光响应性阳离子表面活性剂PCDA-C6-NH3+的合成及其对液滴蒸发行为的调控

Synthesis of a photoresponsive cationic surfactant PCDA-C6-NH3+and its regulation of droplet evaporation

农药的有效利用与农药液滴在植物叶片上的蒸发过程息息相关。传统表面活性剂虽然可以改变液滴的蒸发模式或速率,但并不能根据外界环境变化对蒸发过程进行主动调节。为实现"自主调控"农药液滴蒸发的目的,本文设计合成了一种含丁二炔官能团的光响应性阳离子表面活性剂(PCDA-C6-NH3+),利用紫外光刺激改变其在液滴中的聚集状态,调控液滴的蒸发过程。该表面活性剂以10,12-二十五碳二炔酸(PCDA)作为骨架,通过酰胺化反应引入末端氨基并质子化后得到。采用紫外-可见光谱研究了PCDA-C6-NH3+的拓扑化学聚合反应,并利用静态表面张力和动态接触角分析了其紫外光照前后的表面活性和蒸发行为。该研究为实现液滴"自主调控"蒸发过程提供了一种新思路,对提高农药利用率具有重要意义。

Droplets evaporation on plant leaves plays an important role in the utilization of pesticides.Although traditional surfactants can change the evaporation mode or evaporation rate of droplets,they cannot adjust the evaporation process effectively according to external stimuli.In this research,a photoresponsive diacetylene-based cationic surfactant(PCDA-C6-NH3+)was designed and synthesized,where10,12-pentacosadiynoic acid and protonated terminal amine were used as the photo-responsive motiey and the hydrophilic cation,respectively.The UV light-induced topochemical polymerization of PCDAC6-NH3+was studied by UV-Vis spectroscopy.Its surface activity and evaporation behavior before and after UV irradiation were analyzed by static surface tension and dynamic contact angle.The results showed that the aggregation state of PCDA-C6-NH3+can be regulated by UV light during the droplets evaporation process,because of its topochemical polymerization.This work has provided a new strategy to adjust the evaporation of droplets,which is of great significance for improving the utilization rate of pesticides.