Catalysis Research Center/WACKER-Lehrstuhl für Makromolekulare Chemie, Technische Universität München, Lichtenbergstraße 4, 85747 Garching bei München, Germany.
Nanoscale. 2017 Jun 22;9(24):8489-8495. doi: 10.1039/c7nr02265d.
Among a variety of SiNC functionalization methods, radical initiated grafting is very promising due to its straightforward nature and low propensity to form surface oligomers. In the present study, we employed in situ IR spectroscopy in combination with visible light transmittance measurements to investigate the radical induced grafting process on the well-defined SiNCs. Our findings support the proposed model: unfunctionalized hydride-terminated SiNCs form agglomerates in organic solvents, which break up during the grafting process. However, clearing of the dispersion is not a valid indicator for complete surface functionalization. Furthermore, radical-initiated grafting reactions in which azobisisobutyronitrile (AIBN) is the initiator are strongly influenced by external factors including initiator concentration, grafting temperature, as well as substrate steric demand. The monomer concentration was proven to have a low impact on the grafting process. Based on these new insights an underlying mechanism could be discussed, offering an unprecedented view on the functionalization of SiNC surfaces via radical initiated hydrosilylation.
在各种 SiNC 功能化方法中，由于其简单的性质和低形成表面低聚物的倾向，自由基引发接枝是非常有前途的。在本研究中，我们采用原位红外光谱结合可见光透过率测量来研究在明确定义的 SiNC 上的自由基诱导接枝过程。我们的研究结果支持了所提出的模型：未功能化的氢化末端 SiNC 在有机溶剂中形成团聚体，在接枝过程中会破裂。然而，分散体的澄清并不是完全表面功能化的有效指标。此外，以偶氮二异丁腈 (AIBN) 为引发剂的自由基引发接枝反应强烈受到外部因素的影响，包括引发剂浓度、接枝温度以及底物的空间位阻需求。单体浓度对接枝过程的影响较小。基于这些新的见解，可以讨论一个潜在的机制，为通过自由基引发硅氢化反应对 SiNC 表面进行功能化提供了前所未有的视角。
