Xu Wenyang, Werzer Oliver, Spiliopoulos Panagiotis, Mihhels Karl, Jiang Qixiang, Meng Zhuojun, Tao Han, Resel Roland, Tammelin Tekla, Pettersson Torbjörn, Kontturi Eero
Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland.
Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, Teknikringen 56, SE-10044 Stockholm, Sweden.
ACS Appl Mater Interfaces. 2024 Jun 26;16(25):32874-32885. doi: 10.1021/acsami.4c06182. Epub 2024 Jun 11.
Polymer coating to substrates alters surface chemistry and imparts bulk material functionalities with a minute thickness, even in nanoscale. Specific surface modification of a substate usually requires an active substrate that, e.g., undergoes a chemical reaction with the modifying species. Here, we present a generic method for surface modification, namely, solid-state adsorption, occurring purely by entropic strive. Formed by heating above the melting point or glass transition and subsequent rinsing of the excess polymer, the emerging ultrathin (<10 nm) layers are known in fundamental polymer physics but have never been utilized as building blocks for materials and they have never been explored on soft matter substrates. We show with model surfaces as well as bulk substrates, how solid-state adsorption of common polymers, such as polystyrene and poly(lactic acid), can be applied on soft, cellulose-based substrates. Our study showcases the versatility of solid-state adsorption across various polymer/substrate systems. Specifically, we achieve proof-of-concept hydrophobization on flexible cellulosic substrates, maintaining irreversible and miniscule adsorption yet with nearly 100% coverage without compromising the bulk material properties. The method can be considered generic for all polymers whose and are below those of the to-be-coated adsorbed layer, and whose integrity can withstand the solvent leaching conditions. Its full potential has broad implications for diverse materials systems where surface coatings play an important role, such as packaging, foldable electronics, or membrane technology.
聚合物涂层作用于基底会改变表面化学性质，并以极小的厚度赋予材料整体功能，即便在纳米尺度也是如此。对基底进行特定的表面改性通常需要活性基底，例如，该基底要与改性物质发生化学反应。在此，我们提出一种通用的表面改性方法，即固态吸附，它纯粹是由熵驱动产生的。通过在熔点或玻璃化转变温度以上加热，随后冲洗掉多余的聚合物而形成的超薄（<10纳米）层在基础聚合物物理学中是已知的，但从未被用作材料的构建单元，也从未在软物质基底上进行过探索。我们通过模型表面以及块状基底展示了常见聚合物（如聚苯乙烯和聚乳酸）的固态吸附如何应用于柔软的、基于纤维素的基底上。我们的研究展示了固态吸附在各种聚合物/基底系统中的多功能性。具体而言，我们在柔性纤维素基底上实现了概念验证的疏水化，保持了不可逆且微小的吸附，但覆盖率接近100%，同时又不影响块状材料的性能。对于所有玻璃化转变温度和熔点低于待涂覆吸附层，且其完整性能够承受溶剂浸出条件的聚合物，该方法都可被视为通用方法。其全部潜力对于表面涂层起重要作用的各种材料系统具有广泛影响，如包装、可折叠电子产品或膜技术等。
