A Stable and High‐Efficiency Blue‐Light Emitting Terphenyl‐Bridged Ladder Polysiloxane

A novel blue‐light emitting terphenyl‐bridged ladder polysiloxane ( TBLP) was prepared by the condensation of a tetrasilanol monomer via a ladder supramolecular structure. TBLPs emit narrow blue light (420 nm) with high quantum yields (0.96) in diluted solution and shows no evident fluorophore aggregation in the solid state, indicating that the terphenyls are well isolated due to confinement of the ladder‐rungs. In addition, it has excellent emission stability at high temperature based on TGA, DSC and annealing experiments. Overall, TBLPs can be considered as a potential material for fabricating stable and high‐efficiency blue‐light emitting optoelectronic devices.

     

CFRP阶梯加固钢板端部胶层应力的理论模型研究

CFRP阶梯加固可以有效减小CFRP端部胶层应力,防止胶层过早剥离而导致CFRP加固失效．文中通过理论推导建立CFRP阶梯加固钢板的端部胶层剪应力和正应力的理论模型,并采用有限元模型验证了理论模型,然后利用理论模型研究了加固参数对胶层应力的影响．研究结果表明：理论模型可以有效地计算端部胶层应力,且当阶梯端部长度超过“最小端部长度”时,理论模型可以准确计算端部胶层的最大应力值及其发生位置;利用理论模型便于分析各种参数对端部胶层应力的影响,其中胶层厚度、阶梯数量和CFRP厚度对端部胶层应力影响较大．     

Ladder operators in commutator perturbation method

The present work is a version of Van Vleck–Primas perturbation method in terms of generalized ladder operators. Using the superoperator approach, a fully general, self-consistent and a totally free scheme from representation is developed. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 68: 79–90, 1998     

Cyclopolymerization

The background and summary of the events that led to the discovery and confirmation of an unusual and unexpected mode of polymerization of certain vinyl monomers is presented. Originally, the process was described as an alternating intra‐intermolecular chain propagation mechanism. For convenience and because cyclic structures are introduced into the polymer chain, the term cyclopolymerization has been adopted. Early attempts to determine the relationship of cyclopolymerization to stereochemical control and to ladder polymer formation are reviewed. Also, it is pointed out that within 10 years of the introduction of the cyclopolymerization concept, worldwide commercialization of certain cyclopolymers and cyclocopolymers had begun. The extent of the research activity in this area of chemistry and its relationship to commercialization are emphasized. Two areas of research activity that are featured are chirality induction into well‐known polymers and synthesis of conjugated polymers via cyclopolymerization. Both areas are discussed, and suitable examples are included. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3451–3461, 2000     

Conformational analysis of siloxane-based enzyme-mimic precursors[1]

The conformational flexibility of six hybrid organodisiloxane oligomers were studied using the Low Mode-Monte Carlo conformational search method with the MM2* force field and the Generalized Born/Surface Area continuum solvent model for water. These systems have enzyme-like properties as synthetic acyltransferases and contain aminopyridine groups in various states of protonation. An ensemble of low energy structures was generated and used to investigate the dependence of molecular shape and flexibility on protonation, which plays an important role in catalyst solubility and self-association. The results as measured by the number of unique conformations, end-to-end or longest intramolecular distance and radius of gyration of the conformational point cloud indicate that the number of protonated pyridines plays a significant role in the overall molecular shape. A similar study was also carried out on various POSS-substitutive organodisiloxane oligomers.     

Polyelectrolyte Complexes Consisting of Macromolecules With Varied Stiffness: Computer Simulation

Monte Carlo simulations are employed in order to analyze the structure of polyelectrolyte complexes consisting of two identical but oppositely charged macroions with varying chain stiffness. It is shown that two complex structures can arise depending on the stiffness of the constituent chains. Stiff chains are organized into a “ladder” structure in which chains are located parallel to each other and monomeric units are arranged into ionic pairs according to their position in the chain. Flexible chains form a globular “scrambled‐egg” structure with a disordered position of monomer units. The conformational transition between the two structures proceeds as a phase transition.