The atom‐transfer radical polymerization (ATRP) of acrylates in 1‐butyl‐3‐methylimidazolium hexafluorophosphate was investigated. The solubility of the acrylates in the ionic liquid depends on the substituent. The homogeneous polymerization of methyl acrylate gives polymers with M̄n close to the calculated value and relatively narrow polydispersity. In heterogeneous polymerizations of higher acrylates, with the catalyst present in the ionic liquid phase, deviations from ideal behavior are observed although the polymerization of butyl acrylate approaches the conditions of a controlled polymerization. 相似文献
The primary reason behind the search for novel organic materials for application in thermoelectric devices is the toxicity of inorganic substances and the difficulties associated with their processing for the production of thin, flexible layers. When Thomas Seebeck described a new phenomenon in Berlin in 1820, nobody could have predicted the future applications of the thermoelectric effect. Now, thermoelectric generators (TEGs) are used in watches, and thermoelectric coolers (TECs) are applied in cars, computers, and various laboratory equipment. Nevertheless, the future of thermoelectric materials lies in organic compounds. This paper discusses the developments made in thermoelectric materials, including small molecules, polymers, molecular junctions, and their applications as TEGs and/or TECs. 相似文献
New mechanism of cationic polymerization of cyclic ethers and acetals consisting in the activated (e.g. protonated) monomer addition to the electrically neutral macromolecule e.g.: is discussed. It is shown, that when the -OH in the tail-group is more nucleophilic than monomer itself this mechanism has chances to dominate over the traditional mechanism of propagation, involving tertiary oxonium ion. Kinetics of the polymerization process, elementary reactions, competition with the tertiary oxonium ion growth are discussed. Examples are given, based on the work on ethylene oxide and epichlorohydrin polymerization, showing how to apply the theory of the activated monomer in order to avoid side reactions, namely cyclization and disproportionation of the chains. 相似文献
Single crystals of [Eu(C4H4O6)(H2O)2](H2O)2 were obtained from the combination of solutions of EuCl2, previously obtained by electrolysis of an aqueous solution of EuCl3, and tartraric acid, neutralized by LiOH. The crystal structure (orthorhombic, P212121, Z = 4, a = 948.9(1), b = 954.6(1), c = 1098.4(1) pm; R(F) = 0.0242 and Rw(F2) = 0.0585 for I > 2σ(I); R(F) = 0.0256 and Rw(F2) = 0.0592 for all data) is isotypic with [Ca(C4H4O6)(H2O)2](H2O)2 and [Sr(C4H4O6)(H2O)2](H2O)2 exhibiting a three‐dimensional structure. The divalent cations (Eu2+, Ca2+, Sr2+) are eight‐coordinate by oxygen atoms that originate from carboxylate and hydroxyl groups of the tartraric dianion and two of the four water molecules. 相似文献
A novel and unexpected convenient one-pot synthesis of 1,2,3,4-thiatriazoles has been discovered while investigating the classical tetrazine “Pinner synthesis”. The synthetic route starts from commercially-available nitrile derivatives and gives good to high yields (51–80 %) with no need to isolate any thioacylating agents. The crucial impact of the solvent on the outcome of the modified “Pinner synthesis” is moreover examined and discussed. Using this new synthetic route, a novel donor-acceptor thiatriazole derivative has been prepared, which exhibits prominent thermally-activated delayed fluorescence (TADF) in both solution and film. The photoluminescence quantum yield (PLQY) in methylcyclohexane (MCH) and Zeonex (a cyclo olefin polymer) in oxygen-free conditions were determined to be 76 and 99 %, respectively. This work provides an efficient and practical synthetic approach to functionalized 1,2,3,4-thiatriazole derivatives, and will noticeably facilitate the application of 1,2,3,4-thiatriazole as an electron acceptor in organic electronics. 相似文献
Oxetanes containing hydroxyl groups can conveniently be prepared using commercially available trimethylolpropane or penthaerithritol. The corresponding monomers, such as 3-ethyl-3-hydroxymethyloxetane (EOX) have been polymerized cationically and it has been shown, that resulting polymers are branched. These polymers are of particular interest, since in contrast to some other polyhydroxyethers (like polyglycidol) all of the hydroxyl groups are primary ones. Moreover, all of the -CH2OH groups are attached to the quaternary carbon atoms. These features are rather unique and may be advantageous from the point of view of possible applications. 相似文献
Evidence for the activated monomer (AM) mechanism operating in the polymerization of propylene oxide (PO) initiated with HBF4 is presented. The contribution of AM route of propagation is the highest and formation of cyclic oligomers mostly suppressed when monomer concentration is low enough. This was achieved by slowly adding PO to the reaction mixture, as previously proposed on the basis of kinetic considerations. 相似文献
A reversible, displacive, pressure-induced structural phase transition has been found to occur in nickel monophosphide NiP at approximately 3.5 GPa by means of in situ synchrotron single-crystal X-ray diffraction. The new phase, with Pearson symbol oC56, assumes an orthorhombic structure with Cmc21 space group and unit cell parameters a=23.801(2) Å, b=5.9238(6) Å, and c=4.8479(4) Å at 5.79 GPa. The high-pressure phase is a superstructure of the ambient, oP16 phase with multiplicity of 3.5. The phosphorous sublattice gradually converts from the net of isolated P2 dimers found in the ambient NiP, towards zig-zag polymeric P∞ chains found in MnP-type structures. The transformation involves development of triatomic phosphorous clusters and interconnected Ni slabs with diamondoid topology. The high-pressure phase, which represents intermediate polymerization step, is a commensurately modulated superstructure of the NiAs aristotype. The phase transformation in NiP bears resemblance to the effect of successive substitution of Si or Ge in place of P found in the series of stoichiometric inhomogeneous linear structures in ternary NiP1−xSix and NiP1−xGex systems. 相似文献