Eco-friendly electronics,based on nanocomposites of biopolyester reinforced with carbon nanotubes: a review

ABSTRACT

Fabrication of electronic materials from nanocomposite of biopolyesters reinforced with carbon nanotubes can be regarded as the effective alternative for conventional nanocomposites consisting of non-biodegradable polymers. Commercial availability of biopolyester-based nanocomposites is limited because of their high cost compared to other polymers, but the factor of their compostable nature is worthless for environmental protection. Such nanocomposites have potential applications in biodegradable sensors, EMI materials, etc. In this review, the current progress of biopolyester/CNTs nanocomposites in the field of biodegradable electronics is reviewed and also the impact of CNTs dispersion on electrical, thermal and mechanical properties of eco composites is stipulated.     

Triacetate cellulose gate dielectric organic thin-film transistors

Here, we report on the performance and the characterization of all solution-processable top-contact organic thin-film transistors (OTFTs) consisting of a natural-resourced triacetate cellulose gate dielectric and a representative hole-transport poly[2,5-bis(3-dodecylthiophen-2-yl)thieno[3,2-b]thiophene] (pBTTT) semiconductor layer on rigid or flexible substrates. The bio-based triacetate cellulose layer has an important role in the OTFT fabrication because it provides the pBTTT semiconducting polymer with highly suitable gate dielectric properties including a low surface roughness, hydrophobic surface, appropriate dielectric constant, and low leakage current. The triacetate cellulose gate dielectric-based pBTTT OTFTs exhibit an average filed-effect mobility of 0.031 cm²/Vs similar to that obtained from a SiO₂ gate dielectric-based OTFT device in ambient conditions. Even after a bending stimulation of 100 times and in an outward bending state, the flexible triacetate cellulose gate pBTTT OTFT device still showed excellent electrical device performance without any hysteresis.     

The structure,tensile properties and water resistance of hydrolyzed feather keratin-based bioplastics☆

Feather,as a by-product of the poultry industry,has long been treated as a solid waste,which causes environmental and economic problems.In this work,the hydrolyzed feather keratin(HFK)was extracted from the chicken feather using a cost-effective method of alkali-extraction and acid-precipitation by applying urea and sodium sulfide.The aim was development and characterization of the eco-friendly films based on the HFK with variable glycerol contents by a thermoplastic process.The thermal analysis showed that high temperature and high pressure improved the compatibility between the glycerol and the HFK molecules.Also it was shown that the addition of water is necessary in the hot-pressing process of films.The FT-IR analysis indicated that the formation of the new hydrogen bonds between HFK and glycerol.By increasing the glycerol content,the film tensile strength(σ_b)decreases from 10.5 MPa to 5.7 MPa and the solubility increases from 15.3% to 20.9%,while the elongation at break(εb)achieves the maximum value of 63.8% for the film with 35% glycerol.The swelling was just below 16.9%at 25 °C for 24 h,suggesting a good stability of the films in water.The water vapor permeability(WVP)varied between 3.02 × 10~(-10)g · m~(-2)· s~(-1)· Pa~(-1)and 4.11 × 10~(-10)g · m~(-2)· s~(-1)· Pa~(-1)for the films with 20% and40% glycerol,respectively.The HFK film was uniform,translucent and tough,which could be used in packaging and agricultural field.     

Relaxor antiferroelectric-like characteristic boosting enhanced energy storage performance in eco-friendly (Bi0.5Na0.5)TiO3-based ceramics

Ideal relaxor antiferroelectrics (RAFEs) have high field-induced polarization, low remnant polarization and very slim hysteresis, which can generate high recoverable energy storage W_rec and high energy storage efficiency η, thus attracting much attention for energy storage applications. True RAFEs, on the other hand, are extremely rare, and the majority of them contain environmentally hazardous lead. In this work, we use a viscous polymer rolling process to synthesize a novel and eco-friendly 0.65Bi_0.5Na_0.4K_0.1TiO₃-0.35[2/3SrTiO₃-1/3Bi(Mg_2/3Nb_1/3)O₃] (BNKT-ST-BMN) dielectric material, which possesses a very typical RAFE-like characteristic. As a result, this material has a high W_rec of 4.43 J/cm³ and a η of 86% at an electric felid of 290 kV/cm, as well as a high thermal stability of W_rec (>3 J/cm³) over a wide range of 30–140 °C at 250 kV/cm. Our findings suggest that the BNKT-ST-BMN material could be a potential candidate for use in energy storage pulse capacitors.     

Microwave assisted facile synthesis of {1/1,3-bis/1,3,5-tris-[(2-nitroxyethylnitramino)-2,4,6-trinitrobenzene]} using bismuth nitrate pentahydrate as an eco-friendly nitrating agent

1-(2-Nitroxyethylnitramino)-2,4,6-trinitrobenzene (3a), 1,3-bis(2-nitroxyethyl nitramino)-2,4,6-trinitrobenzene (3b) and 1,3,5-tris(2-nitroxyethylnitramino)-2,4,6-trinitrobenzene (3c) were prepared by the nitration of 1-(2-hydroxyethylamino)-2,4,6-trinitrobenzene (2a) 1,3-bis(2-hydroxyethylamino)-2,4,6-trinitrobenzene (2b) and 1,3,5-tris(2-hydroxyethylamino)-2,4,6-trinitrobenzene (2c) using bismuth nitrate pentahydrate (eco-friendly nitrating agent) in tetrahydrofuran adsorbed on silica gel under microwave irradiation, respectively. Key intermediate compounds viz., 2a, 2b and 2c were synthesized by condensing picryl chloride, styphnyl chloride and 1,3,5-trichloro-2,4,6-trinitrobenzene with ethanol amine, respectively, based on the lines of the reported method. The synthesized compounds were characterized based on their physical constant, infrared (IR) spectroscopy and (1)H nuclear magnetic resonance (NMR) spectroscopy. The spectroscopic data obtained indicated the formation of nitrate esters (3a-3c). The nitration methodology adopted in the present study is of relevance in the context of green chemistry. The target compounds (3a-3c) synthesized using eco-friendly approach are of interest from the point of high energy materials (HEMs).     

Polyurethane Foam Wastes Recycling under Microwave Irradiation

Microwave-assisted (MW-assisted) glycolysis of waste-flexible polyurethane (PU) foams using pentaerythritol in combination with glycerin and sodium hydroxide as a PU bond degradation reagent is reported. Split phases appeared after complete foam digestion. The upper phase contained recycled polyol, and the lower phase was a brown liquid with highly functionalized oligomers, amines and unreacted degradation reagents and showed potential for application in rigid polyurethane foam formulation. Our studies showed the dependence of recovered polyol assay to the additional MW irradiation and amine-free polyol were achieved in high yields and purities.     

Eco-friendly tape casting of borosilicate glass/Al2O3 sheets for LTCC applications

This work reports the innovative development of a borosilicate glass/Al₂O₃ tape for LTCC applications using an eco-friendly aqueous tape casting slurry. Polyvinylpyrrolidone (PVP) and polyacrylic acid (PAA) were the respective dispersants, while carboxymethyl cellulose (CMC) and styrene acrylic emulsion (SA) were the respective binders. The results showed that PVP was more suitable than PAA as the dispersant for the aqueous casting slurry, and that 1.5 wt% PVP would achieve well dispersion of CABS glass/Al₂O₃ powder in the aqueous slurry. Moreover, a small amount of 2.0 wt% CMC binder could yield smooth CABS glass/Al₂O₃ tapes crack free. A high-quality CABS glass/Al₂O₃ tape with a smooth surface was made from an aqueous slurry containing 1.5 wt% PVP dispersant, 2.0 wt% CMC binder, and 2.0 wt% PEG-400 plasticizer. The density, tensile strength, and surface roughness of the green tape were 2.05 g/cm³, 0.87 MPa, and 148 nm, respectively. The resulting CABS glass/Al₂O₃ composites sintered at 875 °C exhibited a bulk density of 3.14 g/cm³, a dielectric constant of 8.09, a dielectric loss of 1.0 × 10^?3, a flexural strength of 213 MPa, a thermal expansion coefficient of 5.30 ppm/^°C, and a thermal conductivity of 3.2 W m^?1 K^?1, thus demonstrating its broad prospects in LTCC applications.     

Mechanical properties of an eco-friendly one-part alkali-activated binder: Influence of metakaolin and water content

Alkali-activated binder (AAB) is a product with lower carbon footprint and has great potential to be an alternative to Portland cement in civil construction. In this study, one-part AAB has been synthesized by mixing alternative sodium silicate powder, obtained from rice husk ash (RHA) and metakaolin (MK). The main objective was to verify the effect of MK (two types were used with different reactivity characteristics) and water content on the mechanical properties of pastes and mortars produced with the one-part AAB. Some tests were conducted (e.g. setting times, flexural and compressive strengths, elastic modulus) and the results indicated that the MK type and the water content directly affect different properties. As expected, the decrease in water content decreased the workability of the mortars and improved the mechanical strength. A more reactive MK provided an increase in compressive strength higher than 60%. The results confirm the possibility of producing an alternative sodium silicate powder from RHA dissolution, that when mixed with MK, results in AAB with acceptable compressive strength. This paper reveals that with the correct materials and a good mix design, the properties of this eco-friendly AAB can be considerably improved.     

Eco-friendly dehydrogenation of dimethylamine-borane catalyzed by core-shell-looking tri-metallic RuNiPd nanoclusters loaded on white-flowering horse-chestnut seed

Generally, white-flowering horse-chestnut seed (WFHC) found in roadsides, parks and gardens, which spills around and causes environmental pollution, is defined as waste-bio material. This study is quite remarkable as it gives WFHC a new field of usage and literally prioritizes the environment. Here, waste-bio WFHC was tested as supporter for tri-metallic RuNiPd nanoclusters in the eco-friendly dehydrogenation of dimethylamine-borane (DMAB). Core-shell-looking tri-metallic RuNiPd@WFHC, with 264.09 ± 45.55 nm particle size, were in-situ synthesized throughout dehydrogenation of DMAB at 35.0 ± 0.1 °C. The WFHC and tri-metallic Ru_2.00Ni_1.86Pd_1.00@WFHC NCs were characterized by advanced analysis and their surface morphologies were studied in detail using adsorption models. The N₂ adsorption-desorption and logarithmic-Freundlich plots indicated that surface morphologies have heterogeneous multi-layer and typical Type-III isotherm with mesoporous surfaces. Also, detailed kinetic studies were actualized on the dehydrogenation of DMAB catalyzed by tri-metallic Ru_2.00Ni_1.86Pd_1.00@WFHC NCs with 158 h^?1 TOF value.     

A straightforward one-pot synthesis of Pd–Ag supported on activated carbon as a robust catalyst toward ethanol electrooxidation

Direct Ethanol Fuel Cells (DEFCs) have fascinated remarkable attention on account of their high current density and being environmentally friendly. Developing efficient and durable catalysts with a simple and fast method is a great challenge in the practical applications of DEFCs. To this end, the bimetallic Pd–Ag with adjustable Pd:Ag ratios were synthesized via a simple and one-pot strategy on activated carbon as a support in this study. The Pd–Ag/C catalysts with different molar ratios were synthesized by simultaneous reduction of Pd and Ag ions in the presence of the ethanolic sodium hydroxide as a green reducing agent for the first time. Several different methods, including FE-SEM, HR-TEM, XRD, XPS EDX, ICP-OES, and BET were used to confirm the structure and morphology of the catalysts. The performance of catalysts was also examined in ethanol oxidation. Obtained results of electrochemical experiments revealed that the Pd₃–Ag₁/C catalyst had superior catalytic activity (2911.98 mAmg^?1_Pd), durability, and long-stability compared to the other catalysts. The excellent catalytic characteristic can be attributed to the synergistic effect between Pd and Ag. We presume that our simple method have the chance to be utilized as a proper method for the synthesis of fuel cell catalysts.