3D printing encouraging desired in-situ polypyrrole seed-polymerization for ultra-high energy density supercapacitors

The tireless pursuit of supercapacitors with high energy density entails the parallel advancement of wellsuited electrode materials and elaborately engineered architectures.Polypyrrole(PPy)emerges as an exceedingly conductive polymer and a prospective pseudocapacitive materials for supercapacitors,yet the inferior cyclic stability and unpredictable polymerization patterns severely impede its real-world applicability.Here,for the first time,an innovative seed-induced in-situ polymerization assisted 3D printing strategy is proposed to fabricate PPy-reduced graphene oxide/poly(vinylidene difluoride-cohexafluoropropylene)(PVDF-HFP)(PPy-rGO/PH)electrodes with controllable polymerization behavior and exceptional areal mass loading.The preferred active sites uniformly pre-planted on the 3D-printed graphene substrates serve as reliable seeds to induce efficient polypyrrole deposition,achieving an impressive mass loading of 185.6 mg cm^(-2)(particularly 79.2 mg cm^(-2)for polypyrrole)and a superior areal capacitance of 25.2 F cm^(-2)at 2 mA cm^(-2)for a 12-layer electrode.In agreement with theses appealing features,an unprecedented areal energy density of 1.47 mW h cm^(-2)for a symmetrical device is registered,a rarely achieved value for other PPy/rGO-based supercapacitors.This work highlights a promising route to preparing high energy density energy storage modules for real-world applications.

Alkali Metal Ion Substituted Carboxymethyl Cellulose as Anode Polymeric Binders for Rapidly Chargeable Lithium-Ion Batteries

The increasing demand for short charging time on electric vehicles has motivated realization of fast chargeable lithium-ion batteries(LIBs).However,shortening the charging time of LIBs is limited by Li^(+)intercalation process consisting of liquid-phase diffusion,de-solvation,SEI crossing,and solid-phase diffusion.Herein,we propose a new strategy to accelerate the de-solvation step through a control of interaction between polymeric binder and solvent-Li^(+)complexes.For this purpose,three alkali metal ions(Li^(+),Na^(+),and K^(+))substituted carboxymethyl cellulose(Li-,Na-,and K-CMC)are prepared to examine the effects of metal ions on their performances.The lowest activation energy of de-solvation and the highest chemical diffusion coefficient were observed for Li-CMC.Specifically,Li-CMC cell with a capacity of 3 mAh cm^(-2)could be charged to>95%in 10 min,while a value above>85%was observed after 150 cycles.Thus,the presented approach holds great promise for the realization of fast charging.

Visualization of adaptive polymer flow and displacement in medium-permeable 3D core-on-a-chip

Polymer flooding has been witnessed an effective technology for enhancing oil recovery from medium-to low-permeability reservoirs;however, direct visualization of polymer solution flow in such reservoir condition is still lacking. In this work, a three-dimensional (3D) core-on-a-chip device with a permeability of around 200 mD was prepared and employed to visualize the pore-scale flow and displacement of a self-adaptive polymer (SAP, 8.7 × 106 g·mol−1)−whose microscopic association structure and macroscopic viscosity can reversibly change in response to shear action−versus partially hydrolyzed polyacrylamide (HPAM), by recording their flow curves, monitoring dynamic transportation process via particle imaging velocimetry, and building 3D structure of remaining oil. The results show that, in single-phase flow, all polymer solutions exhibit flow thinning and then thickening regions as flow rate increases, but the transition between two regimes occurs at a small Weissenberg number (10−3−10−1) in this medium-permeable condition. In contrast to HPAM-1 with close weight-average molecular weight (Mw), the adaptive character not only extends SAP's shear-govern region, allowing SAP to propagate piece by piece and achieve higher accessible pore volume, but it also enhances the elastic resistibility of polymer in the extension-dominated regime, increasing the microscopic displacement efficiency. These two effects result in 1.5–3 times more oil recovery factor for SAP than for HPAM-1. Regarding ultra-high-Mw HPAM-2 (25 × 106 g·mol−1), plugging and chain degradation do occur, thus producing lower oil recovery than SAP. This work provides a direct approach for in-situ assessment of polymer-based displacing system under a more authentic condition of practical reservoirs.

The Research of Complex System Property between Thermosensitive Polymer and Surfactant

In this paper, the rigid structural thermosensitive polymer （made in lab） of NBS （N-butyl styrene）, N, N-DEAM （diethyl acrylamide） and AM （acrylamide） was prepared. The influence of viscosity for copolymer solution under different reaction conditions such as temperatures and inorganic salt （monovalent salt and divalent salt） was analyzed. The experiment studies the combination of polymer situation and three different types of surfactants under certain conditions of the room temperature （25℃） and the formation temperature （76℃）. At last, the influence of the surfactant kinds and concentration on the viscosity of the polymer solution are studied. The results show that： The copolymer solution, the apparent viscosity of which decreases with the increasement of temperature, but its viscosity has suddenly increased and thereafter dropped in the transition temperature. So the temperature sensitive effect ofcopolymer is very significantly. When the concentration of inorganic salt and surfactant can be controlled in certain extent, the copolymer solution, the effect increases with the increasement of the concentration, but the viscosity of which decreases with the increasement of shear rate. Shear rate can be controlled in certain extent, shearing stability properties of the copolymer solution are proved.

3D‑Printed Carbon‑Based Conformal Electromagnetic Interference Shielding Module for Integrated Electronics

Electromagnetic interference shielding(EMI SE)modules are the core com-ponent of modern electronics.However,the tra-ditional metal-based SE modules always take up indispensable three-dimensional space inside electronics,posing a major obstacle to the integra-tion of electronics.The innovation of integrating 3D-printed conformal shielding(c-SE)modules with packaging materials onto core electronics offers infinite possibilities to satisfy ideal SE func-tion without occupying additional space.Herein,the 3D printable carbon-based inks with various proportions of graphene and carbon nanotube nanoparticles are well-formulated by manipulating their rheological peculiarity.Accordingly,the free-constructed architectures with arbitrarily-customized structure and multifunctionality are created via 3D printing.In particular,the SE performance of 3D-printed frame is up to 61.4 dB,simultaneously accompanied with an ultralight architecture of 0.076 g cm^(-3) and a superhigh specific shielding of 802.4 dB cm3 g^(-1).Moreover,as a proof-of-concept,the 3D-printed c-SE module is in situ integrated into core electronics,successfully replacing the traditional metal-based module to afford multiple functions for electromagnetic compatibility and thermal dissipa-tion.Thus,this scientific innovation completely makes up the blank for assembling carbon-based c-SE modules and sheds a brilliant light on developing the next generation of high-performance shielding materials with arbitrarily-customized structure for integrated electronics.

Efficient Electromagnetic Wave Absorption and Thermal Infrared Stealth in PVTMS@MWCNT Nano‑Aerogel via Abundant Nano‑Sized Cavities and Attenuation Interfaces

Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)drying.The fabricated organic-inorganic hybrid PVTMS@MWCNT aerogel structure shows nano-pore size(30-40 nm),high specific surface area(559 m^(2)g^(−1)),high void fraction(91.7%)and enhanced mechanical property:(1)the nano-pore size is beneficial for efficiently blocking thermal conduction and thermal convection via Knudsen effect(beneficial for infrared(IR)stealth);(2)the heterogeneous interface was beneficial for IR reflection(beneficial for IR stealth)and MWCNT polarization loss(beneficial for electromagnetic wave(EMW)attenuation);(3)the high void fraction was beneficial for enhancing thermal insulation(beneficial for IR stealth)and EMW impedance match(beneficial for EMW attenuation).Guided by the above theoretical design strategy,PVTMS@MWCNT nano-aerogel shows superior EMW absorption property(cover all Ku-band)and thermal IR stealth property(ΔT reached 60.7℃).Followed by a facial combination of the above nano-aerogel with graphene film of high electrical conductivity,an extremely high electromagnetic interference shielding material(66.5 dB,2.06 mm thickness)with superior absorption performance of an average absorption-to-reflection(A/R)coefficient ratio of 25.4 and a low reflection bandwidth of 4.1 GHz(A/R ratio more than 10)was experimentally obtained in this work.

3D Printing of Periodic Porous Metamaterials for Tunable Electromagnetic Shielding Across Broad Frequencies

The new-generation electronic components require a balance between electromagnetic interference shielding efficiency and open structure factors such as ventilation and heat dissipation.In addition,realizing the tunable shielding of porous shields over a wide range of wavelengths is even more challenging.In this study,the well-prepared thermoplastic polyurethane/carbon nanotubes composites were used to fabricate the novel periodic porous flexible metamaterials using fused deposition modeling 3D printing.Particularly,the investigation focuses on optimization of pore geometry,size,dislocation configuration and material thickness,thus establishing a clear correlation between structural parameters and shielding property.Both experimental and simulation results have validated the superior shielding performance of hexagon derived honeycomb structure over other designs,and proposed the failure shielding size(D_(f)≈λ/8-λ/5)and critical inclined angle(θf≈43°-48°),which could be used as new benchmarks for tunable electromagnetic shielding.In addition,the proper regulation of the material thickness could remarkably enhance the maximum shielding capability(85-95 dB)and absorption coefficient A(over 0.83).The final innovative design of the porous shielding box also exhibits good shielding effectiveness across a broad frequency range(over 2.4 GHz),opening up novel pathways for individualized and diversified shielding solutions.

A robust viscoelastic surfactant tolerating 20% HCl up to 150℃ for oil well stimulation

Viscoelastic surfactants(VES)are often used as viscous diverters in acidizing stimulation to prolong the acid consumption time and maximize zonal coverage of the acid for improving well productivity.However,the ceiling temperature of commercial VES cannot exceed 120℃in practical use because of the poor thermal stability and fragile molecular structure,hindering their implementation in hightemperature oil reservoirs,i.e.,≥150℃.Here we synthesized a novel C22-tailed diamine,N-erucaminopropyl-N,N-dimethylamine(EDPA),and examined comparatively its rheological behavior,assemblies morphology and molecular stability in 20 wt%HCl with a commercial VES,erucyl dimethyl amidopropyl betaine(EDAB).The feasibility of EDPA for acidizing stimulation was assessed by acid etching of carbonate rock with its HCl solution at 150℃.Rheological results showed that the 2.5 wt%EDPA—20 wt%HCl solution maintains stable viscosity of 90 m Pa s at 150℃for 60 min,while that of 2.0 wt%EDAB HCl solution is just 1 m Pa s under identical conditions.1H NMR spectra and cryo-TEM observations revealed that the chemical structure and self-assembled architectures of EDPA remained intact in such context,but the EDAB suffered from degradation due to the hydrolysis of the amide group,accounting for the poor heat-resistance and acid-tolerance.The reaction rate of 2.5 wt%EDPA HCl solution with carbonate rock was one order of magnitude lower than that of 20 wt%HCl solution at 150℃,underpinning the potential of EDPA to be used in the high-temperature reservoirs acidizing.This work improved the thermal tolerance of VES in highly concentrated HCl solution,paving a feasible way for the acidization of high-temperature reservoir environments(~150℃).

Structure Regulation of Electric Double Layer via Hydrogen Bonding Effect to Realize High-Stability Lithium-Metal Batteries

The interfacial chemistry of solid electrolyte interphases(SEI)on lithium(Li)electrode is directly determined by the structural chemistry of the electric double layer(EDL)at the interface.Herein,a strategy for regulating the structural chemistry of EDL via the introduction of intermolecular hydrogen bonds has been proposed(p-hydroxybenzoic acid(pHA)is selected as proof-of-concept).According to the molecular dynamics(MD)simulation and density functional theory(DFT)calculation results,the existence of hydrogen bonds realizes the anion structural rearrangement in the EDL,reduces the lowest unoccupied molecular orbital(LUMO)energy level of anions in the EDL,and the number of free solvent molecules,which promotes the formation of inorganic species-enriched SEI and eventually achieves the dendrite-free Li deposition.Based on this strategy,Li‖Cu cells can stably run over 185 cycles with an accumulated active Li loss of only 2.27 mAh cm^(-2),and the long-term cycle stability of Li‖Li cells is increased to 1200 h.In addition,the full cell pairing with the commercial LiFePO_(4)(LFP)cathodes exhibits stable cycling performance at 1C,with a capacity retention close to 90%after 200 cycles.

High Areal Capacity and Long Cycle Life Flexible Mild Quasi-Solid-State Ag-Zn Battery with Dendrite-Free Anode

Silver-zinc(Ag-Zn)batteries are a promising battery system for flexible electronics owing to their high safety,high energy density,and stable output voltage.However,poor cycling performance,low areal capacity,and inferior flexibility limit the practical application of Ag-Zn batteries.Herein,we develop a flexible quasi-solid-state Ag-Zn battery system with superior performance by using mild electrolyte and binder-free electrodes.Copper foam current collector is introduced to impede the growth of Zn dendrite,and the structure of Ag cathode is engineered by electrodeposition and chloridization process to improve the areal capacity.This novel battery demonstrates a remarkable cycle retention of 90%for 200 cycles at 3 mA cm^(-2).More importantly,this binder-free battery can afford a high capacity of 3.5 mAh cm^(-2)at 3 mA cm^(-2),an outstanding power density of 2.42 mW cm^(-2),and a maximum energy density of 3.4 mWh cm^(-2).An energy management circuit is adopted to boost the output voltage of a single battery,which can power electronic ink display and Bluetooth temperature and humidity sensor.The developed battery can even operate under the extreme conditions,such as being bent and sealed in solid ice.This work offers a path for designing electrodes and electrolyte toward high-performance flexible Ag-Zn batteries.

Recent Advances in Transition Metal-Based Catalysts for Electrocatalytic Nitrate Reduction Reaction

The accumulation of excessive nitrate in the atmosphere not only jeopardizes human health but also disrupts the balance of the nitrogen cycle in the ecosystem.Among various nitrate removal technologies,electrocatalytic nitrate reduction reaction(eNO_(3)RR)has been widely studied for its advantages of being eco-friendly,easy to operate,and controllable under environmental conditions with renewable energy as the driving force.Transition metal-based catalysts(TMCs)have been widely used in electrocatalysis due to their abundant reserves,low costs,easy-to-regulate electronic structure and considerable electrochemical activity.In addition,TMCs have been extensively studied in terms of the kinetics of the nitrate reduction reaction,the moderate adsorption energy of nitrogen-containing species and the active hydrogen supply capacity.Based on this,this review firstly discusses the mechanism as well as analyzes the two main reduction products(N_(2)and NH_(3))of eNO_(3)RR,and reveals the basic guidelines for the design of efficient nitrate catalysts from the perspective of the reaction mechanism.Secondly,this review mainly focuses on the recent advances in the direction of eNO_(3RR)with four types of TMCs,Fe,Co,Ni and Cu,and unveils the interfacial modulation strategies of Fe,Co,Ni and Cu catalysts for the activity,reaction pathway and stability.Finally,reasonable suggestions and opportunities are proposed for the challenges and future development of eNO_(3)RR.This review provides far-reaching implications for exploring cost-effective TMCs to replace high-cost noble metal catalysts(NMCs)for eNO_(3)RR.

A salt-induced viscosifying smart polymer for fracturing inter-salt shale oil reservoirs

Inter-salt shale oil reservoirs located between two salt layers are always accompanied by high temperature and high salinity. However, the present commonly used water-soluble polymers in fracturing fluids su er from poor tolerance to high temperature and high salinity. Thermoviscosifying polymers(TVP) whose aqueous solution shows viscosity increase upon increasing temperature and salt concentration have received considerable attention recently, which is promising for utilization in fracturing fluids to overcome these problems. In this work, both the salt-induced viscosifying property and mechanism of a TVP solution were investigated and the performance of TVP used as fracturing fluid based on the conditions of the Jianghan inter-salt shale oil reservoir in China was evaluated. It is found that the salt-induced viscosifying property of the TVP solution decreases with temperature and shear rate, but increases with polymer concentration. The number of intermolecular hydrophobic domains increases with the salt concentration contributing to the strengthening of a 3D network structure, which results in an increase in viscosity. In addition, the TVP fracturing fluid formulated with saturated brine exhibits excellent temperature and shear resistance, sand-suspending performance, and gel-breaking performance. Its viscosity remains above50 m Pa s after being sheared for 1 h even at a high temperature of 140 °C and the sand-suspending stability can be maintained for more than 1 week at 100 °C. Furthermore, the fracturing fluid can be easily broken down within 12h using 0.2 wt%–0.3 wt% potassium persulfate without residue.

Composition Dependence of the Thermal Behavior,Morphology and Properties of Biodegradable PBS/PTMO Segment Block Copolymer

A series of aliphatic biodegradable poly（ether-ester）s based on poly（butylene succinate）（PBS）as hard segment and poly（tetramethylene oxide）（PTMO,M_n=1 000 g/mol） as soft segment were synthesized.The composition dependence of thermal behavior,morphology and mechanical properties was investigated by differential scanning calorimetry（DSC）,atomic force microscopy（AFM）,and tensile testing.The crystallization temperature（T_c） and melting temperature（T_m） of the PBS block within poly（ether-ester）s decrease steadily at first,but decrease sharply with PTMO content above 50 wt%.Two crystallization peaks were detected for PTMO in PBSPTMO60 sample,suggesting the occurrence of fractionated crystallization.The crystallization enthalpies（△H_c） and melting enthalpies（△H_m） of PBS block decrease at first,then increase as PTMO content increases further.AFM has demonstrated that phase-separated morphology transforms from a phase of continuous hard matrix to one of continuous soft matrix containing isolated hard domain as PTMO content is increased.Finally,the results of tensile testing show that the poly（ether-ester）s present the behavior of plastics when PTMO content is below 40 wt%,and of thermoplastic elastomers with PTMO content above 50 wt%.By varying the composition of copolymer,the aliphatic poly（ether-ester）s plastics,or especially biodegradable aliphatic poly（ether-ester）s thermoplastic elastomers can be obtained.

A novel iron-chelating polyimide network as a visible-light-driven catalyst for photoinduced radical polymerization

With the aim of developing a low-cost and efficient visible-light-driven photocatalyst for radical polymerization,iron-chelating polyimide networks(Fe@MPI)was fabricated by firstly synthesizing photoactive melamine-containing polyimide(MPI)networks and then incorporating Fe(III)cations into the polymer networks.Fe@MPI exhibits a wide absorption spectrum ranging from 220 to 1250 nm and 3.5 times higher photocurrent intensity as compared with the pristine MPI.Based on its excellent photo-electric properties,Fe@MPI was employed as a recyclable heterogeneous catalyst,providing sufficient activity for the visible-light driven radical polymerization to synthesize poly(methyl methacrylate)with molecular weight up to 31.×10^4 g mol.Taking advantage of the heterogeneous nature of the catalyst,Fe@MPI could be facilely regenerated from the polymerization solution by filtration without an obvious loss of its activity.This research provides a novel recyclable catalyst for visible-light driven radical polymerization.

Fabrication of segregated poly(arylene sulfide sulfone)/graphene nanoplate composites reinforced by polymer fibers for electromagnetic interference shielding

Poly(arylene sulfide sulfone)/graphene nanoplate(PASS/GNP) composites with segregated structure based on continuous polymer fiber skeletons were fabricated by coating a thin conductive layer on the PASS fibers and then performing compression molding. The formation of a unique segregated conductive network endowed the PASS/GNP composites with high electrical conductivity and excellent electromagnetic interference(EMI) shielding effectiveness(SE), reaching 17.8 S/m and 30.1 d B, respectively, when the content of the GNPs in the conductive layer was 20 wt%. The PASS/GNP composites also exhibited outstanding mechanical properties, which was attributed to the continuous PASS fiber skeletons that could withstand large loads and the strong interfacial interaction between the conductive layers and the PASS fibers that could provide good stress transfer. This approach is suitable for most soluble polymers.

Crystallization Behavior of Poly(Tetramethylene Oxide) Influenced by the Crystallization Condition of Poly(Butylene Succinate) in Their Copolymers

The effect of crystallization conditions of poly(butylene succinate)(PBS) component on the crystallization of poly(tetramethylene oxide)(PTMO) component in their segment block copolymer, with a higher PTMO content(PTMO mass fraction is 67%), was investigated by DSC and temperature-dependent FTIR. It is found that the isothermal crystallization time(tIC) of PBS has an effect on the crystallization behavior of PTMO component. Perturbation correlation move-window two-dimensional(PCMW2 D) correlation analysis and generalized 2 D correlation analysis(2 DIR) were performed to explore the origin of this phenomenon. The PCMW2 D and 2 DIR results show that the correlation intensity peak observed at around 20 ℃ for PTMO is due to the PTMO chains movements forced by the PBS chains folded movements. If tIC of PBS at temperature of 20 ℃ is prolonged, more PTMO components are incorporated in the region between PBS lamellae and the peak at-7.6 ℃(belonging to less-constricted PTMO chains) changes smaller and even disappears, while the peak at-16.3 ℃ belonging to more-constricted PTMO chains gets bigger. A crystallization model was also established in this study. The results of tensile testing showed that tensile strength slightly increased and elongation at break decreased with increasing heat treatment time at 40 ℃.

STUDIES ON ULTRASONIC DEGRADATION AND BLOCK COPOLYMERIZATION OF POLYACRYLAMIDE AND POLY(ETHYLENE OXIDE)

The kinetics of ultrasonic degradation of aqueous solution of polyacrylamide（PAM）and poly（ethyleneoxide）（PEO）as well as ultrasonic block copolymerization of aqueous solution of the mixture of PAM/PEOwere studied respectively.The degradation reaction of PEO follows a linear relationship between（P1-P∞）-1and irradiation time,while that of PAM follows a linear relationship between（P1-P∞）-1/2and irradiation time.The structure of the copolymer was identified by IR,NMR and DTA,and the copolymer prepared is a blockone.The copolymer formed by irradiating 1% aqueous solution of PEO/PAM mixture（1:1）for a period of40min.at 18.2 kHz with a sonic intensity corresponding to 2.OA input current on the reversed main circuitamounts to 61.8%.

In situ polymerization preparation and mechanical properties of nanocomposites based on PA10T/10I-block-PEG copolymer and graphene oxide

Poly(decamethylene terephthalamide/decamethylene isophthalamide)-block-polyvinyl alcoho)(PA10 T/10 IPEG) copolymer/graphene oxide(GO) composites were prepared via in-situ melt polymerization and two different nano-filler addition approaches were compared. The relationship between the micro-structure and performance of the elastomer composites prepared by one-step and two-step methods was explored. The results show that the two-step method significantly promoted the dispersion of the GO in a polymer matrix, and facilitated the grafting of more hard molecular chains. Thus, the elastic modulus and tensile strength of the nanocomposite have been significantly improved by the presence of GO. This was because of the strong interaction between the functional groups on the surface of the GO and the hard molecular chains. This would be also be favorable to load transfer across the interface. Additionally, the elongation at the break of composites increased by 10% with the addition of a small amount of GO(0.2% wt). This is because hard domains tend to be enriched on the surface of GO in composites and act as a lubricating layer at the interface between the GO and matrix, leading to increased deformation ability. This work provides an effective strategy to prepare elastomer composites with high strength and toughness.

Solid-state mechanochemistry advancing two dimensional materials for lithium-ion storage applications:A mini review

The vigorous development of two-dimensional(2D)materials brings about numerous opportunities for lithiumion batteries(LIBs)due to their unique 2D layered structure,large specific surface area,outstanding mechanical and flexibility properties,etc.Modern technologies for production of 2D materials include but are not limited to mechanochemical(solid-state/liquid-phase)exfoliation,the solvothermal method and chemical vapor deposition.In this review,strategies leading to the production of 2D materials via solid-state mechanochemistry featuring traditional high energy ball-milling and Sichuan University patented pan-milling are highlighted.The mechanism involving exfoliation,edge selective carbon radical generation of the 2D materials is delineated and this is followed by detailed discussion on representative mechanochemical techniques for tailored and improved lithium-ion storage performance.In the light of the advantages of the solid-state mechanochemical method,there is great promise for the commercialization of 2D materials for the next-generation high performance LIBs.