No abstract

The outbreak of infectious diseases such as COVID-19 causes an urgent need for abundant personal protective equipment (PPE) which leads to a huge shortage of raw materials. Additionally, the inappropriate disposal and sterilization of PPE may result in a high risk of cross-contamination. Therefore, the exploration of antimicrobial materials possessing both microbe interception and self-decontamination effects to develop reusable and easy-to-sterilize PPE is of great importance. Herein, an aggregation-induced emission (AIE)-active luminogen-loaded nanofibrous membrane (TTVB@NM) sharing sunlight-triggered photodynamic/photothermal anti-pathogen functions are prepared using the electrospinning technique. Thanks to its porous nanostructure, TTVB@NM shows excellent interception effects toward ultrafine particles and pathogenic aerosols. Benefiting from the superior photophysical properties of the AIE-active dopants, TTVB@NM exhibits integrated properties of wide absorption in visible light range, efficient ROS generation, and moderate photothermal conversion performance. A series of antimicrobial evaluations reveal that TTVB@NM could effectively inactivate pathogenic aerosols containing bacteria (inhibition rate: >99%), fungi (~88%), and viruses (>99%) within only 10 min sunlight irradiation. This study represents a new strategy to construct reusable and easy-to-sterilize hybrid materials for potential bioprotective applications.

19 F and 13 C solid-state nuclear magnetic resonance (SSNMR) spectra and near edge X-ray absorption fine structure (NEXAFS) spectra at the S 2p, C 1s, O 1s, and F 1s edges of three different types of perfluorosulfonic acid (PFSA) proton conducting polymers are reported. The NEXAFS spectra were recorded in a scanning transmission X-ray microscope (STXM). They are reported on quantitative intensity scales, suitable for use as reference standards for analytical spectromicroscopy studies. The NEXAFS spectral features are assigned using comparisons to the corresponding spectra of small molecule and polymer analogues, including C 1s and F 1s spectra of polytetrafluoroethylene (PTFE) recorded using STXM. The 19 F and 13 C SSNMR spectra are reported and analyzed. Within each type of spectroscopy, the spectra of the three types of PFSA are very similar. However, small but statistically significant differences were identified which give insights into how minor molecular structure differences are reflected in the SSNMR and NEXAFS spectra. The relative chemical sensitivity of SSNMR and NEXAFS for studies of PFSA materials is compared. Solution-state NMR diffusion profile analyses of two PFSA ionomer dispersions are also reported.

Imidazole phosphate and phosphonate solid acids model the hydrogen-bonding networks and dynamics of the anhydrous electrolyte candidate for proton exchange membrane fuel cells. Solid-state NMR reveals that phosphate and phosphonate anion dynamics dominate the rate of long-range proton transport, and that the presence of a membrane host facilitates proton mobility, as evidenced by a decreased correlation time of the composites (80 ± 15 ms) relative to the pristine salt (101 ± 5 ms). Benzimidazole ethylphosphonate (Bi-ePA) is chosen as a model salt to investigate the membrane system. The hydrogen-bonding structure of Bi-ePA is established using X-ray diffraction coupled with solid-state (1)H-(1)H DQC NMR. The anion dynamics has been determined using solid-state (31)P CODEX NMR. By comparing the dynamics of ethylphosphonate groups in pristine salt and membrane-salt composites, it is clear that the rotation process involves three-site exchange. Through data interpretation, a stretched exponential function is introduced with the stretching exponent, β, ranging 0 < β ≤ 1. The (31)P CODEX data for pristine salt are fitted with single exponential decay where β = 1; however, the data for the membrane-salt composites are fitted with stretched exponential functions, where β has a constant value of 0.5. This β value suggests a non-Gaussian distribution of the dynamic systems in the composite sample, which is introduced by the membrane host.