Cellulose Nanocrystals as a Sustainable Raw Material: Cytotoxicity and Applications on Healthcare Technology

Cellulose nanocrystals (CNCs) are an environmentally friendly natural material, consisting of rod‐like crystalline nanoparticles, called whiskers, or nanocrystalline cellulose. The derivation of different natural sources, aligned to their biocompatibility, biodegradability, and versatility, make them a class of fascinating materials with widespread industrial use. In addition, the cellulose species possess intriguing physicochemical and mechanical properties. This paper provides an overview of recent progress in the area of cellulosic nanocomposites, along with details of their structure and liquid crystalline behavior as nematic and cholesteric lyotropic materials. Guidance is subsequently provided for the physicochemical analysis of these materials, including X‐ray diffraction, transmission electron microscopy, optical evaluation, thermogravimetric analysis, and differential scanning calorimetry. Additionally, the functional chemical and physical properties of CNCs are correlated to the resulting nanotoxicity in in vitro and in vivo assays. This review points to relevant concerns, such as sources for the synthesis of CNCs, the nanomaterial size, and the surface chemistry, that must be overcome in order to attain safe use of CNC‐based nanomaterials. The challenging perspectives on the ongoing research are presented in order to explore the technological and industrial perspectives on the use of CNC for the generation of cost‐effective advanced nanomaterials based on cellulosic fibers.     

Physicochemical properties of cellulose nanocrystals treated by photo‐initiated chemical vapour deposition (PICVD)

Cellulose nanocrystals (CNCs) are novel nanomaterials produced by the pulp and paper industry. The surface properties of CNCs are key factors for their dispersion in solvents. These polar materials disperse readily in water, but not in organic solvents. The ability to disperse into typically non‐polar organic matrices is an indispensable requirement to exploit the growing market for nanocomposite materials. We present an innovative approach for modifying the surface of CNCs through scalable, gas‐phase photo‐initiated chemical vapour deposition (PICVD). Using syngas as a treatment precursor, we demonstrate the effectiveness of this technique to render the surface of the CNCs compatible with mildly polar and non‐polar solvents, evidenced by contact angle measurements. Further proof of this successful modification is given through dispersion assays, showing for example the ability to disperse treated CNC in toluene (whereas untreated samples do not disperse). Suspensions in organic solvents remain stable in excess of two weeks. Chemical characterization through XPS and FTIR confirms the presence of an oxygen‐containing coating on the CNC surface.     

芳纶表面化学改性技术研究现状

概述了芳纶表面化学改性的方法。从芳纶分子结构的特点出发,论述了芳纶表面化学刻蚀及化学接枝等化学改性技术的原理、特点和应用效果;详述了基于芳纶结构中苯环上的硝化还原反应、氯磺化反应和酰胺基上的水解反应、氢取代反应、金属化反应等的反应原理及应用效果。指出多种化学改性技术的交叉应用将成为芳纶表面化学改性的趋势。     

常压辉光放电等离子体研究进展及聚合物表面改性

综述了常压辉光放电等离子体(APGDP)的产生机理及研究进展。介绍了难以产生稳定的APGDP 是由于辉光放电容易向细丝放电和弧光放电过渡,其解决措施是选择合适的介质板材料、电极间距、电源电压及频率、气体成分等。指出APGDP对化纤聚合物表面改性的效果与聚合物的分子结构、等离子体气体、介质板材料等因素有关,且改性效果具有时效性,要根据聚合物的分子结构选择合适的等离子体。     

剑麻纤维的表面改性及其复合材料的研究进展

简述了剑麻纤维的组成、结构及力学性能,并总结了剑麻纤维表面改性的几种方法,包括物理方法：热处理、酸碱处理、有机溶剂处理;化学方法：改变表面张力、界面偶合、表面接枝聚合。同时论述了剑麻纤维的表面改性对复合材料力学性能的影响。     

复合材料用天然植物纤维改性研究进展

天然植物纤维的结构和性能独特,与树脂基体复合仍存在诸多问题。天然植物纤维改性对于提高反应活性、改善其与基体树脂的界面相容性及复合材料的综合性能有重要影响。从天然植物纤维原料的组成、结构及性能分析出发,重点介绍了蒸汽爆破预处理、热预处理、高能辐射预处理、碱预处理、过氧化物预处理和组合法预处理等预处理技术以及酯化改性、接枝共聚、偶联剂改性和其他改性方法,并综述了改性天然植物纤维在复合材料中的研究进展,总结了天然植物纤维改性对复合材料性能的影响,以期为天然植物纤维复合材料的研究提供思路和参考。     

活性炭材料改性及其在环境治理中的应用

从活性炭材料的表面结构性质和表面化学性质两方面论述了活性炭材料改性的研究进展,就活性炭材料在环境污水处理以及大气污染防治方面的应用进展进行了评述,并展望了活性炭材料改性的前景.     

金纳米棒表面修饰技术及其功能化的研究进展

各向异性的金纳米棒由于具有独特的光学性质、较好的生物适应性,在生物医学领域得到了日益广泛的应用。本文系统评述了金纳米棒的表面修饰技术及其功能化的研究进展,内容包括:①金纳米棒的无机材料修饰,表面活性剂修饰、有机小分子及有机大分子修饰、金属材料修饰及其功能化;②金纳米棒在生物标记与识别、生物成像、癌症诊断和光热治疗等领域中的应用。     

粉体的表面修饰与表面包覆方法的研究

通过粉体的表面修饰与表面包覆以改善粉体的分散性，粉体的表面性质乃至改变粉体的相结构和性质，已经成为超细与纳米粉体制备和应用的关键技术。本文介绍了陶瓷粉体的各种表面修饰、粉体包覆的方法、基本原理、特点，详细讨论了液相化学包覆技术。     

A Review of Computational Methods in Materials Science: Examples from Shock-Wave and Polymer Physics

This review discusses several computational methods used on different length and time scales for the simulation of material behavior. First, the importance of physical modeling and its relation to computer simulation on multiscales is discussed. Then, computational methods used on different scales are shortly reviewed, before we focus on the molecular dynamics (MD) method. Here we survey in a tutorial-like fashion some key issues including several MD optimization techniques. Thereafter, computational examples for the capabilities of numerical simulations in materials research are discussed. We focus on recent results of shock wave simulations of a solid which are based on two different modeling approaches and we discuss their respective assets and drawbacks with a view to their application on multiscales. Then, the prospects of computer simulations on the molecular length scale using coarse-grained MD methods are covered by means of examples pertaining to complex topological polymer structures including star-polymers, biomacromolecules such as polyelectrolytes and polymers with intrinsic stiffness. This review ends by highlighting new emerging interdisciplinary applications of computational methods in the field of medical engineering where the application of concepts of polymer physics and of shock waves to biological systems holds a lot of promise for improving medical applications such as extracorporeal shock wave lithotripsy or tumor treatment.     

纳米二氧化硅的表面改性及其应用进展

综述了国内外纳米二氧化硅的表面改性方法，并分类介绍了粉体纳米二氧化硅和胶体纳米二氧化硅的表面改性方法及其对材料性能的影响，分析讨论了纳米二氧化硅与有机聚合物的反应机理及其在聚合物基复合材料中的应用，展望了其发展前景。     

介质阻挡放电等离子体改性碳基材料研究进展

介质阻挡放电等离子体因其高效、经济和易操作等优点, 使得其在材料表面改性方面得到了广泛的应用, 同时表现出良好的应用前景。碳基材料由于其许多良好的物化性能, 使得其在很多领域都得到了很好的应用。而经DBD改性后的碳基材料表现出更好的物化性能, 应用更加广泛。主要综述了DBD在改性碳基材料方面的研究现状, 包括活性基团的引入, DBD改性对碳基材料界面结合能、吸附性能、物理结构及其对负载组分分散度的影响。指出改性过程中仍然存在的许多不够完善之处, 提出许多需要进一步深入研究的问题, 如DBD改性对碳基材料物化性能影响的机理研究, 并展望了DBD改性碳基材料技术未来的发展前景。     

ZSM-5沸石分子筛脱硫脱氮机理及改性方法

综述了近年分子筛的脱硫脱氮机理及动力学,从表面酸性和孔结构两方面评述了ZSM-5分子筛的改性。重点综述了基于ZSM-5的杂原子分子筛、分子筛膜、纳米分子筛的研究动态和发展趋势,指出了研究应用中存在的问题以及今后的研究方向。     

介孔分子筛载体在油品深度加氢脱硫中的应用研究进展

介孔分子筛材料以其独特的孔道结构和孔径分布、高的比表面积及较好的热稳定性和水热稳定性等特点,近年来被广泛地用作油品深度加氢脱硫催化剂载体.本文系统综述了近年来MCM、HMS、SBA、KIT等系列介孔分子筛载体应用于油品深度加氢脱硫(HDS)的国内外研究现状.重点讨论了金属、氧化物、酸、磷、与其它载体复合等载体改性方式对...     

仿生表面改性技术研究进展

从结构仿生和功能仿生两个方面对仿生表面改性技术进行了综述，对分子印迹技术、模拟生物酶催化、仿细胞膜结构改性、智能高分子凝胶及生物传感器进行了介绍，并对仿生表面改性技术的发展趋势进行了展望。     

硅氧烷表面活性剂（V）（续4）：作为表面改性剂在聚合物中的应用

聚合物的表面性质在许多应用中起着关键性的作用，用最佳性能是在树脂应用时使整体／表面性质达到平衡。有许多方法可以对聚合材料进行表面改性，其中大多数方法是对终产物的表面进行处理。本中我们将阐述特定的含硅氧烷的共聚物，把它们作为表面改性添加剂加入到各种有机聚合物中，它们在加工过程中移到体系表面，从而使聚合物表面得到改性。虽然硅氧烷苯身是疏水性的，但是如果使用含有亲水链节的硅氧烷共聚物也可以得到亲水性的     

刷状聚乙二醇两亲性共聚物的合成及其对载药的影响研究进展

刷状聚乙二醇（PEG）两亲性共聚物具有独特的性能和良好的应用前景,日益受到人们的重视。本文综述了刷状PEG两亲性共聚物的两种合成策略,即大分子单体法和主链-侧链偶联法,它们主要通过离子聚合、自由基聚合、开环聚合及各种耦合反应等实现。举例分析了这些方法的优缺点,并侧重于聚酯等生物可降解材料形成的刷状PEG共聚物。比较了直链PEG和刷状PEG共聚物胶束表面形态,简要分析了刷状PEG结构对纳米颗粒药物输送性能的影响,指出刷状PEG结构能延长体内循环时间从而提高药物疗效,但有效的合成方法及其胶束的体内外性能还需要更深入的探索。     

聚四氟乙烯的表面处理

分析了聚四氟乙烯（PTFE）难与其他物质粘结的原因,综述了PTFE表面处理方法及应用,并对PTFE的表面改性机理进行了初步探讨.     

Cellulose nanocrystal‐based poly(butylene adipate‐co‐terephthalate) nanocomposites covered with antimicrobial silver thin films

In this study, we reported the preparation and prospective application of the nanocomposites of poly(butylene adipate‐co‐terephthalate) (PBAT) reinforced with cellulose nanocrystals (CNCs). CNCs were isolated from bleached sugarcane bagasse by acid hydrolysis and functionalized with adipic acid. Nanocomposites were prepared with different concentration of CNCs (0.8, 1.5, and 2.3 wt% CNC) by solution‐casting method and then were covered with silver thin film by magnetron sputtering. The results showed that the surface modification increased the degree of crystallinity of nanocrystals from 51% to 56%, decreasing their length and diameter. Moreover, AFM‐IR spectroscopy revealed that the modified CNCs were covered by adipic acid molecules, improving the dispersion of nanocrystals in PBAT. Well‐dispersed modified CNCs acted as heterogeneous nuclei for crystallization of PBAT, and increased the storage modulus of the polymer by more than 200%. These improvements in thermal and mechanical properties of CNC‐based PBAT associated with the decrease of 56% in the Escherichia coli biofilm formation on nanocomposites (antibacterial properties) qualify the CNC/PBAT nanocomposites covered with silver thin films to be used as food packaging. POLYM. ENG. SCI., 59:E356–E365, 2019. © 2019 Society of Plastics Engineers