Blomberg Eva, Poptoshev Evgeni, Caruso Frank
Department of Chemistry, Surface Chemistry, Royal Institute of Technology, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden.
Langmuir. 2006 Apr 25;22(9):4153-7. doi: 10.1021/la052946y.
Interactions between surfaces bearing multilayer films of poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate sodium salt) (PSS) were investigated across a range of aqueous KBr solutions. Three layer films (PAH/PSS/PAH) were preassembled on mica surfaces, and the resulting interactions were measured with the interferometric surface force apparatus (SFA). Increasing the ionic strength of the medium resulted in a progressive swelling of the multilayer films. Interactions in solutions containing more than 10(-3) M KBr were dominated by a long-ranged steric repulsion originating from compression of polyelectrolyte segments extending into solution. In 10(-1) M KBr, repeated measurements at the same contact position showed a considerable reduction of the range and the strength of the steric force, indicating a flattening of the film during initial approach. Furthermore, this flattening was irreversible on the time scale of the experiments, and measurements performed up to 72 h after the initial compression showed no signs of relaxation. These studies aid in understanding the dominant interactions between polyelectrolyte multilayers, including polyelectrolyte films deposited on colloidal particles, which is important for the preparation of colloidally stable nanoengineered particles.
在一系列KBr水溶液中，研究了承载聚（烯丙胺盐酸盐）（PAH）和聚（苯乙烯磺酸钠盐）（PSS）多层膜的表面之间的相互作用。三层膜（PAH/PSS/PAH）预先组装在云母表面上，并用干涉表面力仪（SFA）测量由此产生的相互作用。增加介质的离子强度会导致多层膜逐渐膨胀。在含有超过10⁻³ M KBr的溶液中，相互作用主要由源自延伸到溶液中的聚电解质链段压缩的长程空间排斥力主导。在10⁻¹ M KBr中，在相同接触位置的重复测量表明空间力的范围和强度显著降低，表明在初始接近过程中膜变平。此外，在实验时间尺度上，这种变平是不可逆的，并且在初始压缩后长达72小时进行的测量没有显示出松弛的迹象。这些研究有助于理解聚电解质多层膜之间的主要相互作用，包括沉积在胶体颗粒上的聚电解质膜，这对于制备胶体稳定的纳米工程颗粒很重要。
