ADSORPTION-KINETICS OF BLOCK COPOLYMERS FROM A GOOD SOLVENT - A 2-STAGE PROCESS
ADSORPTION-KINETICS OF BLOCK COPOLYMERS FROM A GOOD SOLVENT - A 2-STAGE PROCESS
复制标题
DOI：
10.1021/ma00012a032
复制
发表时间：
1991-06-10
期刊：
影响因子：
5.5
通讯作者：
TOPRAKCIOGLU, C
中科院分区：
文献类型：
--
作者：
MOTSCHMANN, H;STAMM, M;TOPRAKCIOGLU, C
用椭偏仪原位测定了聚苯乙烯(PS)-聚环氧乙烷（PEO）二嵌段共聚物在甲苯溶液中对硅片的吸附动力学和等温线。两个块体都处于良好的溶剂条件下，但小的PEO块体被吸附，而大得多的PS块体在溶液中悬浮。因此，PS-PEO表现为末端吸附链。吸附动力学在明显分离的时间尺度上表现为两个过程。开始时，吸附量的时间行为可以描述为扩散控制过程，导致表面覆盖，分子之间的相互作用很小。更密集的表面覆盖是通过链穿透现有的单层，结合构象重排到更粗糙的构象来实现的。不同分子量的实验表明，不吸附PS块之间的斥力决定了最大吸附量。所吸附的单层可以被长度与嵌段共聚物中PEO嵌段相当的PEO低聚物快速完全置换。详细讨论了吸附过程的模型。
The adsorption kinetics and adsorption isotherm of a polystyrene (PS)-poly(ethylene oxide) (PEO) diblock copolymer onto a silicon wafer from toluene solution was measured in situ by ellipsometry. Both blocks are in good solvent conditions but the small PEO block is adsorbed while the much larger PS block dangles in solution. Thus, PS-PEO behaves like an end-adsorbed chain. The adsorption kinetics shows two processes on a clearly separated time scale. In the beginning, the time behavior of the adsorbed amount can be described as a diffusion-controlled process leading to a surface coverage with small interaction between molecules. A still denser surface coverage is achieved by the penetration of chains through the existing monolayer combined with the conformational rearrangement to a more brushy conformation. Experiments with different molecular weights indicate that the repulsion between the nonadsorbing PS blocks determines the maximal adsorbed amount. The adsorbed monolayer can be rapidly and completely displaced by PEO oligomer with a length comparable to the PEO block in the block copolymer. Models of the adsorption process are discussed in detail.