The Study On Preparation And Properties Of Polymer Materials With Dual Functions Of Fluorescence And Shape Memory

Shape Memory Polymers(SMPs)are class of smart materials that can return from a temporary shape to an original shape under external stimuli.They have been widely used in aerospace,textile,biomedical and 4D printing fields.But due to lack of visibility,they are limited in clinical imaging and other fields.Fluorescent materials can emit light of different colors and intensities under the irradiation of a certain wavelength of light.They have been widely used in fluorescent probes,biological imaging and light-emitting diodes.Therefore,in order to expand the application field,it is of great significance to combine the fluorescence function and the shape memory behavior.In addition,with the improvement of human environmental protection awareness,people not only care performance,but also pay more attention to environmental protection when developing new materials.Waterborne acrylic resins which use water as dispersion medium have many advantages,such as friend-environment,excellent performance and low price.They have received many attention from researchers.In addition,they have excellent shape memory behavior after solidifying.Therefore,in order to expand the application field,it is of great significance to combine the fluorescence function and the shape memory behavior.Inspired by this,the paper aims to prepare waterborne acrylic resin-based polymer material with dual functions of fluorescence and shape memory,and systematically study its fluorescence functions and shape memory behavior.The paper mainly includes the following three parts:In the first part,the amphiphilic polyacrylate copolymer(PMBDA)was prepared by using methyl methacrylate(MMA),butyl acrylate(BA),acrylic acid(AA)and diacetone acrylamide(DAAM)as monomers by means of radical polymerization method.The PMBDA copolymer was able to co-assemble with fluorescein(FM)in water to form waterborne polymer fluorescent emulsion(PMBDA/FM co-assembled emulsion).Furthermore,the PMBDA/FM co-assembled emulsion mixed uniformly with adipic acid dihydrazide(ADH)at room temperature and solidified to obtain fluorescent shape memory film(PMBDA/FM-ADH film).The structure and properties of PMBDA copolymer,PMBDA/FM co-assembled emulsion and PMBDA/FM-ADH film were characterized.The results showed that the particle size of the co-assembled emuision was in the range of 100?160 nm.The fluorescence intensity of the emulsion was related to the additive amount of fluorescein within a certain range.The film could emit uniform green fluorescence under ultraviolet light irradiation with a fluorescence emission peak wavelength(?_em)of 516 nm.Moreover,the shape recovery rate was almost 100%when temperature was higher than T_g(33?36°C).In the second part,to enhance the stability of fluorescent dyes in the system,the PMBDA-NVK macromolecule was first synthesized be means of radical co-polymerization method using N-vinylcarbazole(NVK)and acrylate monomers as initial materials.The self-crosslinking waterborne polyacrylate fluorescent emulsion(PMBDA-NVK-ADH emulsion)was then fabricated through a phase inverse self-emulsification process.Furthermore,fluorescent shape memory film(PMBDA-NVK-ADH film)can be easily obtained by solidifying emulsion at room temperature.The structure and properties of macromolecule,emulsion and film were analyzed.The results showed that the particle size of the emulsion remained at 90?160 nm and the fluorescence intensity of the emulsion was related to the additive amount of NVK within a certain range.The film which have dual functions of fluorescence and shape memory could emitt strong blue purple fluorescence under ultraviolet light irradiation(?_em=349 and 363 nm)and can recovery almost 100%under T>T_g.In the third part,it was unexpectedly discovered that the blank sample can also emit weak purple fluorescence under ultraviolet light irradiation when exploring the first two systems.Therefore,taking this as a strating point,this part designed a control experiment to explore the source and behavior of this non-traditional fluorescent polymer.By changing the content of DAAM in the system,we explored the change in fluorescence function and shape memory behavior of the copolymer solution and the shape memory film.The results showed that the fluorescence intensitiy of copolymer solution increased with the increase of DAAM content.The fluorescence intensity of film was much greater than copolymer solution.The maximum excitation wavekength of the film(?_ex)was 365 nm and the fluorescence spectra showed a slight red shift as the excitation wavelength increases.In this article,the environmentally-friendly waterborne polyacrylate fluorescent emulsion can be solidified to form film at room temperature.The method has the characteristics of simple preparation process,environmental protection,good controllability and suitability for large-scale production.The film have the dual functions of fluorescence and shape memory,and can be used in anti-counterfeiting,decoration,fluorescent probes,bioimaging,micro-optics,4D printing and smart medical equipment.