Byard Sarah J, Blanazs Adam, Miller John F, Armes Steven P
Department of Chemistry , University of Sheffield , Brook Hill , Sheffield , South Yorkshire S3 7HF , United Kingdom.
BASF SE , GMV/P-B001 , 67056 Ludwigshafen , Germany.
Langmuir. 2019 Nov 5;35(44):14348-14357. doi: 10.1021/acs.langmuir.9b02789. Epub 2019 Oct 22.
For certain commercial applications such as enhanced oil recovery, sterically stabilized colloidal dispersions that exhibit high tolerance toward added salt are desirable. Herein, we report a series of new cationic diblock copolymer nanoparticles that display excellent colloidal stability in concentrated aqueous salt solutions. More specifically, poly(2-(acryloyloxy)ethyltrimethylammonium chloride) (PATAC) has been chain-extended by reversible addition-fragmentation chain transfer aqueous dispersion polymerization of diacetone acrylamide (DAAM) at 70 °C to produce PATAC-PDAAM diblock copolymer spheres at 20% w/w solids via polymerization-induced self-assembly. Transmission electron microscopy and dynamic light scattering (DLS) analysis confirm that the mean sphere diameter can be adjusted by systematic variation of the mean degree of polymerization of the PDAAM block. Remarkably, DLS studies confirm that highly cationic PATAC-PDAAM spheres retain their colloidal stability in the presence of either 4.0 M KCl or 3.0 M ammonium sulfate for at least 115 days at 20 °C. The mole fraction of PATAC chains within the stabilizer shell was systematically varied by the chain extension of various binary mixtures of non-ionic poly(,-dimethylacrylamide) (PDMAC) and cationic PATAC with DAAM to produce ([] PATAC + [1 - ] PDMAC)-PDAAM diblock copolymer spheres at 20% w/w. DLS studies confirmed that a relatively high mole fraction of cationic PATAC stabilizer chains ( ≥ 0.75) is required for the dispersions to remain colloidally stable in 4.0 M KCl. Cationic worms and vesicles could also be synthesized using a binary mixture of PATAC and PDMAC precursors, where = 0.10. However, the vesicles only remained colloidally stable up to 1.0 M KCl, whereas the worms proved to be stable up to 2.0 M KCl. Such block copolymer nanoparticles are expected to be useful model systems for understanding the behavior of aqueous colloidal dispersions in extremely salty media. Finally, zeta potentials determined using electrophoretic light scattering are presented for such nanoparticles dispersed in highly salty media.
对于某些商业应用，如提高石油采收率，需要对添加的盐具有高耐受性的空间稳定胶体分散体。在此，我们报告了一系列新型阳离子二嵌段共聚物纳米颗粒，它们在浓盐水溶液中表现出优异的胶体稳定性。更具体地说，通过在70℃下二丙酮丙烯酰胺（DAAM）的可逆加成-断裂链转移水分散聚合反应，使聚（2-（丙烯酰氧基）乙基三甲基氯化铵）（PATAC）进行链增长，以20% w/w的固含量通过聚合诱导自组装制备PATAC-PDAAM二嵌段共聚物球体。透射电子显微镜和动态光散射（DLS）分析证实，平均球体直径可通过系统改变PDAAM嵌段的平均聚合度来调节。值得注意的是，DLS研究证实，高度阳离子化的PATAC-PDAAM球体在20℃下，在4.0 M KCl或3.0 M硫酸铵存在下至少115天保持其胶体稳定性。通过非离子型聚（N，N-二甲基丙烯酰胺）（PDMAC）和阳离子型PATAC与DAAM的各种二元混合物的链增长，系统地改变稳定剂壳层内PATAC链的摩尔分数，以20% w/w的固含量制备（[χ] PATAC + [1 - χ] PDMAC）-PDAAM二嵌段共聚物球体。DLS研究证实，分散体在4.0 M KCl中保持胶体稳定需要相对较高摩尔分数的阳离子PATAC稳定剂链（χ≥0.75）。阳离子蠕虫状和囊泡状结构也可以使用PATAC和PDMAC前体的二元混合物合成，其中χ = 0.10。然而，囊泡仅在高达1.0 M KCl时保持胶体稳定，而蠕虫状结构在高达2.0 M KCl时被证明是稳定的。这种嵌段共聚物纳米颗粒有望成为理解水性胶体分散体在高盐介质中行为的有用模型系统。最后，给出了使用电泳光散射测定的此类分散在高盐介质中的纳米颗粒的zeta电位。
