Ruiqi Na

A novel poly(ethylene glycol)–grafted poly(arylene ether ketone) blend micro-porous polymer electrolyte for solid-state electric double layer capacitors formed by incorporating a chitosan-based LiClO4 gel electrolyte

A novel strategy was used to prepare a high performance micro-porous polymer electrolyte (MPE) from a poly(arylene ether ketone) (PAEK)/poly(ethylene glycol) grafted poly(arylene ether ketone) (PAEK-g-PEG) polymer composite membrane matrix incorporating a chitosan based LiClO4 gel electrolyte. The morphology, porosity, and thermal and mechanical properties of the PAEK/PAEK-g-PEG polymer blend membrane matrix were investigated. To improve the liquid retention capacity of the MPE, a simple but effective method involving the addition of chitosan was implemented. The effects of chitosan concentration on the liquid uptake and leakage behaviors as well as the ionic conductivity of the electrolyte were also evaluated. The synthesized MPE exhibited an ionic conductivity as high as 8 × 10−3 S cm−1 at room temperature. More importantly, a novel solid-state electric double layer capacitor (S-EDLC) could be fabricated using the synthesized MPE and activated carbon electrodes. For comparison, an EDLC was also assembled using the corresponding aqueous electrolyte and a commercial separator (NKK-MPF30AC-100). Alternating current (AC) impedance measurement results showed that the interfacial compatibility of the MPE and the activated carbon electrodes was high. Meanwhile, the as-prepared S-EDLC showed a specific capacitance of 118.63 F g−1, with an energy density of 7.87 W h kg−1 and power density being 95.97 W kg−1 at a current density of 1 A g−1. Furthermore, the S-EDLC exhibited greater cell-cycling stability after 5000 charge/discharge cycles than did the EDLC, indicating that this novel MPE should be suitable for use in EDLCs and other energy storage systems.

Solvent-free synthesis of an ionic liquid integrated ether-abundant polymer as a solid electrolyte for flexible electric double-layer capacitors

This study develops a solvent-free synthesis technique for producing a poly(ethylene oxide)-co-poly(propylene oxide) copolymer cross-linked by a bisphenol-A diglycidyl ether in an ionic liquid (IL), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (i.e., EMImTFSI). The ether-abundant feature renders the polymer precursors soluble in the IL and enables the integration of the resulting polymer and IL involved in the synthesis into a solid polymer electrolyte (SPE). The SPE exhibits excellent mechanical and thermal stabilities and presents an electrochemical performance similar to liquid-state EMImTFSI (e.g., with an ionic conductivity of 1.38 × 10−3 S cm−1 at 20 °C). When incorporated into a flexible electric double-layer capacitor (EDLC), the SPE is directly synthesized on the carbon electrodes to enable full penetration of the SPE into the carbon micropores. The abundant ether functionalities facilitate the dissociation of the [EMIm]+[TFSI]− pair to improve the ultimate capacitance of the EDLC, despite the polymer network slightly impeding the ion transport across the carbon electrode. The high mechanical strength of the SPE is demonstrated by the negligible difference in the charge-storage performance when the flexible EDLC is bent in a range of 0–90°. This EDLC has superior specific energy and power (41.2 W h kg−1 and 12.3 kW kg−1, respectively) and excellent stability when operated within 0–3 V. The distinct merits of this synthesis technique are its environmentally friendly features and efficient integration of the SPE and electrodes, thus ensuring that this technique is readily applicable at industrial levels.

Light weight and flexible poly(ether ether ketone) based composite film with excellent thermal stability and mechanical properties for wide-band electromagnetic interference shielding

This study proposes an efficient method for fabricating a light weight and flexible composite film with excellent thermal stability and mechanical properties for wide-band electromagnetic interference (EMI) shielding, which was prepared by melt blending and subsequent melt extrusion using poly(ether ether ketone) (PEEK) as a matrix, multi-walled carbon nanotube wrapped poly(ether sulfone) (wrapped MWCNTs) as a conductive filler, and GENIOPLAST® PELLET S (GPPS, high-temperature lubricant) as a processing aid. GPPS was firstly used in EMI application, to reduce the melt viscosity of PEEK as well as to improve the dispersion of wrapped MWCNTs, which enables it to fabricate a highly efficient EMI shielding (∼74.6 dB mm−1) PEEK/wrapped MWCNT/GPPS1.0 composite film with a thickness of 180 μm. Furthermore, the lightweight composite film exhibits high thermal stability (i.e. degradation temperature at 5% mass loss of 586 °C) and good mechanical properties (tensile strength of 101 MPa), being superior to other previously reported EMI shielding films. The above mentioned enhanced property demonstrated its potential application as a high performance EMI shield for certain applications such as in the aerospace, weapons, and microelectronics industries, which require materials exhibits EMI shielding as well as superior mechanical properties and thermal stability.

Hybrid formation of graphene oxide-POSS and their effect on the dielectric properties of poly(aryl ether ketone) composites

An effective method was proposed to prepare low dielectric constant composites based on a hybrid of graphene oxide–POSS and fluoropoly(ether ether ketone) (FPEEK). Through the formation of amide between aminopropylisobutyl polyhedral oligomeric silsesquioxane (POSS-NH2) and oxygen-containing groups (carboxyl groups) on graphene oxide (GO), the covalent functionalization of GO with POSS-NH2 (POSS-NH2–GO) hybrid was carried out, which is highly soluble in many organic solvents. The structure of the POSS-NH2–GO hybrid was confirmed by FT-IR, Raman, XRD, TGA, XPS, and TEM. The POSS-NH2–GO hybrid was well dispersed within the FPEEK polymer matrix to prepare POSS-NH2–GO/FPEEK composite films by solution blending. The dielectric constants of the composites decreased with the increasing content of POSS-NH2–GO hybrid, and a κ value of 2.01 was achieved with the incorporation of the hybrid, only 3.0 wt% could cause a 92.8% high enhancement in Youngs modulus.

High performance disulfonated poly(arylene ether sulfone)/poly(ethylene oxide) composite membrane used as a novel separator for supercapacitor with neutral electrolyte and activated carbon electrodes

High performance disulfonated poly(arylene ether sulfone)/poly(ethylene oxide) (SPAES/PEO) composite membranes were prepared by a simple method such as a novel separator saturated by the lithium sulfate (Li2SO4) aqueous electrolyte for application in supercapacitors (SCs). As prepared composite membranes exhibit excellent mechanical properties and thermal stabilities, which are beneficial for the safety in potential applications, meanwhile, the addition of PEO on membrane also enhanced the affinity with electrolyte and the ion conduction for lithium salts. In addition, the SC cell was fabricated with optimized SPAES/PEO composite membrane and activated carbon electrodes with Li2SO4 aqueous electrolyte. The obtained SC with the SPAES/PEO separator revealed a specific capacitance of 142.5 F g−1 at a current density of 0.1 A g−1. Furthermore, the energy density of the SC was promoted to 19.04 Wh kg−1 due to the wide working voltage range of the neutral electrolyte, and the SC exhibited an excellent coulombic efficiency of almost 99% and nearly 100% cycling retention after 5000 galvanostatic charge/discharge cycles. All of these results indicated that SPAES/PEO composite membrane is suitable as a novel separator for SC.

Mixed matrix membranes decorated with in situ self-assembled polymeric nanoparticles driven by electrostatic interaction

A novel ultrafiltration membrane is developed by incorporating in situ self-assembled polymeric nanoparticles into the membrane matrix. The chemical stability of the nanoparticles in regard to pH and temperature is explored via a rational method. The result indicates that the electrostatic interaction strength between the two polyelectrolytes can withstand a broad pH range (pH 1–11) and a relatively high temperature (80 °C). Meanwhile, the nanoparticle size and distribution in the membranes are investigated by scanning electron microscopy (SEM), which are proved to be affected by the polyelectrolyte concentration and molecular weight. The contact angle values of the prepared membranes show that the membrane hydrophilicity is improved by adding polymeric nanoparticles. Furthermore, the molecular weight cut-off and pore size of the membranes are increased with added nanoparticle loading. More importantly, the mixed matrix membranes exhibit simultaneous increases in permeability and rejection of contaminants compared with the pristine PES membrane, which is ascribed to the appropriate pore size and enhanced hydrophilicity of the membranes. Especially, the composite membrane mixed with 3 wt% polymeric nanoparticles displays the highest pure water flux (460 L m−2 h−1), which is 3 times that of the pristine PES membrane, and 97.6% rejection of BSA. This work provides a new strategy for preparing flexible polymeric nanoparticles and developing high-performance mixed matrix membranes for water treatment.

Preparation of organic–inorganic hybrid membranes with superior antifouling property by incorporating polymer-modified multiwall carbon nanotubes

Functionalized multiwall carbon nanotubes (MWCNTs) were prepared by coating polyvinylpyrrolidone (PVP) on the MWCNTs surface via multiple hydrogen-bonding interactions between polyvinylpyrrolidone and a mussel-inspired polydopamine (PDA) intermediate. The modified MWCNTs exhibited outstanding dispersity and stability in water and were used as a hydrophilic additive to increase the permeability and antifouling properties of polyethersulfone (PES) ultrafiltration membranes. The results of Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed the introduction of PDA and PVP into the MWCNTs. The measured water contact angle of the hybrid membranes revealed dramatically enhanced hydrophilicity. The morphology of the hybrid membranes was investigated by field emission scanning electron microscopy (FESEM). Furthermore, the permeability and antifouling properties of the hybrid membranes when mixed with different types and quantities of MWCNTs were compared. The hybrid membrane containing 0.1% PVP-modified MWCNTs exhibited the best overall performance, including a flux recovery ratio as high as 95%. The facile and universal treatment method developed in the present study can be used to improve the comprehensive performance of membranes, with great potential application in wastewater treatment.