Surface confined retro Diels-Alder reaction driven by the swelling of weak polyelectrolytes.
Recently, the type of reactions driven by mechanical force has increased significantly; however, the number of methods for activating those mechanochemical reactions stays relatively limited. Furthermore, in situ characterization of a reaction is usually hampered by the inherent properties of conventional methods. In this study, we report a new platform that utilizes mechanical force generated by the swelling of surface tethered weak polyelectrolytes. An initiator with Diels-Alder (DA) adduct structure was applied to prepare the polyelectrolyte-carboxylated poly(OEGMA-r-HEMA), so that the force could trigger the retro DA reaction. The reaction was monitored in real time by quartz crystal microbalance and confirmed with atomic force microscopy and X-ray photoelectron spectroscopy. Compared with the conventional heating method, the swelling-induced retro DA reaction proceeded rapidly with high conversion ratio and selectivity. A 23.61 kcal/mol theoretical energy barrier supported the practicability of this retro DA reaction being triggered mechanically at ambient temperature. During swelling, the tensile force was controllable and persistent. This unique feature imparts this mechanochemical platform the potential to "freeze" an intermediate state of a reaction for in situ spectroscopic observations, such as surface-enhanced Raman spectroscopy and frequency generation spectroscopy.
†Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science, Suzhou 215123, People's Republic of China.
Beier
B
Lyu
†Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science, Suzhou 215123, People's Republic of China.|#Nano Science and Technology Institute, University of Science and Technology of China, Suzhou 215123, People's Republic of China.
Wenli
W
Cha
§State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, People's Republic of China.
Tingting
T
Mao
†Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science, Suzhou 215123, People's Republic of China.
Yuanzi
Y
Wu
∥State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, People's Republic of China.
Hujun
H
Qian
†Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science, Suzhou 215123, People's Republic of China.
Yitian
Y
Zhou
Xiuli
X
Chen
†Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science, Suzhou 215123, People's Republic of China.
Shen
S
Zhang
§State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, People's Republic of China.
Lanying
L
Liu
Guang
G
Yang
∥State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, People's Republic of China.
Zhongyuan
Z
Lu
§State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, People's Republic of China.
Qiang
Q
Zhu
†Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science, Suzhou 215123, People's Republic of China.|‡Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, People's Republic of China.
Hongwei
H
Ma
mechanochemistry; polyelectrolyte; polymer brush; quartz crystal microbalance; retro Diels−Alder reaction