丙烯酰胺、3-丙烯酰胺-3-甲基丁酸钠和N-烷基丙烯酰胺三元共聚物的溶液特性研究

讨论了丙烯酰胺、3-丙烯酰胺-3-甲基丁酸钠和N-烷基丙烯酰胺三元共聚物(CAANA)的水溶液特性,并与部分水解聚丙烯酰胺(HPAM)水溶液特性相比较。芘荧光光谱分析和激光光散射仪测量结果表明。CAANA由于引入了疏水性单体,在水溶液中形成了分子间的疏水缔合作用,并使得CAANA在水溶液中具有较大的均方旋转半径,相对于HPAM,CAANA具有更好的耐温抗盐性能。在一定范围内,CAANA中引入的疏水性单体形成的缔合作用愈强,愈有利于改善聚合物的耐温抗盐性能。     

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。     

纳米埃洛石管对HPAM性能的影响

采用油酸改性纳米埃洛石管(HNTs)将部分水解聚丙烯酰胺(HPAM)与改性HNTs(O-HNTs)共混制备一种稳定的分散体系HPAM/O-HNTs。采用红外和接触角对O-HNTs的化学结构进行表征,并系统考察HPAM/O-HNTs的增黏性、耐温耐盐性、抗剪切性和驱油效果。结果表明：O-HNTs分子链中含有长烷基链、双键等疏水基团,具有疏水作用。加入O-HNTs后,HPAM/O-HNTs黏度明显提高,表现为优异的增黏性。HPAM/O-HNTs在30～90℃的NaCl(0～12000 mg·L^-1)和CaCl₂(0～12000 mg·L^-1)溶液中的黏度均比HPAM高,表现出优异的耐温抗盐性能。90℃条件下,随着剪切速率增大,HPAM/O-HNTs黏度逐渐减小。500 r·s^-1条件下溶液黏度大于17.2 mPa䦆Wingdings 2VB@s,表现出优异的抗剪切性能。在相同条件下,HPAM/O-HNTs的驱油采收率比HPAM高12.3%,驱油效果显著。     

亚硫酸酯盐型共聚物的合成及性能研究

以2-(3-甲基丙烯酰胺丙基二甲氨基)乙基亚硫酸内盐(MAPES)和双烯丙基十二烷基苯磺酰胺(DDBSA)为功能单体,在(NH_4)_2S_2O_8-NaHSO_3引发体系下改性部分水解聚丙烯酰胺(HPAM)制备了一种水溶性亚硫酸内盐型两性离子聚合物驱油剂AM/AA/MAPES/DDBSA。通过黏弹性、耐温抗盐抗剪切等流变测试以及室内模拟岩心驱替实验研究了两性离子聚合物提高采收率的能力,结果表明了在同等条件下,0.2 wt%亚硫酸内盐型共聚物溶液比部分水解聚丙烯酰胺(HPAM)具有更好的增黏性(845.3 m Pa.s)、抗剪切性(1000 s~(-1),94.2 m Pa·s)、耐温性(100℃,94.8 m Pa·s),抗老化性(80℃下进行10天的老化性测试,黏度保留率达到25%)以及抗盐性(NaCl:30 g·L~(-1),81.8 m Pa·s;MgCl-2和CaCl_2:3 g·L~(-1),77.4、77.9 m Pa·s)。0.2 wt%共聚物溶液在模拟油藏环境下(地层水矿化度:9374.13 mg·L~(-1),油藏温度75℃),提高采收率(EOR)达到了11.5%。     

疏水基改性聚丙烯酰胺的合成及溶液性质

利用自由基胶束聚合法,由丙烯酰胺和甲基丙烯酸十八酯共聚合成了疏水缔合型水溶性聚合物.通过红外光谱表征了共聚物的结构,考察了共聚物浓度、盐浓度、剪切速率以及温度对共聚物溶液性能的影响.试验结果表明,聚合物质量分数大于临界缔合浓度(2%)时,溶液的粘度急剧增大;疏水缔合聚合物溶液的表观粘度随着溶液中NaCl质量分数的增加而增大.     

化学驱油过程中部分水解聚丙烯酰胺的二级结构研究

高分子量聚丙烯酰胺水溶液因其显著的增粘作用与粘弹性而在三次采油中得到广泛应用 .多年来大庆油田采用注入部分水解聚丙烯酰胺 (HPAM)水溶液驱油 ,实践证明 ,此法可大幅度提高原油采出率[1,2 ] .关于聚丙烯酰胺及其部分水解产物 (结构上等价于丙烯酰胺与丙烯酸的无规共聚物 )的链结构评价及其同高价离子的络合作用已有一些报道 [3～ 6] .在聚合物驱油过程中 ,HPAM水溶液在地下岩层中流动时间较长 ,实验室难以模拟 ,有关 HPAM流经地下岩层后的结构研究尚未见报道 .评价化学驱油油田矿场采出液中 HPAM的链结构 ,并探讨其结构变化机理…     

疏水缔合水溶性聚合物AO的溶液粘度行为研究

研究了稀溶液中疏水链链长、无机电解质NaCl和CaCl2对疏水缔合水溶性丙烯酰胺／甲基丙烯酰氨乙基-二甲基烷基溴化铵／丙烯酸钠共聚物(AO)在水溶液中的特性粘数和Huggins常数的影响，以及聚合物AO-8的特性粘数和Huggins常数随温度的变化。结果表明：在稀溶液中，无机电解质离子强度增大，共聚物AO在NaCl和CaCl2溶液中的特性粘数减小，Huggins常数增大。在亚浓溶液范围对聚合物质量分数、温度、剪切速率及NaCl含量对聚合物的水溶液表现粘度的影响进行了研究，观察到疏水缔合聚合物盐水溶液在NaCl含量提高的情况下，出现的增粘现象。     

含氟疏水缔合聚丙烯酰胺的制备及溶液性质研究

以异佛尔酮二异氰酸酯(IPDI)、四氟丙醇(FOH)和烯丙基聚乙二醇(APEG1200)为原料合成了含氟表面活性单体(FSM),并以FSM为疏水单体,在它的胶束溶液中实现了其与丙烯酰胺(AM)和2-丙烯酰胺基-2-甲基丙磺酸(AMPS)的水溶液共聚合,制备出含氟疏水缔合聚丙烯酰胺(FAPAM)。采用流变仪研究了FAPAM水溶液的疏水缔合性能,并考察了盐、剪切率和温度对FAPAM缔合性能的影响。结果表明,FAPAM水溶液的疏水缔合性能受FSM含量的影响,具有一定的耐盐性。FAPAM属于假塑性体系,表现出较强的抗剪切性能。适当升高温度对FAPAM水溶液的疏水缔合有一定的促进作用。     

孪尾疏水缔合三元共聚物的粘度行为:水解度的影响

以十二烷基硫酸钠(SDS)为表面活性剂,利用氧化还原体系、采用前加碱共聚-共水解的方法制备了孪尾疏水缔合水溶性三元共聚物聚(丙烯酰胺／丙烯酸钠／N,N-二己基丙烯酰胺)[P(AM/NaAA／DiC6AM)],研究了P(AM／NaAA／DiC6AM)稀溶液及亚浓溶液的性能。随理论水解度的增加,P(AM／NaAA／DiC6AM)水溶液的特性粘数[η]增加,Huggins常数KH减小。P(AM／NaAA／DiC6AM)水溶液的表现粘度随理论水解度的增加而增加,随温度、剪切速率的增加而降低,随剪切速率的增加开始时降低较快而后变化较小。P(AM／NaAA/DiC6AM)在盐溶液中随NaCl、CaCl2质量浓度的增加,出现盐增粘现象;理论水解度不同的P(AM／NaAA／DiC6AM)与SDS水溶液的表现粘度在wSDS=0．050～0．400g／L范围内随SDS质量浓度的变化差别不大。     

兼具有强阴离子性与疏水缔合性的丙烯酰胺三元共聚物

在微乳液介质中实施了丙烯酰胺 (AM)、苯乙烯 (St)、2 丙烯酰胺基 2 甲基丙磺酸钠 (NaAMPS)的共聚合 ,制备了既含有强阴离子性基团 (—SO3Na)又含有疏水基团 (St)的丙烯酰胺三元共聚物AM NaAMPS St;通过红外光谱法、紫外分光光度法及元素分析法对共聚物的结构及组成进行了表征 ;稀释外推粘度法测定了共聚物的特性粘数 ;测定了共聚物纯水溶液及盐水溶液的表观粘度 ;荧光探针法考察了三元共聚物的疏水缔合性以及离子基团对疏水缔合性的影响规律 .实验结果表明 ,在聚丙烯酰胺 (PAM )分子主链上同时引入强阴离子性基团与疏水基团后 ,阴离子的电粘效应与疏水基团的疏水缔合作用相互协同 ,会使共聚物水溶液的黏度显著提高 ;盐溶液对疏水缔合作用的增强效应与强阴离子基团对盐的较大容忍度相互结合 ,会使共聚物水溶液的抗盐性能明显得以提高 ;大分子链上的强阴离子基团磺酸根的存在 ,在一定程度上会削弱疏水基团之间的疏水缔合作用 ,即对疏水基团的疏水缔合行为会产生一定的负性影响 .     

Molecular dynamics study of salt effects on micellization of N-dodecyl-N,N-dimethyl-3-ammonio-1-propane-sulfonate

In this paper, molecular dynamics simulation methods were used to investigate salt effects on micellization of N-Dodecyl-N,N-Dimethyl-3-Ammonio-1-Propane-sulfonate (SB12-3) in aqueous solution. It is proved that micelle shapes transform from spherical to prolate spherical shape after 30.0?ns simulation with different NaCl and CaCl₂ concentration. By comparison with the eccentricity value without salt addition, SB12-3 shows salt tolerance behaviors due to its unique “inner salt” structure of amphiphilic surfactant. Radial distribution function (RDF), hydrophobic groups solvent accessible surface area (SASA), hydrogen bond, and the deuterium order parameter (S_CD) are to elucidate salt effects on SB12-3 micelle formation. The radius of micelle is achieved by the related RDF value and in accordance with other researches. The addition of NaCl and CaCl₂ didn’t change the structure of micelle significantly and have little effects on the interactions between SB12-3 and water molecule. By comparison with the results without salt system, SASA of hydrophobic groups is almost the same, and SASA of hydrophilic groups and total molecule fluctuates only slightly. This further indicates that the surface of micelles is more hydrophilic due to the strong interactions between SB12-3 and water molecules. The existence of NaCl and CaCl₂ will enhance the hydrophilic interactions.     

聚丙烯酰胺的形态结构研究

本文用电子显微镜深入的研完了部分水解聚丙烯酰胺在水溶液中的形态。给出大分子的伸展网状结构是其稀溶液高粘度的结构本质。并详细讨论了聚合物的水解度、分子量、外加盐种类及波度与分子聚集状态的关系。     

聚丙烯酰胺及水解聚丙烯酰胺的粘度对加盐浓度及时间的依赖性

高分子量聚丙烯酰胺(PAM)和部分水解聚丙烯酰胺(HPAM)是目前世界上生产量最大的合成水溶性高分子。由于它们在水溶液中只要很低的浓度就具有高粘度的特件,故广泛用作提高石油采收率的堵漏剂和增粮剂。     

纳米SiO2/HPAM/NaCl分散体系的稳定性、流变性及驱油性能研究

利用纳米粒度及Zeta电位分析仪、流变仪和悬滴法对纳米SiO_2/HPAM/NaCl体系60℃的稳定性、流变性及油水界面张力进行了研究。结果表明,HPAM的加入使SiO_2悬浮液的Zeta电位更负、粒径明显增加,静置10 d无明显浑浊现象。加入纳米SiO_2后,HPAM溶液的黏度增加,耐温、耐盐和耐剪切性能得到改善。对于质量分数为0.18%的HPAM溶液,SiO_2质量分数小于0.5%时,随SiO_2质量分数的增加,体系的黏度、储能模量和损耗模量增加,临界线性应变减小,蠕变回复能力增强;SiO_2质量分数大于0.5%时,出现了相反的现象;这是因为SiO_2质量分数不同时,HPAM在SiO_2表面的吸附量、吸附构型及两者之间形成的网状结构不同。纳米SiO_2的加入同时强化了HPAM降低油水界面张力的性能,加入质量分数为0.2%和0.5%的SiO_2后,HPAM的采收率分别提高了4.5%和6.0%。     

Investigation of the salting out of methane from aqueous electrolyte solutions using computer simulations

We calculate the excess chemical potential of methane in aqueous electrolyte solutions of NaCl using Monte Carlo computer simulations. In a recent work [Docherty et al. J. Chem. Phys. 2006, 125, 074510], we presented a new potential model for methane in water which is capable of describing accurately the excess chemical potential of methane in pure water over a range of temperatures, a quantity that can be related to the solubility and which is commonly used to study the hydrophobic effect. Here, we use the same potential model for the water-methane interactions and investigate the effect of added salt on the chemical potential of methane in the solution. The methane molecules are modeled as single Lennard-Jones (LJ) interaction sites, and the water molecules are modeled with the TIP4P/2005 model. A correcting factor of chi = 1.07 for the energetic Berthelot (geometric) combining rule of the methane-water interaction is also used, which mimics the polarization of methane in water. We consider NaCl as the salt and treat the ions with the Smith and Dang model (i.e., as charged LJ interaction sites). Ion-water, ion-ion, and ion-methane interactions are treated using Lorentz-Berthelot combining rules. In addition, the Coulombic potential is used to model charge-charge interactions which are calculated using the Ewald sum. We have carried out isobaric-isothermal (NpT) simulations to determine the equilibrium densities of the solutions. The simulation data is in excellent agreement with experimental densities of aqueous NaCl solutions of different concentration. Hydration numbers are also obtained and found to be in agreement with reported data. Canonical (NVT) simulations at the averaged densities are then performed using the Widom test-particle insertion method to obtain the excess chemical potential of methane in the saline solutions. An increase in the chemical potential of methane, corresponding to a salting out effect, is observed when salt is added to the solution. We investigate different concentrations and ion sizes. An overprediction of the salting out effect as compared with experimental data is observed, which we believe is due to the polarizing effect of the ions in the solution, which is not taken into account by the model. We also find a direct correlation between the increase in the chemical potential and the packing fraction of the solution and argue that the main cause of the observed salting out effect (as represented by an increase in the excess chemical potential) is the increase in the packing fraction of the solutions due to the added salt. Together, with this, we put forward an argument toward explaining the anomalous Hofmeister effect of Li(+).     

加盐浓度及水解度对PAM和HPAM的特性粘数的影响

聚丙烯酰胺(PAM)和部分水解聚丙烯酰胺(HPAM)的特性粘数[η]等物性参数与样品的水解度(DH%)、加盐浓度(C_s)密切相关。在实际应用中,无论油田水、矿山水、洗煤水,一般矿化度都较高,影响PAM和HPAM的使用性能,所以研究DH%、C_s对[η]的影响很有必要。本文在以往工作的基础上研究了[η],C_s,DH%,tgx间的关系,得出了一些有用的结果。     

Nanoelectrospray—More than just a minimized-flow electrospray ionization source

The comparison between electrospray ionization (ESI) mass spectra from NaCl solutions with and without analyte obtained under ionspray and nanospray conditions reveals different mass spectral behavior of the two ESI techniques. This can be attributed to the different initial droplet sizes which are in the microns range for ionspray, while in nanospray they are believed to be about one order of magnitude smaller. In the context of the widely accepted uneven-fission model, nanospray would then enter one fission generation later; in addition, a higher initial droplet surface charge density in nanospray results in early fissions without extensive evaporation and thus increase in sample and salt concentration. This rationalizes that ionspray spectra closely resemble nanospray spectra from solutions with about one order of magnitude higher salt concentrations, showing a higher tolerance of nanospray towards salt contamination. When the analyte is a peptide (in a solution containing a high molar surplus of salt), molecule ion formation effectively competes with salt cluster ion formation; when the analyte is a sugar, it is detectable beside a high salt concentration only with nanospray, indicating the supporting effect of surface activity on ion release in the case of peptides. A model is presented which explains the different mass spectral behaviour of ionspray and nanospray by suggesting different "predominant fission pathways" depending on the size of the initial droplets.     

Monte Carlo simulations of the hydrophobic effect in aqueous electrolyte solutions

The hydrophobic interaction between two methane molecules in salt-free and high salt-containing aqueous solutions and the structure in such solutions have been investigated using an atomistic model solved by Monte Carlo simulations. Monovalent salt representing NaCl and divalent salt with the same nonelectrostatic properties as the monovalent salt have been used to examine the influence of the valence of the salt species. In salt-free solution the effective interaction between the two methane molecules displayed a global minimum at close contact of the two methane molecules and a solvent-separated secondary minimum. In 3 and 5 M monovalent salt solution the potential of mean force became slightly more attractive, and in a 3 M divalent salt solution the attraction became considerably stronger. The structure of the aqueous solutions was determined by radial distribution functions and angular probability functions. The distortion of the native water structure increased with ion valence. The increase of the hydrophobic attraction was associated with (i) a breakdown of the tetrahedral structure formed by neighboring water molecules and of the hydrogen bonds between them and (i) the concomitant increase of the solution density.     

聚丙烯酰胺絮凝效果的母液浓度依赖性及其影响

考察了相同剂量下不同浓度阴离子型聚丙烯酰胺絮凝剂(PAM)母液对三氧化二铁悬浮液的絮凝效果.通过电导率和流变行为测试,阐明了随母液浓度增大絮凝效果先变好后变差的原因.研究结果表明,母液浓度为0.3 g/L时PAM絮凝效果最佳.根据聚电解质标度理论及流变测试结果,认为此最佳母液浓度(cop)接近临界缠结浓度.母液电导率及加入絮凝剂后的搅拌过程中水体电导率变化表明,絮凝剂浓度高于最佳母液浓度时出现的电荷屏蔽现象使得有效电荷减少,导致高母液浓度下絮凝效果变差.向低浓度母液中添加适量β-环糊精后,环糊精分子通过氢键作用搭桥使PAM分子间距变小,发生协同絮凝形成足够大的絮体,从而使絮凝效果得到改善.这一结果表明,低于最佳母液浓度时由于PAM分子相对孤立形成的絮体不足以沉降,是导致絮凝效果较差的原因.