纳米纤维素的氧化法制备工艺及其在气凝胶、水凝胶和膜材料领域的应用研究进展

本文综述了基于氧化工艺制备纳米纤维素的研究进展,包括利用2,2,6,6-四甲基哌啶氧化物(TEMPO)、NaIO₄、过硫酸铵、Fe²⁺和含氯体系制备纳米纤维素相关研究,并介绍了氧化纳米纤维素在气凝胶、水凝胶和膜材料等领域的应用研究进展。     

纳米纤维素基气凝胶的制备及其吸附分离应用研究进展

纤维素基功能材料的产业化是传统造纸行业转型升级的重要发展方向。纳米纤维素基气凝胶是一种基于纳米纤维素制备而成的轻质固体材料,具有孔隙率高、比表面积大、低密度和可生物降解等优点,在吸附分离领域有广泛的应用。本文对纳米纤维素基气凝胶的制备方法进行了总结,探讨了制备过程对纳米纤维素基气凝胶结构的影响,综述了纳米纤维素基气凝胶在吸附分离领域中的应用进展,并展望了其应用前景。     

纳米纤维素基2D/3D重金属吸附材料的研究进展

本文综述了通过氨基、羧基、硫醇基等官能团改性纳米纤维素以及纳米纤维素和其他材料复合,制备成2D膜材料和3D凝胶材料的方法及其性能,同时也介绍了其在水环境中去除重金属离子的应用进展,并对纳米纤维素基吸附剂的制备和应用进行了展望。     

杨絮纳米纤维素气凝胶的制备及表征

本试验以杨絮为原料,经化学预处理,得到纯化纤维素,再经机械处理制备纳米纤维素溶胶,通过液氮对杨絮纳米纤维素溶胶进行冷冻处理,制备得到杨絮纳米纤维素气凝胶。为探究不同超声处理时间对杨絮纤维微纤化的影响,笔者从气凝胶的密度、孔隙率、微观形貌等方面进行分析,进而探究了超声处理时间对所得气凝胶性能的影响。     

疏水亲油型纳米纤维素气凝胶的制备与吸油性能研究

本研究以不同方法制备的针叶木纳米纤维素（CNF、ECNF和TCNF）为原料,通过冷冻干燥法制备纳米纤维素气凝胶,并利用硬脂酰氯（SAC）溶液浸渍法对其进行疏水改性。采用激光粒度仪、X射线衍射分析仪、Zeta电位仪测定了纳米纤维素的粒径分布、结晶度及电荷密度,并对疏水改性前后气凝胶的密度、孔隙率、结构形貌、疏水性能及吸油性能进行了分析和研究。结果表明,TCNF粒径及电荷分布较为均匀;SAC改性不会影响纳米纤维素气凝胶轻质、多孔的特性,改性后的气凝胶表现出优异的疏水性和良好的吸油性,其中S-ECNFA的疏水性最佳,表面水接触角（CA）可达151.6°;S-TCNFA对4种不同密度的油吸附能力最强,其中对食用油的吸油量可达48.96 g/g气凝胶,经5次循环使用后,对食用油的吸油量仍可达初次吸油量的60.8%,具有较好的循环使用性能。     

羟乙基纤维素基载银复合气凝胶的制备及性能

针对生活用水、工业用水细菌含量不达标问题,本文以羟乙基纤维素(HEC)、纳米银溶液为原料,聚乙烯吡咯烷酮(PVP)为保护剂制备了一种基于羟乙基纤维素的复合气凝胶抗菌过滤材料(HEC-PVP)。研究了HEC-PVP复合气凝胶的抗菌性能,探讨了HEC-PVP复合气凝胶的制备工艺,同时分析了较优工艺条件下制备的HEC-PVP复合气凝胶的力学性能、水中结构稳定性、抗菌性能等。     

羧乙基化和碱预处理玉米芯渣制备纳米纤维素的研究

玉米芯提取木糖后剩余的残渣富含纤维素和木质素,采用羧乙基化反应和质量分数1%的NaOH溶液分别对玉米芯渣进行预处理,再经机械解离制备了纳米纤维素,最后经棒涂法制得纳米纤维素膜,并对预处理前后玉米芯渣、纳米纤维素及其膜的化学结构、组分含量、微观形貌、尺寸分布、水接触角和热稳定性进行了分析和表征。结果表明,羧乙基化预处理可增加玉米芯渣的羧基含量,同时脱除部分木质素,而碱预处理可脱除大部分木质素。经预处理后,玉米芯渣纤维尺寸明显降低、可及度增加。经机械解离后,羧乙基化预处理所得纳米纤维素的直径更小、分布更均匀,其经棒涂法所得膜也更加致密平滑,水接触角较大。另外,两种预处理方法均降低了所得纳米纤维素膜的热稳定性。     

静电纺丝制备乙基纤维素纳米载药纤维

本文通过静电纺丝技术制备了乙基纤维素/酮洛芬复合载药纳米纤维膜,利用傅里叶红外光谱仪(FTIR)、扫描电子显微镜(SEM)以及X射线衍射仪(XRD)对载药前后的乙基纤维素纳米纤维分别进行了表征。扫描电子显微镜观察结果表明,用六氟异丙醇为溶剂制备的纳米纤维膜表面光滑,没有粘结现象,纤维直径在500~600 nm之间;红外光谱分析表明,利用静电纺丝技术成功制备了载药乙基纤维素纤维;X射线衍射表明,酮洛芬以无定形的状态存在于纳米纤维中;释药结果表明,酮洛芬在7天左右的累积释药率达到50%左右,可以用作药物缓释材料模型。     

改性纳米TiO2对纤维素包装膜性能及结构的影响

本文利用氯化锂/N,N-二甲基乙酰胺(LiCl/DMAc)溶解纤维素,并与改性、未改性的纳米TiO2进行共混,采用溶胶-凝胶法制备可降解纤维素包装膜.通过红外光谱对改性前后纳米材料的结构进行表征,测试纤维素包装膜的拉伸强度及断裂伸长率,并进行热失重分析;使用扫描电镜和原子力显微镜观察其表面结构.结果表明:改性纳米TiO2比未改性纳米材料在纤维素膜中的分散更均匀,当改性纳米TiO2与纤维素混合比例为0.5∶100时,纤维素包装膜的拉伸强度和断裂伸长率分别为25.6MPa和125％,较加入未改性纳米TiO2的纤维素膜拉伸强度提高了1.45倍,断裂伸长率是原来的1.35倍.     

3种非木材原料制备纳米纤维素及其膜性能的比较

对蔗渣、芦苇、竹子3种典型的非木材原料进行蒸煮、漂白以及TEMPO氧化,以制备纳米纤维素和纳米纤维素膜。比较了由3种原料制备的纳米纤维素材料的热学性能、光学性能和力学性能。通过比较发现,由竹子制备的纳米纤维素材料的综合性能最好。竹子纳米纤维素的热稳定性最好,芦苇纳米纤维素次之,蔗渣纳米纤维素最低;竹子纳米纤维素膜的透明性最高,蔗渣纳米纤维素膜次之,芦苇纳米纤维素膜最低;竹子纳米纤维素膜的力学性能最好,其拉伸强度和杨氏模量分别为92.8 MPa和5945 MPa,芦苇纳米纤维素膜次之,其拉伸强度和杨氏模量分别为72.7 MPa和4780 MPa,蔗渣纳米纤维素膜最低,其拉伸强度和杨氏模量分别为68.4 MPa和3572 MPa。     

包载山苍子油的醇溶蛋白纳米粒子对明胶膜结构和性能的影响

本文以明胶、玉米醇溶蛋白和山苍子油为基材,通过流延法制备包载山苍子油的醇溶蛋白纳米粒子/明胶复合膜,研究了纳米粒子与明胶的相互作用,以及不同纳米粒子添加量对复合膜的透光性、微观结构、热稳定性、机械性能、疏水性、抑菌和抗氧化性能的影响。结果表明,纳米粒子与明胶之间发生了氢键相互作用,具有良好的相容性。随着纳米粒子添加量的增大,复合膜的透明度显著降低,其疏水性和抗氧化性显著增强（P<0.05）。复合膜对大肠杆菌和金黄色葡萄球菌均具有明显的抑菌活性,其抑菌圈直径分别为（9.17~10.00） mm和（10.02~11.10） mm。当纳米粒子分散液添加量为30%（v/v）时,复合膜的截面最致密,其热稳定性最好,断裂伸长率最大。本研究为开发含有山苍子油的食品活性包装材料提供了一定的参考依据。     

Development of Gelatin Bionanocomposite Films Containing Chitin and ZnO Nanoparticles

The gelatin-based nanocomposite films (GNCFs) containing 0, 1, 3, and 5% zinc oxide nanoparticles (N-ZnO) and/or 0, 3, 5, and 10% chitin nanofibers (N-chitin) were prepared, and their water vapor permeability (WVP), chemical structure and microstructure, and their mechanical, thermal, and antifungal properties were investigated. Results showed that incorporation of N-ZnO improved WVP, mechanical, thermal, and antifungal properties of the gelatin-based films. Moreover, physicochemical and antifungal properties of the nanocomposite films improved by increasing N-ZnO concentration. However, applying N-chitin in gelatin films could not enhance barrier properties of the films against water vapor, probably due to the hydrophilic nature of N-chitin. On the other hand, tensile strength of the GNCFs containing N-chitin increased by an increase in nanoparticle concentration, up to 5%, Incorporation of N-chitin in the gelatin film raised both thermal stability and antifungal activity. Simultaneous incorporation of chitin and ZnO nanoparticles in the GNCFs had the interactive effect on improving the physicochemical and antimicrobial properties of GNCFs. For instance, thermograms of differential scanning calorimetry (DSC) showed that the GNCF containing both nanoparticles increased melting point and ?H _m in comparison with net gelatin film. Furthermore, thermograms of thermogravimetric analysis (TGA) indicated that applying both of nanoparticles in gelatin films led to higher thermal stability of polymer against decomposition at higher temperatures, compared to the gelatin film containing each of them.     

纤维素纳米纤维/纳米蒙脱土复合气凝胶制备及其结构与性能

针对纤维素纳米纤维(CNF)气凝胶易燃、强力低等问题,利用纳米蒙脱土(MMT)共混改性纤维素纳米纤维,基于冷冻干燥的方法制备阻燃隔热的CNF/MMT复合气凝胶。研究了MMT质量分数对CNF/MMT复合气凝胶形貌结构、压缩性能、热稳定性、热导率和阻燃性能的影响。结果表明:MMT的引入使气凝胶具有更加紧密的片层结构,气凝胶力学性能、热稳定性和阻燃性能得到改善;在MMT质量分数为50%时,CNF/MMT复合气凝胶的表观密度最大且仅为0.016 8 g/cm³,应变为10%的应力最大为12.45 kPa,应变为70%的应力最大为77.93 kPa,导热系数最大为 0.04 W/(m·K); 气凝胶中MMT质量分数不低于42.9%时,复合基气凝胶的极限氧指数得到明显提升。     

Multifunctional nanocellulose/metal and metal oxide nanoparticle hybrid nanomaterials

Abstract

Nanocellulose materials are derived from cellulose, the most abundant biopolymer on the earth. Nanocellulose have been extensively used in the field of food packaging materials, wastewater treatment, drug delivery, tissue engineering, hydrogels, aerogels, sensors, pharmaceuticals, and electronic sectors due to their unique chemical structure and excellent mechanical properties. On the other hand, metal and metal oxide nanoparticles (NP) such as Ag NP, ZnO NP, CuO NP, and Fe₃O₄ NP have a variety of functional properties such as UV-barrier, antimicrobial, and magnetic properties. Recently, nanocelluloses materials have been used as a green template for producing metal or metal oxide nanoparticles. As a result, multifunctional nanocellulose/metal or metal oxide hybrid nanomaterials with high antibacterial properties, ultraviolet barrier properties, and mechanical properties were prepared. This review emphasized recent information on the synthesis, properties, and potential applications of multifunctional nanocellulose-based hybrid nanomaterials with metal or metal oxides such as Ag NP, ZnO NP, CuO NP, and Fe₃O₄ NP. The nanocellulose-based hybrid nanomaterials have huge potential applications in the area of food packaging, biopharmaceuticals, biomedical, and cosmetics.     

桔子精油优化鱼鳞明胶膜性能的作用研究

为改善鱼鳞明胶膜的性能,测定添加明胶质量的0%、25%、50%、75%、100%桔子精油的可食膜的厚度、机械性能、水溶性、水蒸汽透过率、色泽、透明度和透光率、热性能、红外光谱和抑菌活性。结果表明:随着精油浓度的增加,鱼鳞明胶膜的厚度、断裂伸长率增加,拉伸强度、透光率、水溶性降低,水蒸汽透过率呈现先增加后降低的趋势;差示扫描量热法(DSC)和傅里叶变换红外光谱(FTIR)分析结果表明,鱼鳞明胶分子与桔子精油的部分成分发生相互作用,在一定程度上改善了明胶膜的热稳定性;桔子精油的添加还赋予了鱼鳞明胶膜抑菌作用。综合评价得出75%质量浓度的桔子精油添加量对鱼鳞明胶膜各项性能优化效果最好,本实验结果可为生产高性能的鱼鳞明胶膜提供理论基础。     

Conductive Polyaniline/Cellulose/Graphite Composite Films with High Thermal Stability and Antibacterial Activity

Functional composite films were successfully prepared from cellulose, graphite (GP), and polyaniline (PANI) using a combination of physical and chemical processes. Cellulose was dissolved in N-methylmorpholine-N-oxide monohydrate (NMMO) and regenerated in water to form the matrix. GP was dispersed in the NMMO solvent prior to the dissolution of the cellulose, and PANI was deposited on the surfaces of the cellulose/GP films by in situ chemical polymerization. The structures of the PANI/cellusose/GP composite films were investigated using X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and SEM/energy-dispersive X-ray spectroscopy. The mechanical strengths, thermal stabilities, conductivities, and antibacterial activities of the films were studied in detail. The results showed that GP formed a multilayered structure in the cellulose matrix and that the PANI nanoparticles were tightly wrapped on the film surface. The film thickness increased from 40 m to 100 m after the addition of GP and PANI. The tensile strength of the composite films was 80~107 MPa, with the elongation at break being 3%~10%. The final residual weight of the composite films was as high as 65%, and the conductivity of the composite films reached 14.36 S/m. The cellulose matrix ensured that the films were flexible and exhibited desirable mechanical properties, while the GP filler significantly improved the thermal stability of the films. The PANI coating acted as a protective layer during burning and provided good electrical conductivity and antibacterial activity against Escherichia coli; both of these characteristics were slightly enhanced by the incorporation of GP. These PANI/cellulose/GP composite films should be suitable for use in electronics, antistatic packing, and numerous other applications.     

Development of Antibacterial Carboxymethyl Cellulose‐Based Nanobiocomposite Films Containing Various Metallic Nanoparticles for Food Packaging Applications

In this study, silver (Ag), zinc oxide (ZnO), and copper oxide (CuO) metallic nanoparticles were used in preparation of carboxymethyl cellulose (CMC) nanobiocomposite films. Scanning electron microscopy (SEM), X‐ray diffraction (EDXA), water vapor permeability (WVP), ultraviolet and visible light (UV–Vis) spectroscopy, and mechanical and microbial tests were used to determine the characteristics of the obtained active films. SEM results showed that the CMC nanobiocomposite films had roughness deflection levels and the EDXA test confirmed the presence of Ag, ZnO, and Cuo nanoparticles in the biopolymer tissue. UV–Vis spectroscopy confirmed that with addition of metallic nanoparticles to the pure CMC film, absorption rate increased and WVP decreased. In the mechanical tests, addition of nanoparticles also increased the tensile strength of the films, and the nanobiocomposite films exhibited higher resistance compared to the pure CMC film. Films incorporating metallic nanoparticles showed antibacterial properties against Escherichia coli and Staphylococcus aureus growth. Thus, nanobiocomposite films can be used as active packaging films and could increase the shelf‐life of the food.     

细菌纤维素气凝胶接枝甲基丙烯酸二甲氨乙酯的制备

为制备新型细菌纤维素（BC）气凝胶可控接枝聚合物,采用电子转移活化再生催化剂原子转移自由基聚合(ARGET ATRP)法,以含溴的细菌纤维素为引发剂、维生素C（Vc）为还原剂、N,N,N',N,'N'-五甲基二亚乙基三胺（PMDETA）/溴化铜（CuBr2）为催化剂,制备了含聚甲基丙烯酸二甲氨乙酯（PDMAEMA）的细菌纤维素气凝胶规整接枝共聚物。采用能谱分析仪对大分子引发剂元素含量进行测定。通过凝胶渗透色谱、红外光谱、X射线衍射、扫描电镜、热失重分析表征了接枝物结构和性能。结果表明：以细菌纤维素气凝胶为原料,采用ARGET ATRP聚合法成功制备了BC-g-PDMAEMA聚合物,分子量分布指数为1.27,接枝率为875.76%,接枝后纤维直径增大且在纤维表面形成覆盖层,热稳定性由205℃升高到230℃。     

超声与光催化作用对大豆蛋白/TiO_2复合膜抗菌特性的影响

采用光催化/超声预处理,结合涂膜法制备大豆蛋白/TiO_2纳米复合膜,分析光催化和超声预处理以及膜中TiO_2含量对复合膜性质的影响。当TiO_2含量低于2%时,扫描电子显微镜观察发现TiO_2纳米颗粒均匀地分散在大豆蛋白基质中,从而有效地改善复合膜的机械性能,降低膜的溶胀变形程度,提高膜的热稳定性,增强复合膜的抗菌活性。荧光光谱分析、红外光谱和X-射线衍射分析证实了大豆蛋白和纳米颗粒间以氢键为主要作用力,且光催化可进一步增强TiO_2颗粒与大豆蛋白链间交联作用,因而光催化复合膜的机械性能、热稳定性和抗菌活性均高于超声复合膜。但当TiO_2含量过高(2%)会加剧TiO_2间的自聚,导致复合膜机械性能下降、溶胀变形程度增大及荧光淬灭。因此光催化大豆蛋白/TiO_2纳米复合膜有望成为新型绿色抗菌包装材料。     

Development of functional alginate fibers for medical applications

In this study, antibacterial alginate fibers were developed by using two approaches for fiber development. Firstly, replacing the sodium ions of sodium alginates with metal ions like zinc. Secondly, replacing the sodium ions of sodium alginate with biologically inactive ions like calcium and loading the fibers with ZnO nanorods. Fibers were characterized by liquid absorption and ion release measurements, by placing them separately in distilled water, solution A (0.8298% NaCl & 0.0368% CaCl2) and normal saline solution. Results showed that release of ions from fibers was affected by liquid absorption, physiology of solution and contact time with solution. More ions were released from fibers with higher absorption and longer contact time. Calcium alginate fibers containing zinc ions showed greater absorbency as well as the greater metal ions release. Fibers containing zinc ions, and ZnO nanorods were also tested for their mechanical properties and antibacterial properties against Staphylococcus aureus and Escherichia coli. Alginate fibers containing ZnO nanorods were stronger than alginate fibers containing zinc ions. However, calcium fibers containing zinc ions exhibited more antibacterial activity.