Engineering Material Synthesis through Nano-Interfaces
基于调控液态金属颗粒纳米界面调控材料合成的新方法
Martin Thuo
ABSRACT
Advances in flexible electronics and wearable electronics demand new low temperature solders while a changing climate calls for new affordable approaches to catalyst design or corrosion protection. We inferred that low-temperature solders can be obtained by remote melting of a metal and frustrating solidification while corrosion and catalysis can be addressed through surface engineering. Our group couples fundamental surface thermodynamics and autonomous processes to address these grand challenges. This talk explores; i) how complexity in composition of nanoscale (~5 nm) passivating metal oxides can be used to frustrate solidification of metallic particles leading to significant undercooling. Resulting metal particles are used as heat-free solders or formulated to metal inks for printing conductive traces on textured soft matter like biological tissues, plants, or plastics. Given that solidification occurs upon fracture of the oxide, incorporating these particles in a polymer matrix gives self-stiffening material. ii) how understanding surface plasticity of the underlying liquid-oxide surface enables thermally-triggered distribution of different components of the alloy to the surface in a tiered manner – the so-called chameleon metals. iii) where the passivating oxide is used as a reactive surface, organometallic components can be made and either locally deposited or in situ self-assembled through a polymerization-induced self-assembly of 1D organometallic polymers. This process being a living polymerization, ad infinitum growth leads to high aspect ratio organometallic nanomaterials. Post-synthesis ablation of the ligands leads to carbon-coated metal oxides that show catalytic activity atypical of the parent oxide. In conclusion, a perspective on other potential pathways that can be explored based on our understanding of the underlying surface properties will be given.
柔性可穿戴电子器件的发展对低温焊接技术有着高要求，尤其在气候变化的时代背景下，研发新型廉价的金属烧结和防蚀方法显得更加迫切。与此同时，传统催化材料制备也通常是不够环保的高耗能过程。因此，我们研发了基于液态金属颗粒可控固化的低温烧结及防蚀方法，同时实现了高效可控金属氧化物催化剂制备。界面热力学基础与自发过程紧密结合是指导我们解决上诉问题的基本原理，本次报告将从以下三点对此加以详述：
1.包裹过冷金属颗粒的钝化氧化层（5纳米左右）对于抑制过冷颗粒的固化有着重要作用。通过控制钝化氧化层的复杂成分，过冷金属颗粒可在室温保持液态。若将此氧化层加以破坏，液态金属从氧化壳中流出固化，从而实现常温焊接。因此，其可被制作为“金属墨水”在柔性材料表面涂绘，可作用的柔性材料包括但不限于生物组织，植物，和塑料。此外，将过冷金属颗粒与聚合物基体混合可制备自固化复合材料。
2.位于钝化氧化层之下的固-液相界面具有复杂的氧化层-液态合金结构，热力学调控这一弹性界面可获得组分分层的复杂金属氧化物表面（变色龙金属）。
3.液态金属颗粒可用于生成一维有机金属聚合基体，这些基体可局部或原位自聚合为有机金属聚合材料。该动态聚合过程将生成具有极大长宽比的有机金属纳米材料。通过调控对此金属聚合物纳米材料的灼烧后处理工艺，部分有机材料将以碳单质形式覆盖于所得金属氧化物表面。这种碳参杂的金属氧化物材料的催化属性将异与其本源金属氧化物。
综上，基于我们对界面性质的理解，该报告将给出基于调控液态金属颗粒纳米界面以调控材料合成的新展望。
BIOGRAPHY
Martin Thuo is an Associate professor at Iowa State University where he leads the soft materials and matter transport laboratory. The main theme of the group is to develop frugal and efficient material synthesis and processing methods. For example, the adaptation of complex autonomous composition ordering across nanoscale passivating oxides to engineer structure, composition, and texture of microscale metallic particles. This approach has led to development of tunable ultra-hydrophobic metal coatings showing either the rose petal effect or the lotus effect, low temperature solders, ambient solid metal printing on biological surfaces, self-stiffening composites, and so-called chameleon metals. Understanding surface structure and their plasticity has also enabled new approaches to synthesis of porous high-aspect ratio nanomaterials like mixed metal oxides for CO2 reduction.
马丁∙索副教授任职于爱荷华州立大学，主要研究简洁高效的柔性材料制备与物质传输。马丁∙索副教授的研究重点为通过研究金属微米颗粒的复杂氧化物-金属界面实现对金属颗粒成分，结构和表面的自发调控。所得材料课被用于制备疏水性质可调控的金属超疏水表面，金属常温烧结与生物表面金属印刷，自硬化复合材料以及“变色龙金属”。通过对该弹性界面的进一步研究，多孔高长宽比混合金属氧化物纳米材料得以制备并可被应用于二氧化碳还原反应中。
马丁∙索博士所获奖项包括哈佛大学玛丽费塞尔奖学金,博莱克·威奇developing a world of difference奖, 爱荷华州立大学出色研究奖, 爱荷华大学Lynn-Anderson奖与ACS nano新星奖等。