Liang Yuejiang, Ozawa Masaki, Krueger Anke
Institut für Organische Chemie der Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
ACS Nano. 2009 Aug 25;3(8):2288-96. doi: 10.1021/nn900339s.
Upon reduction of particle size to the nanometer range, one has to deal with the general issue of spontaneous agglomeration, which often obstructs postsynthesis modification of nanoparticle surfaces. A technique to cope with this phenomenon is required to realize a wide variety of applications using nanoparticles in solvents or as refined assemblies. In this article, we report on a new technique to facilitate surface chemistry of nanoparticles in a conventional glassware system. A beads-assisted sonication (BASD) process was examined to break up persistent agglomerates of nanodiamonds in two different reactions for simultaneous surface functionalization. The chosen reactions are the silanization with an acrylate-modified silane and the arylation using diazonium salts. The BASD process can be successfully applied even where the original material is not dispersible in the reaction solvent at all, as the formation of ever smaller, increasingly functionalized agglomerates is improving their solubility. We have confirmed that the presence of ceramic beads enables functionalization of each primary particle, while conventional magnetic stirring or beadless sonication can reach primary particles only when agglomeration is loose. Additionally, mechanical surface modification of nanodiamond was found to take place by BASD with high energy density, leading to sp(2)-hybridized surface patches on nanodiamond. This allowed for the efficient grafting of aryl groups to the surface of primary diamond nanoparticles. Stable, homogeneously functionalized nanodiamond particles in colloidal solution can be obtained by this method.
当颗粒尺寸减小到纳米范围时，必须应对自发团聚这一普遍问题，而这常常会阻碍纳米颗粒表面的合成后修饰。为了实现纳米颗粒在溶剂中或作为精细组装体的各种应用，需要一种应对这种现象的技术。在本文中，我们报道了一种在传统玻璃器皿系统中促进纳米颗粒表面化学的新技术。研究了一种珠辅助超声处理（BASD）工艺，以在两种不同反应中分解纳米金刚石的持久性团聚体，实现同步表面功能化。所选择的反应是用丙烯酸酯改性硅烷进行硅烷化反应以及使用重氮盐进行芳基化反应。即使原始材料在反应溶剂中完全不可分散，BASD工艺也能成功应用，因为形成的越来越小、功能化程度越来越高的团聚体提高了它们的溶解度。我们已经证实，陶瓷珠的存在能够使每个初级颗粒实现功能化，而传统的磁力搅拌或无珠超声处理只有在团聚松散时才能作用于初级颗粒。此外，发现通过具有高能量密度的BASD对纳米金刚石进行机械表面改性，会在纳米金刚石上产生sp(2)杂化的表面斑块。这使得芳基能够有效地接枝到初级金刚石纳米颗粒的表面。通过这种方法可以获得胶体溶液中稳定、均匀功能化的纳米金刚石颗粒。
