N, P-Codoped Carbon Film Derived from Phosphazenes and Its Printing Integration with a Polymer Carpet Via "Molecular Welding" for Flexible Electronics.

Although high-performance graphene-based micro/nano flexible electronic devices have shown promising applications in numerous fields, there are still many problems in converting graphene into practical applications. Heteroatom-doped graphene materials are of huge importance because heteroatom doping can significantly change the electronic structure and introduce the active site, which benefits the integration with a promising substrate and achieves nondestructive transfer of carbon materials. Herein, we analyze in detail the pyrolysis gas composition of heteroatom-enriched phosphazenes with different structures and prepare a series of high-quality in situ N, P-codoped carbon-based films from phosphazene solid sources on a low-cost glass substrate by a convenient one-step method. The N, P-codoped carbon film shows reflectivity, good conductivity, and transparency. In addition, with the help of in situ "molecular welding", we achieve nondestructive transfer of a conductive carbon-based film from a glass substrate to promising layer-polyimide (PI) and prepare a flexible free-standing carbon/PI hybrid film with an excellent binding interface. The flexible conductive hybrid film shows excellent durability under an extremely low temperature environment and superior bending stability after 800 bending cycles. The results suggest that a phosphazene precursor is an amazing choice for constructing high-quality heteroatom-doped conductive carbon films. Besides, this work provides a promising way for nondestructive transfer of the conductive carbon-based films and large-scale preparation of large-area patterned conductive thin films.

In-Situ Synthesis of N, O, P-Doped Hierarchical Porous Carbon from Poly-bis(phenoxy)phosphazene for Polysulfide-Trapping Interlayer in Lithium-Sulfur Batteries.

The shuttling of polysulfides is the most detrimental contribution to degrading the capacity and cycle stability of lithium-sulfur (Li-S) batteries. Adding a carbon interlayer to prevent the polysulfides from migrating is feasible, and a rational design of the structures and surface properties of the carbon layer is essential to increasing its effectiveness. Herein, we report a hierarchical porous carbon (HPC) created by carbonization of bis(phenoxy)phosphazene and in-situ doping of triple heteroatoms into the carbon lattice to fabricate an effective polysulfide-trapping interlayer. The generated carbon integrates the advantages of a hierarchical porous structure, a high specific area and rich dopants (N, O and P), to yield chemisorption and physical confinement for polysulfides and fast ion-transport synergistically. The HPC interlayer significantly improves the electrochemical performance of Li-S batteries, including an exceptional discharge capacity of 1509 mA h/g at 0.06 C and a high capacity retention of 83.7 % after 250 cycles at 0.3 C. This work thus proposes a facile in-situ synthesis of heteroatom-doped carbon with rational porous structures for suppressing the shuttle effect.

Morphology Control of Novel Cross-Linked Ferrocenedimethanol Derivative Cyclophosphazenes: From Microspheres to Nanotubes and Their Enhanced Physicochemical Performances.

Polyphosphazenes have grabbed focal attention in materials research due to their structural diversity, intrinsic backbone stability, and capability to form hybrid molecules. Herein, for the first time, we report morphology-controlled cross-linked hybrid nanotubes and microspheres composed of a novel iron-containing poly(ferrocenedimethano)cyclotriphosphazene synthesized via a facile polycondensation between 1,1'-ferrocenedimethanol and hexachlorocyclotriphosphazene. The morphology was tuned by introducing two sets of mixed solvent systems that are tetrahydrofuran:acetonitrile and acetone:toluene mixtures, for the growth of nanotubes and microspheres, respectively. A growth mechanism for nanotubes and microspheres has been proposed. The nanotubes exhibited intrinsic paramagnetic properties (saturation magnetization of 53 emu/g and coercivity of 19.6) and fluorescence emission (2450 au) as compared to microspheres owing to their remarkable cross-linked structure. Both nanotubes and microspheres demonstrated significant potential to absorb negatively charged hazardous methyl orange dye, and their adsorption capacities came out under the range of 880-2235 and 737-2125 mg g-1, respectively. This facile fabrication route is anticipated to open a new window for structural manipulation of other metal-containing polymers for improved physicochemical properties.

A Novel Polyaniline-Coated Bagasse Fiber Composite with Core-Shell Heterostructure Provides Effective Electromagnetic Shielding Performance.

A facile route was proposed to synthesize polyaniline (PANI) uniformly deposited on bagasse fiber (BF) via a one-step in situ polymerization of aniline in the dispersed system of BF. Correlations between the structural, electrical, and electromagnetic properties were extensively investigated. Scanning electron microscopy images confirm that the PANI was coated dominantly on the BF surface, indicating that the as-prepared BF/PANI composite adopted the natural and inexpensive BF as its core and the PANI as the shell. Fourier transform infrared spectra suggest significant interactions between the BF and PANI shell, and a high degree of doping in the PANI shell was achieved. X-ray diffraction results reveal that the crystallization of the PANI shell was improved. The dielectric behaviors are analyzed with respect to dielectric constant, loss tangent, and Cole-Cole plots. The BF/PANI composite exhibits superior electrical conductivity (2.01 ± 0.29 S·cm-1), which is higher than that of the pristine PANI with 1.35 ± 0.15 S·cm-1. The complex permittivity, electromagnetic interference (EMI), shielding effectiveness (SE) values, and attenuation constants of the BF/PANI composite were larger than those of the pristine PANI. The EMI shielding mechanisms of the composite were experimentally and theoretically analyzed. The absorption-dominated total EMI SE of 28.8 dB at a thickness of 0.4 mm indicates the usefulness of the composite for electromagnetic shielding. Moreover, detailed comparison of electrical and EMI shielding properties with respect to the BF/PANI, dedoped BF/PANI composite, and the pristine PANI indicate that the enhancement of electromagnetic properties for the BF/PANI composite was due to the improved conductivity and the core-shell architecture. Thus, the composite has potential commercial applications for high-performance electromagnetic shielding materials and also could be used as a conductive filler to endow polymers with electromagnetic shielding ability.