粒径可控阳离子型聚苯乙烯纳米粒子的制备及表征

在采用阳离子型双子（gemini）表面活性剂作为乳化剂,不使用任何助乳化剂的条件下,通过改进微乳液聚合工艺制备了窄分布粒径可控的阳离子型聚苯乙烯（PS）纳米乳液。 改进微乳液聚合的主要特点是：大部分苯乙烯以预乳液的形式恒速滴入引发聚合的微乳液中,使用具有高乳化性能的gemini表面活性剂作为乳化剂能明显降低乳胶粒粒径。 实验结果表明,少量阳离子单体三甲基烯丙基氯化铵作为共聚单体能够明显减小Z均粒径、降低粒度分布,乳化剂用量、引发剂用量和反应温度均能影响制备乳胶粒的粒径及其粒度分布。 乳化剂和引发剂用量分别为苯乙烯质量的5%~10%和1.0%~1.5%、反应温度为70~75 ℃时,能够制备粒径小分布窄的阳离子型聚苯乙烯纳米粒子。 Z均粒径与苯乙烯质量之间的线性关系表明,Z均粒径可以通过苯乙烯用量来控制。 不同聚合工艺下制备的聚合物粒度分布曲线表明,改进微乳液聚合工艺（半连续预乳化工艺）在制备窄分布的聚合物纳米粒子方面具有很强的优越性。     

阳离子型微乳液聚合丙烯酰胺的表征

自从Hoar[1]和Schulman[2]利用乳化剂、水和油制得均一透明的微乳液以来,微乳液在许多领域中得到广泛应用.Candau[3,4]通过微乳液聚合得到分子量很高(105～106)的纳米级聚合物粒子,且聚合物分子链采取紧密缠绕的构象.Antonietti[5]在对苯乙烯微乳液聚合的研究报道中认为,聚合物分子链是以一种类似于网状交联结构的形态存在的,这些结果表明,通过微乳液聚合所得聚合物可能存在着一些特殊的性质.本文采用阳离子型乳化剂十六烷基三甲基溴化铵(CTAB)和脂肪族醇助乳化剂制备的油包水(W/O)型反相微乳液体系来聚合丙烯酰胺(Am),并与使用相同乳…     

有机硅-丙烯酸酯聚合物乳液合成及粒径分析

通过种子乳液半连续法合成了有机硅改性丙烯酸酯聚合物乳液,并对其粒子形态及分布进行分析。结果表明:通过种子乳液半连续聚合工艺可制备出固含量42wt%,乳化剂含量4wt%(基于单体量)、窄分布纳米粒子的有机硅改性丙烯酸酯聚合物乳液。随反应进行,粒径分布变窄,平均粒径逐渐增大。随乳化剂中SDS与OP-10的摩尔比减少,粒径增大。     

高固含量丙烯酸酯的微乳液聚合

采用半连续滴加预乳液的微乳液聚合法,合成出聚合物质量分数40%、乳化剂质量分数2.5%的丙烯酸酯微乳液. 考察了单体滴加速度、乳化剂种类及其用量、电解质用量、温度和搅拌等因素对乳液粒径及性能的影响. 研究表明,聚合在相当于Winsor-Ⅰ型的聚合体系中进行,由纯单体相(滴入的单体)和O/W微乳相构成,上层单体只起储存库的作用,它在缓慢的搅拌帮助下扩散进入微乳相中,只要微乳液液面上补加的单体不扰动微乳液的平衡,即不会产生粗粒子. 单体滴加时间控制在4 h,选择质量分数为2.5%的Dowfax2A1/OP-10乳化体系,NaHCO3质量分数为0.16%,反应温度控制在75～80 ℃,搅拌速度控制在150 r/min,可使聚合反应平稳进行,得到了m(聚合物)∶m(乳化剂)=15∶1的丙烯酸酯微乳液.     

醇溶性聚丙烯酸酯乳液的合成及性能研究

以丙烯酸乙酯(EA)、甲基丙烯酸甲酯(MMA)和甲基丙烯酸(MAA)为主单体,采用过硫酸盐作引发剂,经预乳化乳液聚合工艺合成了聚丙烯酸酯乳液.讨论了乳化剂种类、单体种类以及功能性单体、引发剂加入工艺对乳液聚合过程及乳液产品性能的影响.结果表明:单体组成为m(MMA)∶m(EA)∶m(MAA)=45∶40∶15所得乳液聚合物能满足使用性能要求;种子引发剂加入质量控制在单体总质量的0.3%,而总的引发剂用量占单体总质量的0.8%较适宜.用差热分析仪和凝胶渗透色谱仪对乳液聚合物进行了表征.     

聚合物基纳米微球制备及抗腐蚀性能评价

采用对苯乙烯磺酸钠（SSS）和改性SiO₂替代常规非反应型乳化剂,苯乙烯（St）、丙烯酸羟乙酯(HEA)、甲基丙烯酸甲酯(MMA)为单体,通过半连续种子乳液预乳化法制备丙烯酸类聚合物微球(PSAC)。探究了单体配比、乳化剂用量对纳米微球粒径、玻化温度、电位、黏度、亲水性及稳定性等性能的影响,其结构经 FTIR、 TEM及SEM等确证,抗CO₂腐性能同时进行初步探讨。      

阳离子丙烯酸树脂乳液涂饰剂的合成研究

以丙烯酸二乙氨基乙酯及其它丙烯酸酯类、乙烯基类单体作为共聚单体,以过醋酸-双氧水为引发体系,采用核-壳乳液共聚方法,对阳离子丙烯酸树脂的合成进行了研究,结果表明;引发剂体系和乳化剂体系对乳液的性能、乳胶粒的形态结构、聚合物的性能以及工艺过程的平稳性至关重要。该项研究为阳离子丙烯酸系聚合物在制革业中的广泛应用奠定了基础。     

以单分散P(DC-TMPTA)聚合物微球为Pickering乳液稳定剂制备石蜡乳液和石蜡微球

以三羟甲基丙烷三丙烯酸酯(TMPTA)和1-十二烯(DC)为单体,不使用任何乳化剂或分散稳定剂,通过沉淀聚合制备了高度单分散P(DC-TMPTA)的聚合物微球颗粒.以此聚合物微粒为Pickering稳定剂,不添加任何化学助剂,以乙醇-水混合介质在70℃下通过恒速振荡制得了单分散石蜡Pickering乳液.将该体系迅速降温至石蜡熔点之下,制得了窄分布的固体石蜡微球.研究了连续相水含量、振荡频率及稳定粒子尺寸对Pickering乳液及石蜡微球的影响,优化了石蜡乳液和微球的制备条件.利用扫描电子显微镜对石蜡微球的表面和内部形貌进行了表征,结果表明P(DC-TMPTA)微球全部聚集在石蜡液滴和固化后的石蜡微球表面.基于石蜡微球和聚合物稳定粒子的尺寸,计算了不同条件下石蜡微球表面聚合物粒子的数量.通过聚合物粒子在石蜡-乙醇和水混合溶液界面的三相接触角以及石蜡-乙醇和水混合溶液界面张力的测定,计算了聚合物粒子在石蜡-乙醇和水混合溶液界面吸附能,为解释该体系Pickering乳液的稳定性提供了理论支持.     

水性丙烯酸—聚氨酯微乳液的制备及粒子形态

水性聚氨酯作为一种环境友好材料近年来得到了迅速的发展，并以其优良的性能在皮革业、涂料、印刷、油墨等行业呈现广阔的应用前景［‘’‘j．通常采用IPN等技术制备出复合型水性树脂「‘，‘’，其中具有核壳结构的微乳液尤其受到重视．但研究多集中于微米级乳液的实际应用开发，对于纳米级、杂化型聚氨酯微乳液微观结构的研究却少见报道．本文通过在自乳化聚氨酯中自由基引发聚合丙烯酸类单体，制备出了具有核／壳结构的复合型丙烯酸一聚氨酯微乳液，并对微乳液的粒径、粒径分布、粒子形态及交联结构进行了研究．聚己内酯（220AL），日…     

光引发常规乳液聚合制备氨基聚苯乙烯纳米粒子

采用一种简单易行的方法制备了氨基功能化的聚苯乙烯纳米粒子.首先,采用4-乙烯基苄氯与1,3-丙二胺置换反应制备了含有氨基功能基团的可聚合单体N-(3-氨基丙基)对乙烯基苄基亚胺(CVPD).然后,采用乳液聚合,以苯乙烯(St)和CVPD为共聚单体,水溶性的4-(2-羟乙氧基)苯基-(2-羟基-2-丙基)酮(Irgacure 2959)为光引发剂,十六烷基三甲基溴化铵(CTAB)为乳化剂,经紫外光辐照引发,合成了P(St-co-CVPD)二元共聚物的纳米胶乳.体系的乳化剂用量仅为体系总质量的0.1 wt%～0.8 wt%,远小于常用来制备纳米粒子的微乳液体系的乳化剂用量.用透射电子显微镜(TEM)和激光粒度分析仪(DLS)表征了P(St-co-CVPD)纳米粒子的粒径和粒径分布.用红外光谱(FTIR)和核磁共振(NMR)证明了P(St-co-CVPD)纳米粒子上氨基的存在,并通过茚三酮显色反应定量检测了氨基含量.分别研究了单体配比,引发剂浓度,乳化剂用量以及紫外光强度对反应体系的影响.实验结果表明,产物粒子尺寸为30～600 nm,氨基通过共价键连接在粒子上,其含量为1.2×10-5～1.6×10-4 mol/g.该乳液体系聚合反应速率较快,单体转化率在60 min内即可达到80%.所得粒子的氨基含量可以通过单体配比进行调节.粒子尺寸可通过单体配比,引发剂浓度,乳化剂用量以及紫外光强度进行调节.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.