To attain thermally conductive but electrically insulating polymer films, in this study, polyimide (PI) nanocomposite films with 1–30 wt% functionalized hexagonal boron nitride nanosheets (BNNSs) were fabricated via solution casting and following imidization. The microstructures, mechanical and thermal conductive properties of PI/BNNS nanocomposite films were examined by taking account of the relative content, anisotropic orientation, and interfacial interaction of BNNS and PI matrix. The scanning electron microscopy, X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and X‐ray diffractometry data revealed that BNNSs with hydroxy and amino functional groups have specific molecular interactions with PI matrix and they form stacked aggregates in the nanocomposite films with high BNNS loadings of 10–30 wt%. The tensile mechanical strength/modulus, thermal degradation temperatures, and thermal conductivity of the nanocomposite films were found to be significantly enhanced with increasing the BNNS loadings. For the nanocomposite films with 1–30 wt% BNNS loadings, the in‐plane thermal conductivity was measured to be 1.82–2.38 W/mK, which were much higher than the out‐of‐plane values of 0.35–1.14 W/mK. The significant anisotropic thermal conductivity of the nanocomposite films was found to be owing to the synergistic anisotropic orientation effects of both BNNS and PI matrix. It is noticeable that the in‐plane and out‐of‐plane thermal conductivity values of the nanocomposite film with 30 wt% BNNS were ~1.31 and ~3.35 times higher than those of neat PI film, respectively.

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For free-standing and self-doped electrode materials of energy storage devices, in this study, we investigate the microstructures and electrochemical properties of aromatic poly(ether amide) (PEA)-derived carbon nanofibers (CNFs), which are manufactured by electrospinning mixed solutions of PEA and poly(vinyl pyrrolidone) (PVP) at three different compositions and carbonization of the as-spun nanofibers at 1000 °C. The scanning electron microscopy, energy dispersive spectroscopy, Raman spectroscopy, and elemental analyses reveal that PEA-derived CNFs have a unique interfused network structure with nitrogen self-doped and quasi-ordered graphitic features. Accordingly, a high apparent electrical conductivity of 3.72−7.79 S/cm is attained for the CNFs. The cyclic voltammetry and galvanostatic charge−discharge measurements confirm that PEA-derived CNFs have excellent electrochemical properties in terms of a specific capacitance of ∼249.0 F/g at 1.0 A/g, power density of 10,000−1,000 W/kg, energy density of 30.1−69.1 Wh/kg, capacitance retention of ∼79%, and Coulombic efficiency of ∼92% after 3000 cycle tests. These results indicate that PEA-derived CNFs can be used as highly stable, self-supporting, and doping-free electrode materials for high-performance energy storage devices.

To attain eco‐friendly and sustainable polylactide (PLA) materials possessing highly enhanced toughness, thermal stability, and processability without significant loss in elastic modulus, for the first time, PLA‐dominant blends with 1–30 wt% glycidyl methacrylate‐grafted polypropylene (PPGMA) loadings are fabricated via an efficient masterbatch melt‐compounding process. For the purpose, PPGMA is fabricated via in situ grafting reaction of PP with GMA and styrene. The scanning electron microscope images reveal that PLA/PPGMA blends do not show recognizable phase‐separated domains, unlike immiscible PLA/PP blends. The Fourier‐transform infrared spectroscopic and melt‐rheological analyses support the presence of specific interactions between PLA and PPGMA as well as the compatibilizing effect of PPGMA‐g‐PLA formed during the melt‐compounding. The thermal analyses demonstrate that PPGMA component accelerates the crystallization of PLA in the blends and that the thermal decomposition temperatures of PLA/PPGMA blends are higher than those of neat PLA and PPGMA components. The dynamic mechanical analysis shows that a maximum storage modulus is attained for PLA‐dominant blend with 30 wt% PPGMA. Noticeably, the impact strength (≈305.6 J m−1) of PLA‐dominant blend with only 5 wt% PPGMA loading is almost three times higher than that (≈111.6 J m−1) of neat PLA and it is very comparable to the value (≈316.9 J m−1) of neat PP.

The microstructure, electrical and electrochemical properties of MXene/aromatic poly(ether amide) (PEA)‐derived hybrid carbon nanofibers (HCNFs) as high‐performance free‐standing supercapacitor electrode materials are reported. For this purpose, a series of HCNFs are fabricated by sequential methods of electrospinning of PEA solutions, dip‐coating (1–10 cycles) of as‐spun PEA nanofibers into MXene aqueous dispersion, and heat‐treatment of MXene‐coated PEA nanofibers for carbonization. The structural analyses of HCNFs reveal that MXene nanosheets are uniformly deposited on PEA‐derived and nitrogen self‐doped CNFs and that they are accumulated with increasing the number of dip‐coating cycles. Accordingly, the electrical conductivity increases from 3.94 S cm−1 for PEA‐derived neat CNF to 15.74 S cm−1 for HCNF10 (10 dip‐coating cycles) due to the increase in the content of electrically conductive MXene nanosheets. On the other hand, the electrochemical performance is measured to be the highest in HCNF7 (7 dip‐coating cycles) owing to a trade‐off effect of ion barrier function and high electrical conductivity of MXene nanosheets to porous CNF webs. For a symmetric supercapacitor setup of two self‐standing HCNF7 electrodes, outstanding electrochemical properties of specific capacitance of 66.7–179.3 F g−1, power density of 1000–10 000 W kg−1, and energy density of 52.7–91.2 Wh kg−1 are attained at current densities of 1–10 A g−1.