Department of Industrial and Materials Science, Division of Engineering Materials, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
Wallenberg Wood Science Center (WWSC), Chalmers, SE-412 96 Gothenburg, Sweden.
Langmuir. 2023 May 9;39(18):6433-6446. doi: 10.1021/acs.langmuir.3c00210. Epub 2023 Apr 25.
Attractive (non-self-assembling) aqueous cellulose nanocrystal (CNC) suspensions were topologically tailored into isotropic gels through the surface grafting of dialkyl groups. We thus focus on the influence of CNC concentration, including for pristine CNC, surface linker branching, branching degree, and the influence of side group size and branch-on-branch surface-grafted groups. The resulting mobility and strength of interaction in particle-particle interaction mediated by the surface groups was investigated from a rheological point of view. The emphasis is on nonlinear material parameters from Fourier-transform rheology and stress decomposition analysis. The results show that nonlinear material parameters are more sensitive than linear viscoelastic parameters to the onset of weakly interconnected networks in pristine CNC isotropic suspensions. All surface-modified CNC suspensions resulted in isotropic gels. The nonlinear material parameters were found to be broadly sensitive to CNC concentration, branching, degree of branching and surface-grafted linkers' length. However, the length of the grafted chains and the degree of branching were the primary factors influencing the nonlinear material response. Furthermore, the results showed evidence of two strain amplitude ranges with distinct nonlinear signatures that could be attributed to the disruption of weak network connection points and to distortions of more dense (aggregate) network regions, respectively.
具有吸引力（非自组装）的水性纤维素纳米晶体（CNC）悬浮液通过二烷基基团的表面接枝被拓扑地修饰成各向同性凝胶。因此，我们关注 CNC 浓度的影响，包括原始 CNC、表面连接体支化、支化度以及侧基大小和支化表面接枝基团的影响。从流变学的角度研究了由表面基团介导的颗粒间相互作用的迁移率和相互作用强度。重点是非线性材料参数从傅里叶变换流变学和应力分解分析。结果表明，非线性材料参数比线性粘弹性参数对原始 CNC 各向同性悬浮液中弱互连网络的出现更为敏感。所有表面修饰的 CNC 悬浮液都形成了各向同性凝胶。发现非线性材料参数对 CNC 浓度、支化度、支化度和表面接枝连接体长度均敏感。然而，接枝链的长度和支化度是影响非线性材料响应的主要因素。此外，结果表明存在两个应变幅度范围，具有明显的非线性特征，这可能归因于弱网络连接点的破坏和更密集（聚集）网络区域的变形。
