Preparation And Application Of Multiple Stimuli-responsive Fluorescent Polymer Materials

Stimulus-responsive fluorescent materials have received increasing attention due to their broad application prospects,such as pH indicators,temperature monitors,viscosity probes,and mechanical luminescent materials.Recently,the combination of two or more responsive multi-responsive polymers has attracted academic attention.However,it is less common that the preparation of multiple stimuli-responsive fluorescent systems in response to three or more stimuli.In the first part,we used the conjugated luminescent properties of tertiary amines using 1,4-bis(2-hydroxyethyl)piperazine(BHEP)and polyacrylic acid(PAA)as raw materials.Electrostatic interactions were made into fluorescent materials and their fluorescence response under different external stimuli was investigated.The results show that:1)With the increase of temperature,the fluorescence intensity of BHEP/PAA decreases,and it has a good linear relationship in the temperature range of 25 ~oC to 65~oC;2)Under the stimulation of water vapor and volatile organic acids(such as formic acid、acrylic acid),the fluorescence intensity of BHEP/PAA is also significantly reduced;3)The fluorescent properties of this material have certain specificity for ethylenediamine in volatile organic amines;4)The non-covalent fluorescent material also had excellent mechanical properties and self-repairing properties.In the second part,we synthesized PNIPAM-VFc by free radical polymerization using N-isopropylacrylamide(NIPAM)and vinylferrocene(VFc)as monomers.The polymer is capable of spontaneously forming nanoparticles in an aqueous solution and is capable of responding to multiple external stimuli such as temperature,H2O2,and electric field,and undergoing morphological changes.When a small fluorescent molecule(FITC)is embedded in a nanoparticle,the morphological change of the nanoparticle can further cause a fluorescent response under multiple stimulation conditions.The results show that:1)Under the condition of increasing temperature,the morphology of the polymer nanoparticles shrinks,the particle size becomes smaller,and the fluorescence emission is enhanced;2)Under the stimulation of hydrogen peroxide,the polymer nanoparticles expand in shape,the particle size becomes larger,and the fluorescence of the system becomes weaker;3)Under the stimulation of the oxidation voltage,the polymer nanoparticles expand,the particle size becomes larger,and the fluorescence emission is quenched.