纤维素的改性研究进展

对常见的纤维素改性方式如：物理改性、化学改性(酯类改性、醚类改性、接枝类改性)、生物改性进行概括,并对其主要应用领域吸附剂、膜材料、凝胶材料等进行总结,强调了迄今为止对纤维素的功能化开发的应用途径。对未来发展趋势加以分析认为纤维素改性材料在均匀性等方面仍存在一定技术挑战。     

医用可吸收止血材料的功能化改性研究进展

介绍了国内外常用的生物医用可吸收止血材料(包括氧化纤维素或氧化再生纤维素、纤维素醚、壳聚糖、纤维蛋白胶等)的功能化改性及其应用,并对这些止血材料负载凝血酶、钙离子、多聚磷酸盐等的促凝血改性、与各种抗菌药物结合的抗菌改性和其他改性分别进行了介绍;最后对生物医用可吸收止血材料的功能化改性发展趋势进行了总结和展望。     

天然高分子基多孔止血海绵的制备及性能研究进展

介绍了壳聚糖类、明胶类、胶原蛋白类、纤维素类、透明质酸类、海藻酸盐类多孔结构止血海绵的制备方法、止血效果、性能特点、止血机制及存在的问题,并指出了其发展趋势。     

液晶态生物材料

液晶态普遍存在于生物体内。系统研究生物体液晶的形成和功能,液晶态生物材料与人体组织间的作用机制及其生物相容性,对开发新型仿生材料和人工组织器官等研究都有重要意义。介绍了纤维素、壳聚糖及胶原等液晶态生物材料在临床医学、抗凝血材料及组织工程支架材料中的应用,并对其生物相容性的研究状况进行了阐述。     

氧化纤维素的制备研究进展

纤维素是世界上含量最为丰富的天然高分子材料。纤维素富含的分子间氢键使其难以溶解。因此,通过化学氧化的手段对天然纤维素进行修饰改性,可以赋予纤维素更多的用途。着眼于纤维素的氧化过程,介绍了纤维素氧化方法与研究进展,进一步展望了氧化纤维素的发展方向。     

纤维素氧化体系的研究进展

概述了纤维素的选择性氧化及其氧化体系的研究进展,主要介绍了2,2,6,6-四甲基哌啶-1-氧自由基(TEMPO)类复合氧化体系氧化纤维素的降解机理,针对该降解机理提出抑制降解的基本方法。与其他氧化体系相比,过碘酸和过碘酸盐对纤维素C2、C3位仲羟基的选择性氧化能力极强,TEMPO系列氮氧基类氧化体系对纤维素C6位伯羟基的选择性氧化能力极强,但纤维素在各个氧化体系中的降解非常剧烈,纤维素在各个氧化体系中的降解机理有所不同。     

生物技术在能源领域中的应用与发展前景

生物技术作为现代科学的朝阳产业,在能源、医药、材料、化工等领域已经取得了长足的发展。本文主要介绍了与其他能源相比,生物能源的特点与优势,重点对纤维素乙醇方面取得的研究进展进行了介绍。     

生物可降解高分子材料

介绍了生物可降解材料的降解机理,并概述了生物可降解材料的种类,例如天然可降解高分子材料中的纤维素、淀粉,合成生物可降解高分子材料中的微生物合成类和化学合成类,同时阐述了生物可降解高分子材料合成技术的应用、性能改进,以及这些材料的研究现状、发展方向。并对前景进行了展望。     

细菌纤维素/明胶复合止血海绵的制备与性能研究

细菌纤维素(BC)具有纯度高、可再生、生物相容性好及优异的力学性能等特性,成为复合材料中性能优异的增强剂之一.利用2,3-环氧丙基三甲基氯化铵(EPTAC)对BC进行季铵化改性,并将其与明胶混合进行冷冻干燥,再交联制备止血海绵.采用万能材料试验机、紫外分光光度计等对复合海绵的力学性能、凝血性能和抗菌性能进行测量,结果表...     

烷基化壳聚糖/多巴胺/氧化石墨烯粉末用于快速止血

壳聚糖（CS）及其衍生物价廉易得，止血性及生物相容性良好，广泛应用于抗菌、止血等材料的开发。使用十二醛对CS进行N-烷基化改性制备烷基化壳聚糖（N-CS），并在乙酸溶液中将N-CS嵌入到多巴胺修饰的氧化石墨烯（DGO）骨架中制备新型的止血粉末（N-CS/DGO）。FTIR，SEM和BET等表明N-CS/DGO止血粉末表面含有大量的活性基团，且具有优异的亲水性，大比表面积以及丰富的孔结构。DGO占比为15%具有最佳止血潜力，此时材料的吸水率为430%,降解速度适宜，五周达到88%，对大肠杆菌和金黄色葡萄球菌抑菌圈分别为1.92 mm、1.98 mm，具备一定抑菌能力，凝血指数达到最小值32%，体外凝血时间缩短至126±6 s，这些都表明N-CS/DGO材料具备止血方面的潜力。     

Insight into Factors Influencing Wound Healing Using Phosphorylated Cellulose-Filled-Chitosan Nanocomposite Films

Marine polysaccharides are believed to be promising wound-dressing nanomaterials because of their biocompatibility, antibacterial and hemostatic activity, and ability to easily shape into transparent films, hydrogels, and porous foams that can provide a moist micro-environment and adsorb exudates. Current efforts are firmly focused on the preparation of novel polysaccharide-derived nanomaterials functionalized with chemical objects to meet the mechanical and biological requirements of ideal wound healing systems. In this contribution, we investigated the characteristics of six different cellulose-filled chitosan transparent films as potential factors that could help to accelerate wound healing. Both microcrystalline and nano-sized cellulose, as well as native and phosphorylated cellulose, were used as fillers to simultaneously elucidate the roles of size and functionalization. The assessment of their influences on hemostatic properties indicated that the tested nanocomposites shorten clotting times by affecting both the extrinsic and intrinsic pathways of the blood coagulation system. We also showed that all biocomposites have antioxidant capacity. Moreover, the cytotoxicity and genotoxicity of the materials against two cell lines, human BJ fibroblasts and human KERTr keratinocytes, was investigated. The nature of the cellulose used as a filler was found to influence their cytotoxicity at a relatively low level. Potential mechanisms of cytotoxicity were also investigated; only one (phosphorylated microcellulose-filled chitosan films) of the compounds tested produced reactive oxygen species (ROS) to a small extent, and some films reduced the level of ROS, probably due to their antioxidant properties. The transmembrane mitochondrial potential was very slightly lowered. These biocompatible films showed no genotoxicity, and very importantly for wound healing, most of them significantly accelerated migration of both fibroblasts and keratinocytes.     

Ozone treatment for improving the solubility of cellulose extracted from palm fiber

We investigated effects of ozone treatment on solubility of cellulose and chemical composition in cellulose extracted from palm fiber. The initial holocellulose, α-cellulose, and lignin contents of the extracted cellulose were 88.0, 81.9, and 8.75%, respectively. The extracted cellulose was treated with ozone and NaOH solution. Ozone treatment for 5 hr at 40°C using 3% citric acid decreased the lignin content from 8.75 to 2.71%. Under these conditions, the degree of polymerization (DP) of the cellulose decreased to 29 from 160 and the carboxyl content increased to 2.05 mmol/g. When the solid phase was treated with NaOH after ozone treatment, the mass of the solid phase decreased as the ozone treatment time increased. The lowest mass was 0.43 g. Additionally, the mass of cellulose regenerated from the liquid phase increased with increasing treatment time. The highest mass of regenerated cellulose was 0.54 g. The masses of the solid phase and regenerated cellulose obtained without ozone treatment under the same conditions were 0.76 and 0.18 g, respectively. These results suggest that ozone treatment improves the solubility of cellulose by converting hydroxyl groups in the cellulose to carboxyl groups and reducing the DP.     

高分子止血材料研究进展

介绍了壳聚糖、胶原蛋白等天然高分子和聚乙烯醇（PVA）、聚乳酸（PLA）等合成高分子止血材料如海绵、水凝胶、气凝胶、颗粒、纳米纤维膜和薄膜等的研究现状及其在创伤止血中的应用,重点阐述其止血、凝血、抗菌、生物活性和相容性等相关性能,展望了其应用前景。     

基于纤维素及半纤维素的先进材料

综述了基于纤维素和半纤维素的先进材料,如:智能材料、功能材料、高性能材料等。并简要介绍了这些先进材料的制备方法和特点。     

Study of the influence of reaction conditions on the degree of substitution,intrinsic viscosity,and yield of oxidized cellulose acetate by factorial experimental design

A half‐fraction, two‐level, four‐factor factorial experimental design was used to study the effects of the acetic anhydride concentration, reaction temperature, reaction time, and sulfuric acid concentration on the degree of substitution, intrinsic viscosity, and yield of oxidized cellulose acetate (OCA). Oxidized cellulose containing 20% (w/w) carboxylic acid was used as the starting material. The data were fitted by multiple regression analysis with SAS software. The correlation coefficients obtained from plots of the predicted and observed values for the degree of substitution, intrinsic viscosity, and yield were 0.985, 0.993, and 0.991, respectively. Residual normal plots of the regression models showed a linear relationship. Lenth and main‐factor‐effect plots revealed an increase in the degree of substitution of OCA with an increasing concentration of acetic anhydride. The latter had no effect on the intrinsic viscosity and yield of OCA. An increase in the reaction temperature led to an increase in the degree of substitution and a decrease in the intrinsic viscosity and yield of OCA. The influence of the reaction time on the degree of substitution and intrinsic viscosity followed a trend similar to that observed with the reaction temperature, but the yield of OCA was unaffected. Increasing the concentration of sulfuric acid reduced the degree of substitution, intrinsic viscosity, and yield of OCA. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 696–705, 2005     

Cellulose Regeneration and Chemical Recycling: Closing the “Cellulose Gap” Using Environmentally Benign Solvents

Strategies to mitigate the expected “cellulose gap” include increased use of wood cellulose, fabric reuse, and recycling. Ionic liquids (ILs) are employed for cellulose physical dissolution and shaping in different forms. This review focuses on the regeneration of dissolved cellulose as nanoparticles, membranes, nonwoven materials, and fibers. The solvents employed in these applications include ILs and alkali solutions without and with additives. Cellulose fibers obtained via the carbonate and carbamate processes are included. Chemical recycling (CR) of polycotton (cellulose plus poly(ethylene terephthalate)) is addressed because depending on the recycling approach employed, this process is akin to regeneration. The strategies investigated in CR include preferential dissolution or depolymerization of one component of the blend, and separation of both components using ILs. It is hoped that this review focuses the attention on the potential applications of regenerated cellulose from its solutions and contributes to the important environmental issue of recycling of used materials.     

Structure and properties of cellulose nanocomposite films containing melamine formaldehyde

Films of high Young's modulus and low density are of interest for application as loudspeaker membranes. In the present study nanocomposite films were prepared from microfibrillated cellulose (MFC) and from MFC in combination with melamine formaldehyde (MF). The prepared materials were studied with respect to structure as well as physical and mechanical properties. Studies in SEM and calculation of porosity showed that these materials have a dense paper‐like structure. The moisture sorption isotherms were measured and showed that moisture content decreased in the presence of MF. Mechanical properties were studied by dynamical mechanical thermal measurements as well as by tensile tests. Cellulose films showed an average Young's modulus of 14 GPa while the nanocomposites showed an average Young's modulus as high as 16.6 GPa and average tensile strength as high as 142 MPa. By controlling composition and structure, the range of properties of these materials can extend the property range available for existing materials. The combination of comparatively high mechanical damping and high sound propagation velocity is of technical interest. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Processing of Cellulose Using Ionic Liquids

The processing of cellulose dissolved in ionic liquids (ILs) enables the development of new materials. Besides the established production of cellulosic fiber products, interesting technical applications are developed like super micro filament fibers, cellulose/chitin blend fibers, precursors for carbon fibers, and all‐cellulose composites. This review provides a detailed summary of these new developments and describes how ILs are selected for the processing of cellulose with a particular emphasis on industrial realization. State‐of‐the‐art spinning processes are reviewed and it is illustrated how uniquely selected ILs can be used not only for established fiber spinning but for the development of new cellulose‐based materials.     

Facile fabrication of diatomite-based sponge with high biocompatibility and rapid hemostasis

Excessive bleeding causes a large part of deaths in wars and accidents. It is necessary to prepare a hemostatic material with excellent performance and low cost through a facile strategy. Herein, the diatomite is modified with (3-Aminopropyl) triethoxysilane (APTES) to endow the aminated diatomite (ADia) with positive charge and interface compatibility with chitosan (CS) and sodium alginate (SA). Then, the facile fabrication of CS/SA/ADia sponge is successfully obtained by cross-linking with calcium ions. Compared to CS/SA sponge, the introduction of ADia further enhances the mechanical properties and hemostatic performance of CS/SA-based sponges. The composite sponges with 30 wt% ADia are demonstrated to possess high biocompatibility, compressive strength, water adsorption, and rapid hemostatic capability both in vitro and in vivo. The hemostatic performance is interpreted by activation of coagulation factors and platelets in intrinsic pathway, promotion of blood cell adhesion and formation of fibrin network. Our work provides an effective strategy to develop rapid hemostatic materials with low cost and high efficiency.     

A Review on Nanocellulose and Its Application in Supercapacitors

Commercially available supercapacitors offer very limited advantages over other energy storage devices. Balancing their electrochemical performance such as capacitance, energy density, and cyclability is challenging. Studies have shown that this challenge can be overcome by using light and cheap substrates that are highly stable with solvents, and have high loading capacities and compatibility with nanomaterials. Nanocellulose, derived from wastes or biomass, is a good candidate for integrating with other nanosize conductive materials, such as carbon, conducting polymers, and metal oxides, as active materials or nanocomposites for supercapacitors. This review focuses on the properties and preparation of nanocellulose sourced from wastes (biomass) and bacteria, and extends to emerging materials, such as metal–organic frameworks and MXene, for nanocellulose-based supercapacitors. Even though supercapacitors are mainly composed of electrodes, electrolytes, and separators, this paper focuses on the overall electrochemical performance of nanocellulose-based supercapacitors to evaluate the influence of nanocellulose. In addition, the potentials and possible limitations of nanocellulose in supercapacitors are discussed. Overall, the incorporation of waste-derived nanocellulose into energy storage applications is an initiative that improves the circular economy and supports environmental sustainability.