A facile and general method for the large-scale preparation of various three-dimensional (3D) graphene oxide/metal−organic framework (GO/MOF) composites is developed through a simple mixing process using MOFs and graphene oxide. This preparation method is able to rapidly produce GO/MOF composite hydrogels with controllable composition in only several minutes, which is also suitable to a series of different MOFs. The obtained GO/MOF composites are severed as the precursors for the subsequent preparation of MOF-derived composite aerogels, e.g., rGO/Fe 2 O 3 and rGO/ NiO/Ni composite aerogels, through freeze-dry and calcination processes. When used as a supercapacitor electrode, the rGO/Fe 2 O 3 composite shows a good rate capability with high specific capacitances of 869.2 and 289.6 F•g −1 at the current densities of 1 and 20 A•g −1 , respectively, as well as a long cycle life without obvious decrease of capacitance after 5000 cycles. Moreover, the flexible all-solid-state supercapacitor device is also fabricated based on the obtained rGO/Fe 2 O 3 composite aerogel, which exhibits a high volumetric capacitance of 250 mF•cm −3 at 6.4 mA•cm −3 and a capacity retention of 96.3% after 5000 cycles at 50.4 mA•cm −3 , as well as an excellent mechanical flexibility.

The effect of stretching conditions, such as stretching ratios, temperatures and rates of extension, on the relative fraction of b-phase and electron structure as well as dielectric properties of poly(vinylidene fluoride) (PVDF) films was investigated. The fraction of b-phase in PVDF film increases greatly and reaches the peak of 93% after uniaxial stretching. Meanwhile, stretched spherulites and micro-strips paralleling with the stretching direction were observed in the matrix by atomic force microscopy (AFM).The results of fine structure of fluorine and carbon elements in PVDF, identified by X-ray absorption near edge structure (XANES), indicate that the coordination between F and H atoms of the adjacent chains is produced and thus enhances the dielectric response of the stretched film. As a result, the dielectric constant of the stretched film increases by 50% and achieves up to 12.1, as well as the dielectric loss being as low as 0.02.

The transformation of a to b-phase in poly(vinylidene fluoride) (PVDF) induced by the addition of tetradecylphosphonic acid (TDPA)-BaTiO 3 nanoparticles and subsequently the isothermal crystallization kinetics of pristine PVDF and its nanocomposites have been investigated. The result of infrared spectra showed that the relative crystalline fraction of b-phase was enhanced greatly after the introduction of TDPA-BaTiO 3 nanoparticles, and reached the peak of 93% when the concentration of nanofillers was 20%. The interaction between TDPA-BaTiO 3 nanoparticles and PVDF macromolecular chains induced the change of conformation from trans-gauche to all-trans crystal structure in PVDF segment. The isothermal crystallization of TDPA-BaTiO 3 /PVDF nanocomposites was carried out by the differential scanning calorimetry (DSC). The influence of TDPA-BaTiO 3 nanoparticles concentration on crystallization rate, activate energy, melting enthalpy, and peak temperature were studied. The nanocomposite film loaded 20% TDPA-BaTiO 3 nanoparticles exhibited the highest crystallization rate and activate energy, which decreased after loading more nanofillers in the host because of high volume fraction of nanoparticles leading to steric hindrance and further weakening the mobility of PVDF chains during the crystallization.

Large‐scale production of boron nitride nanosheets (BNNSs) is of significant importance for their various applications. Herein, a facile strategy is well demonstrated for BNNS fabrication via liquid‐phase exfoliation of bulk hexagonal boron nitride (h‐BN) in common organic solvents with hyperbranched polyethylene (HBPE) as stabilizer. Synthesized from commercially abundant ethylene stock via a simple process, the HBPE is found to effectively promote h‐BN exfoliation both in tetrahydrofuran and chloroform under sonication, to render stable dispersions of high‐quality monolayer or few‐layer BNNSs with adjustable concentrations. This has been confirmed to originate from the noncovalent CH–π interactions between the HBPE and BNNS surface, which results in irreversible HBPE adsorption on the latter to effectively prevent their reaggregation. The resultant HBPE‐functionalized BNNSs are highly dispersible in chloroform or N,N‐dimethylformamide at a concentration as high as 10.0 mg mL−1, and can be successfully used as nanofiller for a fluorinated copolymer.

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