Synthesis, Characterization Of The Dendrimer And Its Applications In The Process Of Sodium Aluminate Solution Points

Dendrimers, which have hyperbranched, well defined, multi end group and monodisperses 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. Decomposition mechanism of the sodium aluminate solution were introduced in the article, the strengthened methods of seed decomposition process in sodium aluminate solution are also reviewed.The synthesis of PAMAM dendrimers involved in general method cost so much time that its research was limited in lab. In this paper, Generations -0.5G and 0G of poly (amid amine) (PAMAM) dendrimer were synthesized with ethylenediamine and methyl acrylate by divergent method. The optimized synthesis conditions of -0.5G and 0G (generation) PAMAM were studied, and the apt conditions which could shorten reaction time greatly. It was shown that the dendrimer resultant had less defective structure fraction and much yield when synthesized at 25℃for 48 hours; mol ratio of ethylenediamine to methyl acrylate was 1:8 for -0.5G PAMAM, mol ratio of -0.5G PAMAM to ethylenediamine was 1:30 for 0G PAMAM. Adopting infrared spectrums and terminal analysis means to characterize their structure, the results indicated that products were in conformity with their theorystructur. 0.5～4.5G PAMAM were also synthesized, and the method of products purification advanced.Acid-base titration means is important in characterizing amine terminal group of PAMAM. The theory of acid-base titration applied in characterization of PAMAM was discussed. The effect of the initial pH on titrate analysis results was studied by adopting automatic electric potential titration means. The experiment results showed that the core tertiary amines could be completely protonated at pH＜2.PAMAM were applied in the process of decomposition of sodium aluminate solution. The effect of generations, end groups and concentration of PAMAM on decomposition of sodium aluminate solution was studied. Experiment results showed that terminal groups of PAMAM had strong adsorptive capacity to the aluminum hydroxide surface. PAMAM changed the surface properties of the seed crystal, increased particle size of product, and improved precipitation rate of sodium aluminate solution. Because PAMAM dendrimer containing ester end groups had surface activity, it was better than that containing amine end groups as additives which enhanced precipitation ratio, and it could keep much time by producing the carboxyl anion in the solution. Comparing with no additives, the decomposed portion of sodium aluminate increased 10% by adding G2.5 PAMAM, product particle size (＜5μm) decreased 60%, product particle size (＞45μm) increased 3%.The PAMAM action mechanism be extrapolated.