Synthesis Of Aromatic Amide Modified Polydiacetylene And Its Response To Environmental Stimuli

Polydiacetylene(PDA)is a very important functional polymer material,and it presents an ene-yne alternating structure on the molecular backbone,such a molecular structure gives it unique optical properties,especially in chromatic change behavior.Many researchers have done a lot of work using its chromatic change behavior in applications such as sensing,information storage and recognition,etc.By appropriately modifying the side chain,the eneyne main chain conjugated PDA has a more prominent color transition and fluorescence enhancement effect(from no fluorescence to red fluorescence)when exposed to many external stimuli(such as heat,organic solvents,pH,mechanical stress,ligand-receptor interaction and etc.)In this work,two aromatic amine-modified diacetylene derivatives were synthesized and assembled into composite materials and gels,respectively,and the colorimetric response behavior of the polydiacetylene derivative materials to various environmental stimuli were explored.Compared with a single material,the composite material can combine the advantages of a single component and may generate new physical or chemical properties at the same time,so it’s widely used for material performance improvement,and the introduction of PDA into the composite material will further expand its application prospects.In this paper,the aniline-modified diacetylene derivative is embedded in a solid paraffin wax matrix by simple physical blending to form a writable crayon composite material.After 1,4topopolymerization of the written pattern induced by 254 nm UV light,a blue phase PDA composite material was obtained,which clearly showed a chromatic change from blue to purple to red after thermal stimulations.What’s more,with the introduction of two representative near-infrared(NIR)dyes into composite materials,PDA also showed a unique NIR response behavior from blue to red when exposed to the NIR light.Soft matter is a class of materials in the middle zone between the two extremes of fluid and ideal solid and it has a wide range of applications.Supramolecular gels provide a good platform for studying the properties and applications of functional polymers in the form of soft matter.In this paper,through the self-assembly of 5-aminoisophthalic acid modified diacetylene derivative in DMF/H2O mixed solvent system,a new type of supramolecular gel with excellent stability was successfully prepared.After UV irradiation,the blue phase conjugated PDA in the form of supramolecular gel was formed through 1,4-addition topological polymerization.Owing to the intermolecular hydrogen bonds and π-πconjugation and other interactions,this PDA-based supramolecular gel showed a reversible blue-to-purple-to-red colorimetric response after thermal stimulation,showing a good thermal stability.In the meantime,the introduction of carboxyl groups into PDA gives this supramolecular gel an ability to distinguish acidic and alkaline environments.Specifically,when exposed to an acidic environment,no obvious color change was observed and the macroscopic morphology of the gel did not change,showing strong acid resistance.However,when it is exposed to different pH alkaline aqueous solutions or the atmosphere,a clear bluered chromatic change will occur in a short time.At the same time,the supramolecular gel showed a specific selective recognition for organic solvents.Among the ten common organic solvents,only triethylamine could induce the blue-red color change of PDA,which provides a broad prospect for selective identification by the naked eyes.