Morits Maria, Lepo Anneli, Farooq Muhammad, Österberg Monika
School of Chemical Engineering, Department of Bioproducts and Biosystems, Aalto University, Vuorimiehentie 1, 02150 Espoo, Finland.
R&D and Technology, Kemira Oyj, P.O. Box 44, 02271 Espoo, Finland.
ACS Appl Mater Interfaces. 2025 Jun 25;17(25):37068-37080. doi: 10.1021/acsami.5c05234. Epub 2025 May 14.
Dispersion coatings are promising barrier solutions for fiber-based packaging. Among the advantages of water-borne dispersion coatings are easier repulping, recyclability, and composting of fiber packaging compared to other types of coatings. Dispersion coatings can replace fluorochemicals, which pose health hazards in food packaging. The film formation mechanism is the basis for developing barrier dispersion coatings, as a flawless coating structure is a prerequisite for good barrier properties. However, developing cost-efficient dispersion coatings with good film formation properties combined with good barrier and converting properties remains challenging. In this work, we implement atomic force microscopy (AFM) imaging in air and water to study the film formation mechanisms at the nanoscale of a series of styrene-acrylic copolymer barrier dispersion coatings with different surfactant/stabilizer systems and correlate these findings with the barrier properties of the coatings determined by common methods. In particular, AFM is used to characterize the morphology of the films prepared under different conditions, illuminating the effect of both the core polymer chemistry and stabilizing system on film formation. The relationship between the film morphologies and barrier properties of the coatings is subsequently revealed. In addition to AFM, another surface-sensitive technique, quartz crystal microbalance with dissipation monitoring (QCM-D), is used to evaluate the interaction of the dispersion coating particles with cellulosic substrates. The significant impact of the chemical structure of the stabilizer system of the dispersion on the barrier properties of coatings is unraveled by using this approach. Overall, this work reveals the predictive capacity of the AFM technique for evaluating the barrier properties of dispersion coatings.
分散体涂层是基于纤维的包装中很有前景的阻隔解决方案。与其他类型的涂层相比，水性分散体涂层的优势在于纤维包装更容易再制浆、可回收利用以及可堆肥。分散体涂层可以替代在食品包装中会对健康造成危害的含氟化合物。成膜机理是开发阻隔性分散体涂层的基础，因为完美的涂层结构是具有良好阻隔性能的前提条件。然而，开发兼具良好成膜性能、阻隔性能和加工性能且成本效益高的分散体涂层仍然具有挑战性。在这项工作中，我们在空气和水中实施原子力显微镜（AFM）成像，以研究一系列具有不同表面活性剂/稳定剂体系的苯乙烯-丙烯酸共聚物阻隔性分散体涂层在纳米尺度上的成膜机理，并将这些发现与通过常用方法测定的涂层阻隔性能相关联。特别是，AFM用于表征在不同条件下制备的薄膜的形态，阐明核心聚合物化学和稳定体系对成膜的影响。随后揭示了涂层的薄膜形态与阻隔性能之间的关系。除了AFM之外，另一种表面敏感技术——带耗散监测的石英晶体微天平（QCM-D），用于评估分散体涂层颗粒与纤维素基材的相互作用。通过使用这种方法，揭示了分散体稳定剂体系的化学结构对涂层阻隔性能的重大影响。总体而言，这项工作揭示了AFM技术在评估分散体涂层阻隔性能方面的预测能力。
