Electrical Properties of Polyetherimide-Based Nanocomposites Filled with Reduced Graphene Oxide and Graphene Oxide-Barium Titanate-Based Hybrid Nanoparticles

The electrical properties of nanocomposites based on polyetherimide (PEI) filled with reduced graphene oxide (rGO) and a graphene oxide hybrid material obtained from graphene oxide grafted with poly(monomethyl itaconate) (PMMI) modified with barium titanate nanoparticles (BTN) getting (GO-g-PMMI/BTN) were studied. The results indicated that the nanocomposite filled with GO-g-PMMI/BTN had almost the same electrical conductivity as PEI (1 × 10−11 S/cm). However, the nanocomposite containing 10 wt.% rGO and 10 wt.% GO-g-PMMI/BTN as fillers showed an electrical conductivity in the order of 1 × 10−7 S/cm. This electrical conductivity is higher than that obtained for nanocomposites filled with 10% rGO (1 × 10−8 S/cm). The combination of rGO and GO-g-PMMI/BTN as filler materials generates a synergistic effect within the polymeric matrix of the nanocomposite favoring the increase in the electrical conductivity of the system

Thermally Reduced Graphene Oxide/Thermoplastic Polyurethane Nanocomposites: Mechanical and Barrier Properties

This work consists of studying the influence of two thermally reduced graphene oxides (TRGOs), containing oxygen levels of 15.8% and 8.9%, as fillers on the barrier properties of thermoplastic polyurethane (TPU) nanocomposites prepared by melt-mixing processes. The oxygen contents of the TRGOs were obtained by carrying out the thermal reduction of graphene oxide (GO) at 600 °C and 1000 °C, respectively. The presence and contents of oxygen in the TRGO samples were determined by XPS and their structural differences were determined by using X-ray diffraction analysis and Raman spectroscopy. In spite of the decrease of the elongation at break of the nanocomposites, the Young modulus was increased by up to 320% with the addition of TRGO. The barrier properties of the nanocomposites were enhanced as was evidenced by the decrease of the permeability to oxygen, which reached levels as low as −46.1%

Influence of the Surfactant Nature on the Occurrence of Self-Assembly between Rubber Particles and Thermally Reduced Graphite Oxide during the Preparation of Natural Rubber Nanocomposites

Artículo de publicación ISI.The natural rubber (NR) latex consists of polymer particles charged negatively due to the adsorbed phospholipids and proteins molecules. The addition of stable aqueous suspension of thermally reduced graphite oxide (TRGO) stabilized by ionic surfactants to NR latex can favor the occurrence of interaction between the stabilized TRGO and NR particles. Herein, the use of two surfactants of different nature, namely, sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB), for the preparation of (TRGO)/NR nanocomposites, is reported. Zeta potential and particle size measurements indicated that the use of DTAB as cationic surfactant results in the flocculation of NR particles and promoted the formation of ion-pair interactions between TRGO and the proteins and/or phospholipids present on the NR surface. This indicates that the use of DTAB can promote a self-assembly phenomenon between TRGO with adsorbed DTAB molecules and NR particles. The occurrence of self-assembly phenomenon allows obtaining homogenous dispersion of TRGO particles in the polymer matrix. The TRGO/NR nanocomposites prepared by the use of DTAB exhibited superior mechanical properties and excellent electrical conductivities reaching values of stress at 500% strain of 3.02 MPa and 10(-4) S/cm, respectively.National Commission for the Scientific and Technological Research (CONICYT) FONDECYT 1131139 Spanish Ministry of Science and Innovation (MICINN), Spain 2013-48107-C3-2-

A Brief Review on the High-Energy Electromagnetic Radiation-Shielding Materials Based on Polymer Nanocomposites

This paper revises the use of polymer nanocomposites to attenuate high-energy electromagnetic radiation (HE-EMR), such as gamma radiation. As known, high-energy radiation produces drastic damage not only in facilities or electronic devices but also to life and the environment. Among the different approaches to attenuate the HE-EMR, we consider the use of compounds with a high atomic number (Z), such as lead, but as known, lead is toxic. Therefore, different works have considered low-toxicity post-transitional metal-based compounds, such as bismuth. Additionally, nanosized particles have shown higher performance to attenuate HE-EMR than those that are micro-sized. On the other hand, materials with π-conjugated systems can also play a role in spreading the energy of electrons ejected as a consequence of the interaction of HE-EMR with matter, preventing the ionization and bond scission of polymers. The different effects produced by the interactions of the matter with HE-EMR are revised. The increase of the shielding properties of lightweight, flexible, and versatile materials such as polymer-based materials can be a contribution for developing technologies to obtain more efficient materials for preventing the damage produced for the HE-EMR in different industries where it is found

Development of bio degradable nanocomposites based on PLA and functionalized graphene oxide

The use of biodegradable polymers to mitigate the environmental pollution is one of the hot topics of research in the recent years. The current work presents the graphene oxide (GO) nanoparticles functionalized with two types of alkylamines (decylamine (DA) and octadecylamine (ODA)) synthesized at two different temperatures; 25 °C (GODA1 and GOODA1) and 80 °C (GODA2 and GOODA2), which were used as fillers to prepare PLA nanocomposites and their barrier, mechanical, and thermal properties were studied. The elemental analysis showed 2 wt% to 4 wt% of nitrogen content for functionalized GO, confirming the presence of alkyl chains in its structure. The reactions carried out at 80 °C (GODA2 and GOODA2) are the ones that showed the highest mass yields, registering a 7% and 50% increase in the total mass, respectively. These results were supported by X-ray diffraction (XRD), FT-IR spectroscopy and thermogravimetric Analysis (TGA) analyses. The optical microscopy images of the nanocomposites showed that the modified GO has a higher affinity than the GO with the PLA matrix, observing good dispersion at low loads of modified GO (0.2 wt%), with an increasing tendency to form agglomerates for higher loads. Furthermore, the elastic modulus of all nanocomposites showed a decreasing trend, mainly attributed to the formation of agglomerates and the decrease in the crystallinity of the composites. The oxygen permeability progressively decreases with increasing nanoparticle load, the nanocomposites prepared with GODA2 and GOODA2 presented the best results, registering decreases of 28.6% and 30.4% for 2 wt% loads, respectively. On the other hand, the permeability to water vapor decreased by 36.0% and 50.2%, for loads of 0.2 wt% of GODA2 and GOODA2, respectively. However, for higher amount of filler no significant improvements was detected. The results shows that the addition of modified GO to PLA improves its barrier properties, and that its composites could be used in food packaging

In Vitro Hyperthermia Evaluation of Electrospun Polymer Composite Fibers Loaded with Reduced Graphene Oxide

Electrospun meshes (EM) composed of natural and synthetic polymers with randomly or aligned fibers orientations containing 0.5% or 1% of thermally reduced graphene oxide (TrGO) were prepared by electrospinning (ES), and their hyperthermia properties were evaluated. EM loaded with and without TrGO were irradiated using near infrared radiation (NIR) at 808 nm by varying the distance and electric potential recorded at 30 s. Morphological, spectroscopic, and thermal aspects of EM samples were analyzed by using SEM-EDS, Raman and X-ray photoelectron (XPS) spectroscopies, X-ray diffraction (XRD), and NIR radiation response. We found that the composite EM made of polyvinyl alcohol (PVA), natural rubber (NR), and arabic gum (AG) containing TrGO showed improved hyperthermia properties compared to EM without TrGO, reaching an average temperature range of 42–52 °C. We also found that the distribution of TrGO in the EM depends on the orientation of the fibers. These results allow infering that EM loaded with TrGO as a NIR-active thermal inducer could be an excellent candidate for hyperthermia applications in photothermal therapy

Improving carbon nanotube/polymer interactions in nanocomposites

A review of carbon nanotube (CNT) functionalization methods to improve the interfacial interactions with polymers is addressed. The most common CNT functionalization methods to address the issue of interfacial interactions between CNTs and their host polymer matrix in CNT polymer composites are discussed. These CNT chemical modifications include oxidations, silanizations, fluorinations, aminations, and other less conventional methods, such as modifications with itaconic acid. After a brief introduction (Section 5.1), Section 5.2 focuses on functionalization methods and the Section 5.3 covers specific functionalizations for CNT interactions with thermosettings, thermoplastics, and elastomers, with discussion of their interfacial interactions toward improving the mechanical and thermal properties of functionalized nanocomposites

SEBS-grafted itaconic acid as compatibilizer for elastomer nanocomposites based on BaTiO3 particles

Itaconic acid (IA) is an organic acid produced by the fermentation of sugars with aspergillus. It has been identified as one of the top 12 building-block chemicals. Here, we report the use of IA as a possible substitute to petroleum-based compatibilizers in polymer composite. We applied this study to thermoplastic elastomers based on styrene copolymers, since they are commonly used in blends and composites. Poly(styrene-b-ethylene-butylene-b-styrene) (SEBS) was grafted with 2.6 wt.% of itaconic acid (SEBS-g-IA) prepared by a reactive melt-mixing process, and was subsequently used to prepare composites filled with BaTiO3.). IA was successfully grafted as demonstrated by FTIR and XRD. SEBS-g-IA composites presented better mechanical properties, achieving an increase of Young modulus up to 80% compared with the neat polymer. This was ascribed to better dispersion and compatibility with the filler. Additionally, SEBS-g-IA showed increased dielectric permittivity, i.e., showed increased polarity, which indicates that it could potentially be used as a modifier for specialized polymers.National Commission for Scientific and Technological Research (CONICYT), Chile, under Postdoctoral fellowship FONDECYT 3,170,104 Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT 1191642 MINECO MAT2016-81138-

Functionalized Multiwalled CNTs in Classical and Nonclassical CaCO₃ Crystallization

Multiwalled carbon nanotubes (MWCNTs) are interesting high-tech nanomaterials. MWCNTs oxidized and functionalized with itaconic acid and monomethylitaconate were demonstrated to be efficient additives for controlling nucleation of calcium carbonate (CaCO3) via gas diffusion (GD) in classical as well as nonclassical crystallization, yielding aragonite and truncated calcite. For the first time, all amorphous calcium carbonate (ACC) proto-structures, such as proto calcite-ACC, proto vaterite-ACC and proto aragonite-ACC, were synthesized via prenucleation cluster (PNC) intermediates and stabilized at room temperature. The MWCNTs also showed concentration-dependent nucleation promotion and inhibition similar to biomolecules in nature. Incorporation of fluorescein-5-thiosemicarbazide (5-FTSC) dye-labeled MWCNTs into the CaCO3 lattice resulted in fluorescent hybrid nanosized CaCO3. We demonstrate that functionalized MWCNTs offer a good alternative for controlled selective crystallization and for understanding an inorganic mineralization process.publishe

Flexural electromechanical properties of multilayer graphene sheet/carbon nanotube/vinyl ester hybrid nanocomposites

The electrical, mechanical and piezoresistive responses of vinyl ester nanocomposites made of two types of multilayer graphene sheets (GSs) and multiwall carbon nanotube hybrid fillers at different relative concentrations is presented. Two types of GSs are used in order to evaluate the role of their physicochemical properties. The best mechanical properties were achieved with hybrids at 75% relative concentration of GSs. Collaborative effects were also observed in the electrical conductivity of the hybrids at this relative concentration. The flexural piezoresistive response yielded low sensitivity (with both, positive and negative gage factors) at the compression side of the flexural coupon. On the contrary, the tensile side of the coupon always presented positive resistance changes and significantly higher piezoresistive sensitivity. The highest piezoresistive sensitivity was found for hybrid materials with 75% relative concentration of GSs, using the graphenic sheets with larger lateral dimensions and higher structural quality (lower Raman I-D/I-G ratio).Consejo Nacional de Ciencia y Tecnología (CONACyT) 2262 240300 268595 Ministry of Science, Innovation and Universities in Spain MAT2016-81138-R SENER-CONACYT energetic sustainability project 25466