In situ atomic force microscopy imaging of adsorbed block copolymer micelles
In situ atomic force microscopy imaging of adsorbed block copolymer micelles
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DOI：
10.1021/ma049396f
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发表时间：
2004-07-13
期刊：
影响因子：
5.5
通讯作者：
Collins, S
中科院分区：
文献类型：
--
作者：
Hamley, IW;Connell, SD;Collins, S
原子力显微镜用于研究两亲嵌段共聚物在亲水性云母和疏水性二氧化硅基体上的原位吸附。研究了吸附作为浓度的函数-接近或低于体积临界胶束浓度的共聚物以单链或“预胶束聚集体”的形式吸附。随着浓度的增加，胶束形成密集排列的结构。在一定浓度下，二氧化硅上强吸附胶束的有序度较高。在亲水性氮化硅原子力显微镜尖端发生竞争性吸附。在低胶束浓度下，云母上胶束的底物覆盖率随扫描时间大致线性增加。对云母的弱吸附进行了分析，得到了二维扩散系数。研究了针尖振荡频率对原子力显微镜成像的影响，发现需要更高的频率才能成像云母上的聚合物聚集体。最后，力-距离曲线提供了吸附聚合物层的纳米力学性能信息。有证据表明，胶束和聚集体通过疏水的P块吸附到二氧化硅上，而它们通过亲水的E块吸附到云母上。
Atomic force microscopy has been used to study the in situ adsorption of an amphiphilic block copolymer from aqueous solution onto hydrophilic mica and hydrophobic silica substrates. Adsorption was studied as a function of concentration-close to and below the bulk critical micelle concentration the copolymers adsorb as single chains or "premicelle aggregates". As concentration is increased, micelles form into densely packed structures. At a given concentration, the ordering is higher for the strongly adsorbed micelles on silica. Competitive adsorption onto the hydrophilic silicon nitride AFM tip occurs. The substrate coverage of micelles on mica increases roughly linearly with scan time at low micelle concentration. Weak adsorption on mica was analyzed to provide a two-dimensional diffusion coefficient. The effect of tip oscillation frequency on the AFM images was investigated-higher frequencies were required to image polymer aggregates on mica. Finally, force-distance curves provide information on the nanomechanical properties of the adsorbed polymer layers. Evidence is presented to show that micelles and aggregates adsorb to silica via the hydrophobic P block, while they adsorb to mica via the hydrophilic E block.