Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland.
Department of Pure and Applied Chemistry, University of Strathclyde, Thomas Graham Building, 295 Cathedral Street, Glasgow G1 1XL, United Kingdom.
Biomacromolecules. 2021 May 10;22(5):2067-2080. doi: 10.1021/acs.biomac.1c00183. Epub 2021 Apr 26.
Cellulose nanocrystals (CNCs) can spontaneously self-assemble into chiral nematic (cn) structures, similar to natural cholesteric organizations. The latter display highly dissipative fracture propagation mechanisms given their "brick" (particles) and "mortar" (soft matrix) architecture. Unfortunately, CNCs in liquid media have strong supramolecular interactions with most macromolecules, leading to aggregated suspensions. Herein, we describe a method to prepare nanocomposite materials from chiral nematic CNCs (cn-CNCs) with strongly interacting secondary components. Films of cn-CNCs were infiltrated at various loadings with strongly interacting silk proteins and bovine serum albumin. For comparison and to determine the molecular weight range of macromolecules that can infiltrate cn-CNC films, they were also infiltrated with a range of poly(ethylene glycol) polymers that do not interact strongly with CNCs. The extent and impact of infiltration were evaluated by studying the optical reflection properties of the resulting hybrid materials (UV-vis spectroscopy), while fracture dissipation mechanisms were observed via electron microscopy. We propose that infiltration of cn-CNCs enables the introduction of virtually any secondary phase for nanocomposite formation that is otherwise not possible using simple mixing or other conventional approaches.
纤维素纳米晶体（CNC）可以自发自组装成手性向列（cn）结构，类似于天然胆甾型组织。鉴于其“砖”（颗粒）和“灰浆”（软基质）结构，后者表现出高度耗散的断裂传播机制。不幸的是，在液体介质中的 CNC 与大多数大分子具有强烈的超分子相互作用，导致聚集的悬浮液。在此，我们描述了一种方法，可从具有强烈相互作用的次级成分的手性向列 CNC（cn-CNC）制备纳米复合材料。cn-CNC 膜以各种负载量用强烈相互作用的丝蛋白和牛血清白蛋白进行渗透。为了进行比较并确定可以渗透 cn-CNC 膜的大分子的分子量范围，还将其与一系列不与 CNC 强烈相互作用的聚（乙二醇）聚合物进行渗透。通过研究所得混合材料的光学反射特性（UV-vis 光谱）评估了渗透的程度和影响，而通过电子显微镜观察了断裂耗散机制。我们提出，cn-CNC 的渗透可实现几乎任何次级相的引入，否则使用简单的混合或其他常规方法是不可能的。
