Pickering emulsions stabilized by monodisperse latex particles: Effects of particle size
Pickering emulsions stabilized by monodisperse latex particles: Effects of particle size
复制标题
DOI：
10.1021/la0103822
复制
发表时间：
2001-07-24
期刊：
影响因子：
3.9
通讯作者：
Lumsdon, SO
中科院分区：
文献类型：
--
作者：
Binks, BP;Lumsdon, SO
介绍了由不同大小的球形单分散聚苯乙烯胶粒单独稳定的油水乳液的制备、类型和稳定性。根据颗粒是保持完整(在环己烷的情况下)还是溶解得到自由聚合物链(在甲苯的情况下)，会发生两种类型的行为。环己烷与“亲水性”的醛/硫酸盐颗粒或“疏水性”的硫酸盐颗粒形成的乳状液，在各种盐浓度和水体积分数范围内都是油包水(w/o)。乳化液的平均直径最初随着颗粒直径的增加从35微米增加到75微米，然后保持不变。虽然这种乳状液沉淀，但6个多月没有融合的迹象。我们证明了随着水体积分数的增加，从非絮凝乳状液向絮凝乳状液转变的证据，正如理论上对带电油滴的预测。然而，通过使用甲苯和“亲水”颗粒，随着盐浓度的增加，乳状液可以从水包油(O/W)转变为W/O。筛选带负电荷的吸附聚合物之间的斥力所需的盐浓度随着初始颗粒大小的增加而增加，因为平均分子量也增加。直径约为1微米的油包水乳状液可长时间稳定聚结。
The preparation, type, and stability of emulsions of oil and water stabilized solely by spherical, monodisperse polystyrene latex particles of different size is described. Two types of behavior occur depending on whether particles remain intact (in the case of cyclohexane) or dissolve to give free polymer chains (in the case of toluene). Emulsions formed with cyclohexane and either "hydrophilic" aldehyde/sulfate particles or "hydrophobic" sulfate particles are water-in-oil (w/o) over a wide range of salt concentrations and water volume fractions. Average emulsion drop diameters initially increase from 35 to 75 mum with increasing particle diameter and then remain constant. Although such emulsions sediment, there is no sign of coalescence for over 6 months. We show evidence of the transition from nonflocculated to flocculated emulsions upon increasing the water volume fraction, as predicted theoretically fur charged drops in oil. By use of toluene and "hydrophilic" particles however, emulsions can be inverted from oil-in-water (o/w) to w/o with increasing salt concentration. The concentration of salt required to screen the repulsions between negatively charged adsorbed polymers increases with initial particle size as the average molecular weight also increases. Water-in-oil emulsions, of around 1 mum diameter, are stable to coalescence for long periods.