Naderi Ali, Makuska Ricardas, Claesson Per M
Department of Chemistry, Surface Chemistry, Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
J Colloid Interface Sci. 2008 Jul 1;323(1):191-202. doi: 10.1016/j.jcis.2008.02.071. Epub 2008 Mar 22.
Interactions between cationic bottle-brush polyelectrolyte layers adsorbed on mica across salt and oppositely charged surfactant solutions were investigated with the interferometric surface force apparatus, and the results were compared with what is known for similarly charged linear polyelectrolytes. Ellipsometric measurements demonstrated that the bottle-brush polyelectrolytes, which contain 45 units long poly(ethylene oxide) side chains, are more readily desorbed than linear equivalents when the ionic strength of the solution is increased. It is argued that this is due to the steric repulsion between the poly(ethylene oxide) side chains that reduces the surface affinity. The preadsorbed bottle-brush polyelectrolyte layers were also exposed to sodium dodecyl sulfate (SDS) solutions. It was found that the presence of SDS affected the force profiles less than observed for similarly charged linear polyelectrolytes. This observation was attributed to excluded volume constraints imposed by the poly(ethylene oxide) side chains that reduces the accessibility of the charged polyelectrolyte segments and counteracts formation of large aggregates within the layer.
利用干涉表面力仪研究了吸附在云母上的阳离子瓶刷状聚电解质层在盐溶液和带相反电荷的表面活性剂溶液中的相互作用，并将结果与已知的带相同电荷的线性聚电解质的情况进行了比较。椭偏测量表明，当溶液的离子强度增加时，含有45个单元长的聚环氧乙烷侧链的瓶刷状聚电解质比线性等效物更容易解吸。有人认为，这是由于聚环氧乙烷侧链之间的空间排斥降低了表面亲和力。预先吸附的瓶刷状聚电解质层也暴露于十二烷基硫酸钠（SDS）溶液中。发现SDS的存在对力曲线的影响小于带相同电荷的线性聚电解质。这一观察结果归因于聚环氧乙烷侧链施加的排除体积限制，该限制降低了带电聚电解质链段的可及性，并抵消了层内大聚集体的形成。
