TEMPO-Functionalized Aromatic Polymer as a Highly Active, pH Responsive Polymeric Interfacial Catalyst for Alcohol Oxidation
writer：Kecheng Hu, Jun Tang, Shixiong Cao, Qi Zhang, Jianli Wang*, and Zhibin Ye*
keywords：TEMPO, pH responsive polymeric interfacial catalyst, pickering emulsion
source：期刊
specific source：The Journal of Physical Chemistry C
Issue time：2019年
通過將2,2,6,6-四甲基哌啶-N-氧化物(TEMPO)一步接枝到具有苯并咪唑基團的聚芳醚酮(SCBI-PAEK-6F)上，設(shè)計合成了一種pH響應(yīng)性聚合物界面催化劑(PIC)。并用1H核磁共振、傅里葉變換紅外光譜、元素分析、接觸角和透射電鏡對聚合物進行了系統(tǒng)的表征。這種精心設(shè)計的聚合物已經(jīng)應(yīng)用于Montanari條件下的醇的氧化。這種功能化聚合物可在水-油界面聚集并充當有效穩(wěn)定劑以促進穩(wěn)定的Pickering乳液形成，其通過微反應(yīng)器機理對醇的氧化反應(yīng)表現(xiàn)出優(yōu)異的催化活性。此外，由于苯并咪唑基團的存在，PIC具有較好的pH響應(yīng)性。我們通過簡單地將體系pH值調(diào)節(jié)至3，就可以實現(xiàn)Pickering乳液反應(yīng)體系的去乳化，從而促進PIC回收。此外，可持續(xù)催化劑可以在隨后的醇氧化循環(huán)中重復(fù)使用，且催化活性或選擇性沒有明顯的損失。
We report in this paper the design and synthesis of a pH responsive polymeric interfacial catalyst (PIC) via one-step grafting of 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) onto a polyaryletherketone having pendant benzimidazole groups (SCBI-PAEK-6F). The TEMPO-functionalized polymer has been systematically characterized with 1H nuclear magnetic resonance, Fourier-transform infrared spectroscopy, elemental analysis, contact angle, and transmission electron microscopy. Moreover, this well-designed polymer has been applied in the oxidation of alcohols under Montanari conditions. It is found that the functionalized polymer can aggregate at the water-oil interface and act as an efficient stabilizer to facilitate the formation of a stable Pickering emulsion, which shows outstanding catalytic activity for alcohol oxidation through the microreactor mechanism. Moreover, the PIC is featured with desirable high pH responsiveness due to the valuable benzimidazole groups. De-emulsification of the Pickering emulsion reaction system can be conveniently triggered by simply tuning the system pH value to 3, thus facilitating the facile recovery of the PIC. In addition, the sustainable catalyst can be reused for subsequent cycles of alcohol oxidation without appreciable loss in catalytic activity or selectivity.
DOI: 10.1021/acs.jpcc.9b00467