Aiming at fabricating the polyimide (PI) films with low permittivity and excellent comprehensive properties, 2,2′‐bis‐(trifluoromethyl)‐4,4′‐diaminobiphenyl was incorporated into the polyimide backbone composed of 3,3′,4,4′‐biphenyltetracarboxylic dianhydride and p‐phenylenediamine. The introduction of trifluoromethyl (CF3) groups led to a substantial reduction of the PI's permittivity (3.42–2.96). Meanwhile, as‐prepared co‐PI films showed excellent mechanical performance (217.13–238.20 MPa for strength and 3.49–4.90 GPa for modulus), as well as good thermal stability (high glass transition temperature over 354 °C, whereas low thermal expansion coefficient below 10 ppm/K). Structure–property relationship of the PI samples was further established through molecular simulations (MS), which suggested the crucial effects of polarizability per unit volume (α/Vvdw) and free volume on PI permittivity. The computational results were highly consistent with the experimental findings, meaning that MS technique is of guiding importance in copolymer design. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47989.

Acrylonitrile–butadiene rubber (NBR) with different acrylonitrile (ACN) contents was filled with barium titanate (BT) to prepare the polymer dielectrics. The neat NBR, NBR/untreated BT, and NBR/bis‐(γ‐triethoxysilylpropyl)‐tetrasulfide (silane coupling agent KH845‐4) modified BT (MBT) composites were prepared. At low ACN content (ACN content 20 wt %), the tensile strength of the NBR/MBT composites increased by 173.6% from 2.69 to 7.36 MPa compared to the neat NBR. The pleasing results were not found in those composites with high ACN content. Both surface modifications of BT and NBR with low ACN content would result in lower interfacial tension between BT and NBR. A strong interfacial adhesion was observed between MBT and NBR with 20 wt % ACN content. The interfacial adhesion had great contribution to the mechanical strength of composites. Moreover, the dielectric properties of composites were also investigated in detail. The addition of BT enhanced the dielectric constant of composites markedly. This study can be applied in manufacturing electronic devices, which are subjected to oily environments for a long time. At the same time, the study can provide some help for researchers to select the polymer matrix and the appropriate surface modification agent of functional filler. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45936.

Functional polymeric materials with electrical bi-stable states possess significant potential for high-density data storage due to their nanoscale memory site, threedimensional-stacking ability and intrinsic flexibility. Aromatic polyimides bearing donor-acceptor (D-A) skeleton could form charge transfer complex (CTC) under electrical field, leading to their feasibility as memory materials. Three novel porphyrinated polyimides DATPP-DSDA, Zn-DATPP-DSDA and Mn-DATPP-DSDA were designed and synthesized for information memory applications. Metal ions with different electron configurations at 3d orbital have a determining influence on memory behaviors of polyimides: nonvolatile write-once-read-many-times memory (WORM) for DATPP-DSDA, volatile static random access memory (SRAM) for Zn-DATPP-DSDA, but no memory performance for Mn-DATPP-DSDA. By comparing the contribution of orbital transition and hole-electron distribution of charge-transfer excited states, roles of metal ions in regulating memory types were discussed. Molecular simulation results indicate that Zn ion could play a bridge role in paving the route for excited electrons from a D to A, while a trap role for Mn ion in hindering this process. This study proves the feasibility of the strategy for modulating the memory behaviors of porphyrinated polyimides by varying the central metal ion and provides the exact effects of various metal ions on regulating charge transfer processes.

Herein, we design a controllable approach for preparing multifunctional polybenzimidazole porous membranes with superior fire-resistance, excellent thermo-stability, and high wettability. Specifically, the recyclable imidazole is firstly utilized as the eco-friendly template for micropores formation, which is an interesting finding and has tremendous potential for low-cost industrial production. The unique backbone structure of the as-prepared polybenzimidazole porous membrane endows the separator with superb thermal dimensional stability at 300 C. Most significantly, the inherent flame retardancy of polybenzimidazole can ensure the high security of lithium-ion batteries, and the existence of polar groups of imidazole can regulate the Li + flux and improve the ionic conductivity of lithium ions. Notably, the cell with a polybenzimidazole porous membrane presents higher capability (131.7 mA h g À1 ) than that of a commercial Celgard membrane (95.4 mA h g À1 ) at higher charge-discharge density (5C), and it can work normally at 120 C. The fascinating comprehensive properties of the polybenzimidazole porous membrane with excellent thermal-stability, satisfying wettability, superb flame retardancy and good electrochemical performance indicate its promising application for high-safety and high-performance lithium-ion batteries. Fig. 5 (a) The flame retarding behavior of Celgard membrane and PBI-3 membrane; (b) TGA curves of the as-prepared PBI-3 membrane and Celgard membrane in air atmosphere; (c) TMA curves of the PBI-3 membrane and the Celgard membrane.40088 | RSC Adv., 2019,9,[40084][40085][40086][40087][40088][40089][40090][40091] This journal is

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