Hu Xiaobo, Lyon L Andrew
School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
Schmid College of Science and Technology, Chapman University, Orange, California 92866, United States.
ACS Macro Lett. 2015 Mar 17;4(3):302-307. doi: 10.1021/acsmacrolett.5b00016. Epub 2015 Feb 18.
Thin films composed entirely of microgel building blocks were fabricated using two kinds of self-cross-linked, oppositely charged microgels, via centrifugal deposition. Atomic force microscopy studies revealed that both microgels form very thin monolayer films due to a large degree of microgel deformation during deposition. Meanwhile, centrifugal deposition from a mixture of these two kinds of microgels resulted in the formation of microgel bilayers with a total thickness of around 20 nm. The film thickness increased linearly with the deposition time. Additionally, isotropic stretching/release by heating/cooling of the dried microgel films generated complicated buckling patterns, while anisotropic (uniaxial) stretching/release resulted in parallel buckling perpendicular to the stretching direction. The damage caused by anisotropic stretching and 100 °C treatment can be healed by addition of water, while damage caused via treatment at 150 °C cannot be healed due to the occurrence of polymer cross-linking, which inhibits the mobility of the microgel building blocks.
通过离心沉积法，使用两种自交联、带相反电荷的微凝胶制备了完全由微凝胶构建块组成的薄膜。原子力显微镜研究表明，由于沉积过程中微凝胶的大量变形，两种微凝胶均形成了非常薄的单层膜。同时，由这两种微凝胶的混合物进行离心沉积导致形成了总厚度约为20 nm的微凝胶双层。膜厚度随沉积时间线性增加。此外，干燥的微凝胶薄膜通过加热/冷却进行各向同性拉伸/释放会产生复杂的屈曲图案，而各向异性（单轴）拉伸/释放则导致垂直于拉伸方向的平行屈曲。各向异性拉伸和100°C处理造成的损伤可通过加水修复，而150°C处理造成的损伤由于发生聚合物交联而无法修复，这会抑制微凝胶构建块的流动性。
