高分子稀土复合物及层层组装薄膜的制备

发布时间：2018-03-30 04:31

  本文选题：稀土　切入点：高分子金属复合物　出处：《东华大学》2014年硕士论文

【摘要】：本课题首先研究了不同浓度、不同pH条件下聚丙烯酸(PAA)与稀土离子(Ln)的络合行为。在此基础上,将稀土离子引入PAA与聚乙烯基吡咯烷酮(PVPON)的氢键复合体系,利用层层组装技术制备了含有稀土离子的氢键复合薄膜。 研究发现PAA和Ln的络合行为是一个复杂的过程。pH值、摩尔比以及浓度等都对PAA-Ln复合物的形成产生显著影响。与COOH相比,COO-与稀土离子的络合能力更强。当pH值高于2.0时,PAA发生电离。随着pH值的增加,PAA的电离程度增加,COO-的比例增加。当pH值高于7.5时,稀土离子会形成Ln(OH)3,因此我们研究PAA和Ln相互作用的pH值范围为2.0-7.5。在合适的pH值范围内,当稀土离子浓度较高时,PAA-Ln可以形成沉淀,通过过滤可以将沉淀分离；当稀土离子的浓度低于1.0×10-3mol/L或者[AA]/[Ce]大于5时,PAA-Ln可以均匀分布于溶液中而不沉淀出来,此时可以利用透析的方法将PAA-Ln除去。 当pH值增加时,PAA与稀土铈离子(Ce3+)的络合能力增强,可以形成复合物。但pH值过高,PAA与PVPON之间很难形成氢键复合物,因此只有在特定pH值区间才可形成三元的复合物。pH值在2.5-4.0区间时,可以成功制备PAA-Ce-PVPON三元复合物,并且复合物中同时存在氢键作用和配位作用。随着pH值增加,氢键作用逐渐减弱,配位作用逐渐增强。随着pH值的增加,三元复合物中Ce元素的含量逐渐增加,这是因为PAA电离程度逐渐增加,COO比例增加,由于COO-与Ce离子的络合能力远大于COOH与Ce离子的络合能力,因此复合物中的Ce离子含量增加。 在pH值小于3.5的条件下,(PVPON-Ce-PAA)n薄膜可以成膜,pH值大于等于3.5时无法成膜。这是因为随着pH值的增加,PAA的电离程度增加,Ce离子与COO-的配位作用会阻碍PAA与PVPON的氢键的形成,因此pH值高于3.5时无法成膜。 pH值在2.5-3.5范围内,Ce离子浓度为0.01mol/L时,(PVPON-PAA-Ce)n薄膜中同时存在氢键作用和配位作用,此时Ce离子可以成功加入薄膜,而且PVPON和PAA之间的氢键作用仍然存在。
[Abstract]:In this paper, the complexation behavior of polyacrylic acid (PAA) with rare earth ion (Ln) at different concentrations and pH was studied. On the basis of this, rare earth ions were introduced into the hydrogen bonding composite system of PAA and polyvinylpyrrolidone (PVPON). The hydrogen bonding composite films containing rare earth ions were prepared by layer-by-layer assembly technique. It is found that the complex behavior of PAA and Ln is a complex process. The molar ratio and concentration all have a significant effect on the formation of PAA-Ln complex. Compared with COOH, the complexation ability of COOH with rare earth ions is stronger. When pH value is higher than 2.0, the ionization of PAA-Ln occurs. With the increase of pH value, the degree of ionization increases. When pH is higher than 7.5, Therefore, the pH range of the interaction between PAA and Ln is 2.0-7.5. When the concentration of rare earth ions is high, PAA-Ln can be precipitated, and the precipitation can be separated by filtration. When the concentration of rare earth ions is less than 1.0 脳 10-3mol/L or [AA] / [ce] > 5, PAA-Ln can be uniformly distributed in the solution without precipitation, and PAA-Ln can be removed by dialysis. When the pH value is increased, the complex can be formed by increasing the complexing ability of PAA with cerium ion Ce3, but it is difficult to form hydrogen bond complex between PAA and PVPON when pH value is too high. Therefore, ternary complexes can be formed only in a specific pH range. When pH is in the range of 2.5-4.0, PAA-Ce-PVPON ternary complexes can be successfully prepared, and there are hydrogen bonds and coordination roles in the complexes. With the increase of pH value, the content of ce in the ternary complex increases gradually, which is due to the increasing of PAA ionization degree. Because the complexing ability of COO- and ce ions is much higher than that of COOH and ce ions, the content of ce ions in the complexes increases. When pH value is less than 3.5, PVPON-Ce-PAAn film can not form film when pH value is greater than 3.5. This is because the coordination of ce ion with COO- will hinder the formation of hydrogen bond between PAA and PVPON with increasing the ionization degree of PAA. Therefore, when pH value is higher than 3.5, film can not be formed. When the concentration of ce in the range of 2.5-3.5 is 0.01mol/L, the hydrogen bond and coordination exist in the PVPON-PAA-CeOn film. At this time, ce ions can be successfully added into the film, and the hydrogen bond between PVPON and PAA still exists.
【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB383.2

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