Munier Pierre, Hadi Seyed Ehsan, Segad Mo, Bergström Lennart
Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, 10691, Sweden.
Wallenberg Wood Science Center, Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, 10691, Sweden.
Soft Matter. 2022 Jan 5;18(2):390-396. doi: 10.1039/d1sm00837d.
The development of robust production processes is essential for the introduction of advanced materials based on renewable and Earth-abundant resources. Cellulose nanomaterials have been combined with other highly available nanoparticles, in particular clays, to generate multifunctional films and foams. Here, the structure of dispersions of rod-like cellulose nanocrystals (CNC) and montmorillonite nanoplatelets (MNT) was probed using small-angle X-ray scattering within a rheological cell (Rheo-SAXS). Shear induced a high degree of particle orientation in both the CNC-only and CNC:MNT composite dispersions. Relaxation of the shear-induced orientation in the CNC-only dispersion decayed exponentially and reached a steady-state within 20 seconds, while the relaxation of the CNC:MNT composite dispersion was found to be strongly retarded and partially inhibited. Viscoelastic measurements and Guinier analysis of dispersions at the shear rate of 0.1 s showed that the addition of MNT promotes gel formation of the CNC:MNT composite dispersions. A better understanding of shear-dependent assembly and orientation of multi-component nanoparticle dispersions can be used to process materials with improved mechanical and functional properties.
稳健生产工艺的开发对于引入基于可再生且储量丰富的地球资源的先进材料至关重要。纤维素纳米材料已与其他高可用性的纳米颗粒，特别是粘土相结合，以制备多功能薄膜和泡沫材料。在此，使用流变池小角X射线散射（Rheo-SAXS）对棒状纤维素纳米晶体（CNC）和蒙脱石纳米片（MNT）的分散体结构进行了探测。剪切作用在仅含CNC的分散体以及CNC:MNT复合分散体中均诱导了高度的颗粒取向。仅含CNC的分散体中剪切诱导取向的松弛呈指数衰减，并在20秒内达到稳态，而CNC:MNT复合分散体的取向松弛则被强烈延迟且部分受到抑制。在0.1 s的剪切速率下对分散体进行的粘弹性测量和吉尼尔分析表明，添加MNT促进了CNC:MNT复合分散体的凝胶形成。更好地理解多组分纳米颗粒分散体的剪切依赖性组装和取向可用于加工具有改善的机械和功能性能的材料。
