Preparation And Multi-Stimuli-Responsiveness Of A Novel Polydiacetylene-Based Supramolecular Gel

Supramolecular gels have the reversibility of assembly and the diversity of structures,and provide an orderly microenvironment for the controlled polymerization of monomers.At the same time,the combination of the sensitivity of the external action of polydiacetylene and the multi-stimulation responsiveness of the supramolecular gel nano-assembly is beneficial to the in-depth study of the gel system and the application of the special properties of the polymer.Therefore,it is necessary to construct a novel supramolecular gel system based on diacetylene,which can induce the polymerization of diacetylene monomer through appropriate external action,expand the synthesis route and existing form of conjugated polymer.At the same time,the special physicochemical properties of polydiacetylene in gels were studied,and the potential application value of polymer materials was explored.In this paper,a supramolecular gel is formed by co-assembly of polydiacetylene and a synthetic gel factor.First,it is necessary to clarify that the imidazole group and the carboxyl group can be assembled into a gel by non-covalent interaction.In this paper,an amphiphilic co-gelator N,N-bis(2-(1H-imidazol-4-yl)ethyl)glutaramide(DAHA)containing two imidazole groups is designed and synthesized,then synthesized DAHA and purchased 10,12-pentacosadiynoic acid(PCDA)was assembled in a ratio of 1 : 2 to form a supramolecular gel.It is thought that the gel formed by the two imidazole groups is more stable.However,according to the experimental results,the gel formed is not stable,and the gel is slowly collapsed when left for a long time.The gel undergoes topological polymerization upon irradiation of 254 nm ultraviolet light to form a blue gel,and is capable of responding to temperature and solvent and undergoing a color transition from the blue to red,which could be observed by the naked eye.Then,a novel supramolecular gel was fabricated through the bi-component co-assembly strategy of commercially available 10,12-pentacosadiynoic acid(PCDA)and laboratory-synthesized amphiphilic co-gelator N-(2-(1H-imidazol-4-yl)ethyl)stearamide(IMSA),which contains one imidazole head group and a long alkyl chain tail,by synergetic noncovalent interactions.Upon irradiation of normal 254 nm UV light,blue polydiacetylene(PDA)could be obtained by topo-polymerization of the PCDA monomers in the gel phase.This PDA-based supramolecular gel is able to respond to various environmental stimuli and shows a blue-to-red chromatic transition,which could be observed by the naked eye.Specifically,upon exposure to heat,pH,metal cation and organic solvent stimuli,the PDA gel displays thermochromism,halochromism,ionochromism and solvatochromism,respectively.More interestingly,the differences of the above-mentioned stimuli-induced color transition of the blue PDA supramolecular gels could be characterized by UV-vis absorption spectra and Raman spectra,therefore illuminating a bright application prospect in the area of chemosensing.