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Catalyst-free malleable, degradable, bio-based epoxy thermosets and its application in recyclable carbon fiber composites
No full textCarbon fiber reinforced composites (CFRCs) are a kind of most potential materials due to the high strength-to-weight ratio, excellent fatigue and corrosion resistance. However, the vast majority of CFRCs prepared from carbon fiber and thermosetting matrices are difficult to be recycled and depend on limited fossil resources. Here, for the first time, we reported fully bio-based catalyst-free epoxy vitrimers for CFRCs. The epoxy vitrimers exhibited excellent malleability and could be reprocessed by compression molding. Outstanding degradability was also achieved, which enabled multiple recovery of CF from their CFRCs without damage. In addition, CFRCs regenerated from multiple recovered CF exhibited insignificant differences from the original CFRCs. This work will provide an effective method for the sound development of CFRCs from both economic and environmental aspects
Bioinspired ultrathin graphene nanosheets sandwiched between epoxy layers for high performance of anticorrosion coatings
No full textThe special brick-mud layered micro-nano structure of nacre has undergone millions of years of biological evolution, which can withstand the corrosion of seawater in different environments, and has both high strength and toughness. Inspired by mussels and natural nacre, we successfully designed a bionic epoxy-(graphene-dopamine)(n)-epoxy sandwich composite coating. Not only does dopamine act as a binder to improve the interfacial compatibility and adhesion between epoxy resin and graphene, but due to the hydrogen bonding and the electrostatic interaction of -COO - and -NH3+, graphene interlayers is parallel to the substrate and arranged between two epoxy coatings. This not only gives full play to the barrier effect of graphene, but also shielding the galvanic corrosion by avoiding direct contacting with the substrate. The results show that the composite coating prepared 10 scanning of dopamine functionalized graphene oxide has a low-frequency impedance of 1.30 x 10(9) O cm(2) after immersion in 3.5 wt% NaCl solution for 90 days, which is three orders of magnitude higher than that of pure coating, revealing remarkable long-term anticorrosion. We consider that our strategy can be readily extended to the self-alignment of a variety of two-dimensional nanofillers to facilitate the development of long-term corrosion resistant coatings
2D graphene and h-BN layers application in protective coatings
No full textAs two-dimensional (2D) materials, graphene and hexagonal-boron nitride (h-BN) are famous for protective coatings, because of their excellent chemical resistance, barrier property, impermeability along with thermal stability, and a large number of these properties are particularly suitable for protective coatings. However, the applications of graphene for metal protection have been limited by galvanic corrosion issues. Also, h-BN nanosheets are also explored as potential materials for corrosion protecting, especially, electrical insulation of h-BN is influential in solving electrochemical reaction and uniquely suitable to be used as an anticorrosion material. Interestingly, graphene doped h-BN exhibit outstanding functionalities in a synergic manner compare to standalone 2D materials. This review provides the fundamental summary of preparation methods for graphene and h-BN, meanwhile, the key challenges and future potential of protective coatings are discussed and predicted
Recent progress of organic photovoltaics for indoor energy harvesting
No full textThe recent progress of indoor organic photovoltaics (IOPVs) is reviewed in this work for abundant low power consumption applications. In recent years, organic solar cells have attracted significant attention to harvest solar energy. However, many drawbacks of such as discontinuous adequate sunlight, heat instability, and strong illumination instability inhibit outdoor organic photovoltaic technology from entering solar panel market. As the market of IoT nodes (e.g. sensors, watches, calculators, remote control, hearing aid, and monitors) used in relatively mild indoor environment rapidly grows, the demand for artificial light energy harvesters to supply continuous and cordless power for the indoor environment has emerged. Organic photovoltaic technology for indoor harvesters is one of the reliable candidates because the energy level of organic materials is tunable to match the indoor light source spectra so that its power conversion efficiency (PCE) outweighs that of most of the other indoor harvesters. Indoor organic photovoltaics exhibit the PCE over 30% with an output power of 150 ?Wcm? 2 under the illuminance of artificial lights, which is high enough to drive numerous indoor applications. This review summarizes the performance mechanism of organic photovoltaics (OPVs) when the illuminance is switched from 1-sun to dim light, the research progress for indoor energy transformation, and the viewpoint to speed up the development of IOPVs
Reinforcing and discriminative-stimulus effects of two pyrrolidine-containing synthetic cathinone derivatives in rats
No full textThe molecular and behavioral aspects of alpha-pyrrolidinopentiophenone (alpha-PVP) have been characterized; however, how the structural modification of alpha-PVP affects its abuse potential is still unknown. In this study, we investigated the abuse potential of two pyrrolidinylated second-generation cathinones:4-chloro-alpha-pyrrolidinopentiophenone (4cl-alpha-PVP) and 4-chloro-alpha-pyrrolidinopropiophenone (4cl-alpha-PPP). Male Sprague-Dawley rats were trained to self-administer methamphetamine (METH, 0.05 mg.kg(-1).infusion(-1)), alpha-PVP (0.05 mg.kg(-1).infusion(-1)), 4cl-alpha-PVP (0.05 mg.kg(-1).infusion(-1)), and 4cl-alpha-PPP (0.5 mg.kg(-1).infusion(-1)) under a fixed ratio (FR)(-1) reinforcement schedule for-10 sessions. The discriminative-stimulus effect of METH (0.8 mg/kg) from saline was tested under an FR10 schedule of food delivery. alpha-PVP, 4cl-alpha-PVP and 4cl-alpha-PPP produced reinforcement behaviors and presented an inverted U-shaped dose effect. The reinforcing potency was displayed with a rank order of alpha-PVP (0.029 mg.kg(-1).infusion(-1)) > METH (0.040 mg.kg(-1).infusion(-1)) > 4cl-alpha-PVP (0.094 mg.kg(-1).infusion(-1)) > 4cl-alpha-PPP (0.51 mg.kg(-1).infusion(-1)). All three drugs were fully substituted for the discriminative-stimulus effects of METH in rats. The substitution potency for discriminative-stimulus effects of alpha-PVP (ED50 = 0.4 mg/kg) was approximately equal to that of METH (ED50 = 0.3 mg/kg), while the discriminative potency of 4cl-alpha-PVP (ED50 =-1.0 mg/kg) and 4cl-alpha-PPP (ED50 = 5 mg/kg) was approximately 3 and-16-fold less than that of METH. The rank order of potency was alpha-PVP approximate to METH > 4cl-alpha-PVP > 4cl-alpha-PPP. The present data demonstrated that 4cl-alpha-PVP and 4cl-alpha-PPP produced reinforcing effects and fully and dose-dependently substituted for the subjective effects of METH, suggesting that both 4cl-alpha-PVP and 4cl-alpha-PPP have abuse potential that may be similar to METH
Fabrication of bio-based amphiphilic hydrogel coating with excellent antifouling and mechanical properties
No full textAntifouling coatings are crucial to protect marine facilities and aquacultures from the damage of microorganisms for long-term serves. However, it is still a challenge to fabricate coating with excellent antifouling performance and superior mechanical stability. Here, we report a bio-based amphiphilic hydrogel coating with excellent antifouling and mechanical properties. The coating was achieved by the in-situ formation of hydrophobic and hydrophilic interpenetrating polymer network (IPN). The hydrophobic part from a synthesized silicon-containing epoxy resin contributes to superior mechanical properties including high tensile strength and excellent adhesion of 5B. While the hydrophilic hydrogel part from the cross-linking of a hydrophilic polymer with AgNPs gives excellent antifouling properties, resist to proteins, bacteria, algae, and other marine organisms. The antifouling performance of the coating was evaluated by the attachment of proteins (BSA-FITC), bacteria (Escherichia coli and Bacillus subtilis), and Algae (Navicula torguatum and Phaeodactylum tricornutum). The results show that the bio-based amphiphilic hydrogel coating (e.g. SA-1-5) endows surface with excellent resistance to the fouling of proteins, bacteria and microorganisms. The overall antifouling and mechanical properties of the amphiphilic coating was also evaluated by field test in East China Sea from June 3rd 2020 to July 17th 2020 that the bio-based amphiphilic hydrogel coating was intact and almost no marine organisms attached. This work provides a new strategy for the fabrication of bio-based and high-performance antifouling coatings
Improved Thermoelectric Properties of BiSbTe-AgBiSe2 Alloys by Suppressing Bipolar Excitation
No full textBismuth telluride alloys are the only commercialized thermoelectric materials, which have successfully realized the practical applications of active cooling and waste heat harvesting near room temperature. However, the drawbacks of intermediate ZT values and brittle nature of zone-melted materials have limited their future development. Herein, we show that AgBiSe2 alloying is an effective approach to improve both the thermoelectric and mechanical performance of sintered Bi0.48Sb1.52Te3 materials. The addition of AgBiSe2 can not only suppress the bipolar effect by increasing the hole concentration but also decrease the lattice thermal conductivity by introducing various phonon scattering centers. These effects enable a peak ZT value of 1.1 at 375 K and an average value of 0.94 between 300 and 500 K in the composite of Bi0.48Sb1.52Te3-0.3 wt % AgBiSe2. Moreover, the addition of AgBiSe2 can also enhance the Vickers hardness, which reaches 0.75 GPa, 42% times higher than that of pristine zone-melted BiSbTe
Experimental and Theoretical Study on Glycolic Acid Provided Fast Bio/Seawater-Degradable Poly(Butylene Succinate-co-Glycolate)
No full textThe very slow degradation of biodegradable polymers in the marine environment is due to the lack of dedicated degradation enzymes in open seas. As a result, introducing monomers that have a fast hydrolysis process is required to accelerate seawater degradation. Poly(butylene succinate-co-glycolate) (PBSGA) copolyesters with glycolic acid (GA) units ranging from 5 to 40% were synthesized by our newly developed polymerizing method based on oligo(glycolic acid). The results of H-1-NMR and GPC revealed that short GA segments were evenly distributed between BS segments, obtaining random copolyesters with a weight-average molecular weight over 6.24 * 10(4) g/mol. The copolymerized GA units hinder its crystallization capability and increase hydrophilicity of the PBSGAs, which still displayed mechanical properties comparable or even better than most biodegradable polymers. Fast degradation in seawater and enzymatic environments (Candida antarctica lipase B enzymes) is proved experimentally. The quick decomposition in seawater was originated from accelerated hydrolysis. For instance, the weight loss of PBSGA40 (compositions of GA units) exceeded 22% after 49 days. Possible degradation mechanisms were proposed based on Fukui function analysis and frontier molecular orbital calculation. Additionally, the energy barrier for hydrolysis was calculated by the density functional theory method, indicating that the hydrolysis of the polymer chain became more and more easy with the increase in GA units. At last, the addition of GA units only had a mild effect on the shelf life of the PBSGAs
Magnetic Exchange Field Modulation of Quantum Hall Ferromagnetism in 2D van der Waals CrCl3/Graphene Heterostructures
No full textThe efforts toward the experimental realization of spin-polarized transports in ideal materials or platforms, such as the magnetized graphene or various quantum Hall states, is a research hotspot in spintronics. Magnetic van der Waals materials open the door for exploring various physical phenomena, technologies, and integrating novel spintronic devices seamlessly within the 2D limit. Here, we demonstrate magnetic proximity effect in chromium trichloride (CrCl3)/bilayer graphene (BLG) heterostructures by low-temperature transport measurements. An effective exchange field induced in BLG has been demonstrated by the Zeeman spin Hall effect via nonlocal measurements. Furthermore, the exchange field modulates the quantum Hall ground state of BLG and thus favors the formation of a canted antiferromagnetic (CAF) phase in an external perpendicular magnetic field (B-perpendicular to). Asymmetric nonlocal magneto-transport behaviors are also observed at opposite B-perpendicular to directions, due to the asymmetric modulation on the exchange field by external B-perpendicular to directions. Our work suggests that the 2D magnetic van der Waals materials and graphene hybrid systems offer a unique platform for quantum Hall ferromagnetism physics
Photocatalytic performance of TiO2 nanotube structure based on TiN coating doped with Ag and Cu
No full textIn this paper, TiN, TiN-Ag and TiN-Cu coatings were prepared by multi-arc ion plating. TiO2 nanotube arrays were constructed on the coatings by anodization reaction at room temperature. Building TiO2 nanotube arrays on the coating can retain the performance of the hard coating itself and reduce the process of destroying the structure of the TiO2 nanotubes. Non-metallic N doping and co-doping of metallic Ag, Cu and non-metallic N make the nanotubes catalyzed by visible light. The specific surface area of TiO2 by changed the anodizing voltage. The results show that the anodic oxidation voltage is 15V and Cu, N co-doped TiO2 photocatalytic degradation performance is the best