含羧基的含氟嵌段共聚物的合成及表面性能研究

利用原子转移自由基聚合反应以及随后的大分子链中叔丁酯基团的水解反应,合成了一系列具有不同含氟量和羧基含量的二嵌段共聚物,并分别通过GPC, ¹H NMR和FT-IR对共聚物的组成和结构进行了表征.进一步考察了这些含羧基或羧酸钠基团的含氟嵌段共聚物在吡咯烷酮或水中的溶解性能、临界胶束浓度、表面活性、达到饱和吸附时每个分子在表面所占据的面积,以及成膜后的临界表面张力等性能.实验结果表明,此含氟嵌段共聚物能显著降低吡咯烷酮和水的表面张力,成膜后表现出与聚四氟乙烯极为接近的低表面能特性.     

富氢气氛下CO选择性氧化催化剂Pt/γ-Al2O3中添加钴的作用

研究了Pt/γ-Al₂O₃催化剂上添加Co对降低Pt负载量的效应,同时通过XRD,CO-TPD,H₂-TPR和FTIR等手段对Co助催的Pt/γ-Al₂O₃催化剂进行了表征,藉此探讨了Co的改性作用.实验结果表明,在Pt/γ-Al₂O₃催化剂中添加Co可显著降低Pt的用量和改善低温活性.在Pt负载量为w_Pt=0.01,Co添加量为w_Co=0.015～0.03时,在ψ_O2/ψ_CO=1.0和120℃的较低温度下,CO转化率和O₂选择性分别高达99%和47%以上.在Pt/γ-Al₂O₃催化剂中添加的Co以不完全还原的CoO_x形态存在,不仅可以提供活泼氧与CO反应生成CO₂,而且影响Pt的电子性能,使之较难还原.Co的引入还削弱了CO在Pt上的吸附,使CO线式吸附物种消失,同时使碳酸氢盐和甲酸盐吸附物种增加.随温度升高,Co/Pt/γ-Al₂O₃催化剂上碳酸氢盐物种消失并转化成CO₂.     

水热合成介观结构的ZnS纳米纤维

以Zn(Ac)₂和Na₂S为原料、EDTA为稳定剂、OA为结构导向模板,采用水热合成方法成功地制备了具有层状介观结构的ZnS纳米纤维;通过XRD, TEM, SEM, N₂-吸附/脱附以及紫外-可见漫反射等手段对所得的产物进了表征,并初步探讨了其形成机理.     

高频介质阻挡放电烟气脱硫研究

采用高频介质阻挡放电的方式产生低温等离子体,研究在不加入NH₃的情况下流动态SO₂的去除情况.实验表明,在输入电压为12 kV,SO₂浓度为5400 mg/m³,气体流量为0.36 m³/h,相对湿度为55%时,脱硫率可达到70%以上;水气的存在对SO₂的去除有较大的促进作用,升高电压和增加O₂量对脱硫率的促进作用有限.对实验结果进行了解释,并提出了反应机理.     

Hydrogels in aqueous phases of polyvinylalcohol (PVA), surfactants and clay minerals

Aqueous solutions of synthetic clay minerals have been studied in the presence of surfactants and water-soluble polyvinylalcohol (PVA). The PVAs (PVA 1, PVA 2) had a molecular weight of about 10⁵ Dalton and a degree of hydrolysis of 82%. The PVA-samples were surface active and lowered the surface tension to 43 mN/m. As a consequence of their amphiphilic nature the PVA molecules bind strongly to clay mineral particles. On saturation the clay mineral particles adsorb the fivefold weight of PVA of their own weight. It is concluded that the thickness of the adsorbed layers on both sides of the clay mineral is in the range of the hydrodynamic diameter of the PVA-coils in the bulk phase.When the clay mineral particles are not saturated with PVA, they act as cross-linking agents for the PVA. The whole systems are physically cross-linked and assume gel-like properties. Rheological measurements show that samples behave like soft matter with a yield stress value. All of them have a frequency independent storage modulus which is an order of magnitude larger than the loss modulus. The hydrogels become stronger as PVA concentration increases.Small amounts of cationic surfactants bind on the clay mineral. The interface of the clay mineral becomes more hydrophobic and the binding of the PVA on the clay mineral is strengthened. With rising concentration of the surfactant the surfactant molecules bind on PVA and the PVA becomes hydrophilic. As a consequence the PVA can no longer bind on the clay mineral and the gels transform to viscous and turbid solutions. Small amounts of cationic surfactants therefore stiffen the hydrogels while larger amounts cause phase separation and a solution with low viscosity. Anionic surfactants like SDS do not bind on the clay mineral, but strongly on the PVA. With increasing SDS concentration, the hydrogels become stiffer at first but thereafter they break and transform to viscous fluids.In PVA-solutions without the clay minerals both cationic and anionic surfactants bind to the PVAs in the aqueous solution. With increasing concentration of surfactant, the viscosities of the solutions pass over a maximum. In this respect the PVAs behave like hydrophobically modified water soluble polymers. The surfactants bind to the hydrophobic microdomain and thereby crosslink the polymer molecules. On saturation the polyvinyl alcohol with anionic surfactant become hydrophilic and the network character disappears to a certain extent.     

改性淀粉/PVA生物降解材料性能的研究

以BPO为引发剂、正庚烷为溶剂在66℃下制得马来酸酐接枝淀粉。将其与聚乙烯醇(PVA)、增塑剂及加工助剂等于HAAKE密炼机中共混,制备了可生物降解热塑性淀粉塑料。研究了接枝改性淀：粉／PVA共混物的力学性能、生物降解性能及热性能等,并用SEM研究了共混物的微观形态。结果表明接枝改性淀粉／PVA共混物拉伸强度为27．57Mpa,60d失重率达65．1％。     

生物农药微胶囊壁材料研究

用原位聚合法对生物农药阿维菌素进行包囊,然后制备微胶囊制剂,并对用于该制剂的两种高分子囊壁材料-三聚氰胺甲醛树脂和脲醛树脂的性能进行了研究。结果表明,两种树脂皆为较好的生物农药用微胶囊缓释剂型的囊壁材料,其制备工艺简单,具有良好的稳定性、粒径大小与分布、悬浮性、缓释性等,包封率均达80％以上。其中三聚氰胺甲醛树脂悬浮性较脲醛树脂更好,缓释性更持久。     

天然产物Modhephene的全合成研究进展

综述了近年来天然产物Modhephene的全合成方法,并依据其不同的环化方法分为两大类,对每例合成方法进行了详尽的分析。     

一个新的席夫碱——N，N-二甲基甲酰胺水杨酰腙的合成与表征

水杨酰肼和过量的N,N-二甲基甲酰胺(DMF)在三氯氧磷的催化下合成了一种新的席夫碱——N,N-二甲基甲酰胺水杨酰腙,其结构经元素分析和IR确证。研究了可能的反应机理。     

保健食品中褪黑素标准物质的前期研究

通过对褪黑素标准物质的前期研究,选择提纯试剂将褪黑素合成品进行纯化,用高效液相色谱法测定,纯度可达到99．5％,符合标准物质制备的要求。