Polymer-nanoparticle Composites Research Articles

Rationally Designing the Supramolecular Interfaces of Nanoparticle Superlattices with Multivalent Polymers.

In supramolecular materials, multiple weak binding groups can act as a single collective unit when confined to a localized volume, thereby producing strong but dynamic bonds between material building blocks. This principle of multivalency provides a versatile means of controlling material assembly, as both the number and the type of supramolecular moieties become design handles to modulate the strength of intermolecular interactions. However, in materials with building blocks significantly larger than individual supramolecular moieties (e.g., polymer or nanoparticle scaffolds), the degree of multivalency is difficult to predict or control, as sufficiently large scaffolds inherently preclude separated supramolecular moieties from interacting. Because molecular models commonly used to examine supramolecular interactions are intrinsically unable to examine any trends or emergent behaviors that arise due to nanoscale scaffold geometry, our understanding of the thermodynamics of these massively multivalent systems remains limited. Here we address this challenge via the coassembly of polymer-grafted nanoparticles and multivalent polymers, systematically examining how multivalent scaffold size, shape, and spacing affect their collective thermodynamics. Investigating the interplay of polymer structure and supramolecular group stoichiometry reveals complicated but rationally describable trends that demonstrate how the supramolecular scaffold design can modulate the strength of multivalent interactions. This approach to self-assembled supramolecular materials thus allows for the manipulation of polymer-nanoparticle composites with controlled thermal stability, nanoparticle organization, and tailored meso- to microscopic structures. The sophisticated control of multivalent thermodynamics through precise modulation of the nanoscale scaffold geometry represents a significant advance in the ability to rationally design complex hierarchically structured materials via self-assembly.

Flow Behavior of Entangled Polymer Nanoparticle Composites in a Nanotube: Insights into Jamming State.

Using molecular dynamics simulations, this study investigates the equilibrium properties and flow behaviors of entangled polymer nanoparticle composites (PNCs) within a nanotube. The results show that the density distribution of nanoparticles (NPs), displacement of polymer chains and NPs, and the moduli of PNCs remain relatively unaffected when NP volume fractions (ΦN) ≤0.10. However, the flow behavior of entangled PNCs deviates from the ideal parabolic profile seen in unentangled PNCs, displaying plug-like flow characteristics with a significant platform region, indicating the presence of shear bands. Interestingly, entangled PNCs at intermediate ΦN values undergo a significant alteration in NP distribution under steady flow, resulting in notable NP aggregation. At ΦN = 0.30, a distinct change in the static structure of PNCs occurs, reducing the equilibrium distance between neighboring NPs. Consequently, the motion of both polymer chains and NPs becomes restricted, leading to an increase in the moduli of PNCs resembling solid-like behavior. Additionally, the entangled PNCs experience a complete absence of flow, indicating the entry into a jamming state. This study contributes to the understanding of PNCs flow behavior and provides insights into fundamental aspects and practical implications of PNCs.

Fabrication and Design of a Mechanical Polymer Mixer

Abstract: Polymer nanoparticle composites present industrial potential in many applications. However, some limitations for the application of these composites are due to the non-uniformity of their mechanical properties. One of the main issues of that drawback is the lack of uniform distribution of the nanoparticle’s reinforcement inside the polymer matrix. In other words, uniform distribution of nanoparticles throughout polymer matrices presents a crucial issue for obtaining sound parts of fair enough mechanical properties. That would present a limitation for use in different areas of applications. A mechanical mixer with a special design has been developed during the present work. A prototype mixer has been carried out, and used for the synthetization of polystyrene carbon nanoparticles, (CNP’s) composites. The design of the developed mechanical mixer is based on the principle of subjecting the mixture of CNP’s and Polymer to multi-shearing strokes in a bi-directions extrusion die during heating at appropriate temperature for a specific time. The produced composites have been subjected to metallographic examination, and mechanical testing to investigate the effectiveness of using the developed mechanical mixture. Metallographic examination of specimens of the produced composites parts using SEM have shown fair enough distribution of the carbon nanoparticles throughout the polymer matrix. The mechanical properties of the produced composites have been evaluated, and the results showed comparable values with respect to those dismantled in publications.

A thin film resistive humidity sensor based on polymer and carbon black nanoparticle composites

This paper proposes a resistive humidity sensor that uses a carbon-black and polyvinyl alcohol composites thin film, fabricated with a unique film coating method for thinner thickness and higher sensitivity. Improving the sensitivity of sensing films is still of great importance in the research field of gas sensors. The humidity sensor devices with thin composite film and microelectrode structure are fabricated on the glass substrate for a low cost and a simple fabrication process. The sensor gives a rapid response for humidity levels from 10.9% relative humidity (RH) to 73.7% RH, and the response time is about 5.77 s. Experimental results reveal that the sensor has good sensitivity, reproducibility, fast reaction time, and wide range. In addition to humidity, the sensor also responds well to gases such as ethanol. The proposed gas sensor in this paper can be applied to the other combinations of polymers and nanoparticles to form new gas sensors, which have the potential to be used as a gas sensor array for detecting the composition of complex gases such as volatile organic components.

Investigating bio-based solvents as a sustainable alternative in the formulation and fabrication of superhydrophobic surfaces

Organic solvents can be highly toxic to humans, causing damage to the tissues and toxin metabolizing systems. Petroleum-based solvents (such as n-hexane) are likely to trigger endocrine disruption in humans regularly exposed to them. Given this, there is still a high demand for petroleum-based solvents, as they can be used to fabricate materials for various high-performance products. In addition, extensive environmental damage is also caused by petroleum-based solvents. This biological and environmental harm has been the main cause of the demand for sustainable and cost-effective development of environmentally non-hazardous solvent systems. An area targeted to achieve this is bio-based solvent alternatives. In this report, 2-methyltetrahydrofuran (2-MeTHF), a bio-based solvent, is explored as an alternative solvent in the development of superhydrophobic surfaces, replacing n-hexane. This model system explores the factors considered when exploring the implementation of bio-based solvents in the development of highly advanced materials. In this research, both 2-MeTHF/n-hexane are used in the formulation/deposition of superhydrophobic polymer–nanoparticle composites (SPNCs). SPNCs developed using 2-MeTHF have water repelling functionality like those developed using n-hexane, while also demonstrating performance enhancements. Overall, this solvent exchange is aimed to serve as an example of what can be achieved in similar systems to enhance the sustainability of chemical processes that require organic solvents.

High-Angle Structural Color Scattering Features from Polymeric Photonic Structures

Three-dimensional goniometric measurements of structural color from melt-sheared polymer nanoparticle composites is presented revealing high-angle features arising from Bragg scattering. These features are presented in terms of ‘scattering cones’ from full 180° hemispherical scans showing the spectroscopic and angular properties of these scattering spots. This work identifies the Miller indices of the photonic crystal planes responsible for these features and makes further observations as to the appearance of this scattering in the context of these structures as quasi-ordered systems. We probe structural color metrics such as peak wavelength and the tunability of reflectance intensities. As such, this report contributes towards an improved understanding of Bragg scattering and structural color from structures with inherent disorder. The complexity and specificity of color quality across the scattering hemisphere is an important consideration for practical uses such as in sensing applications, and we suggest that soft photonics, in particular, are strong candidates in high-angle color uses.

Microbially Synthesized Polymer-Metal Nanoparticles Composites as Promising Wound Dressings to Overcome Methicillin-Resistance Staphylococcus aureus Infections.

Antimicrobial resistance has been declared one of the top 10 global public health threats. Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of recurring skin and soft tissue infections in patients with chronic skin conditions such as diabetic foot infections, making the treatment of the ulcers challenging. Wound dressings combined with metal nanoparticles have been suggested to prevent and treat MRSA-infected wounds. However, these particles are commonly synthesized by chemical approaches. In this study, we developed bio-based silver (Bio-AgNPs) and copper oxide nanoparticles (CuONPs) polymer composites using a microbially produced polyester from the Polyhydroxyalkanoates (PHAs) family. Poly(3-hydroxyoctanoate)-co-(3-hydroxyhexanoate) (PHO) was synthesized by Pseudomonas putida and functionalized in-situ with Bio-AgNPs or ex-situ with CuONPs. PHO-CuONPs films did not inhibit MRSA growth, while a reduction of 6.0 log CFU/mL was achieved with PHO-Bio-AgNPs synthesized from silver nitrate (AgNO3) solution at 3.5 mM. Exposure of human fibroblast cells (HFF-1) to the bioactive films did not induce notable cytotoxicity and genotoxicity, as seen by a viability higher than 79% and no significant changes in basal DNA damage. However, exposure to PHO-Bio-AgNPs induced oxidative DNA damage in HFF-1 cells. No hemolytic potential was observed, while platelet aggregation was promoted and desired for wound healing. Here we demonstrate the biosynthesis of polymer-nanoparticle composites and their potential as bioactive films for MRSA treatment.

Nanofluids stability on amino-silane and polymers coating titanium dioxide and zinc oxide nanoparticles

The nanofluids technology keeps advancing in the recent decades despite the modus operandi in formulating stable nanofluids is still in the grey area. This paper provides a further understanding of the nanoparticles and nanofluids synthesis methods with surface modification alternative in contemplation of nanofluid stability enhancement. Due to the shortcomings of this technology, which is the dispersity and stability issue owing to the van Der Waals attraction, this paper reports a full formulation design guideline in term of the temperature, crystal growth duration, nanoparticles concentration, pH and nanofluids synthesis method to obtain the stable titanium dioxide (TiO2) and zinc oxide (Zn0) nanofluids. Compatibility of polymers polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP) and an amino-silane; (3-Aminopropyl) triethoxysilane (APTES) with the synthesized nanoparticles were observed. Our findings discovered that the compatible polymer-nanoparticle composites are TiO2-PVP and ZnO-PEG with zeta potential values at 47.2 mV and 56.5 mV respectively.

Magnetoelectric coupling coefficient in multiferroic capacitors: Fact vs Artifacts

Multiferroic materials are characterized by their magnetoelectric coupling coefficient, which can be obtained using a lock-in amplifier by measuring the voltage developed across a multiferroic capacitor in a time-variable magnetic field, Hac cos(ωt), where Hac and ω are the amplitude and frequency of the applied magnetic field. The measurement method, despite its simplicity, is subject to various parasitic effects, such as magnetic induction, which leads to significant over-estimation of the actual magnetoelectric response. This article outlines the measurement theory for a multiferroic capacitor using the lock-in technique. It is demonstrated that the inductive contribution has linear proportionality with Hac, ω, and Hacω. It is shown that the true magnetoelectric coupling response is retrieved from the real component of the lock-in signal. Using a polymer-nanoparticle multiferroic composite, the internal consistency of the proposed measurement method is experimentally demonstrated, and it is shown that the actual multiferroic signal can be retrieved using the lock-in technique by removing the magnetic induction contribution from the signal. It is observed that the magnetoelectric voltage shows only a linear dependence with Hac, a saturating behavior with ω, and Hacω. Furthermore, a measurement protocol for reliable reporting of magnetoelectric coupling coefficient has been provided.

Surface Tension and Viscosity Dependence of Slip Length over Irregularly Structured Superhydrophobic Surfaces.

A comprehensive understanding of the slip phenomenon on liquid/solid interfaces is essential for multiple real-world applications of superhydrophobic materials, especially those involving drag reduction. In the current contribution, the so-called “slip-length” on an irregularly structured superhydrophobic surface was systematically evaluated, with respect to varying liquid surface tension and viscosity. The superhydrophobic polymer–nanoparticle composite (SPNC) material used exhibits a dual-scale surface roughness and was fabricated via coating a surface with a mixture of polydimethylsiloxane solution and functionalized silica particles. A cone-and-plate rheometric device was employed to quantify the slip length. To independently study the impact of surface tension and viscosity, three types of aqueous solutions were used: sodium dodecyl sulfate, ethanol, and polyethylene glycol. Our experimental results demonstrate that a decreasing surface tension results in a decreasing slip length when the fluid viscosity is held constant. Meanwhile, the slip length is shown to increase with increasing viscosity when the surface tension of the various liquids is matched to isolate effects. The study reveals a linear relationship between slip length and both capillary length and viscosity providing a reference to potentially predict the degree of achievable drag reduction for differing fluids on SPNC surfaces.

(Digital Presentation) Engineering Band Gap of Chalcogenide Nanomaterial-Polymer Composites

Over the last two decades, engineering the optical properties of nanoscale structures (nanowires, quantum dots, and nanotubes), i.e., band gap, absorption, and photoluminescence radiation, which can be manipulated in sulfide-based semiconductor materials, has received a lot of attention. Due to their tunable characteristics, these materials were introduced for potential applications ranging from medicine and communications to energy and various sensors (1). In addition, chemical synthesis methods provide the desired structure, material, reproducibility, and possibility of large-scale production, along with sustainable industrialization and foster innovation of these material systems. Polyvinyl-alcohol (PVA) is one of the functional polymers, in addition to the ability to stabilize the nanomaterial solution, which can change the optical properties of the material (2). Currently, the majority of sulfide-based nanomaterials are cadmium, lead, and silver, which have shown a wide range of applications. Here, PVA/CdS, PVA/PbS, and PVA/Ag2S nanocomposites were investigated as the desired composites. For optical studies, band gap, absorption, and photoluminescence irradiation of these material systems were performed. The structural and morphological properties were examined by scanning electron microscopy, DLS, and X-ray diffraction. The band gap value of synthesized nanoparticles in the polymer bed was 3.48, 3.08, and 2.27 eV for PVA/CdS, PVA/PbS, and PVA/Ag2S, respectively, whereas for pure PVA the band gap value was 4.75 eV. As shown in Figure 1, with the entry of nanoparticles into the polymer, a shift in the composite band gap can be seen that corresponds to an increase in absorption. Photoluminescence irradiations for polymer-nanoparticle composites showed that silver-polymer nanoparticles have intense irradiance at 405nm, while cadmium-polymer and lead-polymer composites have intense irradiance at 430nm and 500nm, respectively. An X-ray diffraction pattern was indicated for each of the crystals, confirming the presence of the expected crystal structure. The DLS of materials represents sizes of 150, 125, and 175 nm for PVA/CdS, PVA/PbS, and PVA/Ag2S. Besides, the structure of the material systems was examined by FE-SEM microscopy, which showed a homogeneous distribution of particles in the polymer and a cubic nanoparticle structure for PVA/PbS and a spherical for PVA/Ag2S and PVA/CdS. Our findings show that polymer-nanomaterial composites are potential candidates for use in sensors and solar energy cells, especially non-toxic Ag2S nanomaterials (3) that have already been documented as an emerging platform for in-vivo imaging.

Effect of surface properties and polymer chain length on polymer adsorption in solution.

In polymer nanoparticle composites (PNCs) with attractive interactions between nanoparticles (NPs) and polymers, a bound layer of the polymer forms on the NP surface, with significant effects on the macroscopic properties of the PNCs. The adsorption and wetting behaviors of polymer solutions in the presence of a solid surface are critical to the fabrication process of PNCs. In this study, we use both classical density functional theory (cDFT) and molecular dynamics (MD) simulations to study dilute and semi-dilute solutions of short polymer chains near a solid surface. Using cDFT, we calculate the equilibrium properties of polymer solutions near a flat surface while varying the solvent quality, surface-fluid interactions, and the polymer chain lengths to investigate their effects on the polymer adsorption and wetting transitions. Using MD simulations, we simulate polymer solutions near solid surfaces with three different curvatures (a flat surface and NPs with two radii) to study the static conformation of the polymer bound layer near the surface and the dynamic chain adsorption process. We find that the bulk polymer concentration at which the wetting transition in the poor solvent system occurs is not affected by the difference in surface-fluid interactions; however, a threshold value of surface-fluid interaction is needed to observe the wetting transition. We also find that with good solvent, increasing the chain length or the difference in the surface-polymer interaction relative to the surface-solvent interaction increases the surface coverage of polymer segments and independent chains for all surface curvatures. Finally, we demonstrate that the polymer segmental adsorption times are heavily influenced only by the surface-fluid interactions, although polymers desorb more quickly from highly curved surfaces.

Polymeric hybrid nanocomposites processing and finite element modeling: An overview.

Polymeric hybrid nanocomposites, due to improved mechanical, thermal, and electrical properties, are key factors in recent technologies. Because of anisotropic characteristics of polymeric hybrid nanocomposites, mechanical properties and their behavior are very difficult to predict. If they are fabricated with complicated woven fabric patterns, it becomes more difficult to predict. This review discusses in detail the properties and manufacturing methods of various fibers, focuses on different manufacturing, processing, and characterization techniques used for polymeric hybrid nanocomposites. Theoretical composite models and some recent advances in modeling and simulation techniques for polymer nanoparticle composites are discussed and thus this review can provide significant guidelines for the development of manufacturing, characterization, testing, modeling, and simulation techniques for high performance hybrid polymer nanocomposites as current state of art.

Laser Synthesis of Magnetic Nanoparticles in Liquids and Application in the Fabrication of Polymer–Nanoparticle Composites

The method of synthesis of nanoparticles in solution by laser ablation of a bulk target material immersed in a liquid does not require the use of any reducible chemical precursors or colloidal stabilizing agents. The resulting colloids are ultrapure, and in certain cases, the synthesized nanoparticles are surface-ligand-free (have “bare” surfaces). Furthermore, laser irradiation of micro/nanomaterials suspended in a liquid can lead to the synthesis of nanoparticles in solution with unique physicochemical properties. Interest in the application of the method for the synthesis of magnetic nanoparticles usually originates from the following facts: (i) Magnetic oxide or carbide nanoparticles can be directly synthesized by laser ablating the corresponding elemental target material in the appropriate liquid, (ii) magnetoplasmonic bimetallic alloy nanoparticles (e.g., FeAu), even composed of elements that are immiscible at any temperature in the solid or liquid phase (e.g., FeAg, CoAg), can be synthesized by ablating nonalloyed bimetallic targets, (iii) under the application of an external magnetic field, nanoparticle chains and strands can be fabricated that are characterized by a high packing density of the nanoparticles that together with their “bare” surfaces result in the strands having both a high aspect ratio and electrical conductivity, (iv) magnetic nanostructures that consist of nanoparticles and nanomaterials with different morphologies or properties can be fabricated, and (v) nanoparticles of intrinsically nonmagnetic oxides exhibiting the so-called d0 ferromagnetism can be synthesized. By using laser-synthesized-in-liquid magnetic nanoparticles in the fabrication of polymer–nanoparticle composites (magnetic nanocomposites), the presence of any chemical reaction byproducts in the nanocomposite is avoided. The nanoparticles form direct chemical bonds with the polymer matrix. Nanoparticle strands formed in the nanocomposite provide it with a high electrical conductivity while preserving its optical transparency. This Review is focused on the synthesis of magnetic nanoparticles in solution by laser ablation of a bulk target material immersed in a liquid or laser irradiation of micro/nanoparticles or micro/nanomaterials suspended in a liquid and the fabrication of magnetic nanocomposites using these nanoparticles.

Chain and Segmental Dynamics in Polymer–Nanoparticle Composites with High Nanoparticle Loading

Chain and Segmental Dynamics in Polymer–Nanoparticle Composites with High Nanoparticle Loading

Urea biosensors: A comprehensive review.

Present study is specially designed for the recent advances in biosensors to detect and quantify urea concentration. Urea (carbamide) is an organic compound made up of the carbonyl (C=O) functional group with two -NH2 groups having chemical formula CO (NH2 )2 . In nature, urea is found everywhere as the result of various processes, and in the human body, urea is an end product of nitrogen metabolism. An excessive concentration of urea in the human body is responsible for different critical diseases such as indigestion, acidity, ulcers, cancer, malfunctioning of kidneys, renal failure, urinary tract obstruction, dehydration, shock, burns, gastrointestinal bleeding, and so on. Moreover, below the normal level may cause hepatic failure, nephritic syndrome, cachexia, and so on. As well as in various fields such as fishery, dairy, food preservation, agriculture, and so on, urea is normally found and its detection is necessary. In urea biosensors, enzyme urease (Urs) is used as a bioreceptor element and retains its long last activity is the critical issue in front of the researcher. During recent decades, different nanoparticles (zinc oxide, nickel oxide, iron oxide, titanium dioxide, tin(IV) oxide, etc.), conducting polymer (polyaniline, polypyrrole, etc.), conducting polymer-nanoparticles composites, carbon materials (carbon nanotubes, graphene oxide, reduced graphene oxide graphene), and so on are used in urea biosensors. The main emphasis of the present study is to provide cumulative and comprehensive information about the sensing parameters of urea biosensors based on the materials used for enzyme immobilization. Besides this special task, this review provides a fruitful discussion on the basics of biosensors briefly for new and upcoming researchers. Thus, the present study may act as a gift for a large audience that come from different fields and are working in biosensors research.

Flexible Low-Density Polyethylene–BaTiO3 Nanoparticle Composites for Monitoring Leakage Current in High-Tension Equipment

Polymer–nanoparticle composites prepared using a low-density polyethylene (LDPE) matrix with BaTiO3 nanoparticle compositions of 6, 9, 12, and 15 wt % have shown insulating behavior and are evaluated for their applicability as flexible strain sensors. With increasing percentage of the nanoparticles, the LDPE crystallinity decreased from 38.11 to 33.79% and the maximum electrical displacement response was seen to increase from 2.727 × 10–4 to 4.802 × 10–4 C/cm2. The maximum current, remnant current, and coercive field, all increased with the increasing nanoinclusion loading. Furthermore, the interaction radius values derived from the three-dimensional (3D) model of the nanoparticle dispersion state in polymer–nanoparticle composites were found to be correlated with its key properties. The interaction radius values from the simulated 3D model gave a clear basis for comparing the electrical properties of the samples with the effect of the nanoparticles’ functionalization on the dispersion state in the context of the increased NP loading and giving the values of 275, 290, 310, and 300 nm, respectively. The 12 wt % nanoparticulate-loaded sample demonstrates the best overall trade-off of key parameters studied herein. Overall, the results demonstrate that these flexible polymer–nanoparticle composites could be used for strain-based sensors in the high-tension applications.

Critical role of nanocomposites at air–water interface: From aqueous foams to foam-based lightweight functional materials

The study of aqueous foams has long been an interest of the scientific community. A developing area is the use of foams to prepare lightweight, functional solid foam materials. To design such porous materials, abundant foams should first be generated (good foamability), followed by foam destabilization processes being ceased or significantly retarded (excellent foam stability) to avoid the foam decay upon drying, which can be achieved by finely controlling interfacial behaviour of the foaming agents. The current review considers the interfacial behaviour and foaming potential of emerging nanocomposites such as: surfactant-nanoparticle composites; polymer-nanoparticle composites; and surfactant-graphene oxide (GO) composites. Compared with using only surfactants, polymers or nanoparticles, composite stabilizers are of great interest and importance since they enrich the interfacial behaviour of the bubble-stabilizing film (e.g. mechanical and structural properties), ensuring excellent foamability and long-term foam stability, and novel applications of the solid foam materials. Preparation mechanisms, properties and applications of solid foams prepared via direct foaming methods using the nanocomposite stabilizers are presented and highlighted. For the surfactant-NPs composites, the influences of the property of the foamed suspension and the bubble-stabilizing interface, on the quality of the wet and solid foams, is still elusive. As to the polymer-NPs composites, functional solid foams preparation using their stimuli-responsive performance remains an interesting topic for future research. The fundamental colloidal properties of surfactant-GO composites at the air–water interface and in stabilizing foams remain incompletely understood. Future studies are desired, combining experiments at various scales: interfacial films, Plateau borders, bulk liquid, bubbles, and foams, etc.

Improved electroadhesive force by using fumed alumina/PDMS composites

This work interrogates polymer-nanoparticle (NP) composites in electroadhesive (EA) devices to establish relationships among EA force generation and various parameters such as applied voltage, distance, gap between electrodes, dielectric constant, and the surface roughness. High permittivity is especially key for enhancing EA force thus it was modified by inorganic NP-elastomer composite. Fumed SiO2 or Al2O3 NPs were selected as the dielectric material for their homogeneity and permittivity. The NPs were mixed at 1–10 wt% in a polymer resin by using a planetary mixer and subsequently three-roll mill. The distributions of NPs in the composite were established by scanning electron microscopy, energy dispersive x-ray spectroscopy, thermogravimetric analysis, and viscosity measurements. Composites with 10 wt% of Al2O3 showed improvements in mechanical strengths from 1.5 to 2.7 MPa and dielectric constants from 3.4 to 3.6 versus pristine poly(dimethylsiloxane) (PDMS). Flexible EA devices were fabricated by stacking interdigitated electrode patterns and composite films onto a PET substrate, subsequently. An EA device that integrated an Al2O3/PDMS composite with a 10 wt% Al2O3 content achieved force generation as high as 612 mN cm−2, which is two times higher than the pristine PDMS-coated gripper.

Dramatic enhancement in adsorption of congo red dye in polymer-nanoparticle composite of polyaniline-zinc titanate

In this paper, we report a dramatic enhancement in the adsorptive removal of Congo Red (CR) dye by polyaniline-zinc titanate (PANI/ZTO) nanocomposite as compared with that when PANI or ZTO are used separately. The dye exhibited little adsorption in the presence of lab-synthesized pristine ZnTiO3 (ZTO) powder as adsorbent and somewhat moderate adsorption in the presence of neat polyaniline whereas excellent and much faster adsorption was exhibited in the presence of PANI/ZTO nanocomposite. The composite was prepared by carrying out the polymerization of aniline in the presence of ZTO suspensions. The composite samples were characterized using X-Ray diffraction, FT-IR Spectroscopy, Field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and Dynamic light spectroscopy, and the adsorption kinetics were studied using UV–Vis spectroscopy. The characterization data suggest that the adsorption of the CR dye gets enhanced because PANI chain molecules which are chiefly responsible for adsorption through hydrogen bonding and π–π interactions with the dye, get adsorbed/tethered on to the ZTO nanoparticles, and thereby overcome the mass transfer limitation by being better exposed to the dye molecules. The kinetics of adsorption followed the pseudo-second-order rate equation and the rate of adsorption was controlled by intra-particles diffusion. The isotherm was best described by the Langmuir model and the maximum adsorption was calculated to be 64.51 mg/g. The value of 7.80 kJ/mole obtained from the Dubinin–Radushkevich (D–R) model suggested the physisorption of CR onto PANI/ZTO nanocomposite. These results suggest that the mass of a polymeric substance, in general, can be better utilized for adsorption by suitably dispersing them over the surface of appropriate support nanoparticles.