Lotito Valeria, Karlušić Marko, Jakšić Milko, Tomić Luketić Kristina, Müller Ulrich, Zambelli Tomaso, Fazinić Stjepko
Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
Laboratory of Biosensors and Bioelectronics, Institute for Biomedical Engineering, ETH Zurich, Gloriastrasse 35, 8092 Zurich, Switzerland.
Nanomaterials (Basel). 2020 Mar 3;10(3):453. doi: 10.3390/nano10030453.
Self-assembly of colloidal monolayers represents a prominent approach to the fabrication of nanostructures. The modification of the shape of colloidal particles is essential in order to enrich the variety of attainable patterns which would be limited by the typical assembly of spherical particles in a hexagonal arrangement. Polymer particles are particularly promising in this sense. In this article, we investigate the deformation of closely-packed polystyrene particles under MeV oxygen ion irradiation at normal incidence using atomic force microscopy (AFM). By developing a procedure based on the fitting of particle topography with quadrics, we reveal a scenario of deformation more complex than the one observed in previous studies for silica particles, where several phenomena, including ion hammering, sputtering, chemical modifications, can intervene in determining the final shape due to the specific irradiation conditions. In particular, deformation into an ellipsoidal shape is accompanied by shrinkage and polymer redistribution with the presence of necks between particles for increasing ion fluence. In addition to casting light on particle irradiation in a regime not yet explored, we present an effective method for the characterization of the colloidal particle morphology which can be applied to describe and understand particle deformation in other regimes of irradiation or with different techniques.
胶体单层的自组装是制造纳米结构的一种重要方法。为了丰富可实现图案的种类，对胶体颗粒形状进行修饰至关重要，因为球形颗粒以六边形排列的典型组装方式会限制图案的种类。从这个意义上讲，聚合物颗粒特别有前景。在本文中，我们使用原子力显微镜（AFM）研究了兆电子伏特氧离子垂直入射时紧密堆积的聚苯乙烯颗粒的变形情况。通过开发一种基于用二次曲面拟合颗粒形貌的程序，我们揭示了一种比先前对二氧化硅颗粒研究中观察到的更为复杂的变形情况，在先前研究中，由于特定的辐照条件，包括离子锤击、溅射、化学修饰等几种现象会参与决定最终形状。特别是，随着离子注量增加，颗粒变形为椭球形的同时会伴随着收缩和聚合物重新分布，颗粒之间会出现颈部。除了揭示尚未探索的辐照条件下颗粒的辐照情况外，我们还提出了一种表征胶体颗粒形态的有效方法，该方法可用于描述和理解其他辐照条件或不同技术下的颗粒变形。
