Zdyrko Bogdan, Ofir Pazit Bar-Yosef, Alb Alina M, Reed Wayne F, Santore Maria M
Department of Polymer Science and Engineering, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003, USA.
J Colloid Interface Sci. 2008 Jun 15;322(2):365-74. doi: 10.1016/j.jcis.2008.03.047. Epub 2008 Apr 7.
We examined the adsorption, on hydrophobic and hydrophilic surfaces, of 4 rake-type poly(dimethyl siloxane) (PDMS) copolymers varying the amount of poly(ethylene glycol) (PEG) graft arms from 41 to 72%. The copolymers formed large aggregates in solution, complicating their adsorption kinetics and layer structures. We found the adsorption process always to be dominated by the adsorption of large aggregates, with strongly bound layers resistant to rinsing in adsorbing buffer. Adsorbed amounts were nearly independent of the substrate. However, subtleties in the adsorption kinetics suggested different layer structures for the different systems. On hydrophilic silica, aggregates adsorbed at the transport limited rate until surface saturation, and associated interfacial structures were likely retained. On the hydrophobic surface, a subset of the copolymers exhibited retarded late stage adsorption kinetics suggestive of brush formation. This work demonstrates how subtle differences in adsorption kinetics provide insight into potential interfacial layer structures.
我们研究了4种梳型聚二甲基硅氧烷（PDMS）共聚物在疏水和亲水表面上的吸附情况，这些共聚物中聚乙二醇（PEG）接枝臂的含量在41%至72%之间变化。共聚物在溶液中形成大聚集体，使其吸附动力学和层结构变得复杂。我们发现吸附过程总是由大聚集体的吸附主导，形成的强结合层在吸附缓冲液中耐冲洗。吸附量几乎与底物无关。然而，吸附动力学的细微差别表明不同体系的层结构不同。在亲水性二氧化硅上，聚集体以传输受限速率吸附直至表面饱和，并且可能保留相关的界面结构。在疏水表面上，一部分共聚物表现出后期吸附动力学延迟，这表明形成了刷状结构。这项工作展示了吸附动力学的细微差异如何为潜在的界面层结构提供见解。
