剪切作用对功能聚合物微观结构性能的影响研究

梳型聚合物和活性聚合物是目前常用驱油聚合物,其增黏性和黏弹性是评价其驱油能力的重要指标.为考察剪切作用对两种聚合物溶液性能的影响,分别研究了梳型聚合物和活性聚合物溶液经过模拟炮眼剪切前后的宏观和微观性能变化.结果表明,在高速剪切、拉伸应力作用下,梳型聚合物黏度损失率为40.73%,活性聚合物黏度损失率为70.10%;当剪切频率为0.02 Hz时,梳型聚合物界面扩张弹性降低了19.03%,而活性聚合物界面扩张弹性降低了68.03%;相比活性聚合物,梳型聚合物紧密的空间网状结构虽被部分破坏,但仍有疏松的网络结构,且以聚集体的形式紧密地分散在溶液中,通过DLS及AFM测定表明其粒径尺寸稍有变小;可见梳型聚合物抗剪切能力较活性聚合物强.     

耐温抗盐驱油聚合物溶液黏弹性

对3种不同结构类型的耐温抗盐驱油聚合物〔高分子量聚丙烯酰胺(HPAM)、磺化聚丙烯酰胺(S-HPAM)和疏水缔合聚丙烯酰胺(A-HPAM)〕的溶液黏弹性能进行了研究。在温度85℃下,通过稳态剪切和动态剪切试验,考察了质量浓度和矿化度对聚合物溶液黏弹性的影响。结果表明,随剪切速率增加,溶液表观黏度逐渐降低。质量浓度越高,溶液的储能模量(G')和损耗模量(G″)越大。由动态剪切实验数据,计算得到第一法向应力差(N1)。随质量浓度增加,聚合物溶液的N1逐渐增大;随矿化度增加,聚合物溶液的N1出现不同盐敏感区域,说明不同结构类型的驱油聚合物溶液对矿化度的弹性响应不同。研究结果为高温高盐油藏聚合物驱剂的选择及开发提供了理论参考。     

两亲性ABA三嵌段共聚物的合成及其自组装行为研究

用Grubbs第二代催化剂引发降冰片烯类单体(NBEDE)和链转移剂在离子液体[bmim][BF4]中的开环易位聚合(ROMP)反应,反应体系保持均相,无聚合物析出,得到两端为叔溴的遥爪型官能化聚合物(Br-PNBEDE-Br).以Br-PNBEDE-Br作为大分子引发剂,在离子液体介质中引发甲基丙烯酸2-(二甲氨基)乙酯(DMAEMA)的原子转移自由基聚合(ATRP),制得分子量分布较窄的两亲性三嵌段共聚物(PDMAEMA-PNBEDE-PDMAEMA).利用动态激光光散射(DLS),原子力显微镜(AFM),透射电镜(TEM)等技术,考察嵌段共聚物在选择性溶剂/共溶剂(H2O/THF)中的胶束行为,以及溶液pH值对胶束的影响.结果表明,TEM观察到胶束为球形,由于TEM和AFM是在干态下测得胶束的粒径,而DLS是在溶液中测定胶束的流体力学直径,所以TEM和AFM得到的胶束粒径小于DLS的结果.不同pH值对胶束尺寸大小有明显的影响,胶束微粒随着pH值的增大而增大.     

高温高矿化度条件下驱油剂中聚合物分子结构形态及其在中低渗油层中的渗流特性

利用动态光散射(DLS)、电镜扫描(SEM)和岩心驱替实验等方法, 对高温高矿化度条件下聚合物溶液和“聚合 物/表面活性剂”二元复合驱油体系中聚合物分子线团尺寸及其影响因素和在中低渗油藏环境下的渗流特性进行了实验研究, 并对其渗流规律进行了机理分析. 结果表明, 在高温高矿化度条件下, 随聚合物浓度增加, 聚合物溶液和“聚合物/表面活性剂”二元复合驱油体系中聚合物分子线团尺寸D_h都呈现“先增大后减小”的变化规律. 非离子型表面活性剂以胶束聚集体形式吸附在聚合物分子链上, 造成二元复合驱油体系中聚合物分子线团尺寸D_h大于聚合物溶液. 在溶剂水矿化度较高和岩心渗透率较低条件下, 后续注入水的冲刷和稀释作用造成岩心内滞留聚合物浓度降低, 聚合物分子线团尺寸D_h增加, 最终导致聚合物溶液和“聚合物/表面活性剂”复合体系的残余阻力系数大于阻力系数.     

电解质对聚合物分子尺寸、结构形态和渗流特性影响研究

利用动态光散射（DLS）、扫描电镜（SEM）、表观黏度和岩心流动实验等方法,研究了电解质对聚合物分子线团尺寸、结构形态和渗流特性的影响。结果表明,随电解质浓度增大,聚合物分子线团尺寸呈现“减小、增大和再减小”变化趋势。在Ca2+、Mg2+和Na+三种离子中,Ca2+和Mg2+离子对聚合物分子双电层压缩作用更强,因而对聚合物溶液黏度和线团尺寸及其分布影响更大。随着溶剂水电解质浓度的增加,聚合物分子结构形态逐渐由多层次立体无规网状向树枝状和支状转化。在聚合物驱后的后续水驱过程中,注入压力大小受滞留聚合物采出量和仍滞留聚合物分子线团膨胀两因素的影响。聚合物相对分子质量愈大,电解质对聚合物分子线团压缩或和膨胀作用愈强,后续水驱过程中压力升高幅度愈大。聚合物驱和后续水驱所用水的电解质浓度差异愈大,后续水驱阶段压力升高幅度愈大。因此在油田聚合物驱油方案设计时,建议适当增加聚合物驱和后续水驱所用水的电解质浓度差异,这对改善聚合物驱增油效果十分有利。     

亚铁离子对驱油聚合物溶液黏度的影响及其降黏机理

采用NaOH沉淀法去除胜坨油田T28区污水含有的亚铁离子(Fe2+),使配制的聚合物溶液黏度增加,通过红外光谱仪(IR)、荧光光谱仪及扫描电子显微镜(SEM)对Fe2+的降黏机理进行了分析。 结果表明,采用NaOH沉淀法处理Fe2+含量为5.9 mg/L的污水,控制pH=9,聚合物溶液的黏度可由19.17 mPa·s提高到92.50 mPa·s。 Fe2+使聚合物大分子发生断链,分子间的缔合作用减弱,破坏了分子链间形成的空间网络结构,导致溶液黏度显著降低;当用NaOH处理Fe2+后形成了Fe(OH)2沉淀而析出,同时使聚合物分子链间形成致密的空间网络结构。     

ARGET ATRP 与ROP 结合制备pH 响应两亲性聚合物分子刷及其自组装研究

结合电子转移活化剂再生-原子转移自由基聚合(ARGET ATRP)和开环聚合(ROP)法合成了一种具有无规疏水/ pH 响应结构的两亲性聚合物分子刷聚(甲基丙烯酸聚丙交酯酯-co-甲基丙烯酸)-b-聚甲基丙烯酸单甲氧基聚乙二醇酯 [P(PLAMA-co-MAA)-b-PPEGMA]. 通过核磁共振氢谱(¹H NMR)和凝胶渗透色谱(GPC)表征了聚合物的结构、分子量及分子量分布. 优化了反应条件并合成出分子量可控、分子量分布窄的聚合产物. 采用动态光散射法(DLS)、扫描电子显微镜(SEM)研究了聚合物分子刷在水溶液中自组装胶束的粒径、形貌及pH 响应行为. P(PLAMA-co-MAA)-b-PPEGMA 自组装形成粒径分布均匀的球形胶束. 且随着溶液pH 值从7 降低至3, 胶束中的PMAA 逐渐去离子化, 溶胀的胶束逐渐收缩, 粒径由200～300 nm 减小至150 nm 左右; 但当pH 值减小到2 以下, 胶束表面电荷量非常小, 胶束聚集, 使得粒径增大.     

剪切作用对聚合物溶液流体力学半径分布特征的影响研究

采用近井地带剪切装置及动静态光散射仪研究不同浓度HAWP聚合物溶液、HDP树枝状聚合物溶液在不同剪切强度下的流体力学半径分布特征,并结合粘度、浓度、重均分子量、阻力系数与残余阻力系数的测定探索聚合物溶液粒径分布对宏观流变性和驱替性能的影响。结果表明,具有支化状结构的HDP聚合物在水溶液中的流体力学半径以"极差大"、"数量均匀"、"分布宽"等特征分布,剪切前后峰形均呈现"帽子型"单峰或微弱双峰趋向三峰模式。HAWP聚合物溶液主峰粒径随着浓度升高增大且所占总粒径比例不断增高,而HDP树枝状聚合物溶液主要以分布变宽为主,主峰粒径及所占总粒径比例一直较为均一。剪切作用使HAWP聚合物溶液的粒径分布特征以单峰明显裂变为尖锐双峰模式为主,而HDP聚合物溶液峰型裂变程度相对微弱。     

聚(丙烯酰胺-丙烯酸)/聚(丙烯酰胺-二甲基二烯丙基氯化铵)分子复合型聚合物驱油剂的增粘作用

通过Brookfield粘度测定及室内岩心驱油试验评定,研究了聚(丙烯酰胺－丙烯酸)/聚(丙烯酸胺－二甲基二烯丙基氯化铵)[P(AM－AA)/P(AM－DMDAAC)]分子复合型聚合物驱油剂的增粘、抗温、抗盐性及其驱油效果.结果表明：聚合物组成一定时,其复合比影响溶液复合增粘效果;复合型聚合物溶液的抗盐性明显优于P(AM－AA)溶液的抗盐性;多价金属离子的加入是提高溶液抗盐性的有效途径.该驱油剂的最终采收率达61.91％.     

聚乳酸蜂窝状多孔膜的形成与控制

以单一组分聚L-乳酸(PLLA)为成膜材料,利用水辅助法制备了聚乳酸(PLLA)蜂窝状多孔膜.利用扫描电镜(SEM)和原子力显微镜(AFM)观察多孔膜形貌.研究溶剂、溶液浓度、环境温度和湿度等因素对所成多孔膜结构的影响.实验结果表明,高湿度环境和具有一定浓度的聚合物溶液是制备蜂窝状多孔膜的必要条件.溶剂的挥发性是形成规整蜂窝状孔结构的关键因素.环境相对湿度由43%增加到91%,PLLA多孔膜的孔径由(1.75±0.24)μm增加到(11.50±1.43)μm,且孔呈现六边形的蜂窝状结构.扫描电镜断面和AFM表明:膜表面形成了深度约为1.8μm的单层孔结构.通过控制溶液浓度、环境温度和湿度等因素来控制膜的表面形貌及其所成蜂窝状孔的大小.最佳的成膜条件为溶剂CH2Cl2,湿度75%RH,温度34℃,浓度3 wt%.讨论了蜂窝状多孔膜的形成机理.     

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.