Polymer Nanocomposite Materials Research Articles

Nanocomposite PLA/C20A Nanoclay by Ultrasound-Assisted Melt Extrusion for Adsorption of Uremic Toxins and Methylene Blue Dye.

Design of functional materials it is of great importance to address important problems in the areas of health and environment. In the present work, the synthesis and application of poly-meric nanocomposite materials with poly (lactic acid) (PLA) and modified nanoclay (cloisite 20A) with 1,4-diaminobutane dihydrochloride at different reaction times were studied. The concentra-tions of the nanoclays in the PLA matrix were 0.5, 1 and, 5% by weight (wt%). TGA showed that sample C20AM 120 (120 min of treatment) obtained the highest degree of modification considering the weight losses of the analyzed samples. An FT-IR signal at 1443 cm−1 suggests that the organic modifier is intercalated between the galleries of the clay. XRD, SEM and XPS suggest good disper-sion at low concentrations of the nanoclay. Adsorption tests revealed that the highest percentage of removal of uremic toxins and methylene blue was the sample with 5% wt/wt chemically modified nanoclay, suggesting good affinity between the modified nanoclays in the PLA matrix with the nitrogenous compounds.

Visible-Light-Sensitive Triazine-Coated Silica Nanoparticles: A Dual Role Approach to Polymer Nanocomposite Materials with Enhanced Properties.

Nanocomposite materials are of great interest because of their superior properties. Besides the traditional synthesis methods that require high temperatures or toxic solvents, photopolymerization technology provides a simple, low-cost, and environmentally friendly route in preparing nanocomposites. In this research, the preparation of blue-light-sensitive triazine derivative-coated silica nanoparticles is presented. The resulting triazine-coated silica nanoparticles can play a dual role, i.e., acting as both photoinitiators to trigger photopolymerization reactions under the irradiation of LED@410 nm and fillers to endow the produced photopolymer nanocomposite materials with enhanced properties. Specifically, the triazine-coated silica nanoparticles can successfully induce free radical polymerization of trimethylolpropane triacrylate efficiently under the irradiation of LED@410 nm and demonstrate comparable photoinitiation ability to the triazine derivative-based photoinitiator. The effects of different loading amounts of triazine-coated silica nanoparticles toward the photopolymerization kinetics are also evaluated. By coating with the triazine derivative, the nanoparticles show good dispersion in the polymer matrix and significantly reduce the shrinkage of the samples during the photopolymerization. Moreover, the photocured nanocomposites exhibit enhanced migration stability and mechanical properties when an optimal amount of triazine-coated silica nanoparticles is added in the formulation.

Thermophysical and Magnetic Properties of Magnetite – Polyethylene Composite

In this work, it is shown that the advantage of using matrix-stabilized magnetic nanoparticles to obtain polymer nanocomposites based on them is that such nanoparticles retain their dispersion and stability of size and shape in the technological modes of obtaining polymer nanocomposite materials, and thus ensured stable ferro- and superparamagnetic properties of the obtained target products. For the production of films by the method of hot pressing from blanks obtained in an injection molding machine or a mechanochemical mixture, a manual electrically heated hydraulic press was used. The magnetic properties of nanocomposite samples (about 50 mg on average) were studied using a vibration magnetometer. The character of the dependence of the magnetization on the magnitude of the magnetic field confirms the ferromagnetic character of the behavior of the obtained nanocomposites. The resulting film nanocomposites exhibit ferromagnetic properties at room temperature.

Hybrid Polymeric Nanocomposites Based High Performance Oleds: A Review

This review reports the recent significant progress for achieving the synthesis of various types of polymer-based nanocomposites and understanding of the basic principle which determine their optical, electronic and magnetic properties. Some of the polymeric nanocomposite materials show remarkable electrical as well as optical properties regarding towards interest for applications in OLEDs. Nanoparticles which are basically inorganic, plays important role in the opto-electronic field. A nanoparticle with conjugate polymer matrix makes polymer nanocomposite and that nanocomposite used as an active emissive layer between the structures of optoelectronic device like OLEDs, OPVs etc. Application of such polymeric nanocomposite materials are discussed in this present communication with their success and failure, towards their optical as well as electrical properties in the fabrication of OLEDs.

Effects of triphenyl phosphate (TPP) and nanosilica on the mechanical properties, thermal degradation of polymer nanocomposite materials and coating based on epoxy resin

Epoxy resin DER 671X75 cured with hardener T31. Epoxy polymer composite materials DER 671X75/T31 were improved the mechanical properties, thermal stability by triphenyl phosphate (TPP) and nanosilica (fumed silica S5505). Triphenyl phosphate and nanosilica were dispersed in epoxy resin DER 671X75 by mechanical stirring and ultrasonic vibration. The structural morphology of materials was characterized by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The thermal stability and thermal properties of materials were characterized by Thermo Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The results showed that triphenyl phosphate with a content of 5 wt % in epoxy resin DER 671X75 improved the mechanical properties of epoxy polymer coating film DER 671X75/T31 with an impact strength increased 25%. The contents of 5 wt % triphenyl phosphate and 1 wt % nanosilica in epoxy resin DER 671X75 improved the impact strength of epoxy polymer coating film DER 671X75/T31 by 125%. The thermal stability of epoxy nanocomposite materials DER 671X75/5% triphenyl phosphate/1% nanosilica/T31 increased 45.35%. Epoxy coatings based on epoxy resin DER 671X75/5% triphenyl phosphate/1% nanosilica/pigments/fillers/additives/hardener T31 achieved mechanical properties, physical chemistry properties for coating and, had thermal degradation over 500 °C.

Determination of the effect of carbon nanotubes on the microstructure and functional properties of polycarbonate-based polymer nanocomposite materials

Polymer nanocomposites are widely used in various high-tech industries. Due to the combination of the elasticity of the matrix and the strength of the inorganic filler, they have improved functional characteristics compared to unfilled polymers. The article is devoted to determining the effect of carbon nanotubes (CNT) on the microstructure and properties of polymeric nanocomposite materials for 3D printing based on polycarbonate. As a result of this work, a series of composite materials was manufactured using a piston extruder. Their microstructure and functional characteristics were investigated using methods of optical microscopy, thermophysical, electrical and mechanical analysis. It was found that CNTs form clusters in the polymer matrix, which form a percolation network at a content of 0.5–0.8 %. This feature of the structure formation of CNTs provided an abrupt increase in the functional characteristics of the materials obtained. It is shown that with an increase in the filler content in the system to 3 %, the thermal conductivity rapidly increases to 1.22 W/(m∙K). A similar effect is observed for the electrical conductivity, which increases by seven orders of magnitude from 10-12 to 10-5 S/cm at 3 % CNT content in the system, exhibiting percolation behavior. With the introduction of CNTs, the crystallinity degree of the polymer matrix decreases by almost 15 %, due to the fact that the developed surface of the nanotubes creates steric hindrances for polycarbonate macromolecules. This effect almost negates the reinforcing effect of nanotubes; therefore, the mechanical tensile strength with the introduction of 3 % CNTs increases by only 21 % compared to the unfilled matrix. In terms of their functional characteristics, the obtained materials are promising for the creation of filaments for 3D printing on their basis.

Broadband Radio Frequency Dielectric Permittivity and Electrical Conductivity of Dispersed Tin Oxide and Silica Nanoparticles in Poly(Ethylene Oxide)/Poly(Methyl Methacrylate) Blend Matrix-Based Nanocomposites for Nanodielectric Applications

In regards to the advances in hybrid polymer nanocomposite (HPNC) materials for high-frequency nanodielectric applications, herein we report the broadband radio frequency range (1 MHz to 1 GHz) dielectric permittivity and electrical conductivity of composites of poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA) blend matrices and oxide nanofillers (tin oxide (SnO2) and silica (SiO2)), in the form of PEO/PMMA/SnO2 and PEO/PMMA/SiO2 films at ambient temperature. The results confirmed that these HPNCs have low dielectric permittivity values which decrease slightly, from 3.4 to 2.8, with increasing nanofillers concentrations and the applied electric field frequency. The dependency of the dielectric permittivity on the different oxide nanoparticles sizes and their dielectric constant was explored. The dielectric loss tangent spectra of these hybrid materials indicated that they were reasonably low loss nanodielectrics having a dipolar orientation relaxation in the higher frequency region. The radiofrequency electrical conductivity of the HPNCs was found to increase linearly from ∼10−8 to 10−4 S/cm with the increase of frequency, and it was less dependent on the fillers concentrations. Considering the dielectric and electrical properties, it is proposed that these PEO/PMMA/SnO2 and PEO/PMMA/SiO2 composites could be highly useful materials for dielectric substrates and insulators in the development of radiofrequency operative flexible-type electrical and electronic components and devices.

A High-Sensitivity Flexible Direct X-ray Detector Based on Bi2O3/PDMS Nanocomposite Thin Film.

The characteristics of mechanical flexibility, low health risk, and simple processing of polymer nanocomposite materials make them potentially applicable as flexible X-ray detectors. In this study, we report on a high sensitivity, environmentally friendly, and flexible direct X-ray detector using polymer nanocomposite material consisting of bismuth oxide (Bi2O3) nanoparticles and polydimethylsiloxane (PDMS). This detector was realized by printing patterned Ag electrodes on the polymer nanocomposite material. The response of PDMS to X-rays was verified for the first time, and the effect of doping different contents of Bi2O3 nanoparticles on the performance of the device was tested. The optoelectronic performance of the optimized detector indicated a high sensitivity (203.58 μC Gyair−1 cm−2) to low dose rate (23.90 μGyair s−1) at a 150 V bias voltage and the X-ray current density (JX-ray) was 10,000-fold higher than the dark current density (Jdark). The flexible direct X-ray detector could be curled for 10,000 cycles with slight performance degradation. The device exhibited outstanding stability after storage for over one month in air. Finally, this device provides new guidance for the design of high-performance flexible direct X-ray detectors.

Significant Enhancement of the Polarization Holographic Performance of Photopolymeric Materials by Introducing Graphene Oxide.

Relying on various defects and functional oxygen-containing groups on the basal planes, graphene oxide (GO) is commonly unitized for intimate mixing with a polymer matrix to fabricate high-performance nanocomposite polymeric materials with the characteristics of graphene. Herein, by introducing GO nanosheets in a phenanthraquinone-doped polymethyl methacrylate (PQ/PMMA) photopolymer, we demonstrate that the polarization holographic diffraction efficiency of nanocomposite materials can be dramatically enhanced up to nearly 10 times and the photosensitivity can also be enhanced by more than 3 times. Experimental observations reveal that the incorporation of GO nanosheets serves as a polymerization initiator not only to promote the polymerization of MMA monomers and induce the drafting behavior of the PMMA polymer on its surface but also to effectively modulate the molecular weight of the PQ/PMMA photopolymer by adjusting the doping concentration of GO nanosheets. The current study, for the first time, demonstrates that the modulation of molecular weight for PQ/PMMA photopolymers here exerts a significant impact on their holography performance. In addition, due to the strong physisorption of PQ photosensitizers onto GO nanosheets, the aggregation of PQ around GO-graft-PMMA also facilitates the formation of GO-graft-PMMA/PQ and is beneficial to the enhancement of holographic performance. The emergence of GO-graft-PMMA/PQ nanocomposite materials here is expected to fulfill the requirement of high-performance polarization-sensitive materials in the field of polarization holographic data storage and provide a facile but effective nanocomposite doping strategy to modulate the holographic performance of photopolymers from micro- and mesoscopic levels.

Flexible Piezoresistive Tactile Sensor Based on Polymeric Nanocomposites with Grid-Type Microstructure

Piezoresistive tactile sensors made using nanocomposite polymeric materials have been shown to possess good flexibility, electrical performance, and sensitivity. However, the sensing performance, especially in the low-pressure range, can be significantly improved by enabling uniform dispersion of the filler material and utilization of effective structural designs that improve the tactile sensing performance. In this study, a novel flexible piezoresistive tactile sensor with a grid-type microstructure was fabricated using polymer composites comprising multi-walled carbon nanotubes (MWCNTs) as the conductive filler and polydimethylsiloxane (PDMS) as the polymeric matrix. The research focused on improving the tactile sensor performance by enabling uniform dispersion of filler material and optimizing sensor design and structure. The doping weight ratio of MWCNTs in PDMS varied from 1 wt.% to 10 wt.% using the same grid structure-sensing layer (line width, line spacing, and thickness of 1 mm). The sensor with a 7 wt.% doping ratio had the most stable performance, with an observed sensitivity of 6.821 kPa−1 in the lower pressure range of 10–20 kPa and 0.029 kPa−1 in the saturation range of 30–200 kPa. Furthermore, the dimensions of the grid structure were optimized and the relationship between grid structure, sensitivity, and sensing range was correlated. The equation between pressure and resistance output was derived to validate the principle of piezoresistance. For the grid structure, dimensions with line width, line spacing, and thickness of 1, 1, and 0.5 mm were shown to have the most stable and improved response. The observed sensitivity was 0.2704 kPa−1 in the lower pressure range of 50–130 kPa and 0.0968 kPa−1 in the saturation range of 140–200 kPa. The piezoresistive response, which was mainly related to the quantum tunneling effect, can be optimized based on the dopant concentration and the grid microstructure. Furthermore, the tactile sensor showed a repeatable response, and the accuracy was not affected by temperature changes in the range of 10 to 40 °C and humidity variations from 50 to 80%. The maximum error fluctuation was about 5.6% with a response delay time of about 1.6 ms when cyclic loading tests were performed under a normal force of 1 N for 10,200 cycles. Consequently, the proposed tactile sensor shows practical feasibility for a wide range of wearable technologies and robotic applications such as touch detection and grasping.

Color Changes in Some UV Irradiated Polymer Nanocomposite Materials for the Application in Textile Industry

Four nanocomposites (NCPs), e.g., polyaniline-copper/polymethyl methacrylate (PANI-Cu/PMMA), polyaniline-copper/cellulose triacetate (PANI-Cu/CTA), polyaniline-copper/polycarbonate (PANI-Cu/PC), and polyaniline-copper/polycarbonate-polyester (PANI-Cu/PC-PBT) were fabricated using both chemical oxidation and casting techniques. The morphology of the prepared NCPs was studied using scanning electron microscopy. The induced alterations in the color of the synthesized NCPs owing to UV irradiation, within fluences 25–120 J/cm2, have been illustrated via UV spectroscopy and CIE color divergence methodology. The color variation between the pristine and irradiated NCP samples (color intensity, ΔE) has been computed for the four NCPs. The results show that, upon UV irradiation up to 120 J/cm2, the values of ΔE for the PANI-Cu/PMMA NCP samples achieved a major color difference which is an acceptable match in commercial reproduction on printing presses since ΔE reached the value of 35.8. The value of ΔE for the PANI-Cu/CTA NCP samples reached 23.8 that also indicates a significant color difference. It is worth mentioning that the PANI-Cu/PC-PBT shows a minimum color difference since ΔE exhibited variation up to 7. This means that the PANI-Cu/PC-PBT NCP samples have higher resistance to color changes against UV radiation. Thus, this NCP may be a suitable candidate in textile industry.

A New Hybrid Sensitive PANI/SWCNT/Ferrocene-Based Layer for a Wearable CO Sensor.

Developing a sensing layer with high electroactive properties is an important aspect for proper functionality of a wearable sensor. The polymeric nanocomposite material obtained by a simple electropolymerization on gold interdigitated electrodes (IDEs) can be optimized to have suitable conductive properties to be used with direct current (DC) measurements. A new layer based on polyaniline:poly(4-styrenesulfonate) (PANI:PSS)/single-walled carbon nanotubes (SWCNT)/ferrocene (Fc) was electrosynthesized and deposed on interdigital transducers (IDT) and was characterized in detail using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoemission spectroscopy (XPS), and X-ray diffraction (XRD). The sensor characteristics of the material towards carbon monoxide (CO) in the concentration range of 10–300 ppm were examined, showing a minimal relative humidity interference of only 1% and an increase of sensitivity with the increase of CO concentration. Humidity interference could be controlled by the number of CV cycles when a compact layer was formed and the addition of Fc played an important role in the decrease of humidity. The results for CO detection can be substantially improved by optimizing the number of deposition cycles and enhancing the Fc concentration. The material was developed for selective detection of CO in real environmental conditions and shows good potential for use in a wearable sensor.

Characterization of TiO2 Nanoparticle–Reinforced Polymer Nanocomposite Materials Printed by Stereolithography Method

Characterization of TiO2 Nanoparticle–Reinforced Polymer Nanocomposite Materials Printed by Stereolithography Method

Self-Healing Polymer Nanocomposite Materials by Joule Effect.

Nowadays, the self-healing approach in materials science mainly relies on functionalized polymers used as matrices in nanocomposites. Through different physicochemical pathways and stimuli, these materials can undergo self-repairing mechanisms that represent a great advantage to prolonging materials service-life, thus avoiding early disposal. Particularly, the use of the Joule effect as an external stimulus for self-healing in conductive nanocomposites is under-reported in the literature. However, it is of particular importance because it incorporates nanofillers with tunable features thus producing multifunctional materials. The aim of this review is the comprehensive analysis of conductive polymer nanocomposites presenting reversible dynamic bonds and their energetical activation to perform self-healing through the Joule effect.

Nanofiller controllable optical parameters and improved thermal properties of (PVP/PEO)/Al2O3 and (PVP/PEO)/SiO2 nanocomposites

The optical and thermal characterizations of poly(vinyl pyrrolidone) (PVP)/poly(ethylene oxide) (PEO) blend matrix having gamma-phase alumina (Al2O3) and amorphous silica (SiO2) nanoparticles-based polymer nanocomposite (PNC) films i.e., (PVP/PEO)/Al2O3 and (PVP/PEO)/SiO2 are reported. The ultraviolet-visible (UV–vis) absorbance spectra of these biodegradable nanocomposite materials evidenced significant absorbance which is mainly due to the PEO amount in the blend matrix. Furthermore, the absorbance increased slowly with the decrease of photons wavelength in the visible range and thereafter relatively faster in the UV-range, following a strong absorbance band which is ascribed to electronic transitions in the polymers structures. Also, an increase in absorbance and a redshift of electronic transition band was observed with the increase of Al2O3 and SiO2 concentrations (1–5 wt%) in these nanocomposites. It was observed that the increase of both the Al2O3 and SiO2 contents created polymers structural disordering which caused a gradual decrease in energy band gaps whereas Urbach energy, refractive index, and optical conductivity of these PNC materials increased. Differential scanning calorimetry (DSC) thermograms of these films confirmed a considerable increase in melting temperature and degree of crystallinity of the PNC materials in comparison to the host PVP/PEO blend matrix. Finally, considering the optical parameters, specific applications of these thermally improved nanocomposites such as nanofiller concentration controllable UV–vis absorber, optical band gap tuner, and enhanced optical conductor for advances in optoelectronics are highlighted.

Regenerated chitin reinforced polyhydroxybutyrate composites via Pickering emulsion template with improved rheological, thermal, and mechanical properties

Nanochitin is a promising nanofiller for the development of nanocomposites materials, whose overall performance is greatly dependent on the dispersity of the filler. Here, we employed the Pickering emulsion platform to prepare a uniformly distributed regenerated nanochitin (RCh)/polyhdroxybutyrate (PHB) composites. The produced PHB/RCh nanocomposites were studied for their thermal, mechanical, and rheological properties. It was found that the addition of 1.5% RCh markedly increased the thermal decomposition temperature by 24 °C than pure PHB. Similarly, both the storage modulus and tensile strength were also improved by 37% and 45%, respectively with regards to the neat PHB. Moreover, the rheological results also elucidated that the introduction of RCh improved the viscoelastic characteristics of the neat PHB over the frequencies range. Thus, the Pickering emulsion technique provides a simple and green method for preparing RCh-reinforced polymer nanocomposite materials used in packaging applications.

Study on crystalline phases and degree of crystallinity of the melt compounded PVA/MMT and PVA/PVP/MMT nanocomposites

Polymer nanocomposite (PNC) films comprised poly(vinyl alcohol) (PVA) and also its blend with poly(vinylpyrrolidone) (PVP) (i.e., PVA/PVP = 75/25 wt/wt%) as host matrices loaded with different amounts of montmorillonite (MMT) nanoclay up to 10 wt% were prepared by melt compounded method. X-ray diffraction (XRD) patterns of these PNC films were recorded in the appropriate angular range of 2θ values 3.8°–26° for their crystalline phase structural characterization. In comparison to the broader-type single diffraction peak for the aqueous solution cast prepared pure PVA film and that of the PVA/PVP blend film which is attributed to the hydrogen bonded isotactic and syndiotactic PVA crystals, five sharp diffraction peaks of different intensities corresponding to the evolution of various crystallites in the melt compounded PVA and PVA/PVP blend films were observed. Further, these peaks intensities were found significantly affected by the amounts of loaded MMT in these polymer matrices-based nanocomposites. It was observed that the prominent crystalline phase of the pure PVA converted into alternative tactic phases in the PVA/MMT films with the variation of MMT concentration. The prime crystalline phase of the PVA/PVP/MMT nanocomposites underwent alternative crystal structures formation abruptly on the initial loading of the 1 wt% amount of MMT in the PVA/PVP blend matrix reflecting a substantial alteration in the direction and nature of hydrogen bonding within the PVA crystal structures, and less changes were found with the further increase of MMT concentration up to 10 wt%. The effect of MMT loading on the crystallite sizes, degree of crystallinity, and the exfoliated and intercalated MMT structures in these PNC materials were analyzed in detail.

From polymer configuration and dynamics to protein folding

The force acting on the first bond of a polymer brush directly connected to a surface is low at high graftingdensities, at which nonvanishing end-monomer tension can be observed. The physical properties and variable applications ofthe polymers are determined based on their conformations and transition dynamics. As biological polymers, biomacromolecularproteins include twenty types of amino acids that form a linear polypeptide chain. Most proteins have a stablethree-dimensional native structure because of their one-dimensional amino acid sequences. In this review, we introduce apolymer brush, polymer nanocomposite materials, a polymer network, and their conformational transition dynamics along withthe conformation and folding and unfolding processes of the proteins. The folding and unfolding rates of proteins areregulated by the stretching force. The free energy and folding pathways of proteins can be studied in detail based on themeasurement of the force-dependent folding and unfolding rates of proteins. Furthermore, we consider the muscle proteintitin immunoglobulin domain I27 as an example to demonstrate the investigation of the protein folding and unfolding dynamicsusing single molecular manipulation techniques.

Dielectric properties of polymer nanocomposite interphases from electrostatic force microscopy using machine learning

Interphase regions in polymer nanocomposite materials are difficult to characterize due to their nano-scale dimensions. Electrostatic force microscopy (EFM) provides a pathway to local dielectric property measurements, but extracting local dielectric permittivity in complex interphase geometries from EFM measurements remains a challenge. We demonstrate the efficacy of machine learning (ML) models to extract interphase permittivity using a data set of synthetic EFM force gradient scans generated by finite element simulations. We show that both support vector regression (SVR) and random forest (RF) algorithms are able to ‘invert’ the force gradient scan to predict the permittivity with high accuracy. Feature reduction by principal component analysis (PCA) improves the model's performance and reveals force gradient contrast to be the most important feature in permittivity detection. We find that these ML models perform better than analytical approaches by capturing significant geometric complexity of EFM measurements.

Electroanalysis of Biomolecules: Rational Selection of Sensor Construction.

Methods of electrochemical analysis of biological objects based on the reaction of electro-oxidation/electro-reduction of molecules are presented. Polymer nanocomposite materials that modify electrodes to increase sensitivity of electrochemical events on the surface of electrodes are described. Examples of applications electrochemical biosensors constructed with nanocomposite material for detection of biological molecules are presented, advantages and drawbacks of different applications are discussed.