分散聚合法制备甲基丙烯酸甲酯-苯乙烯共聚物微球

以聚乙烯吡咯烷酮(PVP)为分散剂,以偶氮二异丁腈(AIBN)为引发剂,在甲醇／水混合溶剂中,采用分散聚合法制备出微米级的甲基丙烯酸甲酯一苯乙烯共聚物微球,研究了分散介质组成、单体组成、引发剂浓度、分散剂浓度、反应温度等反应条件对聚合产物粒径及粒径分布的影响。     

单分散、大粒径聚苯乙烯微球的制备

以聚乙烯基吡咯烷酮为分散剂、偶氮二异丁腈为引发剂、醇／水混合物为分散介质进行了苯乙烯的分散聚合，讨论了初始单体浓度、分散剂用量、引发剂浓度、分散介质组成和反应温度等反应条件对所得聚合物颗粒直径和直径分布的影响．通过大量的试验，筛选出了较为理想的分散聚合的条件及配方，制备出了粒径为４８μｍ的单分散聚苯乙烯微球．然后，以分散聚合所制得的聚合物颗粒为种子，用动力学溶胀法制成了粒径增大近四倍的单分散、大粒径聚苯乙烯微球，并讨论了滴水速度和补加分散剂对溶胀的影响     

乙酸乙酯/乙醇混合溶液中分散聚合制备单分散亚微米级聚丙烯酰胺微球

以乙酸乙酯/乙醇混合溶液为分散介质, PVP为分散剂, 通过分散聚合法合成了单分散亚微米级PAM微球. 在反应初期, 自动加速现象明显. 由于凝胶效应的影响, 分子量随着单体转化率的提高而逐渐增大. 考察了分散剂浓度对最终产物增率的影响, 并用IR光谱对产物的结构进行了表征, 证明分散聚合体系中吸附稳定机理和接枝稳定机理同时存在, 且以后者为主. 同时还研究了混合溶剂比例、分散剂浓度、初始单体浓度和引发剂浓度对微球粒径及粒径分布的影响. 结果表明, 乙酸乙酯/乙醇体积比在5∶5-7∶3范围内, 可得到粒径在200 nm左右, 且分布较窄的PAM微球; 分散剂浓度增大, 粒径减小; 引发剂浓度增加, 粒径增大; 初始单体浓度较高或较低时, 都得不到单分散性微球.     

Ni-Co@C-N催化剂的制备及其催化硝基芳烃还原偶联反应

以ZIF-67为前驱体,通过高温热解和乙二醇还原的方法制备了低成本的负载镍纳米粒子催化剂Ni-Co@C-N。研究了催化剂对硝基芳烃化合物合成相应氧化偶氮苯类化合物的催化性能,并讨论了碱及分散剂种类对催化剂结构与性能的影响。结果表明,碱性增强可以加快纳米粒子的成核速率,分散剂分子量增加则会限制纳米粒子的粒径增长。其中,由弱碱与低分子量分散剂制备的Ni-Co@C-N-4 对硝基芳烃还原具有良好的催化活性,原料的转化率和产率在反应30 min 后分别达到92.8%和89.3%,且循环实验表明Ni-Co@C-N-4具有良好的稳定性。     

Ni-Co@C-N催化剂的制备及其催化硝基芳烃还原偶联反应

以ZIF-67为前驱体,通过高温热解和乙二醇还原的方法制备了低成本的负载镍纳米粒子催化剂Ni-Co@C-N。研究了催化剂对硝基芳烃化合物合成相应氧化偶氮苯类化合物的催化性能,并讨论了碱及分散剂种类对催化剂结构与性能的影响。结果表明,碱性增强可以加快纳米粒子的成核速率,分散剂分子量增加则会限制纳米粒子的粒径增长。其中,由弱碱与低分子量分散剂制备的Ni-Co@C-N-4对硝基芳烃还原具有良好的催化活性,原料的转化率和产率在反应30 min后分别达到92.8%和89.3%,且循环实验表明Ni-Co@C-N-4具有良好的稳定性。     

聚丙烯成核剂成核效应及热稳定性研究

为表征在聚合物材料热加工成型过程中成核剂的成核效果的热稳定性，设计了用反复升降温ＤＳＣ实验，通过观察聚合物结晶温度和结晶热焓在反复升降温过程中的变化来考察成核剂的成核效率的稳定性．研究了碳酸钙、苯甲酸钠、对苯二甲酸和脂肪二元酸：庚二酸、辛二酸、壬二酸及其与碳酸钙组成的双组分成核剂对聚丙烯结晶成核效果的热稳定性．结果表明，高熔点物质碳酸钙、对苯二甲酸、苯甲酸钠的成核效果的热稳定性高，而脂肪二元酸的成核热稳定性低．庚二酸与碳酸钙组成的双组分成核剂的成核热稳定性高，但辛二酸、壬二酸与碳酸钙组成的双组分成核剂的成核热稳定性没有得到改善．这可能是由于庚二酸与碳酸钙之间存在某种相互作用，从而使成核效果得以稳定，而辛二酸、壬二酸与碳酸钙组成的双组分成核剂中，两个组分基本独立存在．     

粒径和孔径可控的多孔交联聚苯乙烯微球的制备

采用悬浮聚合方法合成了多孔交联聚苯乙烯微球,研究发现微球的粒径与分散剂含量、水油比、搅拌速度和成孔剂有关,而微球的孔径与成孔剂的种类和含量有关。 增加分散剂的用量,提高水油比和加快搅拌速度都能导致微球的粒径减小。 微球的孔径和粒径均随着成孔剂与聚合物溶度参数差值变大而增加。通过改变以上条件得到粒径为100~300 μm和孔径为8~36 nm的交联度为27%的多孔交联聚苯乙烯微球,并利用光学显微镜、场发射扫描电子显微镜(SEM)和氮气吸附解吸法对微球进行了相应的表征。 得到的微球在固相合成载体中有一定的应用前景。     

偏氟乙烯分散聚合的成核及初级粒径

以分散聚合的相关成核理论为基础,采用核磁共振（19F-NMR）和傅里叶红外分析（FT-IR）等分析方法研究了偏氟乙烯（VDF）分散聚合的成核机理,并确认了以低聚物成核机理为其主要形式。同时,通过实验确定了PVDF乳胶粒粒径（d）与转化率（X）、反应压力（p）、初始引发剂质量浓度（ρI,0）以及初始乳化剂质量浓度（ρS,0）有着如下关系：d∝X0.36 p1.20ρI-,00.76ρS-,00.33。在各个因素中,反应压力（或单体质量浓度）的影响程度最大。     

轻质碳酸钙／聚丙烯共混物中聚丙烯β－晶的成核结晶研究

用Ｘ射线衍射和差示扫描量热法研究了轻质碳酸钙／聚丙烯共混物（Ｌ－ＣａＣＯ３／ＰＰ）中ＰＰβ－晶的成核结晶现象，发现ＰＰβ－晶的成核结晶与ＰＰ的来源和Ｌ－ＣａＣＯ３在共混物中的含量有关，铝酸酯偶联剂对共混体系的ＰＰβ－晶的成核结晶有显著的增强作用．分析认为共混物中ＰＰβ－晶的成核结晶现象是ＰＰ中存在的某些杂质（主要是催化剂残余物）与Ｌ－ＣａＣＯ３组成的复合成核剂作用的结果，而铝酸酯是这种复合成核剂的一种促进剂．     

轻质碳酸钙／聚丙烯共混物中聚丙烯β—晶的成核结晶研究

用Ｘ射线衍射和差示扫描量热法研究了轻质碳酸钙／聚丙烯共混物（Ｌ－ＣａＣＯ３／ＰＰ）中ＰＰβ－晶的成核结晶现象，发现ＰＰβ－晶的成核结晶与ＰＰ的来源和Ｌ－ＣａＣＯ３在共混物中的含量有关，铝酸酯偶联剂对共混体系的ＰＰβ－晶的成核结晶有显著的增强作用。分析认为共混物中ＰＰβ－晶的成核结晶现象是ＰＰ中存在的某些杂质（主要是催化剂残余物）与Ｌ－ＣａＣＯ３组成的复合成核剂作用的结果，而铝酸酯是这种复合成核剂的     

Al2O3纳米粒子在TEM测试中分散性的研究

对自制不同粒径范围的球形和纤维状Ａｌ２Ｏ３纳米粉在电镜（ＴＥＭ）测试中颗粒的分散性进行了研究。以卵磷脂、油酸为表面活性剂，无水乙醇为溶剂进行试验，结果表明：当卵磷脂浓度为０．５％时，能得到颗粒之间无聚集、分散性良好的ＴＥＭ照片。文中给出了可能的分散机理     

A novel dispersion method comprising a nucleating agent solubilized in a microemulsion, in polymeric matrix II. Microemulsion characterization

This second part of our paper focuses on structural characterization of the microemulsion for increasing the crystallization rate of polypropylene (PP) through the entrapment of nucleating agent (nucleator) HPN-68, serving as a transport vehicle. Our concept is based on creating an advantage in dispersion capability of the nucleator that is dissolved in a nanoreactor vehicle, compared with its conventional loading as a crystalline powder. The advantage was achieved by solubilizing the HPN-68 in a microemulsion to decrease its size from micro- to nanoscale. The microemulsions were introduced to the target PP using a mixer. By the end of the mixing, when the water phase had evaporated, only the nucleator and the surfactant remained in the matrix. DSC results showed a 24% improvement in nucleation efficiency of PP by this novel method. It was shown that solubilization of the nucleator depends on the water activity in the microemulsion, and the presence of the nucleator opposes formation of the W/O phase. Light scattering, SD-NMR, and SAXS results showed that HPN-68 is accommodated in the water phase and at the interface, and significantly reduces the level of order in the microemulsion. In intermediate water content, a worm-like structure was proposed instead of the classical bicontinuous one. The structure was confirmed by SAXS and SD-NMR analysis. Viscosity measurements revealed structural transitions in the microemulsions.     

A novel dispersion method comprising a nucleating agent solubilized in a microemulsion, in polymeric matrix I. Dispersion method and polymer characterization

This is the first of a two-part study focusing on a novel dispersion method which enables increasing the crystallization rate of polypropylene (PP) through the incorporation of nucleating agent HPN-68 into the molten polymer using a microemulsion as a nanovehicle. The cycle time for processing the PP is significantly reduced and thus the effectiveness of its production is increased. Our concept is based on creating an advantage in dispersion capability of the nucleator that is dissolved in a nanoreactor vehicle in comparison with its conventional introduction as a crystalline powder. The microemulsions were introduced to the target PP using a mixer. By the end of the mixing, when the water phase had evaporated, only the nucleator and the surfactant remained in the matrix. The microemulsion components that solubilized the HPN-68 were mineral oil, alcohol, surfactant, and water. DSC results showed a 24% improvement in nucleation efficiency of PP by this method. WAXS results showed that HPN-68 is a gamma-nucleator. It causes polymorphism by significantly raising the gamma-phase concentration in the PP. SEM results showed a four-fold decrease in the PP spherulite size due to the improved dispersion of HPN-68 within the matrix via microemulsion compared to conventional nucleator incorporation.     

alpha-Alumina-H2O Interface Analysis by Electroacoustic Measurements

In this work an electroacoustic technique was used to characterize the dispersing behavior of alumina in water with or without the addition of an anionic polyelectrolyte as dispersant. Electroacoustic measurements enabled the zeta potential and particle size distribution to be noted; additionally, the in situ measure of the conductivity allows the ionic strength to be simultaneously determined. In this way the pH or dispersant contribution to powder stabilization has been evaluated. With this technique important colloidal parameters such as the isoelectric point and particle size distribution at various solution or powder conditions (alumina vol%, pH, dispersant wt%, milling time) can be measured and the minimum amount of dispersant (Duramax D3021) required to cover completely the powder can be easily estimated. Copyright 1999 Academic Press.     

水溶性分散剂的合成及其性能研究

合成了苯乙烯－顺丁烯二酸酐共聚型水溶性分解剂，并讨论了这种分散剂对导电粉及炭黑等难分散颜料的分散稳定性作用。结果表明，在水介质中，该发散剂能明显改善导电粉和炭黑颜料的分散稳定性。     

桑色素修饰的纳米TiO_2分离富集铬和铝

建立了在表面活性剂十二烷基硫酸钠(SLS)的活化作用下,桑色素修饰的纳米TiO2分离富集,电感耦合等离子体原子发射光谱(ICP-AES)测定Cr3+和A l3+的新方法。考察了溶液pH、洗脱条件和干扰离子等因素对分析物分离富集的影响。结果表明,在pH 3.0时,Cr3+和A l3+可被桑色素修饰的纳米TiO2定量富集,吸附的金属离子可用1.5 mL 0.50 mol/L HC l溶液完全洗脱。在优化的实验条件下,纳米TiO2-桑色素对Cr3+和A l3+的吸附容量分别为9.69 mg/g和12.76 mg/g。本法对Cr3+和A l3+的检出限(3σ)分别为:0.21和0.49 ng/mL,相对标准偏差(RSD)分别为2.2%和1.6%(n=11,C=50 ng/mL)。本法应用于藏药和扇贝标准样品(GBW 10024)中Cr3+和A l3+的测定,测定值与标准值基本吻合,分析结果满意。     

ADSORPTION BEHAVIOUR AND RHEOLOGICAL PROPERTIES OF NON-AQUEOUS LANTHANUM CHROMITE SUSPENSIONS

Adsorption studies of monosubstituted benzene molecules with various functional groups on doped lanthanum chromite/cyclohexane surface have been performed. The results from the adsorption study can be used in selecting appropriate anchoring groups on the dispersant. It was found that high amount of O relative lo La on the LaCrO₃ surface correlated with high amounts of adsorbed benzoic acid. Increase in the La content relative to the O on the powder surface increased the amount of adsorbed benzylamine. The high amount of benzoic acid adsorbed on 20% Ca-doped lanthanum chromite powder (Al)lated well with good colloidal stability caused by a carboxylic acid containing dispersant. Rheology experiments showed that a low degree of agglomeration is obtained using only a small amount of the carboxylic acid containing dispersant (Hypermer LP1). Etectrophoretic mobility measurements in water of this powder coated with the LP1 dispersant indicated electrosteric stabilisation.     

碳化硅纳米晶须的微波合成

SiC nanometer whisker, whose diameter was about 50nm and purity was 98.54%, was synthesized by microwave heating in an atmosphere of argon. Char pyrolyzed phenolformaldehyde resin and SiO2 nanometer powder were used as starting materials. The properties of the whisker were determined by XRD and TEM. The mechanism for synthesizing SiC nanometer whisker was discussed.     

Speciation of chromium by selective separation and preconcentration of Cr(III) on an immobilized nanometer titanium dioxide microcolumn

Nanometer titanium dioxide immobilized on silica gel (immobilized nanometer-scale TiO2 particles) was prepared by a sol-gel method and characterized by X-ray diffraction and scanning electron microscopy. The adsorptive behavior of Cr(III) and Cr(VI) on immobilized nanometer TiO2 was assessed. Cr(III) was selectively sorbed on immobilized nanometer TiO2 in the pH range of 7-9, while Cr(VI) was found to remain in solution. A sensitive and selective method has been developed for the speciation of chromium in water samples using an immobilized nanometer TiO2 microcolumn and inductively coupled plasma atomic emission spectrometry. Under optimized conditions (pH 7.0, flow rate 2.0 mL/min), Cr(III) was retained on the column, then eluted with 0.5 mol/L HNO3 and determined by ICP-AES. Total chromium was determined after the reduction of Cr(VI) to Cr(III) by ascorbic acid. The adsorption capacity of immobilized nanometer TiO2 for Cr(III) was found to be 7.04 mg/g. The detection limit for Cr(III) was 0.22 ng/mL and the RSD was 3.5% (n = 11, c = 100 ng/ mL) with an enrichment factor of 50. The proposed method has been applied to the speciation of chromium in water samples with satisfactory results.     

微细导电粉体碘化亚铜在乙二醇中的分散性研究

研究了分散方法(球磨、高速剪切、起声波)、分散剂的种类(十二烷基苯磺酸、聚乙二醇、硅烷偶联剂、钛酸酯偶联剂)、分散剂的含量及分散时间对微细导电粉体碘化亚铜在乙二醇中分散性的影响。用SEM对其分散情况进行表征。并对其分散机理进行探讨及研究。结果表明。当采用球磨分散方法、分散荆为钛酸酯偶联剂。含量为1％。分散时间为8h可制得分散性良好的碘化亚铜／乙二醇体系。