Mechanistic Insights into the Synthesis of Fully Condensed Polyhedral Octaphenylsilsesquioxane

A comprehensive study on the efficient one‐pot synthesis of polyhedral octaphenylsilsesquioxane (OPS) is reported via the hydrolytic condensation of phenyltrimethoxysilane (PTMS) in the presence of basic catalyst to investigate the specific synthesis mechanism. The synthetic reactions are monitored with real time infrared (RTIR) spectroscopy. Then RTIR coupled with ²⁹Si nuclear magnetic resonance spectroscopy (NMR) and matrix‐assisted laser desorption/ionization time of flight mass spectrometry (MALDI‐TOF‐MS) are used to monitor the reactions and identify the intermediary species during the reaction. The rapid hydrolysis of PTMS is detected by RTIR. Contrary to previous reports, the ladder‐like structured species are identified as intermediates during the reaction process. It is suggested that formation of caged T₈ OPS is realized through the chain break and rearrangement of the ladder‐like phenyltrimethoxysilanes. Accordingly, a scheme from hydrolysis of the PTMS to formation of the OPS is provided.     

Micro-segregation model calculation of residual tin in boiler and pressure vessel steel

Tin is a typical residual element in steel and mainly originates from Sn-containing complex iron ore and steel scrap. The segregation of Sn in steel is harmful to the performances of steel. In this paper, the micro-segregation of residual element Sn during the solidification process of boiler and pressure vessel steel by micro-segregation model was studied. The results showed that the micro-segregation degree of Sn reduces apparently with the increase of cooling rate and remarkably deteriorates during the solidification process. When the initial content of C is higher than 0.1%, it will cause the solidification transform of the solid phase converting from the ferrite phase to austenite phase and the significant increase in the micro-segregation degree of Sn. However, increasing the initial contents of Si, Mn, P and S separately has non-significant effects on the micro-segregation degree of Sn. In addition, the improvement of initial content of Sn will lead to the micro-segregation degree decrease of Sn and has an inapparent impact on zero strength temperature and zero ductility temperature of the boiler and pressure vessel steel.     

Mixed-cation perovskite solar cells in space

<正>The metal halide perovskite materials demonstrate outstanding performance in photovoltaics because of their excellent optoelectronic properties [1-7]. The perovskite solar cells (PSCs) exhibiting outstanding efficiency [8,9], high power-per-weight [10], and excellent radiation resistance[11-13] are considered to be promising for developing the new-generation energy technology for space application.However, the extreme space environment would impose     

Characterization of moisture mobility and diffusion in fresh tobacco leaves during drying by the TG–NMR analysis

This paper presents the stabilization effects of inorganic filler, cerium-doped lead zirconate titanate on high-density polyethylene. The filler was loaded in two concentrations (1 and 3 wt%). The dopant contents in PbZrO₃ were 0, 0.05, 0.075, 0.1 and 0.125 mol%. The degradation of hybrid samples was accomplished by γ-irradiation at various doses up to 200 kGy. The isothermal and nonisothermal chemiluminescence (CL) and thermal analysis (TG-DSC) were applied for the thermal stability characterization of modified HDPE samples. The mechanistic considerations and radiochemical consequences caused by the variation of filler concentration and doping level are discussed. The results demonstrate that the filler acts efficiently as stabilizer at low concentration of additive when the lower filler amount is present. The start of degradation precedes melting by four processes through which the chain scission and radical oxidation represent the essential degradation stage. The filler concentration influences the degradation due to the intimate interaction between solid-state defects and free radicals. The polymer protection against oxidation is based on the scavenging of radicals by the doping elements, that is, they trap and block radicals delaying material aging. The present results open a new perspective in the quality amelioration of organic products toward high durability.

     

The effects of the size and content of BaTiO3 nanoparticles on solid polymer electrolytes for all-solid-state lithium-ion batteries

Journal of Solid State Electrochemistry - For all-solid-state lithium-ion batteries, several disadvantages such as low ionic conductivity and poor interfacial stability have been concerned....     

Zirconia fiber membranes based on PVDF as high-safety separators for lithium-ion batteries using a papermaking method

Journal of Solid State Electrochemistry - Lithium-ion batteries have been receiving more and more attention because of the energy crisis. As an important subassembly of lithium-ion batteries, the...     

Oxysulfide Semiconductors for Photocatalytic Overall Water Splitting with Visible Light

Photocatalytic overall water splitting by sulfide‐based materials is a great challenge because of the poor resilience of such materials against hole oxidation. In a recent study, Domen and co‐workers developed an innovative strategy to stabilize sulfide‐based photocatalysts by hybridizing S 3p with O 2p orbitals to produce oxysulfides in which S^2? is stable. Further surface engineering of the oxysulfides with dual co‐catalysts promoted charge separation and interface transfer, thus reducing the charge build‐up that inhibits photocorrosion. The pH value of the reaction mixture is a critical consideration for achieving efficient stoichiometric H₂ and O₂ evolution by these oxysulfide photocatalysts.     

Editorial to the Special Issue: Modeling and Characterization of Low Permeability (Tight) and Nanoporous Reservoirs

Transport in Porous Media -