Preparation And Properties Of Photo-thermal Responsive Supramolecular Lubricating Hydrogels

Smart responsive hydrogels,due to their unique properties,can respond to external stimuli such as heat,force,electricity,and light,thereby imparting multiple functionalities to hydrogels for application in various environments and scenarios.Smart responsive hydrogels not only exhibit specific responsiveness to external stimuli,making them highly promising for applications in biomedicine,electronic sensing,flexible skin,and other fields.What’s even more intriguing is that supramolecular smart hydrogels possess dynamic assembly and disassembly properties,enabling reversible transformations between gel and sol states.The emergence of sol states holds wide-ranging prospects for enhancing lubrication,drug release,wound dressings,and more.Near-infrared light,as a convenient,non-contact,environmentally friendly and safe external stimulus,is widely used as a stimulus source for intelligent hydrogels.Therefore,smart responsive supramolecular hydrogels were prepared by incorporating a composite of photo-thermal responsive supramolecular non-covalent networks into covalent polymer networks.These smart responsive hydrogels not only undergo supramolecular sol-gel transitions but also maintain good mechanical properties.They have shown unique advantages in the fields of biomimetic cartilage substitutes and soft robotics control.In chapter two of our work,we introduced a polydopamine/gelatin supramolecular system into a covalent network consisting of polyvinyl alcohol/polyethylene glycol/boric acid,resulting in the synthesis of a photo-thermal responsive supramolecular lubricating hydrogel.The covalent network confers excellent mechanical strength to the hydrogel,while the supramolecular system serves as the smart responsive component,imparting lubrication capability to the hydrogel material.Under near-infrared light irradiation,the temperature increase caused by polydopamine triggers the disassembly of gelatin,leading to a partial sol-gel transition of the hydrogel.The disassembled gelatin appears as a liquid layer on the surface of the hydrogel,promoting surface lubrication.This near-infrared light-controlled supramolecular lubricating hydrogel provides an experimental foundation for the development of novel lubricating hydrogel materials.In chapter three,we incorporated a gelatin supramolecular network into a polyvinyl alcohol/poly(N-isopropylacrylamide)covalent network and added polydopamine to the system to create a photo-thermal responsive mimetic muscle contraction hydrogel.The irradiation of near-infrared light achieves a surface-responsive lubrication function,while the phase transition of the poly(N-isopropylacrylamide)network induces a contraction in the bulk phase of the hydrogel,enabling the simulation of the dynamic muscle contraction process.The preparation of this hydrogel,therefore,offers a new approach for the photothermally regulated lubrication of soft robots.In summary,this paper introduced the photo-thermal responsive supramolecular network into a covalent network to prepare a photo-thermal responsive smart hydrogel.The hydrogel generates a lubricating layer under near-infrared light irradiation,which regulates the lubrication performance of the hydrogel surface,providing a new approach for the preparation of lubricating devices,soft robots,and intelligent wearable devices.