聚乙二醇-四氧化三铁纳米粒子复合材料的结构、物理性质及应用

在β-环糊精作保护剂条件下, 制备了高对称的十八面体四氧化三铁(Fe₃O₄)纳米材料. 通过胶体化学方法, 合成了一系列不同起始计量比的聚乙二醇(PEG)和Fe₃O₄纳米粒子复合物(CM-1-CM-4). 这些PEG复合材料展示出重要特性: 首先, 它们的表面形貌依赖于Fe₃O₄的计量; 其次, PEG的熔化过程受Fe₃O₄的影响, 并且直接与Fe₃O₄的含量相关; 进一步研究表明, 除CM-4外, Fe₃O₄的引入导致PEG结晶度下降, 而且Fe₃O₄纳米粒子量越少, 降低幅度越大; 更为有趣的是, PEG的降解过程受制于Fe₃O₄纳米粒子的影响, 导致不同降解产物的出现; 而且, 与纯Fe₃O₄纳米粒子一样, 复合材料中的Fe₃O₄也显示典型的软铁磁性行为, 但饱和磁化强度相对较小; 此外, X射线光电子能谱(XPS)实验揭示在这些PEG复合材料中, 有从Fe到O的电子转移, Fe电子密度的降低可用来解释复合材料饱和磁化强度的减小; 最后, 这些PEG复合材料呈现出对有机染料的表面增强拉曼效应, 并且这种效应随Fe₃O₄纳米粒子含量的增加而增加. 这些结果将会对聚合物/无机纳米粒子复合材料的发展起到推进作用.

Polyethylene Glycol/Fe3O4 Nanoparticle Composite Materials:Structure, Physical Properties and Application

Fe₃O₄ nanoparticles with a highly symmetric octadecahedral nanobox structure were fabricated using β-cyclodextrin as a protection agent. A series of composites (CM-1-CM-4) of polyethylene glycol (PEG) and Fe₃O₄ nanoparticles with different initial mass ratios were prepared using a colloid process. We found that the shape of the composites depended on the amount of Fe₃O₄ nanoparticles. In particular, the melting process of PEG was not only influenced by the presence of Fe₃O₄ nanoparticles, but also by their amount. We also noticed that the crystallinity of PEG lowered upon compositing with Fe₃O₄ nanoparticles, and decreased as the amount of Fe₃O₄ nanoparticles increased with the exception of CM-4. Interestingly, the degradation of PEG was affected by the Fe₃O₄ nanoparticles, leading to the appearance of different degradation products. Like the initial Fe₃O₄ nanoparticles, the Fe₃O₄ components in the composites exhibited typical soft ferromagnetism but possessed much lower saturation magnetizations. X-ray photoelectron spectroscopy (XPS) experiments revealed that electronic shift occurred from iron to oxygen. The resulting decrease in the electronic density of iron explained the observed decrease in saturation magnetizations of the composites. The composites induced strong surface-enhanced Raman scattering of organic dyes that depended on the amount of Fe₃O₄ nanoparticles in the composite. This study contributes to the development of composite materials combining polymers with inorganic nanoparticles.