高固含量丙烯酰胺反相微乳液的研究进展

丙烯酰胺反相微乳液使丙烯酰胺的聚合易于控制,可生成稳定的微乳液,在实际应用中,高浓度微乳液更有实用价值,可以节省运输和使用成本,但单体浓度增高以后,聚合产生的高热容易破坏微乳液的稳定性,造成破乳、结块。在总结国内外科研成果的基础上,综述了高固含量丙烯酰胺反相微乳液的常用制备方法。     

高固含量聚丙烯酰胺反相微乳胶的制备

依据绘制的Span 80/Tween 80-煤油-水(丙烯酰胺水溶液)拟三元相图,选择高单体质量分数〔如w(丙烯酰胺)=39.2%〕微乳液体系,在反应温度为40℃,引发剂用量为单体质量0.2%的条件下,通过反相微乳液聚合反应,制得了w(聚丙烯酰胺)=39.0%,相对分子质量为5.8×106(引发剂为过硫酸铵)和7.6×106(引发剂为偶氮二异丁腈)的透明、稳定的聚丙烯酰胺微乳胶。考察了相关因素对丙烯酰胺微乳液聚合反应的影响。发现所得聚丙烯酰胺的相对分子质量随着单体、乳化剂质量分数的增加而增大;随反应温度的升高而减小,随引发剂质量分数和反应时间的增加呈现先增大后减小的变化趋势。     

聚丙烯酰胺的反相微乳液聚合研究

在配方主体确定的情况下,研究了引发剂浓度、聚合前通氮除氧时间、聚合降温后持续反应温度及时间等次要因素对丙烯酰胺反相微乳液聚合的影响。正交实验方案结果表明,引发剂浓度及聚合前通氮除氧时间是影响产物相对分子质量和稳定性的主要因素,聚合降温后持续反应温度及时间是影响单体转化率的主要因素;最佳方案如下：引发剂浓度为2 g/L,聚合前通氮除氧时间为15 min,聚合降温后40℃持续反应,持续反应时间1 h。根据最佳方案制得了固含量37.0%、相对分子质量12.8×106的稳定、速溶的聚丙烯酰胺微乳液。     

高固含量苯丙微乳液的制备

采用种子半连续微乳液聚合法合成苯丙微乳液。以苯乙烯、丙烯酸丁酯和丙烯酸为单体,辛基酚聚氧乙烯醚(OP-10)和十二烷基硫酸钠(SDS)为乳化剂,过硫酸钾为引发剂,考察了乳化剂、引发剂、丙烯酸单体和电解质对聚合反应的稳定性和粒径大小及其分布的影响,并由此确定了适宜的合成条件,制备了固含量在48%左右,粒径在60~70 nm的苯丙微乳液。     

反相微乳液聚合制备聚丙烯酰胺

选用ＳＰＡＮ８０－ＯＰ１０复合乳化剂，煤油为油相，进行了丙烯酰胺的反相微乳液聚合研究，制得了水溶解速度显著加快的聚丙烯酰胺，并对构成稳定微乳液的乳化剂ＨＬＢ值进行了研究。     

丙烯酰胺反相乳液共聚研究进展

介绍了反相微乳液聚合体系的组成和单体乳液的稳定性、单体在油水两相中的分配、乳胶粒大小及形态、聚合物的组成及单体残余率、共聚物分子量的测定等的表征与应用 ,以及共聚物在水处理、造纸工业、采油及其他领域的应用。     

丙烯酰胺反相微乳液的制备研究

通过检测乳液电导率,观察其外观、丁达尔现象等方法,研究各种烷烃、乳化体系及单体水相对丙烯酰胺反相微乳液稳定性的影响,得到Isopar M/Span80-Tween60/AM/H2O最优体系微乳液,确定了体系乳化剂用量为18.52%(m/m),最优HLB为8~8.5,最佳单体水溶液浓度50%(m/m),最大水相加入量22.22%(m/m),最佳油水比2.67。     

反相乳液法制备聚丙烯酰胺微球及其性能研究

以丙烯酰胺(AM)为主单体,2-丙烯酰胺-2-甲基丙磺酸(AMPS)为功能单体,N,N'-亚甲基双丙烯酰胺(MBA)为交联剂,通过反相乳液聚合法制备了聚丙烯酰胺微球。优化反应较佳合成条件为:油水质量比13∶7,m(AM)∶m(AMPS)=7∶1,交联剂用量2.9%,引发剂用量0.06%,此时乳液平均粒径为278 nm,黏度最小。采用FT-IR、SEM、TG及RS6000流变仪对产物的结构、形貌和性能进行了分析。结果表明,成功合成了目标产物,乳液呈现高分散度的光滑微球,具有较好的黏弹性及耐温耐盐性能。     

丙烯酰胺反相微乳液体系的制备、聚合及表征

本论文探讨了用Span80,Tween60为复合乳化剂,煤油为分散介质,制备丙烯酰胺的反相微乳液,并研究了所形成微乳兴的微观结构和影响该微乳液体系聚合反应的因素,本文重点研究了复合乳化剂的配比,丙烯酰胺反相微乳液体系的形成机理,并通过紫外分光光度计,旋转粘度计等对微乳液体系可能形成的微观结构和特性进行了分析探讨。其后,采用氧化还原引发剂体系进行了微乳液聚合,并对聚丙烯酰胺的物理性能,化学结构,相对分子质量等进行了测定和表征。     

丙烯酰胺反相微乳液的制备与表征

用复合乳化剂(Span 80/OP-10)制备了稳定的丙烯酰胺(AM)反相微乳液,研究了温度、复合乳化剂的配比及浓度对单体增溶量的影响,并通过紫外分光光度计、乌氏黏度计等对微乳液体系的微观结构和特征进行了分析和表征.     

丙烯酰胺反相微乳液聚合体系及其微观结构

制备稳定的Span80-Tween80/异辛烷/AM-H2O反相微乳液聚合体系;用电导法考察了不同HLB（亲水-亲油平衡）值下电导率的变化规律;研究了正丁醇、氯化钠和乙酸钠对微乳液体系电导率变化的影响规律.采用TEM、AFM、DSC、激光纳米粒度仪等手段测定了聚合前后微乳液的粒子形态、粒度和粒度分布.结果表明：HLB为5.4时,体系的电导率变化较小,正丁醇浓度为25 g•L^-1时电导率几乎没有变化,形成的微乳液较为稳定,而且增溶的水相也比较多.当氯化钠浓度为50 g•L^-1或醋酸钠浓度为25 g•L^-1时会增加体系的稳定性.对该体系聚合,可以得到相对分子质量（M_R）为5.64×10⁶、固含量为32%的聚合物乳液.所制备的聚合物为球形、单分散的准纳米材料,粒径（D）在140 nm左右.反相微乳液聚合的聚丙烯酰胺（PAM）的比表面积为21.684 m²•g^-1,玻璃化转变温度T_g为193℃.     

Inverse microemulsion copolymerization of butyl acrylate and acrylamide: kinetics,colloidal parameters and some model applications

The inverse microemulsion copolymerization of acrylamide and butyl acrylate initiated by ammonium peroxodisulphate, a water‐soluble initiator, and stabilized by anionic emulsifiers sodium bis‐2‐ethylhexylsulfosuccinate and sodium dodecylsulphate (SDS) has been studied. An increase of SDS concentration was observed to increase both the rate of polymerization and the particle size. The average number of radicals per particle (n?) is much below 0.5, which indicates desorption of monomeric radicals from polymer particles. The exit (desorption) rate constants k′_des (cm² s^?1) and k_des (s^?1) were evaluated as a function of SDS concentration (or the particle size) according to the Ugelstad/O'Toole (I), Nomura (II) and Gilbert (III) models. The value of k_des (s^?1) decreases with increasing particle size (or SDS concentration) for all three (I, II and III) models. A complex trend appears for k′_des (cm² s^?1): the Ugelstad/O'Toole model estimates a decrease, the Nomura model finds no variation and the Gilbert model estimates even a slight increase in k′_des with increasing SDS concentration. Copyright © 2006 Society of Chemical Industry     

反相微乳液聚合引发剂对聚丙烯酰胺分子质量影响的研究

分别以三种引发剂体系为引发剂,从引发机理出发,通过正交实验研究了丙烯酰胺反相微乳液聚合中引发剂种类、引发剂浓度、反应温度、单体浓度等对聚丙烯酰胺(PAM)相对分子质量的影响。结果表明,引发剂种类对水溶性PAM相对分子质量有显著的影响;过硫酸铵-亚硫酸氢钠和偶氮二异丁腈复合引发体系是合成高相对分子质量PAM的有效引发体系。该引发体系在反应温度为40℃,氧化还原引发剂与偶氮的质量比为1∶4,单体浓度为20%,引发剂浓度为0.3%,pH为9的最佳条件下合成的PAM相对分子量为1.44×107。     

辛烷/Span80-Tween60/丙烯酰胺/水反相微乳液聚合动力学

对辛烷／Ｓｐａｎ８０－Ｔｗｅｅｎ６０／丙烯酰胺／水反相微乳液聚合的研究表明,其反应速度快,不到３０ｍｉｎ单体转化率即可达９０％以上。聚合过程中基本不存在恒速期,聚合速率在转化率接近２０％时达到峰值后随即迅速下降。通过进一步考察单体浓度（［Ｍ］）、引发剂浓度（［Ｉ］）、乳化剂浓度（［Ｅ］）、乙酸钠浓度以及反应温度对转化率为５％时的聚合速率（Ｒｐ,５％）和最大聚合速率（Ｒｐ,ｍａｘ）以及聚合物平均相对分子质量（Ｍｖ）的影响,得到如下动力学关系式：Ｒｐ,５％∝［Ｍ］１．０２［Ｉ］０．４５［Ｅ］－０．３…     

丙烯酸系单体的反相微乳液聚合及其应用

对丙烯酸系单体反相微乳液聚合过程的动力学、影响因素及一些新型聚合方法进行了综述;此外还对丙烯酸 系,特别是丙烯酰胺(AM)反相微乳液产品的应用进行了介绍。     

Inverse micro-emulsion polymerization of acrylamide in the presence of a mixture of oleophilic/hydrophilic surfactants

The effect of sodium dodecyl sulphate (SDS) on the formation of inverse micro-emulsion toluene/sodium bis(2-ethylhexyl)sulphosuccinate (AOT)/water/acrylamide (AAm)/SDS and on polymerization of acrylamide initiated by oil soluble dibenzoyl peroxide was studied. The presence of SDS shifts the value of the volume fraction of aqueous phase (Φ_aw) at which a two-phase Winsor II system forms, to higher values. It was shown that an increase of the mass ratio of SDS/water led to a decrease of acrylamide polymerization rate, of polyacrylamide particle size and of polyacrylamide molecular mass distribution. It was also found that in the presence of SDS, a nearly constant value for acrylamide polymerization rate in inverse micro-emulsion in the range of Φ_aw values between 5% and 50% can be obtained. The polymerization kinetics and polymer particle formation were explained as consequences of the initiation of acrylamide polymerization in two reaction loci—in inverse micelles and in the oil macrophase of the inverse micro-emulsion. © 1998 SCI.     

反相微乳液聚合制备丙烯酰胺类聚合物微球的研究进展

反相微乳液聚合技术具有稳定性好、固含量高、聚合速率快等优点而成为研究热点。本文系统地综述了近年来国内外应用反相微乳液聚合制备丙烯酰胺类聚合物微球的研究进展,概述了微乳液的基本理论及其特征,对稳定微乳液的制备进行了讨论;着重归纳了丙烯酰胺类的反相微乳液聚合,详述了聚合体系各组分的选择,同时探讨了影响聚合反应的因素,认为应研究新型表面活性剂以实现高单体浓度的聚合;介绍了聚合物微球在油田应用中提高采收率方面的应用现状。最后指出了其在深部调剖堵水领域存在的问题,以离子液体代替传统聚合体系组分制备集智能性、复合性、多功能性等综合性能于一体的聚合物微球是其未来发展方向之一。     

Reactant partitioning in free-radical heterophase polymerization: The case of inverse microemulsion polymerization of acrylamide

Conversion curves have been determined at 60°C for the polymerization of acrylamide in percolating inverse microemulsions. Ammonium peroxo-disulphate (APS) and dibenzoyl peroxide (DBP) were used as initiators of free-radical polymerization in the presence or absence of potassium nitrosodisulphonate (Fremy's salt, FS). The percolation decreases the rate of polymerization of acrylamide initiated by APS. The polymerization is inhibited by FS. After an inhibition period, retardation of acrylamide polymerization is more pronounced in non-percolating microemulsions. No inhibition periods were observed for DBP-initiated polymerization of acrylamide. The percolation shortens the time interval of the ‘slow’ polymerization of acrylamide, but the rates of rapid acrylamide polymerization above 10% conversion are the same for percolating and for non-percolating inverse microemulsions. The polymer particle diameter is a function of acrylamide/water weight ratio and of [water]/[AOT] (AOT: bis(2-ethylhexyl)-sulphosuccinate sodium salt) molar ratio. No effect of the initiator's nature either in the presence or in the absence of FS was found. The results are interpreted on the basis of initiator and/or nitroxide radical partitioning between oil and water phases of the inverse microemulsion, and are discussed with respect to the mechanism of acrylamide polymerization and polymer particle formation proposed for non-percolating inverse microemulsions.