One-pot,one-step,and selective terpolymerization of ethylene oxide,propylene oxide,and COS to copoly(thioether)s with tunable thermal properties

Facile construction of sulfur-rich polymers using readily available raw chemicals is an area aggressively pursued but challenging. Herein we use common feedstocks of ethylene oxide (EO), propylene oxide (PO), and carbonyl sulfide (COS) to synthesize copoly(thioether)s which are traditionally produced from unpleasant and difficult to store episulfides. In this protocol, the EO/COS coupling selectively generates a pure poly(ethylene sulfide) (PES) with melting temperature (T_m) values up to 172°C and high yields up to 98%. The EO/PO/COS terpolymerization leads to the incorporation of soft poly(propylene sulfide) (PPS) and hard PES segments together, affording a random PES-co-PPS copoly(thioether) with the complete consumption of EO and PO. Additionally, by simply varying the EO/PO feeding ratio, the obtained copoly(thioether)s possess tunable thermal properties, T_m values in the range of 76–144°C, and excellent solubility. These copolymerizations are conducted in one-pot/one-step at industrially favored reaction temperatures of 100–120°C using catalysts of common organic bases, suggesting a facile and practical manner. Especially, the copoly(thioether) exhibits high refractive indices up to 1.68 owing to its high sulfur content, suggesting a broad application prospect in optical materials.     

Influence of radiation on thin ZnS-Tb films

Changes in thin zinc-sulfide films under the action of the γ-radiation of Co⁶⁰ are studied by investigating electroluminescence spectra of terbium embedded in these films as a luminescent probe. It is shown that changes in the relation of the intensities of bands, a decrease in their halfwidth and the background component, and simplification of the spectrum are observed in a short-wave region of the Tb radiation spectrum that corresponds to⁵D₃→⁷F_j transitions. The same modification of the radiation spectrum is characteristic of ZnS films whose crystalline structure is ordered in the course of thermal annealing at a temperature of 350°C. Based on the analysis of the data obtained it is inferred that irradiating the ZnS films with small radiation doses of 10⁴–10⁵ rad leads to the ordering of their crystalline structure due to the elimination of one of the types of structural defects. Institute of Physics of Semiconductors, National Academy of Sciences of Ukraine, 45, Nauka Ave., Kiev-28, 252650. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 3, pp. 338–341, May–June, 1997.     

Optical properties of cadmium sulfide nanocrystal film prepared by electrochemical synthesis at liquid-liquid interface

Dendritic nanocrystalline CdS film was deposited at liquid-liquid interface of surfactants and an electrolyte containing 4 mmol L⁻¹ cadmium chloride (CdCl₂) and 16 mmol L⁻¹ thioacetamide (CH₃CSNH₂) with an initial pH value of 5 at 15 °C by electrochemical synthesis. The nanofilm was characterized by transmission electron microscopy (TEM), field emission scanning electron microscope (FE-SEM), atomic force microscopy (AFM), ultraviolet visible (UV-vis) absorption spectroscopy and fluorescence spectroscopy. The surface morphology and particle size of the nanofilm were investigated by AFM, SEM and TEM, and the crystalline size was 30-50 nm. The thickness of the nanofilm calculated by optical absorption spectrum was 80 nm. The microstructure and composition of the nanofilm was investigated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), showing its polycrystalline structure consisting of CdS and Cd. Optical properties of the nanofilm were investigated systematically by UV-vis absorption and fluorescence spectroscopy. A λ_onset blue shift compared with bulk CdS was observed in the absorption spectra. Fluorescence spectra of the nanofilm indicated that the CdS nanofilm emitted blue and green light. The nanocomposites film electrode will bring about anodic photocurrent during illumination, showing that the transfer of cavities produces photocurrent.     

Scanning probe microscopy studies of PbS surfaces oxidized in air and etched in aqueous acid solutions

Natural n-type PbS single crystals have been studied using AFM, STM and STS after long-term oxidation in air at ambient temperatures and extensive etching in aqueous acid solutions, in contrast to previous work devoted to initial corrosion of fresh surfaces. The exposure of PbS to atmosphere at high relative humidity for several days yields widespread loose oxidation products; the process is much slower at low humidity. Surface morphologies diverge after the treatment in 1 M perchloric and hydrochloric acid solutions at room temperature and become widely different at elevated temperatures, displaying commonly etch pits up to several micrometers in size and depth along with rather uniformly distributed 20-100 nm protrusions of PbS phase. The changes both in topography and semiconducting properties of PbS found by tunneling spectroscopy have been explained in terms of the non-uniform distribution of donor- and acceptor-type defects D⁺/D⁻ in the metal depleted surface layer, which are generated by chemical reactions and, in turn, determine the rates of the PbS corrosion. In particular, the D⁻ centers exhibit a self-catalyzing effect on the non-oxidative local dissolution of PbS in HCl media, resulting in the deep etch pits.     

Synthesis and properties of triethylammonium 2,2,5-triphenyl-1,3,2,5-dioxaborataphosphorinane

The reaction of bis(hydroxymethyl)phenylphosphine with isobutyl diphenylborate in the presence of triethylamine leads to the formation of triethylammonium 2,2,5-triphenyl-1,3,2,5-dioxaborataphosphorinane (1). The reaction of compound 1 with electrophilic reagents (O, S, Se, CH₂O, RHal) leads to quaternization of the phosphorus atom, giving the corresponding phosphine oxides, sulfides, and selenides and P,B-containing betaines. In the reactions of compound 1 with amines aminomethylphosphines of the diazaphosphorinane and diazadiphosphacyclooctane series are formed. Ammonium 1,3,2,5-dioxaborataphosphorinanes dissociate in solutions and enter into ion exchange with phosphonium iodides, leading to phosphonium 1,3,2,5-dioxaborataphosphorinanes. The latter, in the case of the aminomethylphosphonium cation, undergo intramolecular rearrangement with the formation of P,B-containing betaines and aminomethylphosphines.Deceased.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences, 420083 Kazan'. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1398–1405, June, 1992.     

Morphological and chemical study of the initial growth of CdS thin films deposited using an ammonia-free chemical process

We study the initial growth stages of CdS thin films deposited by an ammonia-free chemical bath deposition process. This ammonia-free process is more environmentally benign because it reduces potential ammonia release to the environment due to its high volatility. Instead of ammonia, sodium citrate was used as the complexing agent. We used atomic force microscopy (AFM), Rutherford backscattering (RBS) and X-ray photoelectron spectroscopy (XPS) to investigate the morphological and chemical modifications at the substrate surface during the first initial stages of the CdS deposition process. Additionally, X-ray diffraction (XRD) and optical transmission spectroscopy measurements were carried out to compliment the study. XPS results show that the first nucleation centers are composed by Cd(OH)₂ which agglomerate in patterns of bands, as demonstrated by AFM results. It is also observed that the conversion to CdS (by anionic exchange) of the first nucleus begins before the substrate surface is completely covered by a homogenous film.     

助熔剂N_aCl－CdCl_2对CdS∶Cu，In结晶状态作用规律研究

发现在确定的热处理温度和时间下，随炉料中助熔剂ＮａＣｌ－ＣｄＣｌ２，总含量的增加，ＣｄＳ：Ｃｕ，Ｉｎ多晶的粒度分布变窄，数均粒径具有最大值，晶粒外型趋于规整且表面平滑．进而证明，多晶的结晶状态对其光电性能具有显著的影响．     

简便快速的硫化氢测定法

本文提出了有一种简易快速测定剂来测定水样中的硫化氢的方法。该法的检出限为０．１ｍｇ／Ｌ，对１．０１ｍｇ／Ｌ的Ｈ２Ｓ样品７次测定的相对标准偏差＜４．１％，１ｈ能测定１２个样品。用本测定了几种水样中的Ｈ２Ｓ含量，回收率为８４％－１０５％。应用它可上标准法的４ｈ左右缩短到５ｍｉｎ；使分析成本降低９／１０；不需配制一系列分析试剂和仪器，只需一支小型塑料管和几片药片，便于渔业水质和环境水质的野外现场监测。     

碱改性γ－Al_2O_3催化剂表面碱强度分布与COS水解活性的研究

用非水滴定法和Ｈａｍｍｅｔｔ系列指示剂测定了ＣＯＳ水解碱改性γ－Ａｌ_２Ｏ_３催化剂的表面碱强度分布．发现表面碱强度分布不均匀与表面能量分布不均匀相呼应．采用零点酸碱强度（Ｈ_（０，ｍａｘ））及碱中心区域分析法，Ｂｒｏｎｓｔｅｄ催化定律，进一步证实ＣＯＳ水解反应具有明显碱催化特征，较高活性催化剂的Ｈ_（０，ｍａｘ）一般为１０左右，对ＣＯＳ水解反应起主要作用的碱性中心的碱强度（Ｈ_０）为４．８≤Ｈ_０≤９．８．对碱金属氧化物改性后的γ－Ａｌ_２Ｏ_３催化剂，Ｂｒｏｎｓｔｅｄ规律在每个碱强度分区域内是适用的．     

Thermolysis of reactive oligo(p-phenylene sulfide) containing disulfide bond

Oligo(phenylene sulfide) (OPS) containing one disulfide bond at the end of the chain, which was obtained by the oxidative polymerization of diphenyl disulfide, had a relatively low Td_10%(temperature for 10% weight loss) of 412 °C because of degradation of the disulfide bond. But this thermal cleavage of the disulfide bond promoted the curing reaction through thiophenoxy radical formation. OPS was allowed to react with diiodobenzene at 220 °C. The thermal stability of OPS was improved through the consumption of the disulfide bond and the coupling of the chain.