双尾型丙烯酰胺类疏水缔合共聚物的合成与表征

通过光引发自由基聚合的方式,将双尾型丙烯酰胺类疏水单体(N-苯乙基-N-十四烷基甲基丙烯酰胺,PETMAM),与丙烯酰胺(AM)、丙烯酸(AA)等水溶性单体进行共聚,制备出双尾型疏水缔合水溶性共聚物(DTHAP),来解决丙烯酰胺类聚合物耐温抗盐性以及稳定性差的难题。通过测定聚合物溶液的表观黏度作为评价其性能的主要手段,考察了丙烯酸加量、盐、表面活性剂(SDS)含量、疏水单体含量等因素对聚合物性能的影响,从而确定了比较理想的反应条件。实验中发现:丙烯酸加量和表面活性剂含量的变化会影响聚合物的临界缔合行为;盐的引入能够显著降低表面活性剂的用量,提高聚合物的增黏效果;疏水单体含量较低时[0.35%～0.45%(mol)],聚合物可以表现出明显的增黏效果。当聚合物浓度为1 g·L^-1时,聚合物的黏度可以达到141.5 mPa·s,其临界缔合浓度(CAC)为0.75 g·L^-1左右。聚合物在120 g·L^-1的NaCl溶液和120 g·L^-1 NaCl、0.4 g·L^-1 CaCl₂溶液中,80℃下老化90 d,黏度分别为47.6 mPa·s和45.9 mPa·s。采用红外光谱、扫描电镜两种手段,表征了聚合物的结构。     

聚合法对疏水缔合聚丙烯酰胺粘度的影响

为了增强聚丙烯酰胺的增粘性能,提高其抗剪切、抗温和抗盐性,使用实验室自制的疏水单体、丙烯酰胺和离子型单体,通过3种不同的聚合方法进行自由基共聚合。分析了不同聚合途径下,研究组分、剪切、温度和盐对聚合物溶液表观粘度的影响。结果表明,反相乳液聚合法的产物的临界缔合浓度小于0.4 g/L,85℃下粘度保持60%以上,其表观粘度在受剪切后的恢复率达到100%,抗剪切性能明显。利用一种小分子化合物来抑制Fe2+对聚合物的降解作用,达到保持聚合物溶液粘度目的。     

疏水性聚丙烯酰胺的合成实验研究

疏水性聚丙烯酰胺是一种重要的疏水缔合水溶性聚合物,它可以通过多种方法合成。本文结合均相共聚法和表面活性大单体法2种方法,以丙烯酸和Span80为原料首先合成了一种具有表面活性的疏水缔合型单体Span80-AA,然后将Span80一AA与丙烯酰胺聚合反应合成疏水性聚丙烯酰胺,并研究了时间、引发剂浓度、溶剂配比、大单体含量和温度对疏水聚合物粘度和分子量的影响,从而得到比较合适的实验条件。     

Synthesis and solution properties of poly(acrylamide-styrene) block copolymers with high hydrophobic content

Hydrophobically associating block copolymers of polyacrylamide/styrene with a high hydrophobe content were synthesized using micellar copolymerization under various conditions of surfactant and initiator concentrations with the objective of determining the conditions that produce optimum solution properties for enhanced oil recovery. Solubilities, aqueous solution viscosities and interfacial properties with air and oil of the copolymers were investigated. The influence of salt on the solution properties was also studied. Nature of hydrophobic sites and onset of hydrophobic association were studied by measuring the fluorescence of pyrene in polymer solutions. Optimum solution properties were obtained for copolymers synthesized under conditions of high surfactant and initiator concentrations. The copolymers displayed substantial thickening properties at low concentrations with enhanced thickening in the presence of salt. The interfacial tensions of the aqueous solutions with n-decane and air were also reduced. Interfacial properties were slightly sensitive to salt concentration. The copolymer solutions showed shear and temperature thinning behaviors typical of polymer solutions.     

Rheological Behaviour of Poly (Acrylamide-G-Propylene Oxide) Solutions: Effect of Hydrophobic Content,Temperature and Salt Addition

Abstract

The viscosity of hydrophobically modified polyacrylamide was investigated as a function of polymer concentration in aqueous and in salt solutions, and also as a function of temperature. The graft copolymers were constituted of polyacrylamide backbone and different amount of hydrophobic polypropylene oxide) graft chains. Measurements of intrinsic viscosities have been performed by using a Contraves low-shear LS-40 rheometer. From these results, a dependence of the intrinsic viscosity of the polymer solution with the molecular weight was observed, where an increase of the latter resulted in higher intrinsic viscosity. In this case, the effect of the molecular weight was more emphasized than the effect caused by the slightly different degrees of hydrophobic incorporation. When enhancing the temperature, it was not verified a significant change on the reduced viscosities of the copolymer solutions and the graft chain length was also observed.     

Synthesis and properties of hydrophobically modified acrylamide-based polysulfobetaines

Acrylamide-based, hydrophobically modified polysulfobetaines containing 3-[N-(2-methacroyloylethyl)-N,N-dimethylammonio]-propane sulfonate (DMAPS) and varying amounts of the hydrophobic monomer stearyl methylacrylate (SMA) were synthesized by micellar copolymerization. The basic physico-chemical properties of the synthesized copolymers were studied by means of surface tension, dynamic laser light scattering, and rheological measurements. All the copolymers showed surface activity when the copolymer concentration was above 0.07 wt%. The dynamic laser light scattering measurement revealed that both zwitterionic and hydrophobic associations were important in copolymer aggregation. The rheological properties of the copolymers in aqueous solution depended on the content of hydrophobic monomer, the copolymer concentration and the addition of salt, which were characteristic of hydrophobically modified polyacrylamide and acrylamide-based polyzwitterions. The critical aggregation concentration of the copolymers was in the range of 0.07–0.1 wt%.     

Hydrophobically modified poly(sodium 2‐acrylamido‐2‐methylpropanesulfonate): synthesis and viscosity of aqueous solution

BACKGROUND: Hydrophobically modified polyelectrolytes are widely used polymers due to their good water solubility, stretched configuration in water and strong hydrophobic association. The study reported here aimed at researching the double action of hydrophobic association and electrostatic effect of novel hydrophobically modified polyelectrolytes in solution. RESULTS: A series of novel hydrophobically modified polyelectrolytes were synthesized by micellar copolymerization with various feed ratios of sodium 2‐acrylamido‐2‐methylpropanesulfonate, N‐n‐dodecylamine and sodium dodecylsulfonate. Their structure was characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance and gel permeation chromatography, and the viscosities of their aqueous and salt solutions were studied. CONCLUSION: The results show that the addition of the hydrophobic comonomer results in a decrease in molecular weight (M_w). The smaller the initial number of hydrophobes in one micelle, the higher is M_w of the resulting copolymer. The viscosity of PAD‐1.73 polyelectrolyte is less sensitive to salt than those of the others. According to the zero shear viscosity and corresponding concentration, the critical cluster‐forming concentration, critical overlap concentration and critical entanglement concentration of these polymer solutions were determined. Moreover, in the dilute regime the viscosity decreases with increasing salinity, while in the semi‐dilute regime the viscosity decreases first and then increases. It is suggested that in dilute and semi‐dilute regimes, hydrophobic intramolecular association and intermolecular association dominate, respectively. Copyright © 2009 Society of Chemical Industry     

Thermal stability of polymers based on acrylamide and 2-acrylamido-2-methylpropane sulfonic acid in different temperature and salinity conditions

Partially hydrolyzed polyacrylamide (PHPA) is the most widely used polymer in enhanced oil recovery (EOR) applications. However, under conditions of high temperature and salinity, the PHPA molecules become hydrolyzed, causing a drastic reduction of the viscosity of the polymer solution due to the presence of negative charges, making the molecules more susceptible to interactions with cations. In this sense, in order to increase the stability of these polymers, an anionic monomer more resistant to cations such as 2-acrylamido-2-methylpropane sulfonic acid (AMPS) has been incorporated into the HPAM molecules. This work evaluated the thermal stability of a copolymer (acrylamide and AMPS - AN125) and a terpolymer (acrylamide, acrylate, and AMPS-FP5115) in the time course of 360 days. The tests were carried out in typical conditions of Brazilian offshore reservoirs, such as absence of oxygen, high temperature, and high salt concentration. The test method involved measurements of intrinsic viscosity in function of time and determination of the hydrolysis degree of the polymers by elemental analysis. The copolymer AN125 was more stable under the test conditions than the terpolymer FP 5115 due to the presence of a higher concentration of AMPS in the copolymer. The AMPS group was hydrolyzed to AA at a temperature of 100 °C, however, the increase in salt concentration delayed the onset of this degradation. The tests indicated that the presence of a higher AMPS content in the copolymer does not prevent the polymer from undergoing hydrolysis, but delays the polymer precipitation step in the solution.     

复合引发体系制备磺化聚丙烯酰胺及性能评价

采用氧化还原引发剂(过硫酸铵和甲醛合次亚硫酸钠)与水溶性偶氮引发剂(偶氮二异丁脒盐酸盐)复配的复合引发体系引发丙烯酰胺(AM)与2-丙烯酰胺-2-甲基丙磺酸(AMPS)共聚合成磺化聚丙烯酰胺(SPAM),考察了氧化剂与还原剂配比、复合引发剂配比、聚合引发温度、pH值、单体浓度等条件对聚合物溶液表观黏度的影响,同时对其进行了耐温抗盐性能评价。结果显示,与工业上使用的部分水解聚丙烯稀酰胺(HPAM 3 500万)相比,合成的SPAM具有更好的耐温抗盐性能。     

Effect of including a hydrophobic comonomer on the rheology of an acrylamide-acrylic acid based copolymer

Synthesis and design of polymer systems based on acrylamide for enhanced oil recovery (EOR) is essential for reservoirs with high salinity and high temperature conditions. The use of associative monomers or the modification of the polymers with hydrophobic functional groups represents a promising alternative that extends the use of chemical EOR. In this study, terpolymers based on acrylamide, acrylic acid and butyl methacrylate were synthesized and the rheological properties of aqueous solutions of the obtained polymers at different pH values, and salt concentrations were evaluated. The results show that at alkaline conditions the viscosity of aqueous solutions of a polymer synthesized with 68.6 wt% of acrylamide, 22.9 wt% of acrylic acid and 8.6 wt% of butyl methacrylate increases by a factor of more than 1,000 at a 3 wt% concentration. Also, all polymers with the hydrophobic modification showed higher viscosity in saline solutions compared to their acrylamide-acrylic acid analogue.     

一种疏水缔合聚合物的合成及溶液性能

将十八烷基-二甲基甲代烯丙基氯化铵(C18DMMAAC)作为疏水单体,与丙烯酸(AA)、丙烯酰胺(AM)在水溶液中通过自由基聚合得到疏水缔合聚合物HAPAM-18,通过1HNMR和红外光谱对其结构进行了表征。最佳的聚合反应条件为:n(AM)∶n(AA)∶n(C18DMMAAC)=74.94∶25∶0.06,AA的摩尔中和度为95%,单体总质量分数为20%,引发剂质量分数为0.05%(以单体总质量计),温度45℃,反应时间12 h。研究表明,聚合物溶液的临界缔合质量浓度为2 g/L;聚合物溶液对温度较为敏感,80℃时黏度保留率为70.93%;聚合物溶液仍为剪切变稀的假塑性流体,但表现出良好的抗剪切性能,剪切1 h后黏度保留率达115%;由于设计为含较多阴离子的聚合物,该聚合物的抗盐性较差。     

Effect of micro-aggregation behavior on the salt tolerance of polymer solutions

Polymer solution for oil displacement is mostly used in the middle and late stage of water flooding reservoir development, and reservoir groundwater conditions are often one of the main conditions restricting polymer application. Therefore, it is necessary to develop salt tolerance of polymer solutions with different aggregation behaviors, so as to facilitate the synthesis and optimization of suitable polymer systems. The differences in the micro-aggregation behavior of three polymers with different molecular structures were explored. On this basis, the effects of divalent metal cations on the properties of the polymer solutions were analyzed by assessing the micro-aggregation behavior, apparent viscosity, hydrodynamic size, and shear rheological characteristics. The results showed that the linear partially hydrolyzed polyacrylamide (HPAM) was seriously affected by divalent cations, and the viscosity decreased obviously. The aggregation behavior of the polymer changed by hydrophobic association can enhance the salt tolerance of the solution. The hydrophobically modified partially hydrolyzed polyacrylamide (HMPAM) with “chain beam” aggregation behavior has strong intermolecular connection, which enables it to withstand the content of calcium and magnesium ions of 1100 mg l⁻¹. When the content of calcium and magnesium ions exceeds 600 mg l⁻¹, dendritic hydrophobically associating polymer (DHAP) will destroy the interaction between molecular chains, resulting in the decrease of apparent viscosity and hydrodynamic size. For polymer flooding in high-salinity reservoir, salt tolerant polymer system can be constructed by optimizing molecular weight and hydrophobic group content.     

三次采油用聚合物驱油剂PL-2的合成与溶液性能研究

采用胶束聚合的方法合成了三次采油用聚合物PL-2,室内研究了表面活性剂的浓度、疏水单体、阴离子单体含量以及在盐水中聚合物溶液表观粘度的影响,并进一步评价了合成聚合物的抗剪切性与热稳定性。实验结果表明:疏水单体与阴离子单体含量分别在0.6%与10%时,该聚合物驱油剂PL-2具有很好的增粘效果,且抗剪切及热稳定性能优良,其性能可以满足高温、高矿化度油藏聚合物驱油的要求。     

Inverse emulsion polymerization of triple monomers of acrylamide,maleic anhydride,and styrene to achieve highly hydrophilic–hydrophobic modified polyacrylamide

The purpose of this study was the production of copolymers and terpolymers with highly hydrophilic–hydrophobic properties, using inexpensive and available monomers as potential enhancing oil recovery (EOR) and water production control agents for high-temperature and high-salinity (HTHS) oil reservoirs. For this purpose, several copolymers and terpolymers with different molar percentage of acrylamide/styrene, acrylamide/maleic anhydride, and acrylamide/styrene/maleic anhydride were synthesized by the inverse emulsion polymerization technique. The presence of hydrophobic styrene and hydrophilic maleic anhydride monomers in the copolymer and terpolymer structure, provided some unique properties compared to polyacrylamide, was confirmed by several analyses including HNMR, elemental analysis, FTIR, SEM, TGA, and DSC. Simulating HTHS oil reservoir condition under high salinity, temperature, and shear rate, the rheological studies suggested unlike traditional EOR agents such as polyacrylamide, the viscosity of the copolymer, and terpolymer aqueous solutions showed a considerable increase after a critical polymer concentration and less reduction with the salt increment at both ambient and elevated temperatures. Furthermore, the swelling ratio of the insoluble terpolymers measured versus the time and temperature in salt water increased with the maleic anhydride mole fraction, decreased with the salt concentration, and showed a maximum value at around 57 °C. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47753.     

新型孪尾疏水改性聚合物／表面活性剂的溶液性能研究

采用前加碱胶束共聚-共水解法制备了丙烯酰胺、丙烯酸钠和新型孪尾疏水单体N,N-二正辛基丙烯酰胺的三元共聚物P(AM/NaAA/DiC8AM),利用FTIR和1H-NMR确定了共聚物的结构,测定了共聚物/表面活性剂复合体系水溶液的表观粘度,研究了表面活性剂种类、温度、电解质、剪切速率等因素对复合体系溶液表观粘度的影响。P(AM/NaAA/DiC8AM)/SDS和P(AM/NaAA/DiC8AM)/CTAB复合体系的溶液表观粘度与HPAM共聚物溶液相比有明显的提高,疏水单体含量越大,复合体系的溶液表观粘度越大,且其溶液具有一定的耐温、耐盐和抗剪切性。     

三次采油用耐温抗盐聚合物的研究进展

概述三次采油用耐温抗盐聚合物的研究进展,特别是在超高分子量聚丙烯酰胺、丙烯酰胺与耐温抗盐单体的共聚物、疏水缔合聚合物、新型结构的聚丙烯酰胺共聚物等几个热门领域上总结了较新的研究结果。     

Increasing viscosity in entangled polyelectrolyte solutions by the addition of salt

The viscosity of several polyelectrolytes is measured in both salt free solutions and solutions in the high salt limit. At low polymer concentrations, the zero shear rate viscosity decreases as much as 100-fold upon addition of a monovalent salt, namely NaCl. However, as polymer concentration increases, the viscosity difference between polymer in salt free and in monovalent salt solution diminishes. Further, the zero shear rate viscosity becomes independent of added monovalent salt at the critical polyelectrolyte concentration c_D. Above c_D, the addition of monovalent salt increases the zero shear rate viscosity of the entangled polyelectrolyte solutions. The viscosity increase agrees with viscosity scaling theory for polyelectrolytes in the entangled regime. Polyelectrolytes exhibiting an increase in viscosity above c_D in the presence of monovalent salt include three natural anionic polyelectrolytes (xanthan, carrageenan, welan), one synthetic anionic polyelectrolyte (hydrolyzed polyacrylamide), and one natural cationic polyelectrolyte (chitosan). Generally, these polyelectrolytes are relatively high molecular weight (>1 M Dalton), which makes c_D experimentally accessible (e.g., c_D = 0.2 wt% for xanthan). The magnitude of the viscosity increase is as high as 300% for xanthan and nearly independent of monovalent salt concentration in the high salt limit. The increase in viscosity in monovalent salt solution and magnitude of c_D appear to be heavily influenced by the molecular characteristics of the polymers such as monomer weight, molecular structure, and chain conformation.     

Synthesis of Polyacrylamide Grafted Carboxymethylcellulose and Evaluation of Its Flocculation Characteristics

Poly-(acrylamide) grafted carboxymethylated cellulose (CMC) was prepared in aqueous solution using Ce⁺⁴ as its initiator. Two grades of graft copolymer were prepared by varying monomer concentration keeping all other factors constant. Intrinsic viscosity measurement of the graft copolymer showed that the length of the grafted chains depends on the monomer concentration. The polymers were characterized by IR spectroscopy, thermal analysis, and XRD studies. Flocculation performance of the best performing graft copolymer was compared with three commercial flocculants. It was further compared with another laboratory synthesized graft copolymer, sodium alginate-g-polyacrylamide, in coking and non-coking coal suspensions.     

Amphiphilic cycloterpolymers of diallyldimethylammonium chloride,diallyloctadecylammonium chloride,and sulfur dioxide

A hydrophilic monomer (diallyldimethylammonium chloride), a hydrophobic monomer (diallyloctadecylammonium chloride), and sulfur dioxide are cycloterpolymerized in dimethylsulfoxide using azobisisobutyronitrile as the initiator to afford water‐soluble cationic polyelectrolytes having a five‐membered cyclic structure on the polymeric backbone. The molecular weights of the polymers containing varying amounts of the hydrophobic monomer (0–7.5 mol %) are determined by light‐scattering experiments. The solution properties of the series of cationic polyelectrolytes are investigated by viscometric techniques. A polymer concentration (C*_HA) of <1 g/dL is required for the manifestation of hydrophobic associations in these terpolymers containing C₁₈ hydrophobic pendents. This is a notable improvement over the C*_HA values (ca. 15–17 g/dL) for the associating cyclopolymers having a pendant length of C10 to C14. The polymer solutions exhibit a sharp increase in viscosity with increasing polymer concentrations in salt‐free as well as salt‐added solutions. The presence of sodium chloride is shown to enhance the hydrophobic association tremendously. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1298–1306, 2005     

The effects of charge densities on the associative properties of a pH-responsive hydrophobically modified sulfobetaine/sulfur dioxide terpolymer

Sulfur dioxide, zwitterionic monomer, 3-(N,N-diallylammonio)propanesulfonate and a hydrophobic monomer N,N-diallyl-N-octadecylammonium chloride were cycloterpolymerized in dimethyl sulfoxide using azobisisobutyronitrile (AIBN) as the initiator to afford water-insoluble polysulfobetaines (PSB) in excellent yields. The PSBs were converted into the corresponding anionic polyelectrolyte (APE) by treatment with 1 equiv. of sodium hydroxide. Treating the pH-responsive PSB polymers with different equivalents of NaOH varied the zwitterionic and anionic charge densities in the polymer chain. The polymer chains with zwitterionic fraction greater than 0.5 were found to be insoluble in water. The solution properties of the APE and PSB/APE systems containing varying amount of the hydrophobic monomers in the range 0-10 mol% were investigated by viscometric techniques. It was found that PSB/APE polymer with a ratio of 33:67 for the zwitterionic and anionic fractions in the polymer chains, respectively, gave the highest viscosity value. The polymer concentration (C*_HA) of around 1 g/dl was required for the manifestation of significant hydrophobic associations. The polymer solutions exhibited sharp increase in viscosity with increasing polymer concentrations in salt (NaCl)-free as well as salt-added solutions. The presence of sodium chloride is shown to enhance intermolecular associations in polymers having hydrophobes in the lower mol% range, whereas, intramolecular associations were manifested in polymers containing higher proportions of the hydrophobes.