Nyström Gustav, Arcari Mario, Adamcik Jozef, Usov Ivan, Mezzenga Raffaele
Department of Health Sciences and Technology , ETH Zurich , Schmelzbergstrasse 9 , 8092 Zurich , Switzerland.
Paul Scherrer Institute , 5232 Villigen , Switzerland.
ACS Nano. 2018 Jun 26;12(6):5141-5148. doi: 10.1021/acsnano.8b00512. Epub 2018 May 22.
Understanding how nanostructure and nanomechanics influence physical material properties on the micro- and macroscale is an essential goal in soft condensed matter research. Mechanisms governing fragmentation and chirality inversion of filamentous colloids are of specific interest because of their critical role in load-bearing and self-organizing functionalities of soft nanomaterials. Here we provide a fundamental insight into the self-organization across several length scales of nanocellulose, an important biocolloid system with wide-ranging applications as structural, insulating, and functional material. Through a combined microscopic and statistical analysis of nanocellulose fibrils at the single particle level, we show how mechanically and chemically induced fragmentations proceed in this system. Moreover, by studying the bottom-up self-assembly of fragmented carboxylated cellulose nanofibrils into cholesteric liquid crystals, we show via direct microscopic observations that the chirality is inverted from right-handed at the nanofibril level to left-handed at the level of the liquid crystal phase. These results improve our fundamental understanding of nanocellulose and provide an important rationale for its application in colloidal systems, liquid crystals, and nanomaterials.
了解纳米结构和纳米力学如何在微观和宏观尺度上影响物理材料特性是软凝聚态物质研究的一个重要目标。丝状胶体的破碎和手性反转机制备受关注，因为它们在软纳米材料的承载和自组织功能中起着关键作用。在这里，我们对纳米纤维素在多个长度尺度上的自组织有了基本认识，纳米纤维素是一种重要的生物胶体系统，作为结构、绝缘和功能材料有着广泛应用。通过在单粒子水平上对纳米纤维素原纤维进行微观和统计分析相结合的方法，我们展示了该系统中机械和化学诱导的破碎过程是如何进行的。此外，通过研究破碎的羧基化纤维素纳米原纤维自下而上组装成胆甾型液晶，我们通过直接显微镜观察表明，手性从纳米原纤维水平的右手性反转到液晶相水平的左手性。这些结果增进了我们对纳米纤维素的基本理解，并为其在胶体系统、液晶和纳米材料中的应用提供了重要依据。
