Construction Of Supramolecular Hydrogel Based On Charge Transfer Interaction Of Viologen And Pyrene Derivatives

Charge transfer complexes（CT complexes）,which are composed by the charge transfer interaction between electron acceptors and donors,are self-assembled structures with a variety of enriched properties.However,their application in hydrogel construction is less due to the poor water solubility of most of the acceptors and donors.The ionic viologen and pyrene derivatives,as an important group of donor-acceptors,have good water solubility,making it possible to construct supramolecular hydrogels based on their CT complex.The charge transfer interaction existing between the CT complex is dynamically reversible and the viologen derivatives have a quaternary bactericidal structure,which is expected to confer injectability,self-healing and antibacterial properties to the constructed supramolecular hydrogels,showing potential applications in wound dressings.In addition,the binding constant between the CT complex is 10⁴ M^-1,which is much lower than that of covalent bonds and is susceptible to reversible breakage by external forces and temperature,which makes the supramolecular hydrogels constructed based on the CT complex promising as highly sensitive temperature and strain sensors.Based on this,this thesis is centered on the construction of supramolecular hydrogels from CT complexes and two studies are conducted.（1）A series of supramolecular hydrogels（CT-hydrogels）were designed and synthesized by synthesizing polymers with viologen derivative and pyrene derivative,respectively,using the CT complex of the derivatives as crosslinker and N-（2-hydroxyethyl）acrylamide as the main chain monomer.This CT-hydrogel had room temperature injectability and rapid self-healing properties,with complete healing in 3 min.It had an adhesion strength of 13.7 k Pa to the skin and an antibacterial effect of more than 99.97%.Also,CT-hydrogel showed good biocompatibility and good wound healing promoting effect in skin healing experiments,which could effectively inhibit inflammatory infiltration and promote neovascularization.This study not only reports a multifunctional hydrogel that can be used as a wound dressing,but also provides an opportunity to introduce charge-transfer complexes into hydrogels,which expands the available functional units of hydrogels and contributes to the development of new hydrogel materials with desirable properties.（2）A series of conductive hydrogels（CT-K hydrogels）were designed and synthesized by a one-step polymerization method with the CT complex coordinating the ionized monomer,sodium 4-vinylbenzenesulfonate.The mechanical properties of the CT-K hydrogels were significantly modulated by varying the concentration of KCl in the system,with a maximum strain at break of 1044%.Due to the ionic structure of the polymer network and the incorporation of KCl,the CT-K hydrogels had a good conductivity of up to 6.75 S/m.Designed as a strain and temperature sensor,the hydrogels exhibited a strain sensing sensitivity of up to8.71 and a temperature sensing sensitivity of-3.20%°C^-1,as well as a wide sensing range（900%strain and 5-70°C）with reliable sensing stability.After the CT-K hydrogel sensor was thermoplastic,its sensing performance remained good and recyclable after heat treatment,which greatly extended the service life of CT-K hydrogel as a sensor and meets the requirements of sustainable development.