{"title":"单宁酸对纤维素纳米晶体胆固醇结构的调控","authors":"Hui Jie, Kai Feng, Mengfan Lu and Zhaoxia Jin*, ","doi":"10.1021/acs.langmuir.4c00767","DOIUrl":null,"url":null,"abstract":"<p >The chiral nematic phase structure, formed by the self-assembly of cellulose nanocrystals (CNCs) in an aqueous suspension and maintained in a solid film, shows great potential for optical applications. To achieve complex structures in optical devices, it is crucial to subject CNCs to specific shearing processes, such as spinning and printing. Understanding the structural and property changes of the CNC liquid crystal phase in these processes is of utmost importance. In this study, we investigated the effect of adding tannic acid (TA) on the rheological properties and cholesteric phase structures of CNCs/TA mixed suspensions. By calculating the surface site interaction points, we observed that TA can adsorb onto the surface of CNC rods in suspensions through hydrogen bonding. Through characterization techniques, such as polarized optical microscopy, rheology, and synchrotron SAXS, we examined the effects of TA addition on the microstructure and rheological properties of the CNC liquid crystal phase and clarified the change relating to the system composition. Under the same CNC concentration, the volume fraction of the anisotropic phase, the pitch, and the rod spacing of the cholesteric phase were not significantly affected by the addition of TA. However, the system viscosity was significantly reduced with the appropriate amount of TA (2 wt %), in a wide range of CNC concentrations (up to 15 wt % CNCs). The flow indexes (<i>n</i>) in Region I and Region III of steady-state shear curves of CNCs/TA systems (11–15 wt % CNCs) were compared. Moreover, we introduced the well-established theoretical models for liquid crystal polymers to tentatively interpret Region I of the CNCs/TA cholesteric phase and realized that increased numbers of smaller cholesteric-phase domains in the CNCs/TA system and interfacial modification by TA may contribute to the fluidity change. 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However, the system viscosity was significantly reduced with the appropriate amount of TA (2 wt %), in a wide range of CNC concentrations (up to 15 wt % CNCs). The flow indexes (<i>n</i>) in Region I and Region III of steady-state shear curves of CNCs/TA systems (11–15 wt % CNCs) were compared. Moreover, we introduced the well-established theoretical models for liquid crystal polymers to tentatively interpret Region I of the CNCs/TA cholesteric phase and realized that increased numbers of smaller cholesteric-phase domains in the CNCs/TA system and interfacial modification by TA may contribute to the fluidity change. 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引用次数: 0
摘要
纤维素纳米晶体(CNCs)在水悬浮液中自组装形成手性向列相结构,并保持在固体薄膜中,这种结构在光学应用方面显示出巨大的潜力。要在光学设备中实现复杂的结构,必须对 CNC 进行特定的剪切处理,如纺丝和印刷。了解 CNC 液晶相在这些过程中的结构和性质变化至关重要。在本研究中,我们研究了添加单宁酸(TA)对 CNC/TA 混合悬浮液的流变特性和胆甾相结构的影响。通过计算表面位点相互作用点,我们观察到单宁酸可通过氢键吸附到悬浮液中的 CNC 棒表面。通过偏振光学显微镜、流变学和同步辐射 SAXS 等表征技术,我们研究了添加 TA 对 CNC 液晶相微观结构和流变特性的影响,并阐明了其与体系组成的变化关系。在相同的 CNC 浓度下,各向异性相的体积分数、螺距和胆甾相的杆间距均未受到添加 TA 的显著影响。然而,在较宽的 CNC 浓度范围内(最高达 15 wt % CNC),适量的 TA(2 wt %)会明显降低体系粘度。我们比较了 CNC/TA 系统(11-15 wt % CNCs)稳态剪切曲线 I 区和 III 区的流动指数(n)。此外,我们还引入了成熟的液晶聚合物理论模型来初步解释 CNCs/TA 胆甾相的区域 I,并认识到 CNCs/TA 体系中较小的胆甾相结构域数量的增加以及 TA 对界面的修饰可能是流动性变化的原因。偏振光学显微镜观察验证了 CNC/TA 体系畴纹理的特征。
Modulation of Tannic Acid on the Cholesteric Structure of Cellulose Nanocrystals
The chiral nematic phase structure, formed by the self-assembly of cellulose nanocrystals (CNCs) in an aqueous suspension and maintained in a solid film, shows great potential for optical applications. To achieve complex structures in optical devices, it is crucial to subject CNCs to specific shearing processes, such as spinning and printing. Understanding the structural and property changes of the CNC liquid crystal phase in these processes is of utmost importance. In this study, we investigated the effect of adding tannic acid (TA) on the rheological properties and cholesteric phase structures of CNCs/TA mixed suspensions. By calculating the surface site interaction points, we observed that TA can adsorb onto the surface of CNC rods in suspensions through hydrogen bonding. Through characterization techniques, such as polarized optical microscopy, rheology, and synchrotron SAXS, we examined the effects of TA addition on the microstructure and rheological properties of the CNC liquid crystal phase and clarified the change relating to the system composition. Under the same CNC concentration, the volume fraction of the anisotropic phase, the pitch, and the rod spacing of the cholesteric phase were not significantly affected by the addition of TA. However, the system viscosity was significantly reduced with the appropriate amount of TA (2 wt %), in a wide range of CNC concentrations (up to 15 wt % CNCs). The flow indexes (n) in Region I and Region III of steady-state shear curves of CNCs/TA systems (11–15 wt % CNCs) were compared. Moreover, we introduced the well-established theoretical models for liquid crystal polymers to tentatively interpret Region I of the CNCs/TA cholesteric phase and realized that increased numbers of smaller cholesteric-phase domains in the CNCs/TA system and interfacial modification by TA may contribute to the fluidity change. The feature of the domain texture of CNCs/TA systems is verified by polarized optical microscopy observations.
期刊介绍:
Langmuir is an interdisciplinary journal publishing articles in the following subject categories:
Colloids: surfactants and self-assembly, dispersions, emulsions, foams
Interfaces: adsorption, reactions, films, forces
Biological Interfaces: biocolloids, biomolecular and biomimetic materials
Materials: nano- and mesostructured materials, polymers, gels, liquid crystals
Electrochemistry: interfacial charge transfer, charge transport, electrocatalysis, electrokinetic phenomena, bioelectrochemistry
Devices and Applications: sensors, fluidics, patterning, catalysis, photonic crystals
However, when high-impact, original work is submitted that does not fit within the above categories, decisions to accept or decline such papers will be based on one criteria: What Would Irving Do?
Langmuir ranks #2 in citations out of 136 journals in the category of Physical Chemistry with 113,157 total citations. The journal received an Impact Factor of 4.384*.
This journal is also indexed in the categories of Materials Science (ranked #1) and Multidisciplinary Chemistry (ranked #5).