Reactive surfactants in heterophase polymerization for high performance polymers

 A variety of nonionic reactive surfactants have been prepared from block copolymer precursors. These precursors are formed from a commercially available polyoxyethylene glycol monomethylether as the hydrophilic sequence of the surfactant; this product is used as initiator of ring opening anionic polymerization of butylene oxide. Finally the reactive surfactants are obtained after proper functionalization of the precursor. The reactive surfactants are an inisurf with an asymmetric azo compound, a transurf with a thiol group, and a few surfmers with acrylic, methacrylic, styrenic and α-methyl styrenic reactive groups. These compounds have been engaged in styrene emulsion or dispersion polymerization. Several of them have been found to be useful for preparing stable latices. Received: 22 July 1997 Accepted: 11 December 1997     

Metalization of polypropylene. I. Synthesis and melt free‐radical grafting of novel maleimides and methacrylates containing chelating moieties

Several chelating monomers with methacrylate and maleimide residues as polymerizable groups and diketone and aspartic acid residues as metal‐bonding groups were synthesized. A long‐chain aliphatic spacer was introduced to increase the solubility of the monomers in the polymer melt and to enhance the compatibility of grafted side chains and homopolymers with polypropylene (PP). PP was functionalized by melt free‐radical grafting, and some properties of the modified polymer were investigated. The grafting of a chelating methacrylic ester by injection molding afforded grafting yields of 30–50%. A comparison with products obtained by the grafting of commercially available acetoacetoxy methyl methacrylate showed the beneficial effect of the aliphatic spacer with respect to the grafting yield as well as the tensile strength and flexural modulus. The grafting of an aspartic acid based maleimide in an extruder afforded grafting yields of 80–95% and a significant increase in the surface wettability, as shown by contact‐angle measurements. A comparative study using samples obtained by the grafting of maleimidobenzoic acid indicated that the homogeneity‐increasing effect of the spacer was neutralized by the detrimental effect of the dicarboxylic chelating group. Nevertheless, the results showed that the maleimides were well suited for grafting by reactive extrusion because of their low susceptibility to homopolymerization under melt‐processing conditions. Preliminary metalization experiments showed the feasibility of plating without the use of corrosive etchants. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3400–3413, 2003     

射频磁控溅射法制备SnO2:Sb薄膜的结构和光致发光性质研究

采用射频磁控溅射法在玻璃衬底上制备出锑掺杂的氧化锡（SnO2₂:Sb）薄膜.制 备薄膜是具有纯氧化锡四方金红石结构的多晶膜薄，晶粒生长的择优取向为［110］.室温下光致发光测量结果表明，在392nm附近存在强的紫外-紫光发射.研究了不同氧分压对薄膜结构及发光性质的影响，并对SnO2₂:Sb的光致发光机制进行了探索性研究.     

非平衡磁控溅射法类金刚石薄膜的制备及分析

利用非平衡磁控溅射物理气相沉积技术制备了光滑、致密、均匀的类金刚石薄膜.分析沉积工艺参数对所得类金刚石薄膜的电学特性的影响以及溅射粒子的大小、能量、碰撞及沉积过程中的相变机理后认为：溅射粒子越小、与环境气体分子的碰撞次数越多、与衬底相互作用时具有适当动量等，能够有效提高薄膜中sp^３杂化碳原子的含量.利用拉曼光谱 、纳米力学探针、红外光谱、扫描电镜等分析了所得类金刚石膜的结构、力学及光学性能、 表面形貌等特征.结果表明，类金刚石膜中sp^３杂化碳原子的含量较高，显微硬 度大于11GPa，薄膜光学透过率达到89.4％，折射系数为1.952，沉积速率为0.724μm/h，表 面光滑、致密、均匀，不存在明显的晶粒特征. 关键词： 非平衡磁控溅射 类金刚石膜 拉曼光谱 红外光谱     

用磁控溅射和真空硒化退火方法制备高质量的铜铟硒多晶薄膜

用双靶磁控溅射的方法在玻璃衬底上制备了Cu11In9合金薄膜,然后将Cu11In9合金薄膜封闭在石墨盒中进行真空硒化退火得到CuInSe2薄膜.用扫描电子显微镜(SEM)和X射线粉末衍射(XRD)对CuInSe2薄膜进行了表征,结果表明CuInSe2薄膜具有单一的晶相,均匀、致密的结构,以及粒径超过了3μm的晶粒. 关键词： 铜铟硒多晶薄膜 磁控溅射 真空硒化 太阳能电池     

STUDIES ON ORGANOSILICON REACTIVE INTERMEDIATES (Ⅴ)~*——STEREOSPECIFIC ADDITION OF CYCLOPROPYLPHENYLSILYLENE TO OLEFINS

This paper reports that cyclopropylphenylsilylene (1) is obtained by photolysis of 2-cyclopropyl-2-phenylhexamethyl-trisilane. 1 added stereospecifically to cis-and trans2-butene gives the corresponding siliranes. Opening of the sillranes by methol also occurs in stereospecifically cis fashion.     

Theory of stimulated desorption of ions and neutrals

Summary To understand the electronic processes that occur during desorption, we must allow simultaneously for the intrinsic nonadiabatic character of electron states and for correlation-induced features like two-hole resonances. A recently proposed theory describes the Menzel-Gomer-Redhead and Knotek-Fiebelman mechanisms on equal footing and reveals a complex interplay of electronic and kinematic effects on the ion yield. Here, I wish to show how in the same scheme we can also obtain the yield of ions that have suffered (partial or total) re-neutralization in the course of desorption. Closed-form expressions for the relevant escape probabilities are given in terms of one-hole and two-hole Green’s functions. The surface molecule limit of the theory is worked out in detail assuming that the hopping parameters decay exponentially in time during desorption. It is shown that, in general, when a given species can be desorbed by different mechanisms, we can discriminate them experimentally by the energy and angular dependence of the yield.

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Riassunto Per comprendere i processi elettronici che avvengono nel desorbimento, dobbiamo tener conto che gli stati hanno un carattere intrinsecamente non adiabatico. Allo stesso tempo, occorre includere gli effetti di correlazione, come, ad esempio, le risonanze a due buche. Una teoria recente consente una descrizione unificata dei meccanismi di Menzel-Gomer-Redhead e di Knotek-Feibelman; essa mostra che effetti elettronici ed effetti cinematici concorrono in modo complesso a determinare la resa di ioni. Qui si vuol far vedere come tale teoria consenta di ottenere la resa anche per le specie che subiscono una rineutralizzazione parziale o totale nel corso del desorbimento. Le probabilità che lo ione desorba nei vari stati di carica sono espresse in forma chiusa in termini delle funzioni di Green a una e due buche. Il limite della molecola superficiale è risolto in dettaglio nel caso in cui i parametri di salto decadono esponenzialmente nel tempo durante il desorbimento. Si trova che, quando diversi meccanismi portano al desorbimento di una stessa specie, è generalmente possibile distinguerli per le diverse dipendenze dall’energia cinetica e dagli angoli.

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Резюме Чтобы понять электронные процессы, происходящие при десорбции, мы должны одновременно учитывать внутренний неадиабатический характер электронных состояний и особенности, подобные двухдырочным резонансам. Недавно предложенная теория описывает механизмы Менцеля-Гомера-Редхеда и Нотека-Фейбелмана и обнаруживает комплексное влияние электронного и кинематического эффектов на выход ионов. В рамках этой схемы мы хотим показать, как можно получить выход ионов, которые испытывают (частичную и полную) ренейтрализацию в процессе десорбции. Приводятся замкнутые выражения для соответствующих вероятностей вылета в терминах одно-дырочных и двух-дырочных функций Грина. Разрабатывается предел теории для молекулы на поверхности, предполагая, что параметры ?перепыгивания? экспоненциально затухают во времени в процессе десорбции. Показывается, что, когда заданный тип частиц может быть десорбирован за счет различных механизмов, мы можем дискриминировать их экспериментально, используя энергетическую и утловую зависимости выхода.

     

Thermodynamic conditions for formation of single phase in Bi-superconductor thin films

High quality BSCCO thin films have been fabricated by means of an ion beam sputtering at various substrate temperatures, T_sub, and ozone gas pressures, pO₃. The correlation diagrams of the BSCCO phases appearing against T_sub and pO₃ have been established in the 2212 and 2223 compositional films. In spite of 2212 compositional sputtering, Bi2201 and Bi2223 phases as well as Bi2212 have emerged as stable phases depending on T_sub and pO₃. From these results, the thermodynamic evaluations of ΔH and ΔS, which are related with Gibbs’ free energy change for single Bi2212 or Bi2223 phase have been performed.     

Beam optics optimization of a negative-ion sputter source

A negative-ion sputter source has been studied in order to increase the beam intensity delivered by the Vivitron tandem injector. The aim was to characterize the influence on the beam intensity of some factors related to the configuration of the source such as the shape of the target holder, the target surface topography and the anode/cathode voltage. The paper reports the results carried out by experimentation on a test facility and on the injector itself as well as the investigations performed with computer simulations.