Preventing the coffee-ring effect and aggregate sedimentation by in situ gelation of monodisperse materials.
Preventing the coffee-ring effect and aggregate sedimentation by in situ gelation of monodisperse materials.
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DOI：
10.1039/c8sc03302a
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发表时间：
2018-10-21
期刊：
影响因子：
8.4
通讯作者：
Plumeré N
中科院分区：
文献类型：
--
作者：
Li H;Buesen D;Williams R;Henig J;Stapf S;Mukherjee K;Freier E;Lubitz W;Winkler M;Happe T;Plumeré N
通过单分散结构单元的原位凝胶化，实现了通过滴铸组装的多功能膜的微观均匀性和长程内聚性。滴铸和喷墨印刷实际上是在表面上沉积活性材料的最通用和最具成本效益的方法。然而，与咖啡环效应相关的缺点以及涂层材料的不受控制的聚集阻碍了这些方法用于需要高度控制膜性能的应用。我们现在报告一个简单的方法的基础上共价交联的单分散材料，使薄膜形成均匀的厚度和宏观凝聚力。咖啡环效应通过经由硫代乙酸盐-二硫化物转变触发涂层材料的凝胶化来阻止，所述硫代乙酸盐-二硫化物转变抵消由蒸发引起的毛细管力。通过单分散结构单元防止聚集，确保所得凝胶抵抗沉降直到完全液滴干燥。这种组合策略在100 nm至10 μm范围内的所得薄膜厚度中产生了前所未有的均匀性水平。此外，宏观尺度的凝聚力被保存证明了矩阵内的长程电荷转移。我们强调了这种方法与生物电催化剂对H2和NADPH氧化的影响。与传统方法相比，由于对膜内聚性和厚度均匀性的高度控制，在催化剂载量低约10倍的情况下达到峰值催化性能，从而在催化剂利用方面设定了新的基准。
Microscale uniformity and long-range cohesion in multi-functional films assembled through drop-casting is realized by in situ gelation of monodisperse building blocks. Drop-casting and inkjet printing are virtually the most versatile and cost-effective methods for depositing active materials on surfaces. However, drawbacks associated with the coffee-ring effect, as well as uncontrolled aggregation of the coating materials, have impeded the use of these methods for applications requiring high control of film properties. We now report on a simple method based on covalent cross-linking of monodisperse materials that enables the formation of thin films with homogeneous thicknesses and macroscale cohesion. The coffee-ring effect is impeded by triggering gelation of the coating materials via a thioacetate–disulfide transition which counterbalances the capillary forces induced by evaporation. Aggregates are prevented by monodisperse building blocks that ensure that the resulting gel resists sedimentation until complete droplet drying. This combined strategy yields an unprecedented level of homogeneity in the resulting film thickness in the 100 nm to 10 μm range. Moreover, macroscale cohesion is preserved as evidenced by the long-range charge transfer within the matrix. We highlight the impact of this method with bioelectrocatalysts for H2 and NADPH oxidation. Peak catalytic performances are reached at about 10-fold lower catalyst loading compared to conventional approaches owing to the high control on film cohesion and thickness homogeneity, thus setting new benchmarks in catalyst utilization.
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