Optical Properties of Self‐Assembled Cellulose Nanocrystals Films Suspended at Planar–Symmetrical Interfaces

Hierarchically structured materials comprising rod‐like, chiral, nanoparticles are commonly encountered in nature as they can form assemblies with exceptional optical and mechanical characteristics. These include cellulose nanocrystals (CNCs), which have a large potential for the fabrication of bioinspired materials mimicking those advanced properties. Fine‐tuning the optomechanical properties of assemblies obtained from CNCs hinges on the transformations from suspensions of liquid crystals to long‐range order in the dry state. So far, associated transitions have been studied using trivial interfaces such as planar substrates. Such transitions are explored as they evolve onto meshed supports. The meshed substrate offers a complex topology, as is encountered in nature, for the formation of CNCs films. The CNCs self‐assembly occurs under confinement and support of the framework bounding the mesh openings. This leads to coexisting suspended and supported nanoparticle layers exhibiting nematic and/or chiral nematic order. Optical microscopy combined with crossed polarizers indicate that the formation of the suspended films occurs via intermediate gelation or kinetic arrest of CNCs across the mesh's open areas. The formation of self‐standing, ultrathin films of CNCs with tunable optical properties, such as selective reflections in the visible range (structural color), is demonstrated by using the presented simple and scalable approach.     

Freestanding hierarchical porous carbon film derived from hybrid nanocellulose for high-power supercapacitors

Nanocellulose is a sustainable and eco-friendly nanomaterial derived from renewable biomass.In this study,we utilized the structural advantages of two types of nanocellulose and fabricated freestanding carbonized hybrid nanocellulose films as electrode materials for supercapacitors.The long cellulose nanofibrils (CNFs) formed a macroporous framework,and the short cellulose nanocrystals were assembled around the CNF framework and generated micro/mesopores.This two-level hierarchical porous structure was successfully preserved during carbonization because of a thin atomic layer deposited (ALD) Al2O3 conformal coating,which effectively prevented the aggregation of nanocellulose.These carbonized,partially graphitized nanocellulose fibers were interconnected,forming an integrated and highly conductive network with a large specific surface area of 1,244 m2·g-1.The two-level hierarchical porous structure facilitated fast ion transport in the film.When tested as an electrode material with a high mass loading of 4 mg·cm-2 for supercapacitors,the hierarchical porous carbon film derived from hybrid nanocellulose exhibited a specific capacitance of 170 F.g-1and extraordinary performance at high current densities.Even at a very high current of 50 A·g-1,it retained 65％ of its original specific capacitance,which makes it a promising electrode material for high-power applications.     

一锅法制备纳米纤维素及其性能研究

采用一种操作简单、绿色环保的以对甲苯磺酸为催化剂对竹纤维进行水热处理制备纳米纤维素(NCC)的方法.考察了反应时间、反应温度和超声作用对纳米纤维素得率和性能的影响.结果 表明,在反应温度110℃、反应时间45 min、超声时间120 min的条件下,纳米纤维素得率最高.     

Polylactide latex/nanofibrillated cellulose bionanocomposites of high nanofibrillated cellulose content and nanopaper network structure prepared by a papermaking route

Previous attempts to use polylactide (PLA) latex particles and nanofibrillated cellulose (NFC) in papermaking processing have been limited to low NFC content. In the present study, a bionanocomposite material was successfully produced using a PLA latex and NFC. The components were mixed using a wet mixing method and bionanocomposite films were made by filtration followed by hot pressing. In composite materials, the dispersion of the reinforcing component in the matrix is critical for the material properties. Biopolymers such as PLA are non-polar and soluble only in organic solvents; NFC is, however, highly hydrophilic. By utilizing latex, i.e., an aqueous dispersion of biopolymer micro-particles, wet mixing is possible and the problem of aggregation of the hydrophilic nanocellulose in organic solvent is avoided. The properties of the resulting NFC/PLA latex bionanocomposite films were analyzed. Thorough blending resulted in good dispersion of the reinforcing component within the matrix. Adding increasing amounts of NFC improved the Young's modulus, tensile strength, and strain at break of the bionanocomposite material. The increase in the tensile properties was linear with increasing NFC content as a result of the good dispersion. The NFC also improved the thermal stability of the bionanocomposite material. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Reinforcement of polypropylene with lignocellulose nanofibrils and compatibilization with biobased polymers

Freeze‐dried and milled lignocellulose nanofibrils (LCNF) were used to reinforce polypropylene (PP) nanocomposites. The LCNF, containing up to 9% lignin, was obtained from residual Empty Palm Fruit Bunch (EPFB) fibers. Soy protein isolate (SPI) and hydroxypropyl cellulose (HPC) were tested as coupling agents as well as maleic anhydride grafted polypropylene (MAPP), which was used as a reference. A good level of dispersion of LCNF in the PP matrix while mechanical testing and thermal analyses indicated an improvement of the thermo‐mechanical behavior of the nanocomposites was revealed upon loading of the lignin‐containing nanofibrils. The tensile modulus of PP was increased by 15% upon the addition of 1% LCNF with SPI as a compatibilizer. Likewise, the thermal stability of the composites was most markedly enhanced. Overall, LCNF and SPI, two important bioresources, are introduced here for the development of novel and cost‐effective PP‐based composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43854.     

纳米纤维素的制备及其在造纸领域的应用

纳米纤维素具有来源广泛、生物相容、绿色环保、可再生等特点,具有的特殊纳米层级形貌赋予了其特殊的性质。本文简述了纳米纤维素的制备工艺,其中包括化学法、物理法、生物法和其他方法等,并总结了纳米纤维素作为纸浆添加剂、涂料和特种材料在制浆造纸领域的应用研究。     

原位形成碳酸钙协同纳米纤维素对老化纸张脱酸增强的研究

本课题提出在老化纸张中原位形成碳酸钙并协同纳米纤维素脱酸处理增强的保护措施,探讨了不同处理方式及纳米纤维素浓度对老化纸张性能的影响。结果表明,先利用0.1 mol/L丙酸钙及0.1 mol/L碳酸钠水溶液压力雾化处理纸张,在纸张中原位形成碳酸钙进行脱酸,再利用1 wt%纳米纤维素进行增强。处理后老化纸样pH值达8.40,碱存储量约245 mmol/kg,抗张指数和耐折度较处理前分别提升了19%、109%,且具有优异的抗老化和防霉性能。     

Orientated Immobilization of FAD-Dependent Glucose Dehydrogenase on Electrode by Carbohydrate-Binding Module Fusion for Efficient Glucose Assay

The discovery or engineering of fungus-derived FAD-dependent glucose 1-dehydrogenase (FAD-GDH) is especially important in the fabrication and performance of glucose biosensors. In this study, a novel FAD-GDH gene, phylogenetically distantly with other FAD-GDHs from Aspergillus species, was identified. Additionally, the wild-type GDH enzyme, and its fusion enzyme (GDH-NL-CBM2) with a carbohydrate binding module family 2 (CBM2) tag attached by a natural linker (NL), were successfully heterogeneously expressed. In addition, while the GDH was randomly immobilized on the electrode by conventional methods, the GDH-NL-CBM2 was orientationally immobilized on the nanocellulose-modified electrode by the CBM2 affinity adsorption tag through a simple one-step approach. A comparison of the performance of the two electrodes demonstrated that both electrodes responded linearly to glucose in the range of 0.12 to 40.7 mM with a coefficient of determination R² > 0.999, but the sensitivity of immobilized GDH-NL-CBM2 (2.1362 × 10⁻² A/(M*cm²)) was about 1-fold higher than that of GDH (1.2067 × 10⁻² A/(M*cm²)). Moreover, a lower detection limit (51 µM), better reproducibility (<5%) and stability, and shorter response time (≈18 s) and activation time were observed for the GDH-NL-CBM2-modified electrode. This facile and easy immobilization approach used in the preparation of a GDH biosensor may open up new avenues in the development of high-performance amperometric biosensors.     

纳米微纤丝纤维素及其在造纸中的应用研究现状

本文结合纳米材料定义,简述纳米微纤丝纤维素与传统意义纳米纤维素的共性与区别,在此基础上介绍此类纳米纤维素的制备方法及现阶段存在的主要问题。同时介绍了纳米微纤丝纤维素在造纸中潜在的应用方式,分析其对造纸规模化生产及纸张性能的影响并浅谈其发展面临的机遇与挑战。     

纳米纤维素中氢键网络调控技术的研究进展

本文讨论了近年来采用衍生化、低共熔溶剂和离子液体处理等技术调控纳米纤维素中氢键网络的研究成果,对比分析了各种技术的调控机理,归纳总结了氢键网络的变化对纳米纤维素结构与性能的影响,简单介绍了分子模拟在氢键断裂与重构研究方面的应用,展望了纳米纤维素氢键网络调控的发展方向。