Mechanochemical Study Of DA And Tetrazole Centered Polymer In Dilute Solution Under Ultrasonication

Polymer mechanochemistry has gained great development in recent years after the change of research idea from "destructive" to "productive",and the key issue that promotes this development is the research of mechanophore.In this work,the polymer chain containing DA adducts and 2,5-Diaryltetrazoles are studied based on sonochemical transformation,our researcher include:(1)The selective chain scission of polymer main chain containing DA adducts and the influence of sonication power outputs on selectivity.The polymer that contains DA adducts in the chain center was synthesized,and the chain scission behavior was studied both on low power output and high power output.By comparison of the chain scission kinetics and NMR results,it is observed that:low power output favors the selective chain scission on DA adducts;in a short period of time,the chain scission is dominated by the selective cleavage of DA adducts,but with the increase of time,the non-selective chain scission gradually occupied a larger portion;the mechanical force induced chain scission includes both selective cleavage and non-selective cleavage on the site of mechanophore,totally selective chain scission is difficult to realize under the present condition.(2)Stability of the 2,5-diaryltetrazole in the center of polymer chain under ultrasonication.2,5-diaryltetrazole was introduced into the center of polymer main chain,and the mechanochemical behavior of the macromolecule was studied under ultrasound.By comparison with the researches of chain-center control and chain-end control,it is observed that after sonication the chain scission kinetics of tetrazole-center polymer and chain-center control were almost the same,and the NMR results of tetrazole-center polymer was the same as those of chain-end control.The kinetics results and NMR results were verified by each other,both indicated that tetrazole-center polymer would not cleavage at the site of tetrazole hetero-ring,therefore it had a certain.stability under ultrasonic condition.In conclusion,in this work detailed researches about DA adducts and 2,5-diaryltetrazole were conducted under ultrasonic condition,our research method and conclusion would have guiding significance for future research on macromolecule selective response under ultrasonication.