Naderi Ali, Olanya Geoffrey, Makuska Ricardas, Claesson Per M
Department of Chemistry, Surface Chemistry, Royal Institute of Technology, Drottning Kristinas väg 51, SE-10044 Stockholm, Sweden.
J Colloid Interface Sci. 2008 Jul 15;323(2):223-8. doi: 10.1016/j.jcis.2008.04.022. Epub 2008 May 22.
The possibility of exchanging adsorbed layers of PEO(45)MEMA:METAC-X brush polyelectrolytes (with two different charge densities, 10 and 75 mol%, denoted by X), with poly(MAPTAC), a highly charged linear polyelectrolyte, was investigated by quartz crystal microbalance with dissipation and reflectometry. The studies were conducted on a silica substrate at pH 10, conditions under which only electrostatic interactions are effective in the adsorption process. Based on the results, it was concluded that PEO(45)MEMA:METAC-10 forms an inhomogeneous layer at the interface through which poly(MAPTAC) chains can easily diffuse to reach the surface. On the other hand, the PEO(45)MEMA:METAC-75 layer was not affected when exposed to a poly(MAPTAC) solution. We argue that the observed effect for PEO(45)MEMA:METAC-75 is due to the formation of a homogeneous protective brush layer, in combination with the small difference in surface affinity between the bottle-brush polyelectrolyte and poly(MAPTAC), together with the difficulty of displacing highly charged polyelectrolyte chains once they are adsorbed on the oppositely charged surface. We also use the combination of QCM-D and reflectometry data to calculate the water content and layer thickness of the adsorbed layers.
通过石英晶体微天平结合耗散和反射测量法，研究了具有两种不同电荷密度（分别为10%和75%，用X表示）的PEO(45)MEMA:METAC-X刷状聚电解质的吸附层与高电荷线性聚电解质聚（甲基丙烯酰氧乙基三甲基氯化铵）（poly(MAPTAC)）进行交换的可能性。研究在pH值为10的二氧化硅基底上进行，在此条件下，吸附过程中只有静电相互作用起作用。根据结果得出结论，PEO(45)MEMA:METAC-10在界面处形成了一个不均匀层，poly(MAPTAC)链可以很容易地通过该层扩散到表面。另一方面，当暴露于poly(MAPTAC)溶液时，PEO(45)MEMA:METAC-75层不受影响。我们认为，观察到的PEO(45)MEMA:METAC-75的效应是由于形成了均匀的保护刷层，再加上刷状聚电解质和poly(MAPTAC)之间表面亲和力的微小差异以及高电荷聚电解质链一旦吸附在带相反电荷的表面上就难以被取代。我们还使用石英晶体微天平结合耗散测量法（QCM-D）和反射测量数据的组合来计算吸附层的含水量和层厚度。
