Renbo Wei

Crosslinked Polyarylene Ether Nitrile Interpenetrating with Zinc Ion Bridged Graphene Sheet and Carbon Nanotube Network

We report the fabrication and improved properties of crosslinked polyarylene ether nitrile (CPEN) interpenetrating with a zinc ion bridged graphene sheet (GS) and carbon nanotube (CNT) network (GS-Zn-CNT) (CPEN/GS-Zn-CNT). Graphene oxide (GO) and acidulated CNT were firstly prepared and then coordinated with zinc ions to form the zinc ion bridged GO and CNT network (GO-Zn-CNT). The mass ratio of GO and acidulated CNT in GO-Zn-CNT was controlled to be 1:3 and the optimized content of Zn2+ was Zn2+/C = 0.01 mmol/mg (mole of zinc acetate/total weight of GO and acidulated CNT). Phthalonitrile end-capped polyarylene ether nitrile (PEN-Ph) permeated into the GO-Zn-CNT in N-methyl-2-pyrrolidone (NMP) and the corresponding composite PEN/GO-Zn-CNT was fabricated through the solution-casting method. After thermal annealing at 230 °C for 1 h and further curing at 320 °C for 2 h, the GO in GO-Zn-CNT was partly reduced into GS, and PEN-Ph was crosslinked, offering the CPEN/GS-Zn-CNT. The mechanical, thermal, and electrical properties of the obtained CPEN/GS-Zn-CNT were investigated in detail. The glass transition temperature, relative permittivity, and tensile strength of CPEN/GS-Zn-CNT with 2.0 wt % GS-Zn-CNT, compared to that of PEN, were increased by 18%, 181%, and 27%, respectively. The CPEN/GS-Zn-CNT based composite is a potential candidate as material in high performance electronic devices.

Crosslinked polyarylene ether nitrile film as flexible dielectric materials with ultrahigh thermal stability.

Dielectric film with ultrahigh thermal stability based on crosslinked polyarylene ether nitrile is prepared and characterized. The film is obtained by solution-casting of polyarylene ether nitrile terminated phthalonitrile (PEN-Ph) combined with post self-crosslinking at high temperature. The film shows a 5% decomposition temperature over 520 °C and a glass transition temperature (Tg) around 386 °C. Stable dielectric constant and low dielectric loss are observed for this film in the frequency range of 100–200 kHz and in the temperature range of 25–300 °C. The temperature coefficient of dielectric constant is less than 0.001 °C−1 even at 400 °C. By cycling heating and cooling up to ten times or heating at 300 °C for 12 h, the film shows good reversibility and robustness of the dielectric properties. This crosslinked PEN film will be a potential candidate as high performance film capacitor electronic devices materials used at high temperature.

Double-layer core/shell-structured nanoparticles in polyarylene ether nitrile-based nanocomposites as flexible dielectric materials

Copper tetra-amine phthalocyanine (NH2-CuPc) was grafted onto barium titanate (BaTiO3) whose surface was modified by carboxyl-functionalized polyarylene ether nitrile (CPEN), (CPEN-f-BT@CuPc), using rotary coating technology combined with an ultrasonic dispersion technology and a post-treatment bonding process. The CPEN-f-BT@CuPc/polyarylene ether nitrile (PEN) nanocomposites show stable dielectric constant and energy density in the temperature range of 25–160 °C, which demonstrate huge potential for use as organic film capacitors.

Photo-responsive liquid crystalline elastomer with reduced chemically modified graphene oxide

ABSTRACT Photo-responsive liquid crystalline elastomer (LCE) with reduced chemically modified graphene oxide (RMGO) was fabricated and studied. Mesogenic groups modified graphene oxide (MGO) was prepared, reduced and characterised, then the obtained RMGO was mixed with an acrylate monomer containing a side-on mesogen, a crosslinker and a photoinitiator. After being oriented with magnetic field, well-defined LCE micropillar as photo-responsive actuators were fabricated from the mixture by the method combining soft lithography and photo-polymerisation/photo-crosslinking. The LCE micropillars showed reversible thermo-mechanical deformation during the nematic-to-isotropic transition temperature. Upon irradiating with red light (650 nm), photo-mechanical responses of the RMGO-containing LCE was demonstrated. This micron-sized LCE actuators can be used for remote photo-responsive devices. GRAPHICAL ABSTRACT

Mechanical, dielectric, and rheological properties of poly(arylene ether nitrile)–reinforced poly(vinylidene fluoride)

In this study, poly(vinylidene fluoride) (PVDF) and poly(arylene ether nitrile) (PEN) polymer alloys with different mass ratios were prepared by solution casting method. The morphological, thermal, dielectric, mechanical, and rheological properties of the obtained polymer alloys were systematically studied. Scanning electron microscopic images showed that the polymer alloys exhibited two-phase system with PEN dispersed in PVDF matrix, which was consistent with the Cole–Cole plots obtained from rheological study. With the introduction of PEN, the crystallinity of the alloys decreased obviously, the dielectric properties of the alloys were stable before the melting temperature. When the content of PEN increased to 7 wt%, both the tensile strength and elastic modulus reached the maximum values (35.1 MPa and 1545.3 MPa), with an increment of 24% and 31% compared with those of PVDF, respectively. Rheological studies showed that the addition of PEN could obviously broaden the linear viscoelastic region of PVDF. Furthermore, the complex viscosities and storage modulus of polymer alloys increased obviously with the addition of PEN.

Crystallization behaviors of polyarylene ether nitrile filled in multi-walled carbon nanotubes

The static isothermal and dynamic crystallization behaviors of poly(arylene ether nitrile) (PEN) filled in multi-walled carbon nanotubes (MWCNT) (F-MWCNT) are studied in this work. The ends of the MWCNT are opened by NaOH at high temperature and then filled with PEN by capillary action. The filling of PEN in the MWCNT is confirmed by TEM observation, FT-IR and TGA measurements. The mass fraction of PEN filled in F-MWCNT is calculated to be 61.56 wt%. The static isothermal crystallization of F-MWCNT is investigated by placing the sample in a high temperature oven. DSC, TEM and STEM results show that the crystallization of F-MWCNT is constraint. The dynamic crystallization of F-MWCNT is investigated by shearing on a parallel-plate rheometer with different frequencies and different times at 320 °C. The evolution of the dynamic storage modulus (G′) as well as DSC, TEM and STEM measurements prove the crystallization of F-MWCNT under the shearing.

Facile fabrication of multilayer films of graphene oxide/copper phthalocyanine with high dielectric properties

Novel multilayer films of graphene oxide/copper phthalocyanine (GO/CuPc) were fabricated by self-assembling in the orientational ordered liquid crystalline state and immobilizing of the ordered structure upon casting and drying. The formation of the compact and highly ordered structures effectively enhances the dielectric constant of GO/CuPc nanocomposites.

Dielectric Properties of Reduced Graphene Oxide/Copper Phthalocyanine Nanocomposites Fabricated Through π–π Interaction

Reduced graphene oxide/copper phthalocyanine nanocomposites are successfully prepared through a simple and effective two-step method, involving preferential reduction of graphene oxide and followed by self-assembly with copper phthalocyanine. The results of photographs, ultraviolet visible, x-ray diffraction, x-ray photoelectron spectroscopy, and scanning electron microscopy show that the in situ blending method can effectively facilitate graphene sheets to disperse homogenously in the copper phthalocyanine matrix through π–π interactions. As a result, the reduction of graphene oxide and restoration of the sp2 carbon sites in graphene can enhance the dielectric properties and alternating current conductivity of copper phthalocyanine effectively.

MWCNT-reinforced polyarylene ether nitrile nanocomposites Influence of surface roughness of MWCNT

In this study, we investigated the effect of surface roughness of acidulated multi-walled carbon nanotube (MWCNT) on the physical performances of MWCNT/polyarylene ether nitrile (MWCNT/PEN) nanocomposites. Acidulated MWCNTs with different surface roughnesses were prepared by ultrasonicating and refluxing of MWCNTs in the mixture solvent of sulfuric acid/nitric acid and characterized by atomic force microscopy. With longer acidulating time, more and more oxygen functional groups including carboxyl and hydroxyl groups which result in the coarser surface of the obtained MWCNT, were generated. MWCNT/PEN composites were fabricated by using the solution-casting method with the acidulated MWCNTs and PEN. SEM observation showed that the acidulated MWCNTs are well-embedded in the polymer matrix without aggregation. differential scanning calorimetry and thermogravimetric analysis results showed that the incorporation of acidulated MWCNTs can improve the thermal behavior of the resulted polymer composites. The coarser the surface of the acidulated MWCNT, the better the mechanical performances of the obtained composites, while opposite results were observed for the dielectric properties of the nanocomposites. The dynamical rheological results showed that a better compatibility between the MWCNT and PEN is achieved when the coarser MWCNT is used.

Crystalline, Mechanical and Dielectric Properties of Polyarylene Ether Nitrile with Multi-Walled Carbon Nanotube Filled with Polyarylene Ether Nitrile

Multi-walled carbon nanotube (MWCNT) filled with poly(arylene ether nitrile) (PEN) (PEN-in-MWCNT) is used as additive to improve the physical performances of PEN matrix. The influences of PEN-in-MWCNT on the crystallization, mechanical, dielectric and thermal properties of PEN are investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier Transform Infrared Spectoscopy (FT-IR), dielectric testing, mechanical testing and scanning electron microscope (SEM) observation. The filling of the PEN into the MWCNT is confirmed by transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) observation, FT-IR spectra, TGA and DSC curves. TGA results indicate that the mass fraction of PEN filled in the MWCNT is 61.56 wt% and the thermal property of PEN-in-MWCNT is significantly enhanced after the filling of PEN. Comparing with MWCNT, the oxidation temperature of PEN-in-MWCNT increases more than 180 °C. DSC results demonstrate that PEN-in-MWCNT is a better nucleating agent for PEN than MWCNT, as it can promote the crystallinity of PEN at relative lower concentration. When the concentration of MWCNT is 0.5 wt%, the melting enthalpy of the composite PEN-in-MWCNT/PEN5 is 41.13 J/g. The tensile strength of the obtained composite PEN-in-MWCNT/PEN10 enhances by 34% after 1.0 wt% of MWCNT is incorporated. Improved dielectric properties are also observed when PEN-in-MWCNT is incorporated into the PEN matrix. The PEN-in-MWCNT appears to be an excellent additive candidate for PEN.