Molecular Design, Preparation, and Characterization of Fluoro-Containing Polyimide Ultrafine Fibrous Membranes with High Whiteness, High Thermal Stability, and Good Hydrophobicity.

Polymeric ultrafine fibrous membranes (UFMs) with high thermal stability and high whiteness are highly desired in modern optoelectronic applications. A series of fluoro-containing polyimide (FPI) UFMs with high whiteness, good thermal stability, and good hydrophobicity were prepared via a one-step electrospinning procedure from the organo-soluble FPI resins derived from a fluoro-containing dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), and various diamines containing either pendant trifluoromethyl (-CF3) groups or alicyclic units in the side chains. The obtained FPI UFMs, including FPI-1 from 6FDA and 3,5-diaminobenzotrifluoride (TFMDA), FPI-2 from 6FDA and 2'-trifluoromethyl-3,4'-oxydianiline (3FODA), FPI-3 from 6FDA and 1,4-bis[(4-amino-2-trifluoromethyl)phenoxy]benzene (6FAPB), FPI-4 from 4,4'-bis[(4-amino-2-trifluoromethyl)phenoxy]biphenyl (6FBAB), and FPI-5 from 6FDA and 4'-tert-butyl-cyclohexyl-3,5-diaminobenzoate (DABC) showed whiteness indices (WI) higher than 87.00 and optical reflectance values higher than 80% at the wavelength of 457 nm (R457), respectively. The FPI-5 UFM, especially, showed the highest WI of 92.88. Meanwhile, the prepared PI UFMs exhibited good hydrophobic features with water contact angles (WCA) higher than 105°. At last, the PI UFMs exhibited good thermal stability with glass transition temperatures (Tg) higher than 255 °C, and the 5% weight-loss temperatures (T5%) higher than 510 °C in nitrogen.

Covalent grafting of carbon nanotubes with a biomimetic heme model compound to enhance oxygen reduction reactions.

The oxygen reduction reaction (ORR) is one of the most important reactions in both life processes and energy conversion systems. The replacement of noble-metal Pt-based ORR electrocatalysts by nonprecious-metal catalysts is crucial for the large-scale commercialization of automotive fuel cells. Inspired by the mechanisms of dioxygen activation by metalloenzymes, herein we report a structurally well-defined, bio-inspired ORR catalyst that consists of a biomimetic model compound-an axial imidazole-coordinated porphyrin-covalently attached to multiwalled carbon nanotubes. Without pyrolysis, this bio-inspired electrocatalyst demonstrates superior ORR activity and stability compared to those of the state-of-the-art Pt/C catalyst in both acidic and alkaline solutions, thus making it a promising alternative as an ORR electrocatalyst for application in fuel-cell technology.

Cu2- xS Nanocrystals Cross-Linked with Chlorin e6-Functionalized Polyethylenimine for Synergistic Photodynamic and Photothermal Therapy of Cancer.

Achieving an integrated system for combinational therapy of cancer with enhanced efficacy is always a challenge. A multifunctional system (CCeT nanoparticles (NPs)) for a synergistic photodynamic and photothermal cancer therapy was successfully developed. This system is composed of Cu2- xS nanoclusters functionalized with chlorin e6 (Ce6)-conjugated branched polyethylenimine (PEI-Ce6) and mitochondria-targeting 3-(carboxypropyl)triphenylphosphonium bromide (TPP-COOH). The colocalization of the resulted CCeT NPs inside the mitochondria of cancer cells was proven. The CCeT NPs exhibited significant photodynamic therapy (PDT) efficacy due to efficient singlet oxygen (1O2) generation triggered by a 630 nm laser. This system also showed excellent photothermal conversion capability upon the irradiation of 808 nm laser for photothermal therapy (PTT). In particular, the platform achieved nearly 100% inhibitory rate of the tumor growth in vivo through combinational PDT and PTT. Thus, the CCeT NPs could efficiently inhibit the tumor growth in vitro and in vivo by combinational PDT and PTT, offering synergistic therapeutic efficiency as compared to PTT or PDT alone.

Bio-inspired multinuclear copper complexes covalently immobilized on reduced graphene oxide as efficient electrocatalysts for the oxygen reduction reaction.

Inspired by the multicopper active site of laccase, which efficiently catalyzes the oxygen reduction reaction (ORR), herein we report a novel bio-inspired ORR catalyst composed of a multinuclear copper complex that was immobilized on the surface of reduced graphene oxide (rGO) via the covalently grafted triazole-dipyridine (TADPy) dinucleating ligand. This rGO-TADPyCu catalyst exhibited high ORR activity and superior long-term stability compared to Pt/C in alkaline media.