Bioinspired Manufacturing of Aerogels with Precisely Manipulated Surface Microstructure through Controlled Local Temperature Gradients
Bioinspired Manufacturing of Aerogels with Precisely Manipulated Surface Microstructure through Controlled Local Temperature Gradients
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通过受控局部温度梯度仿生制造具有精确操纵表面微观结构的气凝胶
DOI：
10.1021/acsami.0c19087
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发表时间：
2021
影响因子：
9.5
通讯作者：
Lin, Dong
中科院分区：
文献类型：
--
作者：
Tetik, Halil;Feng, Dan;Oxandale, Samuel W.;Yang, Guang;Zhao, Keren;Feist, Katelyn;Shah, Nasrullah;Liao, Yiliang;Leseman, Zayd C.;Lin, Dong
冷冻铸造工艺由于其通用性和环境友好性而被广泛用于制造气凝胶。该方法提供了多种工具，通过操纵冷冻动力学和前体悬浮液化学，以整体方式定制最终产品的整个结晶形态。然而，具有非单片微结构形态的气凝胶，具有位于气凝胶的某些区域中的各种尺寸的孔，是某些应用例如受控药物递送、骨组织工程、细胞外模拟、选择性液体吸附、固定化催化剂和分离器高度期望的。此外，由具有预先设计的尺寸、形状和位置的微孔组成的气凝胶可以在气凝胶设计中开辟新的范例并导致新的应用。在这项研究中，一个通用的制造方法来控制气凝胶表面上的孔的尺寸，形状和位置，通过应用在单向冷冻铸造过程中使用的基板上的局部导热性的精确控制。利用我们的方法，我们通过沉积图案化的光致抗蚀剂聚合物特征在衬底上创建了图案化的低热导率和高热导率区域。光致抗蚀剂聚合物具有低得多的热导率，这导致与硅衬底相比更低的冷却/冻结速率。图案化的导热性产生了设计的温度分布，从而产生具有更快和更慢冻结速率的局部区域。从本质上讲，我们制造的气凝胶，其表面上的多孔形态是图案化基底在微孔的尺寸和位置方面的复制品。使用相同的基底，我们进一步展示了具有精确控制的表面微结构的3D打印气凝胶的可能性。据我们所知，这是第一个报道具有微形态的气凝胶的研究（例如，尺寸、形状和位置），其通过衬底的局部控制的热导率精确控制。
The freeze casting process has been widely used for fabricating aerogels due to its versatile and environmentally friendly nature. This process offers a variety of tools to tailor the entire micropore morphology of the final product in a monolithic fashion through manipulation of the freezing kinetics and precursor suspension chemistry. However, aerogels with nonmonolithic micropore morphologies, having pores of various sizes located in certain regions of the aerogels, are highly desired by certain applications such as controlled drug-delivery, bone tissue engineering, extracellular simulation, selective liquid sorption, immobilized catalysts, and separators. Furthermore, aerogels composed of micropores with predesigned size, shape, and location can open up a new paradigm in aerogel design and lead to new applications. In this study, a general manufacturing approach is developed to control the size, shape, and location of the pores on the aerogel surface by applying a precise control on the local thermal conductivity of the substrate used in a unidirectional freeze casting process. With our method, we created patterned low and high thermal conductivity regions on the substrate by depositing patterned photoresist polymer features. The photoresist polymer has a much lower thermal conductivity, which resulted in lower cooling/freezing rates compared to the silicon substrate. Patterned thermal conductivity created a designed temperature profile yielding to local regions with faster and slower freezing rates. Essentially, we fabricated aerogels whose micropore morphology on their surface was a replica of the patterned substrates in terms of size and location of the micropores. Using the same substrates, we further showed the possibility of 3D printed aerogels with precisely controlled, surface micropore morphologies. To the best of our knowledge, this is the first study that reports aerogels having micropore morphologies (e.g., size, shape, and location) that are precisely controlled through locally controlled thermal conductivity of the substrates.