缓膨耐盐性纳米复合凝胶颗粒的合成及性能研究

通过AM/AMPS在水溶液中共聚,并向凝胶体系中引入锂皂石纳米颗粒,制备了缓膨耐盐的纳米复合凝胶颗粒(NCPG)。考察了单体质量比、纳米颗粒质量分数、交联剂和引发剂的质量分数对凝胶颗粒吸水性能的影响,优化出最佳配方为:m(AM)∶m(AMPS)=18∶2,锂皂石质量分数为0.75%,交联剂质量分数为0.05%,引发剂质量分数为0.05%。性能研究实验结果表明,NCPG具有p H敏感性、缓膨性以及耐温耐盐性。在碱性水中NCPG具有较高的膨胀倍数;常温下NCPG膨胀倍数较低,而在80℃下膨胀倍数会大幅增加,且在80℃下矿化度为81 521.2 mg/L的地层水中稳定吸水膨胀18.1倍,并保持稳定30 d以上,可满足油藏温度80℃以上的高盐油藏深部调剖需求。     

储层改造可降解暂堵剂的制备及表征

采用水溶液聚合法,以丙烯酰胺(AM)、丙烯酸钠为聚合单体,膨润土为填充剂,聚乙二醇二丙烯酸酯(PEGDA)为交联剂、过硫酸钾与亚硫酸钠为氧化还原引发剂制备了一种暂堵剂。考察了膨润土质量分数、交联剂质量分数、引发剂质量分数、丙烯酸中和度对暂堵剂性能的影响,采用FTIR和SEM对聚合物进行了表征。结果表明:当反应温度50℃、PEGDA质量分数0.02%(以单体质量为基准,下同)、引发剂质量分数0.6%(以单体质量为基准,下同)、膨润土质量分数5%(以总质量为基准,下同)、丙烯酸中和度80%时,合成的暂堵剂性能最好,吸水倍率达184 g/g,80℃水浴下,21 h完全降解。另外,2-丙烯酰胺-2-甲基丙磺酸(AMPS)和磺化沥青的引入提高了暂堵剂耐盐性及降解速度,岩心封堵实验表明封堵效果好。     

AA/AM/AMPS/DAC体膨型堵水剂的合成及性能

以丙烯酸(AA)、丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)和丙烯酰氧乙基三甲基氯化铵(DAC)为原料,N,N-亚甲基双丙烯酰胺(MBA)为交联剂,合成了一种体膨型堵水剂。考察了合成条件对产物性能的影响,确定的最优合成条件是:AA与AM质量比4∶1,反应温度60℃,AMPS用量7%(以反应物总质量为基准),DAC用量4%(以反应物总质量为基准),引发剂用量0.5%(以单体总质量为基准),交联剂用量0.05%(以单体总质量为基准)。合成的堵水剂具有较好的抗盐能力,且在煤油中几乎不膨胀,通过岩心流动实验评价了堵水剂的封堵能力和耐冲刷性能,该堵水剂封堵率能达到86.1%,经过25倍孔隙体积的后续水冲刷,注入压力仅下降0.13 MPa,该堵水剂具有较强的耐冲刷能力。     

机械活化花生壳-丙烯酸/丙烯酰胺水凝胶的制备及性能研究

利用机械活化后的花生壳粉末为基质,丙烯酸/丙烯酰胺为复合单体,过硫酸钾作引发剂,N,N一亚甲基双丙烯酰胺作交联剂,在水溶液中接枝聚合制备复合水凝胶。讨论了丙烯酸中和度、机械活化时间、单体配比、引发剂用量、交联剂用量、反应温度和反应时间对水凝胶的吸水倍率的影响。实验结果表明,在较佳的工艺条件下水凝胶对去离子水和生理盐水吸水倍率分别为148.37 g/g和19.78 g/g。     

颗粒体膨型耐温耐盐堵漏剂的研究

合成了一种耐高温高矿化度的聚合物凝胶堵剂,以聚乙二醇(PEG-8000)为互穿剂,二乙二醇二乙烯基醚为交联剂,探讨了单体比例、单体浓度、PEG加量及交联剂用量对凝胶性能的影响。通过质构仪、FT-IR、SEM及TGA进行了压缩强度测定及结构表征,优化了携带液体系,采用岩心渗透率测试仪考察了凝胶的封堵性能。结果表明,该堵剂在160℃高温油浴中放置40 d,凝胶强度及吸水率较好,在25%模拟地下水中吸水倍率为10 g/g左右,凝胶耐温耐盐性能良好,凝胶在携带液中膨胀较小,岩芯实验测定封堵率为95%以上,突破压力大于2 MPa。     

蛋膜改性接枝丙烯酸高吸水树脂的制备及性能研究

以废弃蛋膜和丙烯酸为主要原料,以N,N'-亚甲基双丙烯酸胺为交联剂,过硫酸钾为引发剂,采用水溶液聚合法制备了改性蛋膜-聚丙烯酸高吸水性树脂。考察了聚合温度、引发剂和交联剂的用量以及改性蛋膜用量等各因素对树脂吸水倍率的影响。结果表明,聚合温度70℃,改性蛋膜用量为单体质量的10%,丙烯酸中和度为70%,引发剂用量为单体质量的0.1%,交联剂用量为单体质量的0.12%,树脂的吸水倍率可达667 g/g,在0.9%的NaCl溶液中吸盐水倍率达到106 g/g,其吸水速率较快。IR初步表明了蛋膜与丙烯酸的接枝聚合作用。     

羧甲基纤维素接枝丙烯酸高吸水性树脂的研究

研究了对CMC与丙烯酸在水溶液中接枝共聚反应规律,分别考察了单体CMC比、中和度、交联剂、引发剂、反应时间、反应温度对吸水性树脂吸液倍率的影响。实验结果表明,在本实验考察范围内的最佳反应条件是单体CMC比6:1、中和度70%、交联剂0.006g、引发剂0.08g、反应时间3h、反应温度60℃。在该条件下聚合物在蒸馏水、自来水和生理盐水中最大吸液倍率分别为401g/g、84 g/g和53g/g。     

聚甲基丙烯酸丁酯-苯乙烯高吸油树脂的制备及其吸油性能研究

以甲基丙烯酸丁酯(BMA)和苯乙烯(St)为单体,二乙烯苯(DVB)为交联剂,偶氮二异丁腈(AIBN)为引发剂,聚乙烯醇(PVA)为分散剂,水为分散介质,运用悬浮聚合法制备了自溶胀型高吸油树脂。通过正交试验考察了单体配比、交联剂用量、引发剂用量和分散剂用量对树脂吸油性能的影响。结果表明:当m(BMA):m(St)=5:5、交联剂用量、引发剂用量和分散剂用量分别为单体总质量0.5%、2%和2%时,吸油树脂吸油倍率达到14.12 g g 1,吸附动力学研究发现此时吸油速率最大;通过热重表征和重复吸油试验,合成的高吸油树脂能够重复吸油多次,第五次的吸油倍率能够达到第一次的93%。     

P(AA-AM)复合石墨烯凝胶暂堵剂的研制及性能评价

基于微流体与乳液聚合技术,以丙烯酰胺和丙烯酸为功能单体,硝酸铝为交联剂,过硫酸钾为引发剂,通过油包水乳液形成的微反应器进行自由基聚合,并引入氧化石墨烯纳米材料制备得到各向同性良好的P(AA-AM)复合石墨烯(GO)凝胶暂堵剂颗粒。在模拟地层条件下对新型暂堵剂颗粒的性能进行了综合评价,结果表明,复合凝胶暂堵剂颗粒不但尺寸均一,而且由于纳米材料的引入,暂堵剂颗粒自身的吸水倍率、耐盐性和承压强度等性能显著提高,在石油钻采和老油田稳产领域具有良好的应用前景。     

P(AA-AM)复合石墨烯凝胶暂堵剂的研制及性能评价

基于微流体与乳液聚合技术,以丙烯酰胺和丙烯酸为功能单体,硝酸铝为交联剂,过硫酸钾为引发剂,通过油包水乳液形成的微反应器进行自由基聚合,并引入氧化石墨烯纳米材料制备得到各向同性良好的P(AA-AM)复合石墨烯(GO)凝胶暂堵剂颗粒。在模拟地层条件下对新型暂堵剂颗粒的性能进行了综合评价,结果表明,复合凝胶暂堵剂颗粒不但尺寸均一,而且由于纳米材料的引入,暂堵剂颗粒自身的吸水倍率、耐盐性和承压强度等性能显著提高,在石油钻采和老油田稳产领域具有良好的应用前景。     

Effect of swelling on spatial inhomogeneity in poly(acrylamide) gels formed at various monomer concentrations

The effect of swelling on the spatial inhomogeneity in poly(acrylamide) (PAAm) gels has been investigated with the static light scattering measurements. Four sets of gels were prepared using N,N′-methylenebis(acrylamide) (BAAm) as a crosslinker at various initial monomer concentrations. The crosslinker ratio X (the mole ratio of BAAm to the monomer acrylamide) was fixed at 1/50, 1/61.5, 1/66, and 1/100 in each set of gels. The gels, both at the state of preparation and at the equilibrium swollen state in water, exhibit a maximum degree of spatial gel inhomogeneity at a critical monomer concentration (ν_2,cr⁰). ν_2,cr⁰ shifts toward smaller concentrations as X is decreased or, as the gel swells beyond its swelling degree after preparation. Swelling enhances the extent of spatial inhomogeneity in PAAm gels and, this enhancement mainly occurs at low crosslinker ratios. The theoretical prediction of the Panyukov-Rabin theory was found to be in qualitative agreement with the experimental findings. It was also shown that three different effects, namely crosslinker, concentration, and swelling effects determine the extent of inhomogeneities in gels formed at various monomer concentrations.     

Effects of cyclization and pendant vinyl group reactivity on the swelling behavior of polyacrylamide gels

A series of polyacrylamide (PAAm) gels were prepared by free-radical crosslinking copolymerization of acrylamide and N,N′-methylenebis(acrylamide) (BAAm) in water at various crosslinker (BAAm) and chain transfer agent (isopropyl alcohol, IPA) concentrations. It was shown that only 5% of the crosslinker used in the feed forms effective crosslinks in the final hydrogels. At BAAm contents as high as 3 mole%, the equilibrium swelling ratio of the gels in water is independent of the crosslinker content in the feed. This is due to the prevailing multiple crosslinking reactions during the gel formation process. At a fixed crosslinker content, the onset of gelation is shifted towards higher conversions and reaction times as the amount of IPA increases. Addition of IPA in the monomer mixture also increases the equilibrium swelling ratio of PAAm gels. It was shown that the gel crosslinking density increases on rising IPA concentration in the feed due to the increasing rate of intermolecular crosslinking reactions. Received: 30 May 1997/Accepted: 26 June 1997     

Hydrogel characteristics of a novel temperature‐sensitive polymer,poly(N‐2‐methoxyisopropylacrylamide)

In this study, a novel temperature‐sensitive polymer, poly(N‐2‐methoxyisopropylacrylamide), PNMIPA, in the crosslinked hydrogel form was obtained. The monomer, N‐2‐methoxyisopropylacrylamide (NMIPA) was synthesized by the nucleophilic substitution reactions of acryloyl chloride with 2‐methoxyisopropylamine. Hydrogel matrix of PNMIPA was obtained by the bulk polymerization method. The bulk polymerization experiments were performed at +4°C, by using N,N‐methylenebisacrylamide (MBA) as crosslinker, polyethyleneglycol (PEG) 4000 as diluent, and potassium persulfate (KPS) and tetramethylethylenediamine (TEMED) as the initiator and accelerator, respectively. The same polymerization procedures were applied by changing monomer, initiator, crosslinker and diluent concentrations in order to obtain crosslinked gel structures having different temperature–sensitivity properties. The equilibrium swelling ratio of PNIMPA gel matrices at constant temperature increased with increasing initiator concentration and decreasing monomer concentration. The use of PEG 4000 as diluent in the gel synthesis resulted in about two times increase in equilibrium swelling ratios in the low temperature region. A decrease in the equilibrium swelling ratios of gel matrices started at 30°C and the decrease became insignificant at 55°C. Temperature‐sensitivities were determined in two different media. Distilled water medium was used in order to observe the temperature‐sensitivity of the gel clearly and the phosphate buffer medium was used in order to represent the temperature‐sensitive swelling behavior of the gel when it is used in biological media. Step effect was applied on ambient temperature in two opposite directions in order to examine the dynamic swelling and shrinking behaviors of the gels. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A novel thermoresponsive hydrogel matrix based on poly(N-ethoxypropylacrylamide)

Summary A new temperature sensitive hydrogel matrix, poly(N-ethoxypropylacrylamide), PNEPAM, was obtained by the bulk polymerization of N-ethoxypropylacrylamide (NEPAM). The monomer, NEPAM was synthesized by the nucleophilic substitution reaction of 3-ethoxypropylamine and acryloyl chloride. The polymerization was performed at +4 °C, by using N,N-methylenebisacrylamide (MBAM) as crosslinker, polyethyleneglycol (PEG) 4000 as diluent, and potassium persulfate (KPS) and tetramethylethylenediamine (TEMED) as the initiator and accelerator, respectively. PNEPAM gel matrices exhibited a thermosensitive bahaviour reasonably similar to poly(N-isopropylacrylamide), PNIPAM gels. The equilibrium swelling ratio at constant temperature increased with increasing initiator concentration and decreasing monomer concentration. The use of PEG 4000 as a diluent in the gel synthesis resulted in a significant enhacement in the thermosensitivity of gel matrix. The equilibrium swelling ratios up to 60 g water/g dry gel were observed in the low-temperature region. The results indicated that PNEPAM gel is a new alternative thermosensitive material to the NIPAM based gels.     

Thermoreversible hydrogels. IV. Effect of some factors on the swelling behavior of N-tetrahydrofurfurylacrylamide

A thermoreversible hydrogel, poly(N-tetrahydrofurfurylacrylamide) [poly-(NTHFAAm) gel], was prepared from N-tetrahydrofurfurylacrylamide, which was synthesized from N-tetrahydrofurfurylamine and acryloyl chloride (through acylation), with N,N′-methylenebisacrylamide, a crosslinker, in various aqueous solutions. The influences of temperature, gel thickness, and polymerization media on the swelling behaviors in water were investigated. The effect of the gel thickness on the swelling ratio for NTHFAAm gel indicated that the equilibrium swelling time and diffusion coefficient for the thinner gel were faster than those for the thicker gels. The effects of different polymerization media on the gel swelling ratio showed that the larger the solvent molecular size and the poorer the miscibility of the monomer and solvent, the higher the swelling ratio and diffusion coefficient. The drug release profiles in the various gels were also investigated. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1597–1603, 1998     

2‐Hydroxypropylmethacrylate based mono‐ and bifunctional gel beads prepared by suspension polymerization

Spherical and swellable gel beads in the size range 35–200 µm were prepared by suspension polymerization of 2‐hydroxypropylmethacrylate (HPMA). In the proposed method, a mixture of cyclohexanol and octanol was used as a diluent phase dispersed in an aqueous medium including poly(vinyl pyrrolidone) (PVP) as the stabilizer. The polymerization was initiated within the organic phase including the monomer and the crosslinker (ethylene glycol dimethacrylate) by an oil soluble initiator benzoyl peroxide. Spherical and swellable gel beads carrying both hydroxyl and carboxyl functional groups were also prepared by suspension copolymerization of HPMA and a water soluble comonomer (methacrylic acid). For this purpose, the suspension polymerization method proposed for HPMA was modified by using poly(vinyl alcohol) as a stabilizer instead of PVP. The effect of initiator concentration, polymerization temperature, monomer/diluent ratio, crosslinker concentration, stirring rate on yield, average size, size distribution, and carboxyl content of the HPMA based gel beads, were investigated. The swelling characteristics of the gel beads were defined. © 2000 Society of Chemical Industry     

Preparation and properties of silicone‐containing poly(methyl methacrylate) gels

Poly(methyl methacrylate) (PMMA) gels with varying amounts of silicone and solvent and constant amounts of crosslinker were prepared by solution free radical crosslinking copolymerization of methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDM), tetraethoxysilane (TEOS) and vinyltriethoxysilane (VTES) comonomer systems. They were then studied in benzene at a total monomer concentration of 3.5 mol L^?1 and 70 °C. The conversion of monomer, volume swelling ratio, weight fraction and gel point were measured as a function of the reaction time, silicone concentration and benzene content up to the onset of macrogelation. Structural characteristics of the gels were examined by using equilibrium swelling in benzene, gel fraction and Fourier‐transform infrared (FTIR) analysis. The morphology of the copolymers was also investigated by SEM. Based on the obtained results, it was concluded that the FTIR data did not have the capacity to show the presence of the VTES or TEOS moiety in these kinds of copolymers. On the other hand, the variation of weight fraction of gel, W_g, and its equilibrium volume swelling ratio in benzene, q_v, exhibited the same behaviour as that of MMA/EGDM copolymers. Also, the dilution of the monomer mixture resulted in an increase in the gel point and swelling degree and a decrease in the percent of conversion and gel fraction. Finally, TEOS is not an ideal silicone compound for reaction in the MMA/EGDM copolymerization system, whereas VTES is a suitable silicone comonomer for this system and it has been proved useful. Copyright © 2005 Society of Chemical Industry     

Early bird gets the network: The relative importance of reactivity ratios, Ψ parameter,and crosslinker level on gel formation in FRP

Network topology is manipulated in free-radical copolymerization via proper selection of crosslinker type and its respective properties when paired with specific monomers. Our prior work has focused on the impact of the reduced reactivity parameter Ψ applied to a pendent vinyl, characteristic for each monomer/crosslinker pair, yet here we assess the relative importance of the comonomer reactivity ratios to see whether one factor can counterbalance the other. The traditional reactivity ratio determines when the crosslinker molecule is incorporated into the polymer backbone, while the reduced reactivity Ψ parameter relates to the efficiency of the resulting pendent side chain vinyl being utilized to form a crosslink node at some later point during the polymerization. Both factors are then contrasted with simply the overall loading of crosslinker. Either n-butyl methacrylate (n-BMA) or styrene (STY) was chosen as a primary backbone monomer to copolymerize with one of three crosslinkers: 1,4-butanediol dimethacylate (BDDMA), 1,4-butanediol diacrylate (BDDA), or divinylbenzene (DVB). Both kinetics and gel can be most dramatically boosted when a crosslinker is applied having a reactivity ratio favouring early insertion. This in turn leads to an earlier onset of gel formation, which ultimately results in greater final gel content. This amplification of both kinetics and gel can overcome an otherwise small Ψ due to crosslinker or main monomer choice. This reactivity ratio effect was further confirmed by Monte Carlo simulations. By whatever mechanism (higher Ψ, lower r_A, or higher crosslinker level), earlier onset of gelation produces more gel overall and a tighter network topology.     

Non-Gaussian elasticity of poly(2-acrylamido-2-methylpropane sulfonic acid) gels

Summary A series of strong polyelectrolyte hydrogels was prepared from the sodium salt of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) as the monomer and N,N-methylene(bis)acrylamide (BAAm) as a crosslinker. The hydrogels prepared between 9 and 50 mol % BAAm appeared homogeneous to eye but exhibited large spatial fluctuations of polymer concentration, as determined by the light scattering measurements. The elasticity tests show that the modulus of elasticity of gels increases with increasing degree of swelling, starting from the gel preparation state. Thus, the mechanical properties of the hydrogels are improved on their swelling in water. It was shown that the hydrogels even at a gel state just after their preparation are in the non-Gaussian regime due to the high degree of spatial gel inhomogeneity.     

γ射线辐射聚合制备吸油凝胶及其性能研究

以丙烯酸2-乙基己酯(EHA)为聚合单体,二乙烯基苯(DVB)为交联剂,通过γ射线辐射聚合制备吸油凝胶,采用傅里叶红外光谱(FTIR)和热重分析(TG)研究制备的吸油凝胶。在此基础上,研究交联剂含量、单体含量、辐射剂量以及剂量率对凝胶吸附性能和凝胶含量的影响,并进一步研究凝胶的重复使用性能。研究表明,单体含量为31. 9%,交联剂含量为0. 57%,辐射剂量为7.2kGy,辐射剂量率为48Gy/min为凝胶制备的最佳条件。此外,重复吸附实验表明制备的凝胶具有优良的可重复使用性,其第二次使用过程中可快速达到吸附饱和,对甲苯的最大吸附倍率为33.9g/g。