Construction of hierarchical functionalized black phosphorus with polydopamine: A novel strategy for enhancing flame retardancy and mechanical properties of polyvinyl alcohol
CHEMICAL ENGINEERING JOURNAL
Authors: Qiu, Shuilai; Zhou, Yifan; Ren, Xiyun; Zou, Bin; Guo, Wenwen; Song, Lei; Hu, Yuan
As a rising star of two-dimensional (2D) materials, single or few-layer black phosphorus (BP) possess great potential as nanofiller in fabricating polymer nanocomposites, due to its thermodynamic stability, nano-size effect and structural characteristics. Herein, few-layer BP nanosheets were scalable exfoliated via solvent thermal method, the Lithium ion intercalation was achieved during this procedure. Follow by a polydopamine (PDA) encapsulated BP sandwich nanostructure was developed by oxidation-reduction strategy, which improved the air stability of few-layer BP and its interfacial compatibility with polymer matrix. As could be expected, the PDA encapsulated BP (BP-PDA) can effectively enhance the mechanical properties and flame retardancy of polyvinyl alcohol (PVA) nanocomposite films. For instance, the PVA/BP-PDA5.0 nanocomposite film loaded with 5 wt% BP-PDA exhibited 57.2% maximum decrease in peak heat release rate and 47.9% maximum reduction in total heat release. Meanwhile, while the BP-PDA loading achieved 2 wt%, PVA/BP-PDA2.0 nano composite film revealed an 81.1% increase in the tensile strength. In particular, on account of dual protection of the PDA encapsulation and polymer matrix embedding, the air stability of BP in PVA matrix was significantly improved. As an evidence, the ratio of A(g)(1)/A(g)(2) in Raman spectra of BP-PDA decreased from the initial 0.72 to 0.62, even after exposed to air for five months, indicating a low level of oxidation. This work provides a novel strategy for scalable exfoliation and functionalization of BP, and enables a wide range of potential applications of BP in polymer nanocomposites.
The cut-off effect of n-alcohols in lipid rafts: A lipid-dependent phenomenon
JOURNAL OF MOLECULAR GRAPHICS & MODELLING
Authors: Zapata-Morin, Patricio A.; Sierra-Valdez, F. J.; Ruiz-Suarez, J. C.
c n-Aliphatic alcohols act as anesthetics only up to a certain chain length, beyond which its biological activity disappears. This is known as the 'cut-off' phenomenon. Although the most accepted explanation is based on action sites in membrane proteins, it is not well understood why alcohols alter their functions. The structural dependence of these protein receptors to lipid domains known as 'lipid rafts', suggests a new approach to tackle the puzzling phenomenon. In this work, by performing molecular dynamic simulations (MDS) to explore the lipid role, we provide relevant molecular details about the membrane-alcohol interaction at the cut-off point regime. Since the high variability of the cut-off points found on protein receptors in neurons may be a consequence of differences in the lipid composition surrounding such proteins, our results could have a clear-cut importance. (C) 2020 Elsevier Inc. All rights reserved.