Layer-by-Layer Deposition of All-Nanoparticle Multilayers in Confined Geometries
Layer-by-Layer Deposition of All-Nanoparticle Multilayers in Confined Geometries
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DOI：
10.1021/am2014647
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发表时间：
2012-01-01
影响因子：
9.5
通讯作者：
Cohen, Robert E.
中科院分区：
文献类型：
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作者：
DeRocher, Jonathan P.;Mao, Pan;Cohen, Robert E.
采用含有高纵横比纳米通道的纳米流控阵列作为沉积所有纳米颗粒多层的平台。6纳米二氧化钛和15纳米二氧化硅纳米颗粒的LbL组装在纳米通道中形成了均匀厚度的共形多层膜。这些多层材料本质上是纳米多孔的，其空隙体积分数约为0.5。与相同材料在平面基底上的无约束组装相比，由于表面电荷引起沉积物质的静电损耗，在受限通道几何形状中沉积的多层膜被观察到更薄。此外，随着多层组装的进行，纳米通道发生了系统和可重复的桥接，这是我们在早期涉及聚电解质的工作中没有看到的现象。这种行为归因于相对较弱的纳米颗粒吸附和由此形成的大聚集体。这些结果展示了一种新的途径，通过这种途径，可以将受限的几何形状涂覆，甚至用纳米多孔多层膜桥接，而不需要煅烧或其他组装步骤来将孔隙引入保形涂层中。
Nanofluidic arrays containing high-aspect-ratio nanochannels were used as a platform for the deposition of all nanoparticle multilayers. LbL assembly of 6 nm titania and 15 nm silica nanoparticles resulted in conformal multilayers of uniform thickness throughout the nanochannels. These multilayers are inherently nanoporous with void volume fractions of about 0.5. Compared to unconfined assembly of the same materials on flat substrates, thinner multilayer films were observed for the case of deposition within confined channel geometries because of surface charge-induced electrostatic depletion of the depositing species. Additionally, systematic and reproducible bridging of the nanochannels occurred as multilayer assembly progressed, a phenomenon not seen in our earlier work involving polyelectrolytes. This behavior was attributed to relatively weak nanoparticle adsorption and the resulting formation of large aggregates. These results demonstrate a new route by which confined geometries can be coated and even bridged with a nanoporous multilayer without the need for calcination or other postassembly steps to introduce porosity into the conformal coating.