Institute of Organic Chemistry III-Macromolecular Chemistry and Organic Materials, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
Langmuir. 2010 May 18;26(10):7054-61. doi: 10.1021/la904380k.
Cobalt-containing hybrid particles have been prepared through the encapsulation of cobalt tetrafluoroborate hexahydrate (CoTFB) via inverse miniemulsion polymerization of 2-hydroxyethyl methacrylate (HEMA). We systematically varied the amount and type of cosolvent (water, methanol, ethanol, ethylene glycol), apolar continuous phase (cyclohexane, isooctane, isopar M, hexadecane), amount of cobalt salt, and molecular weight of the polymeric surfactant. The influence of those parameters on the particle size, size distribution, and particle morphology were investigated. Narrowly size-distributed hybrid particles with good colloidal stability could be obtained in a wide range of cobalt content between 5.7 and 22.6 wt % salt relative to the monomer. The addition of a cosolvent such as water not only promotes the loading of metal salt but also has a positive influence on narrowing the particle size distribution. We assume that generally narrowly size-distributed particles can be obtained for a large variety of combinations of polar/apolar phase by adjusting the balance between osmotic and Laplace pressure via the solubility of the metal salt in the continuous phase and lowering the interfacial tension by adjusting the hydrophilic-lipophilic balance (HLB) value of the surfactant. The results show a significant advantage of the inverse miniemulsion over the direct system with respect to the variability and total amount of metal salt without losing the narrow particle size distribution and colloidal stability.
通过 2-羟乙基甲基丙烯酸酯（HEMA）的反相细乳液聚合，将六水合四氟硼酸钴（CoTFB）包封在含钴的杂化粒子中。我们系统地改变了共溶剂（水、甲醇、乙醇、乙二醇）的量和类型、非极性连续相（环己烷、异辛烷、异十二烷、正十六烷）、钴盐的量和聚合表面活性剂的分子量。研究了这些参数对粒径、粒径分布和颗粒形态的影响。在单体的 5.7 到 22.6wt%盐之间的宽钴含量范围内，可以获得窄粒径分布且具有良好胶体稳定性的杂化粒子。添加水等共溶剂不仅促进了金属盐的负载，而且对缩小粒径分布也有积极的影响。我们假设，通过调整金属盐在连续相中的溶解度来平衡渗透压和拉普拉斯压力，以及通过调整表面活性剂的亲水亲油平衡（HLB）值来降低界面张力，通常可以为各种极性/非极性相的组合获得窄粒径分布的粒子。与直接体系相比，反相细乳液在金属盐的可变性和总量方面具有显著优势，同时不失去窄粒径分布和胶体稳定性。
