聚酰胺-胺型树形分子模板法制备Pt纳米簇

Preparation of Pt Nanoparticles Templated by Poly(amidoamine) Dendrimers

利用紫外-可见吸收光谱和红外光谱对Pt2+与G5.5-COOCH3聚酰胺-胺型树形分子的络合机理进行了研究,结果表明Pt2+与G5.5-COOCH3 PAMAM的最外层叔胺基发生络合作用,但两者之间达到络合平衡需要较长时间,且平衡时间随Pt2+与树形分子物质的量比增大而增长;Pt2+与G5.5-COOCH3树形分子的最大络合数为50～55;采用硼氢化钠还原法原位制备了G5.5-COOCH3 PAMAM包裹、平均粒径小于2nm、多晶的球形Pt纳米簇,并研究了Pt2+与PAMAM物质的量比对Pt纳米簇形貌的影响,实验结果表明,Pt2+与PAMAM物质的量比为10时,生成尺寸较小分布较窄的内型Pt纳米簇/树形分子复合材料,而物质的量比为50时,会生成部分尺寸较大、分布较宽的外型Pt纳米簇/树形分子纳米复合材料.

The complexation of Pt^2＋ ions with G5.5-COOCH3 PAMAM dendrimers was investigated by UV-VIS and FT-IR spectral methods, showing that Pt^2＋ ions are coordinated with the interior amino groups of dendrimers. It needs more time for the complexation reaction to come to balance with the increase of molar ratios of Pt^2＋ ions to dendrimers. The maximum loadings of 50-55 Pt^2＋ ions within the G5.5-COOCH3 dendrimers were also obtained. Following reduction with NaBH4 resulted in spherical and well-dispersed Pt nanoparticles （average size〈2 nm） encapsulated in the dendrimers as shown in HRTEM images. When the ratio of Pt^2＋ ions to dendrimers was 10, the yielded Pt nanoparticles with smaller sizes and a narrow distribution were intradendrimer templated. When the ratio of Pt〉 ions to dendrimers was 50, new partially formed Pt nanoparticles with larger sizes and a broad distribution were interdendrimer templated.