Design,Preparation And Properties Of Stretchable Electrochromic Hydrogels Based On Acrylamide

In recent years,flexible electronics has become a hot spot over the world,which is attracting intensitive research interest for home and abroad researchers.Particularly,smart-responsive flexible optoelectronic devices have drawn wide interest due to their great potential in the field of organic electronics.Among them,flexible electrochromic devices have been widely used in various fields such as smart displays,smart windows,rearview mirrors,and smart glasses.However,poor mechanical properties and self-healing properties of flexible electrochromic devices hindered its realworld applications.In this thesis,a class of flexible electrochromic hydrogel was prepared by combing acrylamide(AAm)hydrogels with stimuli-responsive materials.The main research contents are as follows:1.The preparation and study of acrylamide based electrochromic hydrogelIn this chapter,ammonium persulfate and N,N’-methylenebisacrylamide were used as initiators and crosslinking agents,and polyacrylamide(PAAm)formed by radical polymerization of acrylamide(AAm)monomer,which was used as the hydrogel matrix.First,acidified CNTs were added as conductive fillers and toughening agents to improve the electrical and mechanical properties of the hydrogel;second,the k-carrageenan network was introduced to endow the hydrogel with self-healing properties;finally,CNTs/PAAm flexible electrochromic hydrogel was successfully prepared by coating polydiacetylene(PCDA)on the hydrogel surface to impart electrochromic properties to the hydrogel.The mechanical properties of the hydrogels were characterized by stress-strain tests,and it was found that by optimizing the mass ratio of CNTs and AAm,the obtained CNTs/PAAm electrochromic hydrogels could not only withstand a wide range of stretching(1800%),compression,and folding,and after the hydrogel is completely broken,the performance can be repaired by simple heating,and the repair efficiency of tensile properties can reach 100%.When a certain voltage is applied to the hydrogel,a significant change from blue to red occurs,and the critical response current of its coloration rate is closely related to the mass ratio of CNTs and AAm.Finally,the prepared hydrogel was successfully applied to the electronic components of wearable devices,realizing the efficient detection of electric current.2.The preparation and study of acrylamide based acid/base hydrogelIn this chapter,3-(pentacosane-10,12-diynamide)benzoic acid(PDA-m Bz A)was synthesized by terminal modification of PCDA.Then,PDA-m Bz A was prepared as nanoparticles,which can be uniformly dispersed in acrylamide hydrogels,and p-benzoquinone(p-BQ),an "electro-alkali molecule" that could undergo redox reactions under the applicaition of an electric field,was introduced.By adjusting the p H value in the hydrogel by electric field stimulation,the prepared hydrogel will turn from translucent to opaque brown,and its color will deepen with the increase of the voltage.Stress-strain tests show that the hydrogel has good mechanical properties and can withstand a wide range of stretching(400%).In addition,the prepared hydrogel has good adhesion and can be adsorbed on the surface of various substances.This work provides a new way and design princple for improving the transparency of flexible electrochromic hydrogels,and provides a new idea for developing flexible electrochromic hydrogel visual windows with high transparency.