Auh Yang Hyun, Neal Natalie N, Arole Kailash, Regis Nolan A, Nguyen Tran, Ogawa Shuichi, Tsuda Yasutaka, Yoshigoe Akitaka, Radovic Miladin, Green Micah J, Yamaguchi Hisato, Lutkenhaus Jodie L
Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States.
Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77840, United States.
ACS Appl Mater Interfaces. 2025 May 28;17(21):31392-31402. doi: 10.1021/acsami.5c03632. Epub 2025 May 13.
MXenes are a promising class of 2D nanomaterials and are of particular interest for gas barrier applications due to their high aspect ratio. However, MXene nanosheets naturally bear a negative charge, which prevents assembly with negatively charged polymers, such as polyacrylic acid (PAA), into gas barrier coatings. Here, we present MXene- and PAA-based layer-by-layer (MXene/PAA LbL) multilayers formed by leveraging hydrogen bonding interactions. When assembled in acidic conditions, MXene/PAA LbL multilayers exhibit conformal, pinhole-free, nacre-like structures. The MXene/PAA LbL multilayers yield high blocking capability and low permeability (0.14 ± 0.01 cc·mm·m·day·MPa) for hydrogen gas which is over 9000 times lower than uncoated niobium (Nb) substrate. These nacre-like structures are also electronically conductive (σ, up to 370 ± 30 S cm). Because these multilayers utilize hydrogen bonding, their properties are highly sensitive to the pH of the assembly and its external environment. Specifically, the reversible deconstruction of these multilayers under basic conditions is experimentally verified. This study shows that hydrogen bonding interactions can be leveraged to form MXene LbL multilayers as gas barriers, electronically conductive coatings, and deconstructable thin films via pH control.
MXenes是一类很有前景的二维纳米材料，由于其高纵横比，在气体阻隔应用中特别受关注。然而，MXene纳米片天然带有负电荷，这阻碍了它与带负电荷的聚合物（如聚丙烯酸（PAA））组装成气体阻隔涂层。在此，我们展示了通过利用氢键相互作用形成的基于MXene和PAA的逐层（MXene/PAA LbL）多层膜。在酸性条件下组装时，MXene/PAA LbL多层膜呈现出保形、无针孔、类似珍珠母的结构。MXene/PAA LbL多层膜对氢气具有高阻隔能力和低渗透率（0.14±0.01 cc·mm·m·day·MPa），比未涂层的铌（Nb）基板低9000倍以上。这些类似珍珠母的结构也是导电的（电导率σ，高达370±30 S cm）。由于这些多层膜利用了氢键，它们的性能对组装时的pH值及其外部环境高度敏感。具体而言，通过实验验证了这些多层膜在碱性条件下的可逆解构。这项研究表明，通过pH控制，可以利用氢键相互作用形成MXene LbL多层膜作为气体阻隔层、导电涂层和解构性薄膜。
