聚酰胺—胺的合成表征及其对铝酸钠溶液的影响

【作者】 周婷；

【导师】 黄坚；

【作者基本信息】 中南大学 ， 分析化学， 2010， 硕士

【摘要】 树枝状大分子是一种特殊结构的新型高分子,具有高度支化、结构规整、单分散等独特的结构。这类化合物由小分子通过重复的反应过程来合成,分子量、分子尺寸、形状和表面官能团等都可控。这些特点使其在许多领域有潜在的应用价值,成为相关领域的研究热点。铝酸钠溶液种分分解过程的强化一直是铝酸钠晶种分解过程的一个研究热点。如何强化晶种分解过程,提高分解率和产品氢氧化铝的粒度,对我国铝工业的发展有重要意义。添加剂强化铝酸钠溶液分解具有效果好、操作简单、成本低等优点,是一种具有工业应用前景的强化方法。本文在研究优化聚酰胺-胺(PAMAM)合成条件的同时,重点研究了这类新型树状大分子作为铝酸钠种分添加剂的性能。采用发散法,以乙二胺为核心,甲醇为溶剂,通过交替进行Michael加成反应和酰胺化反应合成了G-0.5～G5.0PAMAM。针对文献报道的合成方法反应时间过长提纯困难的缺点,从加料顺序、反应温度、反应时间、投料比对聚酰胺-胺合成条件进行了优化。大大地缩短了合成反应的时间,改进了产物的纯化方法。通过元素分析、电位滴定、红外光谱、热重分析等方法对其结构进行了表征。实验结果表明：采用此法合成的PAMAM纯度较高,具有较好的结构完整性,小分子含量较小。将P树状大分子用作添加剂,研究了不同代数的聚酰胺-胺对铝酸钠溶液的表面张力和晶种分解过程的影响。实验使用最大气泡法测定添加了P后铝酸钠溶液的表面张力,结果表明半代数的PAMAM有着较好的表面活性,有望成为新一代的表面活性剂。通过表面张力曲线图可以得出-0.5G、0.5G、1.5G及2.5GPAMAM的临界胶束浓度分别为：1350mg/L、1220mg/L、156mg/L及130mg/L。整代数的P也有一定的表面活性。PAMAM属于非离子型表面活性剂,实验结果表明,PAMAM可以提高铝酸钠溶液的分解率,并能增大产品氢氧化铝的粒度。在不同代的PAMAM中,2.5G PAMAM加入量为临界胶束浓度时强化作用最为明显,相比未加添加剂铝酸钠分解率提高10%以上,小于20μm粒子减少6.85%,大于45μm增加30.38%以上。更多还原

【Abstract】 The Poly-amidiamine (PAMAM) Dendrimers, which have hyperbranched, well defined and monodisperse structures, can be formed by reiterative reaction sequences starting from smaller molecules named "initiator core". And its molecular weight, size, shape and functional group over surface can be controlled by the reactions and synthetic building blocks used. Great attention has been paid to dendrimers in many fields.The synthesis of PAMAM dendrimers involved in general method cost so much time that its research was limited in lab. So the optimal condition of synthesis of PAMAM were studied such as the monomer recycling use, the feeding order, the reaction temperature, the reaction time, mol ratio of reactants in the paper. The apt conditions which can shorten reaction time greatly are presented and the method of products purification was advanced. PAMAM dendrimers (-0G0.5～G5.0) were synthesized by divergent growth.Poly-amidiamine (PAMAM) dendrimers (-0G0.5～G5.0) were synthesized by divergent growth.The promotion of decomposition of sodium aluminate solution is always a hotspot on investigating of seeded precipitation of sodium aluminate solution. How to strengthen the seed decomposition process, and to raise the rate of dissociation and the product particle size of aluminum hydroxide has the important meaning to the development of aluminum industry in our country. Seed Precipitation of sodium aluminate solution enhanced with additives has good advantages such as simple operation condition and low cost, and thus has good application foreground.The properties of this kind of new type macromolecular surfacant as additives in the seed decomposition process of sodium aluminate solution, at the same time we have investigated the optimal condition of synthesis of PAMAM.A series of polyamidoamine (PAMAM) dendrimers were prepared, with an ethylenediamine core through repetitive Michael addition and amidation in methanol. Their structure and compositon were characterized by means of Elemental Analysis、potentiometric titration、 Infrared Spectrums and Thermogravimetric Analysis. As a result, the purity of PAMAM dendrimers was much higher and the architecture of it was much more profect at that condition, the small-molecule content was tiny.PAMAM dendrimers were adopted as additives in the seeded precipitation process. The influence different generation polyamidoamine on surface tension and the seed precipitation of sodium aluminate solution have been investigated. It has shown that surface tension of sodium aluminate solution to PAMAM was determined through the biggest bubble method. The half generation PAMAM dendrimers, which are ecpected to be a kind of novel Surfacant, have fine surface activity. we can accurately obtain the critical micelle concentration from surface tension curves of -0.5G、0.5G、1.5G and 2.5G PAMAM:1350mg/L、1220mg/L、156mg/L and 130mg/L. The integrated generation PAMAM dendrimers also have some surface activity. The addition of PAMAM can enhance the decomposition ratio of the sodium aluminate solution and improve the particle size an strength of the Al(OH)3 product. When concentration of 2.5G PAMAM reached critical micelle concentration, the effect to precipitation ratio was maximal. Comparing with no additives, the decomposed portion of sodium aluminate inereased 10% by adding G2.5 PAMAM, Product particle size(<20μm) decreased 6.85%, Product particlesize (>45μm) increased 30.38%.更多还原