A series of fluorinated N-aminoaziridines have been synthesized by the PhI(OAc)2-mediated aziridination procedure. The reaction was carried out with various protected hydrazides and fluorinated alkenes. The reaction was extended to alkenes bearing an amino acid and the ring opening of the CF3–N-aminoaziridines has been investigated. 相似文献
Tetracarboxylic dianhydrides were synthesized from hydrogenated trimellitic anhydride (HTA) and some diols to obtain novel poly(ester imide)s (PEsIs). The HTA-derived tetracarboxylic dianhydrides showed much higher reactivity with various diamines than conventional cycloaliphatic tetracarboxylic dianhydrides and led to PEsI precursors with high molecular weights (Mw). The results can be explained in terms of a spacer effect. The PEsI films were essentially colorless regardless of diol and diamine components owing to inhibited charge-transfer interactions. The HTA-derived PEsIs also exhibited excellent combined properties: relatively high glass transition temperatures (Tg), relatively low water absorption (WA), and relatively low dielectric constants. The outstanding processability (thermoplasticity and solubility) observed for the HTA-derived PEsIs was discussed on the basis of a non-planar/bent structure at the HTA-based imide units. The use of a fluorene-containing diol component was effective for enhancing Tg’s by restricted internal rotation and for reducing WA by a decreased imide group content. On the other hand, the use of 4,4′-biphenol as another diol gave rise to a prominent toughening effect without sacrificing other target properties. One of the HTA-derived PEsI systems can be a promising candidate as plastic substrates because of its excellent combined properties: a high Tg close to 300 °C, high optical transparency, significant toughness (elongation at break > 100%), and good thermo- and solution-processability. 相似文献
It has been clarified that syndiotactic polystyrene (sPS) forms co‐crystalline structures with polyethylene glycol dimethyl ethers (PEGDMEs) with molecular weights ranging from 178 to 1 000 g · mol−1 through a guest exchange procedure assisted by a plasticizing agent. The PEGDME molecules are incorporated into the spaces between sPS polymer sheets consisting of (T2G2)2 helices. The results of X‐ray diffraction and gravimetric measurements suggest that one or less molecules are included per unit cell for PEGDME with average molecular weight of 1 000 g · mol−1, which indicates the possibility that longer polymeric molecules can be introduced into sPS lattices with multiple site occupation.
A new layered carbide, [Zr0.72(3)Y0.28(3)]Al4C4, has been synthesized and characterized by X-ray powder diffraction, transmission electron microscopy and energy dispersive X-ray spectroscopy (EDX). The atom ratios [Zr:Y] were determined by EDX, and the initial structure model was derived by the direct methods, and further refined by Rietveld method. The crystal is trigonal (space group , Z=1) with lattice dimensions of a=0.333990(5) nm, c=1.09942(1) nm and V=0.106209(2) nm3. This compound shows an intergrowth structure with [Zr0.72Y0.28C2] thin slabs separated by Al4C3-type [Al4C4] layers. It is a new member with l=1 and m=1 of the homologous series, the general formula of which is (MC)l(T4C3)m (l=1, 2 and 3, m=1 and 2, M=Zr, Y and Hf, T=Al, Si and Ge). 相似文献
The rheology properties (viscosity and elasticity) of chemisorbed soft matters on a solid-liquid interface oscillating at MHz were investigated using a quartz crystal microbalance (QCM). As a chemisorbed soft matter, we employed the self-assembled monolayers (SAMs) of mercapto oligo(ethylene oxide) methyl ethers, HS(CH2CH2O)nCH3 (n?=?5, 11, 12, 19, 27, 35 and 43), where those molecular weights had unity. The systematical analyses on the basis of the Voight model revealed the relationships of and , where η and μ are the viscosity and elasticity of the SAM, and Mn is the molecular weight of HS(CH2CH2O)nCH3. As a result, we found that the SAM consisting of the oligomer followed the formula of polymer. 相似文献
Coherent control of the precession motion of magnetizations in a single crystal YFeO3 with double half-cycle pulse terahertz waves was demonstrated. Quasiferromagnetic (0.299 THz) and quasiantiferromagnetic (0.527 THz) precession modes were selectively excited by choosing an appropriate interval of two pulses and were observed as free induction decay (FID) signals from the spin system. By observing the circularly polarized FID signals due to ferromagnetic resonance, we also succeeded in confirming directly the energy storage in the spin system and recovery from that to the electromagnetic radiation. 相似文献
Some molecular probes, whose fluorescence spectra were responsive to the polarity, were tested for monitoring the formation of admicelles. N-Phenyl-1-naphthylamine (PN) was the best choice for evaluating the hydrophobicity of sodium dodecylsulfate (SDS)/γ-alumina admicelles. The fluorescence intensity of PN in the aqueous suspension of the admicelles enhanced in the SDS concentration far below its critical micelle concentration. The intensity was greater than that in the normal SDS micellar system. Additionally, the wavelength at the maximum intensity of the fluorescence in the admicellar system was shorter than that in the micellar solution. These facts strongly suggest that the admicelles provide more hydrophobic environment than conventional micellar media. Comparison of the wavelength with those in several solvents indicated that the admicelles have hydrophobic properties corresponding to 1-octanol or ethyl acetate. 相似文献
Facilitated transport of oxygen in a solid Polymer membrane containing cobaltporphyrin (CoP) which carries oxygen specifically and reversibly, leads to permselectivity of oxygen against nitrogen in the membrane. The increase in concentration of the CoP carrier is expected to enhance the oxygen transport. The membranes of poly(octylmethacrylate-co-vinylimidazole) containing 0.8 ~ 10 wt% CoP were prepared, and the effects of the CoP-concentration on the transport and the diffusion constants of oxygen are studied. Although the induction period before the steady state of oxygen permeation was prolonged with the CoP concentration in the polymer membrane, the glass transition temperature (Tg) of the membrane was increased and the diffusion constants of oxygen were decreased with the CoP concentration to yield unexpected reduction of the oxygen permeation in the highly CoP loaded membrane. 相似文献