纳米纤维素的制备及其在医药领域的应用进展

通过概括制备纳米纤维素的传统及优化方法,列举纤维素通过表面改性、加工纳米纤维素复合材料以改善纤维素的机械性能的研究;讲述了纳米纤维素作为具有良好生物降解性、易改性、机械强度、低毒性、高比表面积等特性的纳米尺度纤维素而被应用于医药领域的最新研究,总结了纳米纤维素作为药物载体、伤口敷料以及被应用在其他医药领域的研究进展。     

纳米纤维素膜疏水化改性研究进展

近些年来,以纳米纤维素为原料制备出的柔性透明薄膜,因其优异的机械性能、可再生性、生物相容性等,在新型包装材料、透明电子元器件基底等领域展现出巨大的应用价值。然而在潮湿环境下,纳米纤维素膜如何维持高的机械性能,成为其在高附加值领域应用中一个重要又易被忽视的问题。先阐述了纳米纤维素膜以及天然亲水性对其隔绝和机械性能的影响,接着从化学改性、物理吸附、共混交联三种改性方法入手,综述了近些年来纳米纤维素膜疏水改性的研究与进展,以及不同改性方式对膜材料应用性能的影响。     

醋酸纤维素纳米纤维膜的改性及性能研究

在生产纳米纤维过程中最常用的方法是静电纺丝,另外纳米纤维优点是表面面积大,孔隙率高,在重金属离子吸附区域具有良好的应用前景。(CA)纳米纤维膜,来自乙酸纤维素的胺化纳米纤维膜和来自氨基纤维素的乙酸纤维素膜与碳纳米管的膜生产醋酸纤维素。因此,本文主要研究和分析了醋酸纤维素纳米纤维膜的改性和性能。     

纤维素基油水分离材料研究进展

石油泄漏事故及工业含油废水排放等严重破坏了人类赖以生存的生态环境,如何有效分离油水混合物成了当前的研究热点。传统的油水分离材料的不可回收性带来材料的二次污染极大限制了它们的广泛应用。纤维素是地球上最丰富的天然聚合物,并且具有生物相容性、生物降解性、化学稳定性和低成本等特点,因此纤维素基油水分离材料亦受到广泛关注。本文系统总结了近年来过滤型和吸附型纤维素基油水分离材料的研究进展,重点围绕纤维素类物质作材料基底（滤纸、棉布等）、用其进行表面改性（纤维素纳米晶体、纤维素衍生物等）以及全纤维素基油水分离材料等方面进行详细分析和介绍,对纤维素基油水分离材料存在的问题进行了探讨,并对其未来发展进行了展望。     

纳米纤维素的疏水改性及应用研究进展

纳米纤维素作为一种性能优越的可再生纳米材料,应用前景极为广阔。然而,由于纳米纤维素结构上富含羟基,使其具有极强的亲水性,严重影响了纳米纤维素的疏水性能,并且在一定程度上限制了其在复合材料领域的应用。综述了纳米纤维素疏水改性的研究进展,从物理吸附、表面化学修饰（甲硅烷化、烷酰化、酯化等）、聚合物接枝共聚3个方面简述了目前应用较为广泛的疏水化改性方法,并对疏水纳米纤维素在包装材料、造纸、水净化等方面的应用现状进行了总结。最后对疏水改性纳米纤维素的未来发展进行了展望,旨在为疏水纳米纤维素的研究和应用提供参考。     

纳米纤维素基水凝胶的制备及其在传感器中的应用进展

随着国家“双碳”战略的提出，可持续、可再生的原材料正在受到广泛的关注。作为地球上分布广泛的天然资源，纳米纤维素具有可再生、可生物降解、较好的热稳定性等特性。纳米纤维素表面富含的羟基使其成为制备水凝胶的理想材料。重点介绍了几种热门的纳米纤维素基水凝胶的制备方法，及其在传感器中的应用。研究表明，目前纳米纤维素基水凝胶的制备已存在相对环境友好的生产方法，纳米纤维素基水凝胶的传感性能在力学性能、灵敏度、稳定性、回收率等方面表现出优于通过常规传统材料制备的传感器，在解决成本问题后具有广阔的使用前景。     

纳米纤维素构建超疏水材料研究进展

纳米纤维素表面富含活性羟基,具有高度的亲水性和吸水性,这在很大程度上成为影响纳米纤维素在工业上大规模应用的主要因素。对纳米纤维素表面的活性羟基进行化学修饰提高其疏水性,日益成为国内外学者研究的热点。本文在简要阐述超疏水材料基本特征和制备方法的基础上,对比了不同超疏水材料制备方法 (模板法、喷涂法、沉积法、刻蚀法)的优劣,重点介绍了国内外学者利用纳米纤维素构建超疏水材料(气凝胶、纸张、涂层、薄膜等)在生物医学、造纸工业、油水分离、食品包装、储能材料等不同领域的研究进展,归纳并分析了目前纳米纤维素构建超疏水材料在改性方式和性能提升等方面仍存在的问题,同时指出了纳米纤维素构建超疏水材料未来将朝着过程无污染化、工艺简化、稳定性优化等方向发展。     

纳米纤维素在柔性电子器件的应用进展

从纳米纤维素的物理化学性能出发概述了纤维素纳米基柔性材料在柔性电子领域的应用优势,重点介绍了纤维素纳米基柔性材料在电极、隔膜和电解质以及超级电容器等储能器件中的前沿研究,展示了材料复配、化学改性、工艺改进等对电子器件电化学性能和机械性能的改进;同时介绍了纤维素纳米基柔性材料在传感器中的最新应用,对应变、湿度和pH具有响应的弹性体、气凝胶和膜材料的开发,以及传感灵敏度、耐环境性和相容性等的改善。最后展望了纤维素纳米基柔性材料的发展前景并总结了当前面临的挑战,对柔性电子材料的研究工作具有一定参考价值。     

静电纺丝乙酸纤维素在生物医药领域的应用研究进展

乙酸纤维素具有良好的溶解性、生物相容性和生物降解性,常用来替代纤维素作为静电纺丝的基体材料,广泛应用于生物医药、电化学、过滤膜等领域。本文介绍了通过物理共混、同轴电纺、层层自组装等多种手段将酶、药物、细胞等有效成分搭载于乙酸纤维素纤维中,获得功能化的改性乙酸纤维素电纺纤维的方法。阐明了电纺乙酸纤维素纤维因具有较大的孔隙率、比表面积、特殊的三维网络结构,能够有效绑定生物基团,实现药物的控释,促进细胞的黏附与增长的显著优势。综述了电纺乙酸纤维素纤维在酶的固定化平台、药物的包载与缓释、组织工程、生物传感器、抗菌膜、创口敷料等领域的应用。明晰了其在生物医药领域应用的科学价值及现实意义,指出了其在科学研究及工业化生产的中难点,并对其发展方向进行了展望。     

细菌纤维素生物医学材料的现状及展望

细菌纤维素是由细菌合成的纯净纳米纤维素构成的网状纤维,具有优良的形态学、生物学、物理学性能以及合成可控性,因此在生物医学材料领域被广泛应用。介绍了近年来细菌纤维素应用于敷料、人造皮肤、组织修复材料和膳食纤维等方面的研究进展,并对其生物降解能力、生物相容性和纤维定向等性能的提高作出了展望。     

静电纺丝法制备醋酯纳米纤维的最新研究进展

采用静电纺丝法制备醋酯纳米纤维,既可以保留醋酯纤维的耐化学性和可生物降解性等优点,又具有纳米材料的高比表面积、高孔隙率和量子效应。综述了近几年国内外静电纺丝法制备纳米级醋酯纤维的最新研究进展,系统介绍了几种新型纳米纤维结构的制备方法、原理及影响因素,同时对醋酯纳米纤维在吸附过滤方面的应用研究状况进行了概述,最后对静电纺丝法制备醋酯纤维的发展前景进行了展望。     

纤维素热塑改性研究进展

热塑性纤维素的合成在解决人类所面临的能源、资源和环境问题方面具有重要意义,通过传统工艺如挤出、注射、模塑加工纤维素基可降解材料具有很好的应用前景。综述了近年来纤维素热塑改性的主要方法及进展,主要包括纤维素化学改性和通过接枝改性使其内部塑化,分析了改性纤维素内増塑制备可降解材料各方法的优缺点。     

Grafting cellulose acetate with styrene maleic anhydride random copolymers for improved dimensional stability of cellulose acetate

Graft copolymers of cellulose acetate (CA, d.s.:2.45) with styrene maleic anhydride random copolymers (SMAs) were synthesized by reacting the hydroxyls on CA backbone with the anhydride on SMA. The formation of graft copolymers leads to compatibilized blends with microscopic phase domains under appropriate conditions. The grafting reaction was studied in detail. The uniform dispersion of SMA in the CA matrix brings new properties to the grafting reaction products. Tests from acetone-cast films showed improved dimensional stability in comparison to cellulose acetate; i.e., in the presence of 50% SMA in the formulation, there is more than 50% reduction on the dimensional change as compared to CA. The dimensional stability of the grafting products is better or comparable to cellulose triacetate. There are, for the alloys, reduced moisture adsorption, improved tensile strength, tensile modulus, reduced elongation, as compared to cellulose acetate. © 1994 John Wiley & Sons, Inc.     

High performance forward osmosis cellulose acetate (CA) membrane modified by polyvinyl alcohol and polydopamine

Cellulose acetate (CA) is a low cost and readily available material widely used in forward osmosis (FO) membranes. However, the performance of pure CA membranes is not good enough in salt separation and the traditional modification methods are generally multistep and difficult to control. In this paper, we reported high performance cellulose acetate (CA) composite forward osmosis (FO) membranes modified with polyvinyl alcohol (PVA) and polydopamine (PDA). PVA was first cross-linked onto the surface of CA membranes, and then PDA was coated with a rapid deposition method. The membranes were characterized with respect to membrane chemistry (FTIR and XPS), surface properties comprising wettability (by water contact angle), and osmosis performance. The modified membrane coated by PVA and PDA shown better hydrophilicity and exhibited 16.72 LMH osmotic water flux and 0.14 mMH reverse solute flux with DI water as feed solution and 2.0 M NaCl as draw solution and active layer facing the feed solution. This simple and highly effective modification method makes it as an excellent candidate for further exploration for FO.     

A new thermoset for separation of polystyrene and naphthalene in preparative chromatography

Many research groups in recent years have demonstrated the importance of obtaining new materials and reducing environmental impact. In this context, the chemical modification of cellulose and its derivatives has received much attention. This study synthesized cellulose acetate gel (CAMDIH) obtained through the modification of cellulose acetate (CA) with a degree of substitution of 2.5, by crosslinking reactions using 4,4′‐diphenylmethane diisocyanate in homogeneous medium. The formation of crosslinks were observed by the presence of Fourier transform infrared spectroscopy absorption bands at 3046 and 864 cm^?1, which correspond to the absorption of aromatic groups associated with the incorporation of 4,4′‐diphenylmethane diisocyanate in the CA structure. The potential applications of the gel as a stationary phase were tested using column chromatography in the fractionation and separation of standard solutions of polystyrene and naphthalene. The findings showed the effectiveness of the gel as a stationary state in the separation of mixture compounds. Furthermore, the study found that CAMDHI is an innovative material when considering its simple synthesis and the low costs involved in the process. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46063.     

Biodegradation studies of cellulose and its vinylic graft copolymers by thermal analysis and mechanical spectroscopy

Cotton cellulose with different % NaOH treatments and graft copolymers of cellulose prepared with vinyl acetate (AV) and methyl acrylate (MA), and Ce(IV) ion as an initiator were submitted to biodegradation conditions. Cellulose is a biopolymer consisting solely of glucose units, and, consequently, is also easily biodegradable. Nevertheless, modified cellulose, for example, by graft copolymerization, shows an increased resistance to biodegradation. The aim of this work was to study by calorimetric and dynamic‐mechanical analysis how the chemical modification of cellulose affects its biodegradability. From the obtained results some information has also been deduced about the composition and mechanical behavior of the vinylic grafted chains. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 326–335, 2000     

可降解的热塑性纤维素材料的主要改性方法

由于纤维素分子间有强氢键作用,使得其取向度和结晶度都高,而且不溶于一般溶剂,高温下分解而不熔融。为了使其具有热塑性可加工性,必须对其改性。主要的改性方法有加入增塑剂,或与其他可生物降解材料进行共混改性,或进行接枝改性等。     

醋酸纤维素的降解性研究进展

介绍了醋酸纤维素的生物降解、水解、光解的降解机理与研究现状,并对影响醋酸纤维素降解速率的因素进行了探究。从现有研究中可知,影响醋酸纤维素降解速率的主要因素为醋酸纤维素自身的分子结构（如取代度、取代度分布及结晶性等）,物理改性、化学改性及增塑改性会通过改变醋酸纤维素的分子结构,进而影响醋酸纤维素的降解性能。最后,总结了醋酸纤维的应用领域,并做出了展望。     

Preparation of poly (isophthalamide-graft-methacrylamide) and its utilization in the modification of cellulose acetate ultrafiltration membranes

Methacrylamide was grafted on to poly (isophthalamide) (PIPA-g-MAA) to improve its solubility and hydrophilicity. Then, PIPA-g-MAA incorporated high performance cellulose acetate ultrafiltration (CA) membranes were prepared by phase inversion technique and physical properties of the membranes were studied by various analytical methods. The efficiency of these membranes in the removal of arsenic from aqueous stream was studied and an effort has been taken to correlate the separation efficiency with morphology. Overall results suggest that membrane hydrophilicity, structure and performance were improved significantly by the addition of PIPA-g-MAA. Thus PIPA-g-MAA can be considered as an effective modification agent for CA membranes.     

Modification of cellulose acetate with oligomeric polycaprolactone by reactive processing: Efficiency,compatibility, and properties

Oligomeric polycaprolactone (oPCL) was used for the modification of cellulose acetate by reactive processing in an internal mixer at 180°C, 50 rpm, 60 min reaction time, and 45 wt % caprolactone (CL) content. The product of the reaction was characterized by several analytical techniques and its mechanical properties were determined by dynamic mechanical thermal analysis and tensile testing. The synthesized oPCL contained small and large molecular weight components. The small molecular weight fraction plasticized cellulose acetate externally and helped fusion. Although composition and structure did not differ considerably from each other when CL monomer or polycaprolactone oligomer was used for modification, the grafting of a few long chains had considerable effect on some properties of the product. The large molecular weight chains attached to CA increased the viscosity of the melt considerably and resulted in larger deformability. oPCL homopolymer is not miscible with cellulose acetate and migrates to the surface of the polymer. Exuded polycaprolactone oligomers crystallize on the surface but can be removed very easily. More intense conditions may favor the grafting of long chains leading to polymers with advantageous properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009