Bhairamadgi Nagendra S, Pujari Sidharam P, Trovela Florencio Gerardo, Debrassi Aline, Khamis Ahmed Arafat, Alonso Jose Maria, Al Zahrani Abdulrahim A, Wennekes Tom, Al-Turaif Hamad A, van Rijn Cees, Alhamed Yahia A, Zuilhof Han
Laboratory of Organic Chemistry, Wageningen University and Research Center , Dreijenplein 8, 6703 HB Wageningen, The Netherlands.
Langmuir. 2014 May 27;30(20):5829-39. doi: 10.1021/la500533f. Epub 2014 May 13.
A comparative study is presented of the hydrolytic and thermal stability of 24 different kinds of monolayers on Si(111), Si(100), SiC, SiN, SiO2, CrN, ITO, PAO, Au, and stainless steel surfaces. These surfaces were modified utilizing appropriate organic compounds having a constant alkyl chain length (C18), but with different surface-reactive groups, such as 1-octadecene, 1-octadecyne, 1-octadecyltrichlorosilane, 1-octadecanethiol, 1-octadecylamine and 1-octadecylphosphonic acid. The hydrolytic stability of obtained monolayers was systematically investigated in triplicate in constantly flowing aqueous media at room temperature in acidic (pH 3), basic (pH 11), phosphate buffer saline (PBS) and deionized water (neutral conditions), for a period of 1 day, 7 days, and 30 days, yielding 1152 data points for the hydrolytic stability. The hydrolytic stability was monitored by static contact angle measurements and X-ray photoelectron spectroscopy (XPS). The covalently bound alkyne monolayers on Si(111), Si(100), and SiC were shown to be among the most stable monolayers under acidic and neutral conditions. Additionally, the thermal stability of 14 different monolayers was studied in vacuum using XPS at elevated temperatures (25-600 °C). Similar to the hydrolytic stability, the covalently bound both alkyne and alkene monolayers on Si(111), Si(100) and SiC started to degrade from temperatures above 260 °C, whereas on oxide surfaces (e.g., PAO) phosphonate monolayers even displayed thermal stability up to ∼500 °C.
本文对24种不同单分子层在Si(111)、Si(100)、SiC、SiN、SiO2、CrN、ITO、PAO、Au和不锈钢表面的水解稳定性和热稳定性进行了比较研究。利用具有恒定烷基链长度（C18）但表面反应基团不同的合适有机化合物对这些表面进行改性，例如1-十八碳烯、1-十八碳炔、1-十八烷基三氯硅烷、1-十八烷硫醇、1-十八烷基胺和1-十八烷基膦酸。在室温下，于酸性（pH 3）、碱性（pH 11）、磷酸盐缓冲盐水（PBS）和去离子水（中性条件）的恒流水性介质中，对所得单分子层的水解稳定性进行了三次系统研究，时间分别为1天、7天和30天，从而获得了1152个水解稳定性数据点。通过静态接触角测量和X射线光电子能谱（XPS）监测水解稳定性。结果表明，在Si(111)、Si(100)和SiC上的共价键合炔烃单分子层在酸性和中性条件下是最稳定的单分子层之一。此外，使用XPS在高温（25 - 600°C）下于真空中研究了14种不同单分子层的热稳定性。与水解稳定性类似，在Si(111)、Si(100)和SiC上的共价键合炔烃和烯烃单分子层在温度高于260°C时开始降解，而在氧化物表面（例如PAO）上，膦酸酯单分子层甚至在高达约500°C时仍表现出热稳定性。
