【作者】 庞洪涛；

【导师】 张志焜；

【作者基本信息】 中国海洋大学 ， 药物化学， 2008， 博士

【摘要】 纳米材料的制备方法对其结构、性能有重要影响。通过不同方法制备了纳米金属氧化物和壳聚糖纳米微球,并对其结构进行表征;在此基础上提出制备金属氧化物/壳聚糖纳米复合材料的新思路,并以之为指导制备了金属氧化物/壳聚糖纳米复合材料,研究了该复合材料的结构和性能。用常温化学沉淀法和水热反应法制备了MnO₂的纳米结构。常温化学沉淀法是通过KMnO₄和MnSO₄的常温化学反应来获得MnO₂纳米结构。所制备的纳米结构微观形貌为不规则的球笼型结构,球笼型结构由相互交织在一起的纳米短片构成,纳米片厚度10～20 nm,宽度50～80nm。XRD分析表明,该产物属于ε-MnO₂晶体结构,但结晶度较低。添加阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）能够改变纳米结构的形貌,形成由纳米片交织的不规则多孔网片状结构。以KMnO4和MnSO4为前驱体,用水热反应法在160℃制备了粒径50nm,长1～2μm的棒状MnO₂纳米结构。晶体结构测试表明,该纳米棒从常温制备的ε-MnO₂转变为β-MnO₂,且纯净无杂质,结晶度高。表面活性剂CTAB存在时纳米结构微观形貌转变为层叠的宝塔状。以颗粒状的MnO₂粉体为前驱体,以NaOH水溶液为反应介质,用水热反应法制备了MnO₂一维纳米结构。当反应条件160℃/48h时,得到厚度10～20nm,宽度80～100nm,长约数微米的一维纳米带。XRD数据显示,纳米带是γ-MnO₂晶体结构,结晶度较高。当反应介质为LiOH时,得到类似的结果。用液体回流法制备了TiO2纳米微粒。在丁醇水溶液中滴加钛酸四丁酯,将得到的反应产物粉碎后500℃煅烧,得到白色纳米TiO2粉体。结构分析表明,所得TiO2纳米结构为粒径50～100nm的球形微粒,是锐钛矿和金红石的混合晶型,其中金红石型约占41%。用分子自组装方法制备了脱氧胆酰修饰壳聚糖的纳米微球。首先以壳聚糖和脱氧胆酸为原料,以碳化二亚胺为交联剂制备了脱氧胆酰修饰壳聚糖,1H NMR测试其取代度为0.051,同时研究了它在Ac、HCl溶液中的自聚集能力。在乙酸-乙酸钠溶液中,以二氯甲烷为乳化剂、三聚磷酸钠为交联剂制备了脱氧胆酰修饰壳聚糖纳米微球。TEM观察表明,纳米微球的粒径介于100～600nm之间。以TiO2纳米微粒和壳聚糖为原料,强碱性的NaOH浓溶液为溶剂,利用水热反应法制备了TiO2/壳聚糖一维纳米复合材料。SEM、TEM电镜观察显示,复合材料为厚度小于10nm,宽度200～300 nm,长度为几微米的半透明带状纤维。结构分析表明,复合材料的主体为纳米二氧化钛。同时,在壳聚糖存在情况下大部分纳米TiO2由锐钛矿型转变为金红石型。反应机理分析认为,NaOH在反应中决定纳米TiO2晶体的生长方向,并能够使壳聚糖活化,进而参加反应。在抗菌试验中,TiO2/壳聚糖一维纳米复合材料表现出较强抑菌能力,在含量为3%时可以完全抑制金黄色葡萄球菌的生长。壳聚糖具有优良的成膜能力。用壳聚糖、聚乙烯醇、羧甲基壳聚糖制备了三层复合膜结构,表面层壳聚糖膜具有良好的抗菌抑菌能力,底层羧甲基壳聚糖膜生物相容性好,能够促进正常皮肤纤维细胞生长并抑制疤痕疙瘩成纤维细胞的生长。在壳聚糖膜层添加纳米TiO2来提高膜性能,测试表明随TiO2含量增加,膜的抗水能力和热稳定性提高,膜层由晶态逐渐转变为非晶态。更多还原

【Abstract】 The methods for the preparation of nanomaterials have significant influences on their structures and performances. Nanocrystalline metal oxides and chitosan microspheres have been synthesized by different methods, and their structures were characterized. Furthermore, a new route for the synthesis of metal oxide / chitosan nanocomposites has been presented, and their structures and performances have been investigated. The main texts are as follows:MnO₂ nanostructures have been fabricated by precipitation method at room temperature and hydrothermal method, respectively. Spherical MnO₂ nanostructures composed of interweaved nanosheets have been prepared by precipitation method at room temperature. The thickness and lateral dimension of the nanosheets are about 10²0 nm and 50⁸0 nm, respectively. XRD pattern shows that the products areε-MnO₂, which have low crystallinity. Porous net-like anomalous structures made up of nanosheets can be formed with the aid of CTAB.Rodlike MnO₂ nanostructures with diameters of 50 nm, and lengths up to 1²μm have been synthesized at 160℃by hydrotherma method using KMnO4 and MnSO4 as precursors. Theseβ-MnO₂ nanorods are changed fromε-MnO₂ under thermal conditions and have high crystallinity. In addition, tower-like nanostructures are obtained in the presence of CTAB.One-dimensional MnO₂ nanostructures have been produced by hydrothermal treating commercial MnO₂ particles as precursors in NaOH media. As the reactions are carried out at 160℃for 48 h, MnO₂ nanobelts with thickness of 10²0 nm, width of 80¹00 nm, and lengths up to several micrometers are obtained. XRD result reveals that these nanobelts areγ-MnO₂ and have high crystallinity. When the reactions are performed in LiOH media,γ-MnO₂ nanofibers are formed and the reaction process is similar to that in NaOH media.TiO2 nanoparticles have been prepared by butanol refluxing method. In the process, tetrabutyl titanate is added dropwise into butanol-water solution to form precipitates. White TiO2 powders are obtained after the precipitates are calcined at 500℃. The characterization results show that spherical TiO₂ nanoparticles are 50¹00 nm in diameter, and mix-crystals of anatase （59%） and rutile（41%）.DE-chitosan nanospheres are synthesized by self-assembly method. Firstly, DE-chitosan is prepared using chitosan and deoxycholic acid as the reagents, and carbodiimide as crosslinking agents. 1H NMR spectrum shows that the substitution degree of DE-chitosan is 0.051. The self-aggregation ability of DE-chitosan in Ac, and HCl solution are investigated. DE-chitosan nanospheres are obtained in acetic acid - sodium acetate solution using methylene chloride as emulsifier, and sodium triphosphate as crosslinking agents. TEM image reveals that these nanospheres are ununiform, and in the range of 100⁶00 nm in diameters.One-dimensional TiO2/chitosan nanocomposites have been fabricated by hydrothermal method using TiO2 nanoparticles and chitosan as raw materials, and NaOH solution as solvent. SEM and TEM images show that the thicknesses are less than 10 nm, the widths are about 200³00 nm, and the lengths are about several micrometers. XRD patterns shows that the main components of the composites are rutile TiO2, indicating that anatase are changed to rutile in the presence of chitosan. It is supposed that the formation of one-dimensional TiO2/chitosan nanocomposites is due to the activation of chitosan in the NaOH solution, which controls the crystal growth of TiO2. Antimicrobial experiments reveal that TiO2/chitosan nanocomposites have high antimicrobial ability. The growth of staphyloccocus aureus is prohibited as the contents of TiO2/chitosan nanocomposites is 3%.Chitosan has displayed good membrane forming capacity. Three-layer membranes were prepared with chitosan, polyvinyl alcohol and carobxymethy chitosan, the top-layer was chitosan,the intermediate was polyvinyl alcohol, and the substrate was carboxymethyl chitosan.The top-layer had high antibacterial activity, the substrate-layer had the activity of promoting growth of human skin fibroblast and inhibiting the growth of keloid fibroblast. The performances of chitosan films are enhanced by adding TiO2 nanoparticles. It is found that the waterproof ability and thermal stability of the films are promoted with the contents of TiO2 nanoparticles increased.更多还原