oxide (RGO) and multiwalled carbon nanotubes (MWCNT) on the dielectric and mechanical properties of plasticized polyvinyl chloride (PPVC). This system of hybrid composite incorporating RGO‐CNT and PPVC has not been prepared and reported yet. Melt mixing techniques were effectively used for the fabrication of PPVC nanocomposites containing the hybrid filler in different ratios. The prepared composites showed enhanced dielectric strength in the lower frequency region up to 450 and high AC conductivity. The mutual stacking and penetration of the 1D‐2D nanomaterials lead to effective dispersion and enhancement in the electronic conduction. Among the hybrids, the R1C5 (with the filler ration RGO 1 wt% and CNT 5%) was having the optimum properties. The tensile modulus showed a cumulative variation with the addition of CNT. Even though the tensile strength decreased slightly because of the immobilization of the PPVC chains by the hybrid effect, the modulus value showed a marked increase of over 90% from the virgin polymer. The PPVC composite with R1C5 hybrid filler exhibited an EMI shielding efficiency of ⁓23 dB and it was frequency independent. The results suggest the composite R1C5 should be used as a cost‐effective material for applications in the L‐band and S‐band regions.

Enhancing electrical insulation and thermal conductivity in polydimethylsiloxane polymer nanocomposites through silica coating on carbon fibers

Mesophase pitch-based carbon fibers (MPCFs) exhibit high thermal conductivity (∼900Wm−1K−1) and are considered to be an important candidate for future thermal management. However, MPCFs lead to an increase in the electrical conductivity of nanocomposites due to the low volume electrical resistivity (∼10−3 Ω cm). The development of MPCFs nanocomposites with high thermal conductivity and good electrical insulation remains a challenging problem. In order to solve the problem, we utilized the surfactant cetyltrimethylammonium bromide (CTAB) as an anchor for hydrolysis, and employed a sol-gel method to deposit a silica coating on MPCFs (silica@MPCFs). Silica@MPCFs was used as the filler for polydimethylsiloxane (PDMS) matrix. The nanocomposites exhibit commendable thermal conductivity (achieving 1.52 Wm−1K−1) and excellent volume electrical insulation (exceeding 1013 Ω cm) at a 30 vol% concentration. Notably, both the thermal conductivity and volume electrical insulation exceed MPCFs/PDMS. This approach to electrical insulation treatment holds substantial potential for the future preparation of high-performance nanocomposites of electronic devices.

Direct Writing of SiC-polymer nanocomposites for humidity sensing with enhanced performance

Humidity sensors are essential for monitoring humidity levels in various fields. This paper investigates the development and optimization of humidity sensitive SiC-Fe3O4 polymer nanocomposites with varying Fe3O4 concentrations fabricated using Direct Writing (DW) process. The inks were evaluated for flow behavior to ensure proper extrudability through the nozzle. The rheological behavior was then correlated with the printing parameters to optimize the printing accuracy of the nanocomposites. It was observed that all the inks exhibited shear-thinning behavior, enabling a smooth extrusion process. To ensure high-resolution features, a new image analysis method was introduced to quantify corner rounding in printed features, enabling the optimization of printing parameters. In terms of humidity sensing performance, all the inks displayed a change in electrical properties with humidity adsorption. The fabricated nanocomposites showed a decrease in electrical conductivity with increasing humidity, suggesting potential for humidity-sensing applications. Notably, the humidity sensitivity of the nanocomposites was highly dependent on the Fe3O4 concentration in the inks. These findings provide valuable insights into the DW of SiC-Fe3O4 polymer nanocomposites for humidity sensing applications.

Modifying of surface properties and structural characteristics of low energy argon beam irradiated methylcellulose/TiO2 nanocomposite films

Flexible polymeric nanocomposites MC/TiO2 films, which consisting of titanium dioxide (TiO2) and methyl cellulose (MC) were fabricated in this research for applied in coating devices. The successful manufacturing of MC/TiO2 sheets were verified by FTIR, SEM and XRD methods, which demonstrated a uniform distribution of TiO2 in MC. Additionally, the chemical bonds of MC and TiO2 contribute for the broadening and decreasing of MC in the peaks intensity of XRD and FTIR with increasing TiO2, indicating the successful incorporation of TiO2 in MC. The impacts of argon beam bombardment on MC/TiO2 composites using cold cathode source with fluencies (2.5×1015, 5×1015 and 7.5×1015 ions/cm2 ). The contact angle, work of adhesion and surface free energy of MC/TiO2 were determined as a function of ion irradiation. The water contact angle is decreased from 70.32o to 43.34o by increasing ion fluence from 2.5×1015 ions/cm2 to 7.5×1015 ions/cm2 , while the surface free energy is enhanced from 38.83 mJ/m2 to 64.17 mJ/m2 . The collected data confirmed that the surface wettability of the irradiated MC/TiO2 films were improved to be can usage in coating and printing applications

Insights and perspectives on PVDF/MgO NCs films: Structural and optical properties for optoelectronic device applications

In the current investigation, pure polyvinylidene fluoride (PVDF) and PVDF-MgO nanocomposite (NC) thin films are fabricated via solvent casting method using PVDF as a polymer matrix with different proportions of magnesium oxide (MgO) (0.5–2 wt%). The structural, morphological and optical properties of the prepared polymer NCs are studied by using XRD, FTIR, SEM, Raman and UV–Vis spectroscopy techniques. The α and β phases are detected in XRD measurements. MgO powder peaks are in good agreement with the reported literatures. The average crystallite size, lattice strain, and dislocation density of the prepared thin films are estimted by using Williamson-Hall (W-H) plot. SEM micrographs reveals the fluorine-containing carbon chain network that forms the spherulite and fiber-like structure in the PVDF/MgO NCs films. The Raman and FTIR spectra of PVDF/MgO and pure PVDF films are also evaluated. UV–Vis spectroscopy is used to examine the absorbance, transmittance, and reflectance spectra of pure PVDF and PVDF/MgO NCs thin films. The dipole polarization interaction causes the absorption coefficient, direct band gap, indirect band gap, optical activation energy, and skin depth of pure PVDF and PVDF/MgO thin films to decrease, whereas increasing the dielectric constant at high frequency value, refractive index, loss, optical conductivity, and dielectric constant per effective mass of NCs films. Optical dispersion parameters are estimated by the single oscillator model. The obtained results can be employed in the possible applications in supercapacitors. The method used for the preparation of thin films are inexpensive and eco-friendly.

Maximizing the toughness of polymer nanocomposites based on the radial strength of carbon nanotubes

Similarity in the mechanical properties of a matrix and an inclusion is key to designing tough nanocomposites. Matching the matrix and inclusions with similar mechanical strengths prevents stress perturbation at the interface, enabling nanocomposites to withstand higher loads as a homogeneous material. We tabulate the chirality-dependent radial buckling properties of multi-walled carbon nanotubes (MWCNTs) and present a design methodology for providing optimal strengthening properties for poly(p-phenylene terephthalamide) matrices. The structural orientation effect of the aromatic rings of polymer chains surrounding MWCNTs provides a strong support against transverse loading. The effect of the interfacial area of different materials on the toughness of the entire continuum system is characterized through a nonlinear finite element model. MWCNT buckling and polymer yielding occur simultaneously under conditions selected by the proposed methodology, thereby maximizing the reinforcing effect of the nanocomposites by creating a continuous stress field at the interface.

МЕТОД РАСЧЕТА ОПТИМАЛЬНОГО РЕЖИМА ДИСПЕРГИРОВАНИЯ РАСТВОРОВ ПОЛИМЕРНЫХ КОМПОЗИТОВ В ТУРБИННОЙ МЕШАЛКЕ

LSTU has developed a turbine stirrer for mixing and dispersing solutions of polymer nanocomposites designed to restore mounting holes in the body parts of equipment. Formula is proposed for calculation of optimal rotation frequency of turbine mixer, which takes into account structural parameters of mixer and physical properties of nanoparticles, which provides effective mixing of nanoparticles of filler in solution of nanocomposite. An experiment was carried out to assess the adequacy of a mathematical model of the turbine stirrer speed. Experimental turbine agitators of three different sizes were used in the experiment. A solution of elastomer nanocomposite F-40S was used for mixing. The dispersion quality was evaluated by the light transmission coefficient. For each turbine stirrer size, experimental non-linear dependences of the transmittance on the stirrer speed were obtained. After approximation of experimental dependences and taking partial derivatives, their extremes are determined, i.e. actual optimal rotation frequencies for each mixer size: n оф1 = 1325 min-1; nof2 = 1113 min-1;, nof3 = 973 min-1. Then the power consumed by stirrers of various sizes at a speed of 500, 1000 and 1500 min-1 was measured. Further, the values of the circumferential velocity coefficients k were calculated for each stirrer using the measured power values. As the stirrer diameter increases from 34 to 90 mm, the corresponding circumferential velocity factor k increases from 0.9534 to 0.9703, indicating an increase in circumferential flow.Further, according to the proposed formula, using the values of the coefficients of peripheral speeds, the calculated values of the optimal speed for stirrers No. 1, No. 2 and No. 3 were obtained: n op1 = 1307 min-1; nop2 = 1100 min-1;, nop3 = 965 min-1. Analysis of variance showed that the calculated Fischer value does not exceed the table value, which confirms the adequacy of the formula for calculating the optimal speed of the turbine stirrer.

Macromolecular PEI-modified carbon nanotubes as multifunctional additives in controlling crystallization and enhancing comprehensive performance of polyamide 6 nanocomposites

Despite the promising potential of carbon nanotubes (CNTs) in polymer nanocomposites, their propensity for aggregation and random dispersion within the polymer matrix poses significant challenges. This study introduces a novel approach to enhance the interfacial properties between the CNTs and the polyamide 6 (PA6) matrix by anchoring the polyethyleneimine (PEI) onto the CNT surfaces. The integration of PEI, with abundant amino groups, provides the high density of nucleation sites, facilitating transcrystallization along the surfaces of the macromolecular polyethyleneimine (PEI) modified CNTs (m-CNTs). This transcrystallization process enhances the physical interactions between the m-CNTs and the PA6 matrix, resulting in the substantial improvements in the mechanical properties of the PA6 nanocomposites. Specifically, as compared to the neat PA6, the PA6/m-CNT nanocomposites exhibited the increase of 131.2 % and 54.3 % in tensile strength and Young's modulus, respectively. Additionally, the intimate contact between the embedded CNTs forms the efficient thermally conductive networks. The robust molecular interactions between the m-CNTs and the PA6 polymer chains promote the highly homogeneous dispersion within the PA6/m-CNT nanocomposites, thereby reducing the thermal resistance. This straightforward and effective method presents a viable strategy for improving the interfacial properties of the CNTs reinforced polymer nanocomposites, offering the extensive potential for the future advancements in the interfacial modifications of the polymer matrix nanocomposites.

Polyaniline/reduced graphene oxide nanocomposites for electrochemical and solar cell applications

Polyaniline nanocomposites are synthesized via in situ chemical oxidation method by reinforcing reduced graphene oxide nanoparticles of various weight percentage. Structural, optical, thermal and electrochemical studies are performed to know the significance of introducing reduced graphene oxide into polyaniline and to analyse the importance of filler weight percentage in determining various properties of the nanocomposites. X-ray diffraction peak intensity is appeared to be maximum for nanocomposite doped with 2% filler. This composite shows minimum crystallite size and maximum photoluminescence intensity. Maximum ID/IG ratio obtained for 2% filler added nanocomposite from Raman spectroscopy studies proved that the presence of more surface defects and recombination of charge carriers are the reasons for enhanced photoluminescence. Thermal stability is found to be better for a nanocomposite with 1% reduced graphene oxide and obtained a mass retention of 60% even after heating up-to 600 °C. SEM images give various shapes of nanocomposite such as nanorods, spherical nanoparticles and button shaped nanocomposites for different filler weight percentage. Carbon to oxygen ratio is observed to be decreased as the filler percentage increased from 1% to 4% in SEM-EDAX analysis. Polymer nanocomposite with 1% reinforcement possess maximum UV and visible absorption and is found to be decreased as filler concentration increased from 1 to 4%. Electrochemical analysis is performed for polyaniline and 1% reduced graphene oxide reinforced polyaniline nanocomposite. Specific capacitance of the electrode is obtained as 212 F g−1 and 609 F/g for polyaniline and nanocomposite respectively at a scan rate of 0.01 V/S. Solar cell device performance study shows that power conversion efficiency is 5.54% for 1% reduced graphene oxide nanocomposite, 4.7% for 2% reinforced, 4.16% for 3% filler and 3.61% for 4% nanocomposite.

Xanthated cellulose nanofibers dispersion: Stability, pickering emulsion with styrene, and latex composite via polymerization

Leveraging xanthated cellulose nanofibers (XCNF) from a modified rayon process, this study explores their use as stabilizers in Pickering emulsion polymerization for nanocomposite production. XCNF was produced from softwood pulp through a xanthation process that utilized a reduced NaOH concentration of 8.5 %, lower than the typical rayon process, and was followed by mechanical defibrillation, resulting in fiber widths under 10 nm. Following the protective allylation of xanthate groups and hydrophobic modification, 1H NMR analysis was conducted, revealing a xanthation degree of 0.144. When stored at 4 °C, a 0.5 wt% XCNF dispersion gelled by the fifth day, as confirmed by visual and rheological assessments. UV and TEM analyses indicated xanthate detachment and nanofiber aggregation over time, respectively. The addition of a low-temperature initiator to the XCNF-stabilized styrene-water emulsion enabled polymerization, yielding nanofiber-encapsulated polystyrene latex. This led to transparent sheets upon thermal pressing, demonstrating the potential of XCNF in developing polymer nanocomposites.

Enhanced radiation shielding efficiency of polystyrene nanocomposites with tailored lead oxide nanoparticles

In this study, we investigated a novel polymer nano-composite, PS-PbO, containing two distinct nano-sizes of lead oxide nanoparticles (PbO-A and PbO-B), in addition to the bulk size (PbO-K). These nanoparticles were embedded separately in a polystyrene (PS) matrix at different weight percentages (10%, 15%, 25%, and 35%) using roll mill mixing and compressing molding. Our evaluation focused on the radiation attenuation ability of PS-PbO and the effect of particle size, considering gamma-ray energies ranging from 0.06 to 1.3 MeV (from sources like 241Am, 133Ba, 137Cs, and 60Co). The linear attenuation coefficient (LAC) was determined by analyzing samples of the synthesized composite with different thicknesses. Then, various shielding parameters were calculated, including total molecular, atomic, and electronic cross-sections (σmol, σatm, σel), as well as the effective atomic number and the electron density (Zeff and Neff). Surprisingly, modifying PbO particle sizes had a significant impact on shielding efficiency. For instance, the composite with 25 wt% of the smallest PbO-B particles showed a 26.7% increase in LAC at 0.059 keV compared to the composite with 25 wt% of PbO-K (larger particles). Notably, the LAC peaked at low energy (0.059 keV), close to the K-edge of Pb, where interaction is directly proportional to Z4. With increasing PbO concentrations, the LAC of PS-PbO composites increased steadily. Additionally, as PbO concentration increased, the composite’s effective atomic number Zeff and the electron density Neff increased, leading to a greater total Gamma-ray interaction cross-section. Furthermore, when comparing the Half-Value Layers of the novel nanocomposite to traditional lead shielding, a 70% reduction in mass was observed. Notably, the composite containing the smallest nano-size of PbO exhibited the highest radiation-shielding efficiency among all combinations and could therefore be used to create inexpensive and lightweight shields.

Prediction of Mechanical Properties of Nano-Clay-Based Biopolymeric Composites.

An understanding of the mechanical behavior of polymeric materials is crucial for making advancements in the applications and efficiency of nanocomposites, and encompasses their service life, load resistance, and overall reliability. The present study focused on the prediction of the mechanical behavior of biopolymeric nanocomposites with nano-clays as the nanoadditives, using a new modeling and simulation method based on Comsol Multiphysics software 6.1. This modeling considered the complex case of flake-shaped nano-clay additives that could form aggregates along the polymeric matrix, varying the nanoadditive thickness, and consequently affecting the resulting mechanical properties of the polymeric nanocomposite. The polymeric matrix investigated was biopolyamide 11 (BIOPA11). Several BIOPA11 samples reinforced with three different contents of nano-clays (0, 3, and 10 wt%), and with three different nano-clay dispersion grades (employing three different extrusion screw configurations) were obtained by the compounding extrusion process. The mechanical behavior of these samples was studied by the experimental tensile test. The experimental results indicate an enhancement of Young's modulus as the nano-clay content was increased from 0 to 10 wt% for the same dispersion grades. In addition, the Young's modulus value increased when the dispersion rate of the nano-clays was improved, showing the highest increase of around 93% for the nanocomposite with 10 wt% nano-clay. A comparison of the modeled mechanical properties and the experimental measurements values was performed to validate the modeling results. The simulated results fit well with the experimental values of Young's modulus.

Improving flame resistance and shielding properties for cross-linked polyethylene (XLPE) using nanoclay filler

Polymers play an essential role in both industry and medical fields due to their diverse and adaptable properties. In this work, prepared crosslinking polyethylene (XLPE) samples with hydrophilic bentonite nanoclay fillers (H2Al2O6Si) at concentrations of 0, 1, 2.5, 4, and 5 wt% enhance their flame-retardant and radiation shielding efficiency. The research investigated flame retardancy and thermal stability parameters. The XLPE/H2Al2O6Si nanocomposite polymer sheets were exposed to a collimated beam of fast neutrons using an Am/Be neutron source (5 Ci) and to gamma radiation using a 137Cs point source (5 μCi) to assess their radiation shielding properties. The study found that uniform dispersion of nanoclay particles enhanced the thermal properties of the composite, forming a char layer that acted as a barrier, slowing thermal decomposition and reducing the heat release rate. Limiting oxygen index (LOI) increased from 28% to 34%, and burning rate improved with higher nanoclay concentrations. Additionally, absorption and optical band gap calculations decreased with increasing filler concentrations. Radiation attenuation capabilities increased by approximately 40% for neutrons and 30% for gamma radiation compared to pure XLPE. The study concluded that incorporating nanoclay fillers into XLPE enhances its shielding capabilities and improves flame resistance properties, making the prepared samples suitable for various industrial applications.

Synergistic effects on dielectric and complex impedance properties in Ti3AlC2 MAX phase‐infused PVDF‐HFP/PMMA nanocomposites

AbstractA simple solution casting technique was used to formulate films of polyvinylidenefluoride‐co‐hexafluoropropylene, polymethylmethacrylate, and Ti3AlC2 MAX phase polymer nanocomposites (PPT) with different filler content. The functional groups present in the PPT films were studied using the Fourier transform infrared spectroscopy and the nature of crystallinity was observed using X‐ray diffraction technique. The morphology of the films was studied by scanning electron microscopy. The thermal analysis was done using the thermogravimetric analysis and differential thermogravimetry analysis. The tensile behavior of the prepared films was studied from the stress‐strain graphs. The ultraviolet–visible spectra revealed their optical characteristics. The dielectric parameters of the polymer blend and nanocomposite films like dielectric constant, loss tangent, AC conductivity, and complex impedance spectroscopy with corresponding equivalent circuits were studied. A comparative study of the above parameters was done for both the polymer blend and nanocomposites to find out the advancement in the properties of the prepared nanocomposite compared with the polymer blend. The nanocomposite film having 3 wt% of Ti3AlC2 MAX phase filler loading exhibited the best properties among all the nanocomposites. The enhanced dielectric properties of the nanocomposites with mechanical and thermal resistance can be used for real‐time efficient energy storage applications.

Fabrication of free standing nano-SiO2 incorporated solid polymer electrolytes based on poly(vinyl) chloride

AbstractFree standing nanocomposite polymer electrolytes (NCPEs) based on the polymer host poly(vinyl) chloride (PVC) were successfully prepared using the solution casting technique. Lithium nitrate (LiNO3) and nano-sized silica (SiO2) (< 100 nm) were employed as the electrolyte and filler, respectively. Impedance studies revealed a maximum ionic conductivity value of 1.226 × 10−4 S/cm at room temperature for the PVC/LiNO3 with 5 wt.% nano-SiO2. X-ray diffraction (XRD) analysis verified the sample’s amorphous nature. Dielectric permittivity and relaxation time values were consistent with impedance results. Additionally, parameters such as diffusion coefficient, mobile concentration, and mobility were evaluated for the prepared samples. Differential scanning calorimetry (DSC) studies confirmed a change in glass transition temperature (Tg) of PVC/LiNO3/SiO2 sample. The scanning electron micrograph (SEM) images revealed a honeycomb morphology, indicating ease of Li+ ion transportation.

Nanoparticle Diffusion in Crowded Polymer Nanocomposite Melts.

This study examines nanoparticle diffusion in crowded polymer nanocomposites by diffusing small Al2O3 nanoparticles (NPs) in SiO2-loaded P2VP matrices. Time-of-flight secondary ion mass spectroscopy (ToF-SIMS) measures Al2O3 NP diffusion coefficients within a homogeneous PNC background of larger, immobile SiO2 NPs. By developing a geometric model for the average interparticle distance in a system with two NP sizes, we quantify nanocomposite confinement relative to the Al2O3 NP size with a bound layer. At low SiO2 concentrations, Al2O3 NP diffusion aligns with the neat polymer results. In more crowded nanocomposites with higher SiO2 concentrations where the interparticle distance approaches the size of the mobile Al2O3 NP, the 6.5 nm Al2O3 NPs diffuse faster than predicted by both core-shell and vehicular diffusion models. Relative to our previous studies of NPs diffusing into polymers, these findings demonstrate that the local environment in crowded systems significantly complicates NP diffusion behavior and the bound layer lifetimes.

Investigation on mechanical and tribological properties of PTFE nanocomposites reinforced by surface-modified graphene using molecular dynamics simulations

Surface-modified nanoparticles are commonly used to improve the mechanical properties and wear resistance of polytetrafluoroethylene (PTFE). However, fewer studies have been devoted to quantitatively revealing the action mechanism of graphene (Gr) modified with different functional groups on the mechanical and tribological properties of PTFE. Herein, the effects of four functional groups (−OH, −NH2, −COOH, and −COOCH3 functional groups) on the surface of Gr nanosheets on the mechanical and tribological properties of PTFE nanocomposites are studied using molecular dynamics simulations. The results indicate that the incorporation of functional groups to the Gr surface is able to significantly improve the mechanical properties and wear resistance of the nanocomposites, and the COOH-functionalized Gr nanosheet shows the best reinforcing effect due to the synergistic effect of its own high surface roughness and strong interfacial interaction between itself and the matrix. It is also found that the friction coefficient of the nanocomposites is obviously increased by the inclusion of functionalized Gr nanosheets, and the greater the surface roughness of the functionalized Gr nanosheet, the more significant the growth of the friction coefficient of the nanocomposites. The pull-out test and confined shear simulation reveal that due to the increased interfacial shear strength and the isolation of functional groups, an inhomogeneous transfer film is formed at the friction interface, leading to a decreased anti-friction property. This study provides some guidance for the future design and development of polymer nanocomposites with excellent mechanical and tribological performance for use in extreme service conditions.

Tailoring the luminescent and structural behaviors of pH-driven PPy/gC3N4/ZrO2 nanocomposite as an emissive layer material for OLED application

The polymeric nanocomposites were synthesized via an in-situ polymerization method, optimized through pH adjustment of zirconium oxide rather than concentration variation. X-ray powder diffraction analysis revealed phase transitions and average crystallite sizes ranging from approximately 6.52–9.16 nm, depending on the pH levels. Field Emission Scanning Electron Microscopy tool is used to analyze the granular nanosheets and nanoparticles like the microstructure of polypyrrole, graphitic carbon nitride and zirconium oxide at a high resolution. UV–visible spectroscopy determined an optical bandgap energy of about 2.44 eV, a refractive index of 2.17, and an optical conductivity of 3.15 × 1010 S/cm2. Forster resonance energy transfer between Zirconium dioxide and graphitic carbon nitride significantly enhanced photoluminescence emission. PL emission and color purity (45 %) of the optimized sample were examined using photoluminescence data. Electrical conductivity of ∼15.9 × 10−4 S/cm and dielectric constant of ∼14.77 were obtained from I to V and LCR meter measurements. These properties indicate that the pH-driven nanocomposite exhibits optimized electron-hole recombination rates, electrical conductivity, and suitable bandgap energy, making its potential impact as an emissive layer material for OLED applications.