Poly(vinylidene fluoride) (PVDF)-based composites attract tremendous attention as dielectric materials. However, their development has been limited due to the raised problem in the in-homogeneous polymer composites. In this work, a novel PVDF-based film incorporated with polyamide-1, containing the highest density of dipole among all polyamides, was prepared to improve the crystallization behaviors and dielectric properties. The results showed that the optimal concentration of polyamide-1 in PVDF was 6 wt.%. The crystallization rate of PVDF was improved in the presence of polyamide-1. Interestingly, the polyamide-1 was conductive to the formation of β form crystal of PVDF, which exhibited great electric performance. The dielectric constant of PVDF increased sharply and loss tangent still kept at a low level of 0.03@100 Hz when the concentration of polyamide-1 was 6 wt.%. This work may provide a new direction to design dielectric materials for PVDF blends.

Free-standing flexible supercapacitive electrodes have practical application for wearable energy storage devices. In this paper, graphene paper (GP), a flexible electrode substrate, was prepared by one-step reduction of graphene oxide (GO) using HI solution. GP can be used independently as a flexible electrode with specific capacitance of 227 F/g. In order to make up for the shortage of GP specific capacitance storage, polyaniline (PANI) with high specific capacitance and good electrical conductivity was selected to composite with GP by electrochemical polymerization approach. This method to fabricate electrode material by direct electrochemical polymerization avoids the use of conductive binder and organic solvent. Owing to the specific capacitance contribution of PANI and GP, the PANI/GP composites exhibit higher specific capacitance when the polymerization time is 30 s and the polymerization voltage is 0.8 V. At 1 A/g current density, the specific capacitance of composite is up to 759 F/g, which is 3.34 times of neat GP.

A symmetrical dicyclopentyl substituted cucurbit[6]uril (CyP2Q[6]) was synthesized, and crystallized under the conditions of 3 mol/L hydrochloric acid solution and the induction of ZnCl2. The crystal structure was characterized by X-ray single crystal diffractometer, 1H NMR and MS, and the results show that the crystal belongs to the monoclinic crystal system with P21/n space group, a = 13.095 (2), b = 33.002 (6), c = 15.770 (3), α = 90°, β = 102.828(5)°, γ = 90°, Z = 4, and a macroporous honeycomb structure appears in the crystal.

In order to improve the interfacial adhesion of stainless-steel mesh reinforced poly(ether-ether-ketone) (SSM/PEEK) heating elements (HEs) used in the resistance welding process for continuous carbon fiber reinforced PEEK composites (CF/PEEK composites), three kinds of surface treatments, sandblasting, aryl diazonium grafting and silane grafting, were adopted on SSM surfaces. The functional groups were grafted successfully according to the Fourier Transform Infrared (FTIR) results and Energy Dispersive Spectrometer (EDS) results, and the surface morphologies of SSM changed significantly after different treatments. Although the tensile performances of sandblasted stainless-steel (SS) wire and sandblasted SSM were distinctly reduced, the lap shear strength (LSS) of joints with sandblasted SSM still slightly improved. Besides, the interfacial shear strength (IFSS) increased from 28 MPa for untreated SSM to 34 MPa for diazonium grafted SSM and 38 MPa for silane grafted SSM. Furthermore, the LSS results were in agreement with this trend, representing a 9% improvement for joints with diazonium grafted SSM and a 23% improvement for joints with silane grafted SSM compared with untreated CF/PEEK joints. After comparison, silane grafting was the most suitable surface modification for resistance-welded CF/PEEK joints. The interfacial bonding mechanism of CF/PEEK joints with silane grafted SSM was compared with that of untreated CF/PEEK joints, suggesting that the mechanical interlocking contributed to improved interfacial bonding.

Benzoxazine resin exhibits excellent properties and is widely used in many fields. Herein, the synthesis of a novel compound, the bis(2,4-dihydro-2 H-3-(4- N-maleimido)phenyl-1,3-benzoxazinyl)biphenyl (BMIPBB), has been reported, which was synthesized by reacting N-(4-aminophenyl)maleimide (APMI), formaldehyde, and 4,4’-dihydroxybiphenyl. 1,3,5-three(4-(maleimido)phenyl)-1,3,5-triazine (TMIPT) was formed as an intermediate during the reaction. The proton nuclear magnetic resonance (1H-NMR) and Fourier transform-infrared (FTIR) spectroscopy experiments were conducted to determine the structure of BMIPBB. BMIPBB was obtained as a reddish-brown solid in 40.1% yield. The thermal properties of BMIPBB were investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. Analysis of the DSC curves revealed that the broad peak representing the release of curing reaction heat appeared in the temperature range of 140–330°C. The peak temperature was 242.59°C and the heat of the reaction was 393.82 J/g, indicating that the rate of the curing reaction was low and the heat of the reaction was high. Analysis of the TGA results revealed that the weight loss rate was 5% at 110°C. The monomer exhibited a significant weight loss in the range of 320–500°C. The compound lost 50% of its weight at a temperature of 427°C.

In this paper, the synthesized thermoplastic polyimide (TPI) precursor is coated on both surfaces of the surface-treated polyimide (PI) base film, and the TPI/PI/TPI multilayer films is obtained by thermal imidization. The mechanical properties, heat resistance, water absorption of the multilayer film and the interface between the TPI and the PI base film were investigated in detail. Then, multilayer film-2 (MF-2) with excellent comprehensive performance and the two copper foils were pressed together to prepare a double-sided flexible copper clad laminate (FCCL) by thermal lamination method, and the properties of FCCL were studied in detail. The results show that the FCCL has a high peel strength of 1.22 N/mm, passed a solder bath test of 288°C, and the surface condition was good under hot-pressing temperature of 360°C, hot-pressing pressure of 15 MPa and hot-pressing time of 60 s. In addition, the SEM and EDS spectra of the stripped copper foil confirmed that the TPI layer was immersed into the interstitial space of the Cu nodules, forming a strong physical bite with the copper foil. The current work provides a promising solution for the design and fabrication of multilayer printed circuit boards with excellent performance.

Because of its flawed toughness, the scope of application of bismaleimide resin (BMI) in the field of aeronautics, industry and electricity is greatly restricted. Herein, a novel Hyperbranched unsaturated polymers (HBP) with the flexible chains grafted was incorporated to reinforce BMI resin’s toughness, where the new interpenetrating networks (IPN) structure was formed. The rich unsaturated double bond of HBP polyester could react with the BMI resin for chemical crosslinking and be used for the toughening agent. 13C-NMR and FT-IR were used to characterize HBP’s hyperbranched structure. Consequently, after adding 20 wt.% HBP, the impact strength of BMI modified by HBP increased by 211.1%. In comparison with neat BMI, the flexural strength of BMI modified by HBP was enhanced by 209.3%. It is worth noticing that HBP available in BMI resin significantly improved its electrical performance.

Both better mechanical and rheological properties are pursued for composite solid propellant. In this work, varying proportions of a modified hyperbranched polyester (MHBPE) were added to HTPE/AP/Al propellant. The static tensile property as one kind of mechanical properties of MHBPE/HTPE/AP/Al propellant were found to be superior to those of blank HTPE/AP/Al propellant as a result of the entanglement and interpenetration of molecular chains caused by the introduction of the hyperbranched structure. Evaluations on the related improved creep resistance and stress relaxation performance further demonstrated the advantages of introduction of MHBPE to HTPE/AP/Al propellant. Rheological properties of HTPE/AP/Al propellant with and without MHBPE during the casting process were investigated and compared and the results confirmed the improvement benefiting from low viscosity and loose void structure. Thus, modified hyperbranched polyester provided a novel route to potentially meet the requirements for propellant manufacturing and applications.

Long curing duration and high curing temperature are commonly known to restrict the application of the phthalonitrile resin. In this study, a deep eutectic solvent (DES) containing ZnCl2 and urea has been developed to improve the curing process of the resorcinol-based phthalonitrile resin (DPPh) without sacrificing the useful properties of the resin. For the molar ratio of ZnCl2 and urea as 1:1 (ZnCl2-urea (1–1)), the initial curing temperature and apparent activation energy of the system were recorded as 179.5°C and 90.1 kJ/mol, respectively, indicating a reduction of 31.2% and 39.0% as compared to the pristine ZnCl2 system. More importantly, with curing time of 6 h and post-curing temperature of 300°C, the temperature at 5% weight loss as well as glass transition temperature of the resin with DES as the curing agent were 523.1°C and 370.2°C, respectively, demonstrating a significant improvement as compared to the resin cured with ZnCl2. In addition, the satisfactory long-term oxidation stability of the resin could also be obtained by employing the new curing agent. The findings from this study open a functional pathway for facile preparation of the high-performance curing agent for the phthalonitrile resin.

Under solid-phase conditions, mechanical ball milling can be used to selectively prepare cucurbit[6]uril (CB[6]) and its derivatives without the use of catalysts and solvents. Using response surface method to determine the optimal conditions for the synthesis of CB[6]. The yield of CB[6] and its derivatives is 75–95%, with a high selectivity of more than 95%. In the synthesis of CB[6] using this method, the amount of acid required is significantly less, no organic solvent is needed, and the preparation of the fully aryl-substituted CB[6] is possible, which is otherwise difficult to be synthesized directly using traditional methods. Mechanical ball milling, thus, is of great significance in the synthesis and research of new cucurbituril supramolecules. Process scale-up experiments show that the yield and selectivity of the various types of cucurbiturils is higher than 95%, because of which they find good industrial applications.