Research Institute for Chemical Process Technology, National Institute of Advanced Industrial Science and Technology (AIST) , 4-2-1, Nigatake, Miyagino-ku, Sendai 983-8551, Japan.
ACS Appl Mater Interfaces. 2016 Jan 27;8(3):1627-34. doi: 10.1021/acsami.5b07566. Epub 2016 Jan 12.
Zerovalent copper nanoparticles (CuNPs) (diameter, 26.5 ± 9 nm) capped with polyvinylpyrrolidone (PVP) were synthesized in supercritical water at 400 °C and 30 MPa with a continuous flow reactor. The PVP-capped CuNPs were dispersed in distilled water, methanol, ethanol, 1-propanol, 2-propanol, butanol, and their mixed solvents to study their long-term stability. Temporal variation of UV-vis spectra and surface plasmon resonance were measured and showed that ethanol, the propanols, and butanol solvents provided varying degrees of oxidative protection for Cu(0). Fourier transform infrared spectroscopy showed that PVP adsorbed onto the surface of the CuNPs with a pyrrolidone ring of PVP even if the CuNPs were oxidized. Intrinsic viscosities of PVP were higher for solvents that provided antioxidation protection than those that give oxidized CuNPs. In solvents that provided Cu(0) with good oxidative protection (ethanol, the propanols, and butanol), PVP polymer chains formed large radii of gyration and coil-like conformations in the solvents so that they were arranged uniformly and orderly on the surface of the CuNPs and could provide protection of the Cu(0) surface against dissolved oxygen. In solvents that provided poor oxidative protection for Cu(0) (water, alcohol-water mixed solvents with 30% water), PVP polymer chains had globular-like conformations due to their relatively high hydrogen-bonding interactions and sparse adsorption onto the CuNP surface. Antioxidative properties of PVP-capped CuNPs in a solvent can be ascribed to the conformation of PVP polymer chains on the Cu(0) particle surface that originates from the interaction between polymer chains and its interaction with the solvent.
在 400°C 和 30 MPa 的超临界水中，使用连续流反应器合成了聚维酮（PVP）包覆的零价铜纳米颗粒（CuNPs）（直径 26.5 ± 9nm）。将 PVP 包覆的 CuNPs 分散在去离子水、甲醇、乙醇、1-丙醇、2-丙醇、正丁醇及其混合溶剂中，研究其长期稳定性。测量了紫外-可见光谱和表面等离子体共振的时间变化，结果表明，乙醇、丙醇和正丁醇溶剂为 Cu(0) 提供了不同程度的氧化保护。傅里叶变换红外光谱表明，即使 CuNPs 被氧化，PVP 也会吸附在 CuNPs 表面上，其吡咯烷酮环仍保持完整。对于提供抗氧化保护的溶剂，PVP 的特性粘度高于那些提供氧化 CuNPs 的溶剂。在为 Cu(0) 提供良好氧化保护的溶剂（乙醇、丙醇和正丁醇）中，PVP 聚合物链在溶剂中形成较大的回转半径和类似线圈的构象，从而使它们在 CuNPs 表面均匀有序地排列，并能够保护 Cu(0) 表面免受溶解氧的影响。在为 Cu(0) 提供较差氧化保护的溶剂（水、水-醇混合溶剂中含 30%水）中，由于 PVP 聚合物链具有较高的氢键相互作用和稀疏吸附在 CuNP 表面上，因此其聚合物链具有球形构象。PVP 包覆的 CuNPs 在溶剂中的抗氧化性能可归因于聚合物链在 Cu(0) 颗粒表面的构象，这源于聚合物链之间的相互作用及其与溶剂的相互作用。
