School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
Langmuir. 2012 Oct 23;28(42):14960-7. doi: 10.1021/la303216n. Epub 2012 Oct 15.
The influence of pore size, relative block size, and solvent quality on the extent of diblock copolymer adsorption on alumina surfaces was determined. To this end, the block copolymer that was chosen was poly(styrene)-b-poly(methyl methacrylate) (PS-b-PMMA), in which the PMMA block strongly chemisorbs to the surface and the PS block weakly physisorbs. Several architectures (i.e., different ratios of M(n(PMMA)) and M(n)((PS))) of the PS-b-PMMA copolymers were adsorbed from various solvents onto porous alumina membranes with various pore sizes. It was determined that the diblock copolymer coverage decreased significantly as the pore size decreased, similar to the behavior of the PMMA homopolymer under the same conditions. However, the coverage decreased as the molecular weight of the anchoring block (PMMA) increased for all pore sizes, which is in contrast to the behavior of the PMMA homopolymer under the same conditions. The dependence of the coverage on the relative block size and solvent quality is analyzed on the basis of the anchor-buoy model and the deviation from it in a nonideal system. The results presented in this work are relevant to the study of block copolymer conformation in solutions and on surfaces, adsorption chromatography, and solvent sensors and controls.
孔径、相对嵌段尺寸和溶剂质量对两亲嵌段共聚物在氧化铝表面吸附程度的影响已确定。为此，选择的嵌段共聚物是聚苯乙烯-b-聚甲基丙烯酸甲酯（PS-b-PMMA），其中 PMMA 嵌段强烈化学吸附到表面，PS 嵌段弱物理吸附。几种 PS-b-PMMA 嵌段共聚物的结构（即不同的 M(n(PMMA))和 M(n)((PS)))从各种溶剂中吸附到具有不同孔径的多孔氧化铝膜上。结果表明，随着孔径的减小，两亲嵌段共聚物的覆盖率显著降低，与相同条件下 PMMA 均聚物的行为相似。然而，对于所有孔径，随着锚固嵌段（PMMA）分子量的增加，覆盖率降低，这与相同条件下 PMMA 均聚物的行为相反。基于锚泊模型及其在非理想体系中的偏差，对覆盖率与相对嵌段尺寸和溶剂质量的依赖性进行了分析。本工作的结果与嵌段共聚物在溶液和表面中的构象、吸附色谱以及溶剂传感器和控制的研究相关。
