Synthesis And Properties Of Magnetically Responsive Hydrogel And Liquid Crystal Aerogel

Gel,as a special dispersion system,has a a connected network structure full of dispersion medium.Due to the unique properties and internal structure,it has attracted more and more attention in the fields of intelligent actuators and micro-robots.Particularlly,the combination of gels with other materials can endow them with new functions while retaining the characteristics of gel materials.This mothed is also regarded as one of the most promising ways to expand the application fields of gels.Firstly,a novel magnetic thermo-sensitive hydrogel material,which can realize the sol-gel transformation under the stimulation of the external alternating magnetic field,is fabricated and characterized by FTIR Spectrometer,Vibrating Sample Magnetometer and TEM.The results show that based on the hydrophobic self-assembly effect,the magnetic hydrogel possessing superparamagnetic properties has a core-shell structure in which lipophilic Fe₃O₄ nanoparticles as the core and the PCLA-PEG-PCLA thermosensitive hydrogel as the shell.The preliminary study on its application show that the magnetic hydrogel can move freely in the narrow pipe using external magnets and transform into gel state under the stimulation of alternating magnetic field.In this work,we put forward the concept of a movable chemical valve,which will provide a new idea for the design of chemical valves in the field of microfluidics.Secondly,a novel two-way shape-memory LCE-based aerogel,possessing both the porous structure of typical polymeric aerogel materials and the reversible shape morphing of the LCEs,was designed and prepared by an orthogonal thermal and photo curing strategy coupled with an intermediate mechanical stretching step.The DSC,POM and WAXS results proved that the LCE-based aerogel possessed a nematic phase and the mesogens in the aerogel were well oriented along the stretching direction.Besides,the LCE-based aerogel had distinct hierarchical porous structures,good compressibility and excellent shape stability,which were typical properties of conventional polymeric aerogels.Moreover,this LCE-based aerogel could perform a reversible shrinking/expanding deformation during the heating/cooling cycle and the two-way shape-memory property of this LCE-based aerogel possesses superior fatigue resistance during several heating/cooling cycles.To the best of our knowledge,this is the first example of polymer aerogel materials exhibiting two-way shape-memory behaviors under external stimuli,which might endow this novel LCE-based aerogel material with potential applications in the field of control devices,soft actuators and beyond.