Study On The Hydrochromism Properties Of Donor-acceptor Stenhouse Adducts And Applications

As a new type of photoresponsive molecules,the current research mainly focused on the photochromism property of Donor-acceptor Stenhouse adducts（DASAs）,while the hydrochromism property has not been explicitly revealed.This thesis systematically investigated the relationship between the color and absorption band of DASAs and the chemical structure of the electron-donating and-withdrawing moieties,as well as the effects of humidity and temperature on the water-induced isomerization properties,and suggested innovative applications.By synthesizing DASAs with different electrondonating and-withdrawing moieties,the color and absorption properties of DASAs were first studied.We found that by altering the chemical structure of electron-donating and-withdrawing moieties,it is able to control the color and absorption properties of DASAs.In this thesis,a strategy to study the kinetics and efficiency of water-induced isomerization of DASAs with different chemical structure was proposed by controlling temperature and relative humidity.Firstly,DASA-1 and DASA-2 with good water isomerization performance and heat induced efficiency were selected from the 8synthesized DASAs.By studying the hydrochromism performances at different temperatures and relative humidity,it was found that temperature affects the isomerization kinetics,and relative humidity changes the isomerization equilibrium.At the same time,while investigating the water-induced isomerization kinetics,an isomerization competition phenomenon was found: under high humidity and temperature,DASAs would first isomerize from the cyclic to the linear state,and then return to the cyclic state.This was observed in the study of DASA-1 and DASA-2.A novel multi-color repeatable writing paper was prepared by coating DASAs onto the paper surface.The colors on paper surface could be varied by controlling the writing speed,and a recycle utilization was realized by erasing the written information through a humid environment.Overall,this thesis proposes new ideas for the relationship of water sensitivity between humidity and temperature on water-induced isomerization of DASAs,and demonstrates innovative applications.Finally,the study of the combination of polymers and DASAs is investigated.Due to the of hydrophilic property of polymer polyethylene glycol（PEG）,where the PEG is used for separating two different DASAs between the coated paper,and controlling the heat conduction.Overall,DASAs were further grafted on the polymer and coated on the surface of the paper to form self-assembled polymer shell to study its effect on the water-induced isomerization of DASAs.Different polymers and DASAs were synthesized.After evaluating its properties,the grafted DASAs is able to isomerize under the treatment of humidity,but it not prominent as the small molecules of DASAs which might contribute to the hindered effect of external polymer,alleviating the contact between DASAs and water.It might also be caused by the disordered polymerization method that impede the water-induced isomerization.Generally,the proposed of such polymer molecules is important for the development of water-sensitive materials,but the shortcomings of this work are that the mechanism of the water-induced isomerization for polymer-based DASAs has not yet been clarified.