微波种子乳液聚合制备多孔乳胶粒

微波辐照下，通过间歇无皂种子乳液聚合制得聚(苯乙烯-甲基丙烯酸甲酯-丙烯酸)复合乳液，将所得复合乳液进行碱／酸分段处理，得到具有多孔结构的乳胶粒。用透射电镜对胶粒形态进行了表征。研究了酸处理初始pH值及酸处理时间对胶粒成孔的影响。     

种子乳液聚合法制备多孔乳胶粒

用批量乳液聚合法制备了苯乙烯（Ｓｔ）———甲基丙烯酸甲酯（ＭＭＡ）二元共聚种子乳液Ｓ１以及Ｓｔ ＭＭＡ 丙烯酸（ＡＡ）三元共聚种子乳液Ｓ２,通过连续法无皂种子乳液聚合合成了一系列不同ＡＡ或ＭＡＡ（甲基丙烯酸）含量的Ｓｔ、ＭＭＡ三元共聚乳液．将所得复合胶乳进行碱／酸分步处理,得到具有多孔结构的乳胶粒．用透射电镜对胶粒形态进行了表征,考察了不饱和酸种类和用量、碱处理初始ｐＨ值及溶胀剂对胶粒成孔的影响．     

多孔结构聚合物乳胶粒

介绍了多孔结构乳胶粒的制备方法、表征手段以及成孔机理。着重阐述了“碱酸分段处理法”中不饱和酸与交联剂的种类与用量、以及碱酸处理条件等因素对乳胶粒成孔的影响。     

不同水煤浆分散剂与煤之间的相互作用规律研究 Ⅶ 酸碱脱灰处理煤的性质变化及其对成浆性的影响

研究了酸－碱脱灰处理对鹤壁、淮南和靖远煤的有机组成、表面性质以及成浆性的影响。结果表明，酸－碱脱灰处理后煤质特性都发生了明显变化。主要表现在灰分下降，水分增加，挥发分降低，总碳量和芳香碳增加；氧的质量分数下降，酚羟基氧质量分数增加；硫的质量分数降低。酸－碱脱灰处理后煤的成浆性明显变差，在煤粒度分布、分散剂种类和用量相同时，脱灰处理使鹤壁、淮南、靖远三种煤成浆的定黏（1 000 mPa·s）浓度，分别比相应原煤下降了4.6%，6.6%和4.4%。进一步研究表明，经酸－碱脱灰处理，上述3种煤对所用4种分散剂的吸附量都明显增加，煤粒的Zeta电位也明显增加。酸－碱脱灰处理使研究用煤的成浆性变差，主要是由于煤的有机组成和表面性质变化引起的。     

ZSM-5/MCM-41复合分子筛的合成与表征

以碱处理的ZSM-5浆液为硅铝源,通过水热自组装过程合成了介孔-微孔复合孔道结构的分子筛,并采用XRD、BET、HRTEM、Py-IR和水热处理等手段对合成分子筛进行了表征。结果表明,碱处理ZSM-5时的苛刻程度是影响复合分子筛合成的重要因素,适宜的碱处理条件为NaOH浓度1 mol/L、80℃时处理1 h。表征结果表明,复合分子筛具有规整互通的微孔-介孔梯级复合孔道结构,孔容、比表面积和平均孔径分别为0.63 mL/g,684 m²/g和3.76 nm,属典型的MCM-41结构;与MCM-41相比,复合分子筛的B酸(尤其是强B酸)酸量明显增强,水热稳定性显著提高。     

Zn／HZSM—5分子筛上乙烯,乙烷芳构化的协同作用机理

运用ＮＨ３－ＴＰＤ、ＩＲ－ＯＨ、Ｐｙ－ＩＲ、ＣＯ－ＩＲ及ＸＰＳ等手段对Ｚｎ／ＨＺＳＭ－５及其浸碱催化剂的酸组分和金属组分构成的Ｌ酸性质进行了表征，考察了催化剂对乙烯、乙烷的芳构化作用，发现Ｚｎ／ＨＺＳＭ－５中形成了Ｚｎ＾２＋－Ｌ强酸中心，使分子筛的Ｂ酸中心减少，浸碱也可使分子筛的Ｂ酸减少，芳构化反庆的活性和选择性均与Ｚｎ／ＨＺＳＭ－５的双中心Ｚｎ＾２＋－Ｌ酸的相互匹配密切相关。Ｂ酸和Ｌ酸存在最适合     

交联剂对无皂P(MMA-EA-MAA)种子聚合乳胶粒成孔的影响

采用完全无皂种子乳液聚合技术合成了粒径窄分布的P(MMA-EA-MAA)乳胶粒,通过对上述胶乳进行碱处理,制备出了具有空腔结构和多孔结构的聚合物乳胶粒,研究了交联剂的种类和用量对聚合过程、胶粒特性及胶粒结构形态的影响.结果表明,体系中加入交联剂后,单体转化率都有不同程度的提高;随交联剂用量的增加,乳胶粒粒径略有减小,交联剂用量较高时,乳胶粒粒径分布加宽;二乙烯基苯(DVB)的交联效率稍高于双甲基丙烯酸乙二醇酯(EGDMA);不加入交联剂及EGDMA用量低于0.5%时,处理后乳胶粒呈空腔结构,加入DVB及EGDMA用量高于1.0%时,处理后乳胶粒呈多孔结构,并且乳胶粒体积增量随交联剂用量的增加而减小.     

头孢氨苄降解产物荧光性质的研究及分析应用

详细研究了头孢氯苄在酸，碱介质中的降解反应，建立了酸，碱降解的荧光分析法，线性范围是０．５０－１００ｎｇ／ｍＬ（酸降解）和２．０－７０ｎｇ／ｍＬ（碱降解）。从精密度和准确度看，酸降解优于碱降解的荧光分析，将酸降解荧光分析应用于血清和尿样中头氨苄的测定，结果良好。     

手性胺—铜配合物的合成及其在菊酸不对称合成中的应用

报导了新型希夫碱－铜配合物的合成，及其对菊酸不对称合成的催化诱导效应，用降解脱氢松香胺和水杨醛反应，形成希夫碱，再与醋酸铜反应，制行希夫碱－铜配合物。将该配合物作为手性催化剂，催化重氮乙酸乙酯及重氮乙酸冰片酯与２，５－二甲基－２，４－己二烯合成菊酸的反应，讨论了重饩     

Zn／HZSM－5分子筛上乙烯、乙烷芳构化的协同作用机理

运用ＮＨ＿３－ＴＰＤ、ＩＲ－ＯＨ、Ｐｙ－ＩＲ、ＣＯ－ＩＲ及ＸＰＳ等手段对Ｚｎ／ＨＺＳＭ－５及其浸碱催化剂的酸组分和金属组分构成的Ｌ酸性质进行了表征，考察了催化剂对乙烯、乙烷的芳构化作用．发现Ｚｎ／ＨＺＳＭ－５中形成了Ｚｎ￣（２＋）－Ｌ强酸中心，使分子筛的Ｂ酸中心减少．浸碱也可使分子筛的Ｂ酸减少，芳构化反应的活性和选择性均与Ｚｎ／ＨＺＳＭ－５的双中心Ｚｎ￣（２＋）－Ｌ酸和Ｂ酸的相互匹配密切相关，Ｂ酸和Ｌ酸存在最适合匹配，因此Ｚｎ／ＨＺＳＭ－５在乙烯、乙烷芳构化反应中存在最佳锌含量．     

Infrared spectroscopy of acetic acid and formic acid aerosols: pure and compound acid/ice particles

Acetic acid aerosol particles, formic acid aerosol particles and mixed acid/ice particles were generated in a collisional cooling cell at a temperature of 78 K and investigated using in situ rapid scan Fourier transform infrared spectroscopy. The infrared spectra reveal that the internal structure of the particles critically depends on the particle formation conditions and, especially for the mixed particles, on the composition. The acetic acid particles are likely to have only a partially crystalline structure whereas the formic acid particles are likely to have an overall crystalline structure. The existence of acid in the mixed acid/ice particles prevents the ice from crystallization even at low acid concentrations (less than 10%). Mid-infrared refractive index data were derived from the different particle spectra, which can be helpful for remote sensing of such systems.     

Fe_2O_3超微粒/硬脂酸复合LB膜的制备和表征研究

用超声分散的方法将Ｆｅ２Ｏ３超微粒分散于硬脂酸／正己烷／氯仿溶液中，用ＬＢ膜技术进行组装。结果表明：Ｆｅ２Ｏ３超微粒能均匀地分散在有机溶剂中，并且能够被硬脂酸包裹；Ｆｅ２Ｏ３超微粒／硬酯酸单分子膜的成膜性能良好，Ｆｅ２Ｏ３超微粒／硬脂酸复合ＬＢ膜具有层状结构；在Ｆｅ２Ｏ３超微粒的晶格结构和硬脂酸单分子膜的晶格结构相匹配的情况下，Ｆｅ２Ｏ３超微粒能够被有序组装。     

Production of multi-hollow polymer particles by the stepwise acid/alkali method

 Recently, we reported that multi-hollow polymer particles can be prepared from carboxylated polymer particles by the stepwise alkali/acid method. In this article, an attempt was made to prepare similar particles from acid-swellable polymer particles by the stepwise treatment with acid and alkali, which was named the stepwise acid/alkali method. The acid-swellable particles were produced by emulsion terpolymerization of styrene, butyl acrylate, and dimethyl 2-amino ethyl methacrylate. The effects of initial pH value, temperature, and time in the acid and alkali treatment processes on the multi-hollow structure were examined. Received: 18 December 1996 Accepted: 11 March 1997     

Interfacial properties of emulsions stabilized with surfactant and nonsurfactant coated boehmite nanoparticles

The properties of emulsions stabilized with surface-modified boehmite particles of 26 and 8 nm in diameter have been investigated. The surface-modified particles were prepared by mixing aqueous dispersions of cationic boehmite particles with aqueous solutions of the surfactant p-dodecylbenzenesulfonic acid (DBSA) or the nonsurfactant p-toluenesulfonic acid (TSA). For the 26 nm particles, interfacial tension measurements indicate that p-dodecylbenzenesulfonic acid partitions between the particle surface and the oil-water interface, while p-toluenesulfonic acid remains on the particle surface. The partitioning of p-dodecylbenzenesulfonic acid supports the formation of emulsions, although in the absence of the particles the same surfactant concentration is not sufficient for emulsion stabilization. Due to the fast exchange kinetics, p-dodecylbenzenesulfonic acid is gradually replaced by particles. At equilibrium, the interfacial tension in the presence of the surface-modified particles is between the values for the pure particles and the pure surfactant solutions. However, the interfacial tension is independent of the surfactant concentration used in the preparation of the particles. Reducing the particle size to 8 nm leads to increased emulsion stability, and thus, the minimum particle concentration required to prepare stable emulsions was reduced to 0.1 g/L. However, above approximately 3.5 mmol/L of the sulfonic acids, the small particles dissolve slowly, and the emulsion stability is lost. This mechanism can be used to trigger the collapse of the emulsions.     

接枝微粒材料P4VP-SiO_2对酸性氨基酸的吸附性能与吸附机理

将4-乙烯基吡啶(4VP)接枝聚合于微米级硅胶表面,制得了接枝有聚4-乙烯基吡啶(P4VP)的接枝微粒P4VP-SiO_2,测定了P4VP-SiO_2的红外光谱,袁征了其化学结构,并测定了该复合型功能微粒材料的Zeta电位.采用静态法研究了P4VP-SiO_2对酸性氨基酸天冬氨酸与谷氨酸的吸附性能,考察了介质pH、离子强度及温度对其吸附性能的影响,探索了吸附机理.研究结果表明:在较大的pH范围内,P4VP-SiO_2的Zeta电位为较高的正值,即微粒表面携带有高密度的正电荷;酸性氨基酸天冬氨酸与谷氨酸等电点都较低,所以在一般的介质pH范围内,它们的分子带有负电荷;凭借静电相互作用,P4VP-SiO_2对酸性氨基酸天冬氨酸与谷氨酸均表现出很强的吸附能力,而对中性与碱性氨基酸(在一般的介质pH范围内分子带有正电荷)的吸附能力则很弱;随介质pH的增大,P4VP-SiO_2对天冬氨酸与谷氨酸的吸附能力呈现先增强后减弱的规律,在pH＝4处,吸附容量具有最大值,分别为280 mg/g与230 mg/g;温度升高,吸附容量减小;盐度增大,吸附容量降低.     

Inhibition of aluminum oxyhydroxide precipitation with citric acid

Citric acid has been shown to act as an agent for increasing the solubility of aluminum oxyhydroxides in aqueous solutions of high (>2.47 mol/mol) hydroxide-to-aluminum ratios. Conversely, citric acid also colloidally stabilizes particles in aqueous suspensions of aluminum-containing particles. Solutions of aluminum chloride, with and without citric acid added, were titrated with NaOH(aq). The presence and size of particles were determined using quasi-elastic light scattering. In solutions that contained no citric acid, particles formed instantaneously when NaOH(aq) was added but these were observed to rapidly diminish in size, disappearing at OH/Al ratios below 2.5 mol/mol. When the OH/Al ratio was raised beyond 2.5 by adding more NaOH(aq), suspensions of colloidally stable particles formed. Large polycations containing 13 aluminum atoms were detected by (27)Al solution NMR in citric-acid-free solutions with OH/Al ratios slightly lower than 2.5. In comparison, adding citric acid to solutions of aluminum chloride inhibited the formation of large aluminum-containing polycations. The absence of the polycations prevents or retards the subsequent formation of particles, indicating that the polycations, when present, act as seeds to the formation of new particles. Particles did not form in solutions with a citric acid/aluminum ratio of 0.8 until sufficient NaOH(aq) was added to raise the OH/Al ratio to 3.29. By comparison, lower amounts of citric acid did not prevent particles from forming but did retard the rate of growth.     

Heterogeneity among multihollow polymer particles prepared by the alkali/cooling method under partial neutralization conditions

Heterogeneity in the formation of multihollow structure among styrene-methacrylic acid copolymer particles, which were produced by emulsion copolymerization, by the alkali/cooling method under partial neutralization conditions with potassium hydroxide was investigated. There was a threshold acid content to form the multihollow structure. The heterogeneity among the multihollow particles was based on the heterogeneity of acid contents among the original particles.     

Mass spectral evidence that small changes in composition caused by oxidative aging processes alter aerosol CCN properties

Oxidative processing (i.e., "aging") of organic aerosol particles in the troposphere affects their cloud condensation nuclei (CCN) activity, yet the chemical mechanisms remain poorly understood. In this study, oleic acid aerosol particles were reacted with ozone while particle chemical composition and CCN activity were simultaneously monitored. The CCN activated fraction at 0.66 +/- 0.06% supersaturation was zero for 200 nm mobility diameter particles exposed to 565 to 8320 ppmv O3 for less than 30 s. For greater exposure times, however, the particles became CCN active. The corresponding chemical change shown in the particle mass spectra was the oxidation of aldehyde groups to form carboxylic acid groups. Specifically, 9-oxononanoic acid was oxidized to azelaic acid, although the azelaic acid remained a minor component, comprising 3-5% of the mass in the CCN-inactive particles compared to 4-6% in the CCN-active particles. Similarly, the aldehyde groups of alpha-acyloxyalkylhydroperoxide (AAHP) products were also oxidized to carboxylic acid groups. On a mass basis, this conversion was at least as important as the increased azelaic acid yield. Analysis of our results with K?hler theory suggests that an increase in the water-soluble material brought about by the aldehyde-to-carboxylic acid conversion is an insufficient explanation for the increased CCN activity. An increased concentration of surface-active species, which decreases the surface tension of the aqueous droplet during activation, is an interpretation consistent with the chemical composition observations and K?hler theory. These results suggest that small changes in particle chemical composition caused by oxidation could increase the CCN activity of tropospheric aerosol particles during their atmospheric residence time.     

双亲性离子液体功能化复合胶体颗粒的合成与催化性能

采用硅烷偶联剂4-氯苄基三氯硅烷对二氧化硅颗粒表面进行改性, 制得表面接枝氯苄基的亲油二氧化硅颗粒. 在亲油二氧化硅颗粒表面继续接枝亲水性的十二烷基咪唑, 即可制得含有离子液体基团的双亲性二氧化硅颗粒. 通过静电吸附氯铂酸和硼氢化钠还原, 可在两亲性二氧化硅颗粒表面负载铂纳米颗粒, 从而得到双亲性二氧化硅颗粒催化剂. 用扫描电镜、 透射电镜、 X射线衍射和红外光谱等对所得样品进行表征, 并以苯甲醇氧化反应为研究对象对催化剂性能进行评价, 结果显示, 使用此催化剂可使苯甲酸的产率达到90%.     

Pressure and concentration profiles in filter cake consisting of core/shell latex particle

Poly(styrene-co-acrylic acid) latex particles with different acrylic acid contents have been synthesized and used for filtration studies. Effective pressure and dry matter concentrations were measured at different positions in the filter cakes during the filtration processes, and dry matter concentration was not found to change significantly with effective pressure. Nevertheless, the local dry matter concentration did increase with time for latex particles containing 1 and 3%, w/w acrylic acid, which indicate that filter cake comprising latex particles with a high acrylic acid content will creep during the filtration stage. The filter cakes were examined using stepped-pressure filtration experiments as well, and an almost instantaneous deformation of the filter cake was observed after the pressure step. Furthermore, a minor deformation was observed over the following 2 h for latex particles both containing and not containing acrylic acid. This is thought to be due to the rearrangement of particles in the filter cake.