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.     

木薯渣纳米纤维素的制备与表征

目的 为了增加木薯渣的废物利用途径,对木薯渣进行高值化利用,制备木薯渣纳米纤维素,并对其进行表征。方法 以木薯渣为原料,对其进行酶处理和漂白处理,随后采用高压均质法制备纳米纤维素,再通过扫描电镜、透射电子显微镜、原子力显微镜、红外光谱、X-射线衍射仪和热稳定性分析对木薯渣进行表征分析。结果 木薯渣经过酶解和漂白后,纤维素质量分数从20.21%增加到77.39%,淀粉质量分数从50.39%降低到1.87%,半纤维素质量分数从18.38%降低到5.11%,木质素质量分数从3.69%降低到0.74%。结论 木薯渣纤维在103.425 MPa下均质30次后成功制备出了纳米纤维素,透射电子显微镜和原子力显微镜结果表明,CNF的直径为10 nm左右。淀粉酶处理、漂白和高压均质并没有改变木薯渣纤维的晶型结构,仍为纤维素I型。     

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.     

超级电容器中纳米纤维素基电极的研究进展

纳米纤维素机械强度高、密度低且表面含有可化学改性的羟基官能团,可作为组装高性能超级电容器电极的优选材料。本文综述了纳米纤维素与导电聚合物、过渡金属氧化物等活性材料制备超级电容器软材料和碳基复合电极的机理,对冷冻干燥、碳化、原位聚合、过滤、涂覆等组装方法进行了详细讨论,并对纳米纤维素基电极的机械性能和电化学性能进行了对比和分析。最后,对纳米纤维素基电极在超级电容器中的应用前景进行了展望。     

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。     

RGO/CNTs/CNF柔性电极的制备及表征

本研究以纤维素纳米纤丝（CNF）为基底,氧化石墨烯（GO）、碳纳米管（CNTs）为活性物质,通过机械共混结合真空抽滤制备了GO/CNTs/CNF薄膜,经氢碘酸还原制得还原氧化石墨烯（RGO）/CNTs/CNF柔性电极材料（简称RCC电极）,并探讨了GO含量对RCC电极电化学性能的影响。结果表明,CNF能良好地分散GO和CNTs,氢碘酸能够有效地将GO还原为RGO,且随着GO含量的增加,RCC电极的电化学性能更优。当GO含量为30%时,在1 A/g的电流密度下,RCC电极的质量比电容为129.7 F/g,经过1000次充放电循环测试后,电容保留率仍维持在96.15%左右。