Application Of Photosensitive Amphiphilic Diacetylene In The Control Of Droplet Evaporation

The utilization efficiency of pesticides in China is actually extremely low with an efficiency of only 36.6%.In practical pesticide spraying,the bounce,diffusion and evaporation behaviors of the droplets have significant influence on the utilization efficiency of pesticides.Surfactants are usually added to the system in order to adjust these behaviors,thereby improving the utilization efficiency of pesticides.However,conventional surfactants do not have the stimuli-responsive properties.Therefore,this work chose to develop stimuli-responsive surfactants.We used diacetylene-based molecules,because self-assembled diacetylene moieties can be topologically polymerized under ultraviolet light or gamma-ray irradiation to polybutadiene which exhibits a blue color.When exposed to external stimuli,color change from blue to red and fluorescence change from non-fluorescent to fluorescent will take place.Polydiacetylene has attracted much attention due to its unique structure and excellent detection and sensing capabilities.In this thesis,two types of diacetylene-based surfactants,i.e.,non-ionic and ionic surfactants,with photo-responsive properties were designed and synthesized.Their surface activity and their application in droplet evaporation control were studied in detail.On the one hand,two nonionic surfactants by connecting glycyrrhizic acid and tetra(ethylene glycol)to diacetylene,respectively,were prepared.It was found that the glycyrrhizic-based diacetylene derivative can form gels in water and chloroform,respectively.The tetra(ethylene glycol)-based diacetylene derivative can significantly reduce the surface tension.On the other hand,we prepared two ionic surfactants by modifying the end function of the 10,12-pentacosadiynoic acid to-COO-Na+and to-NH3+Cl-.It was proved by ultraviolet-visible spectroscopy that both ionic surfactants can undergo topological polymerization.The surface tension and contact angle test showed that both ionic surfactants accelerate droplet evaporation.We believe this study will help the development of diacetylene-based photoresponsive surfactants for the application in the field of agriculture.