Castor Oil Based Biothiol as a Highly Stable and Self-Initiated Oligomer for Photoinitiator-Free UV Coatings

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• 作者：Qing Wang ; Guangxue Chen ; Yanyan Cui ; Junfei Tian ; Minghui He ; Jian-Wen Yang
• 刊名：ACS Sustainable Chemistry & Engineering
• 出版年：2017
• 出版时间：January 3, 2017
• 年：2017
• 卷：5
• 期：1
• 页码：376-381
• 全文大小：361K
• ISSN：2168-0485

文摘

In this paper, we reported castor oil based biothiol (CO-SH) as a highly stable and self-initiated oligomer for photoinitiator (PI)-free UV coating. CO-SH was synthesized via esterification reaction between castor oil (CO) and 3-mercaptopropionic acid (MPA). The results of both proton nuclear magnetic resonance (¹H NMR) and Fourier transform infrared spectroscopy (FTIR) revealed that the targeted oligomer was successfully prepared. The oligomer with the number-average molecular weight of 2040 g mol^–1 exhibited a narrow molecular weight distribution (PDI = 1.23). CO-SH could be stored at 80 °C for 7 days with only a light C═C conversion (≈6%); hence, the steric effect of the vegetable oil molecule gave the primary biothiol an excellent temporal stability. Furthermore, real-time FTIR results indicated that excellent photopolymerization profiles were obtained, and the final conversions of double bond and thiol were 100% and 77% in the absence of PI, respectively, showing the rapid self-initiated photoactivity. In addition, the self-initiated photopolymerization mechanism of CO-SH was investigated. Finally, the UV-curable films of CO-SH also showed good physical and chemical properties.