Preparation Of MXene Based Asymmetric Nanofibre Membranes And Study Of The Unidirectional Transport Properties Of Water

In recent years,with the development of the times and the advancement of technology,the demand for flexible wearable electronic devices is increasing day by day.Conductive fibre/fabric composites(ECFCs),which are lightweight,flexible,flexible,economical and have good sensing properties,have become ideal materials for wearable electronic devices.Commonly,flexible conductive composites have a single immersion(hydrophilic or hydrophobic).As a wearable material,sweat does not spread smoothly to the outside,greatly sacrificing human comfort.This thesis constructs MXene based conductive networks on the surface of flexible polyurethane(PU)nanofibres and constructs hydrophilic/hydrophobic Janus structures by electrostatic spinning,resulting in multifunctional nanofibre composites with both unidirectional transport and temperature sensing,investigates the interactions between the multilayer structures and elaborates on the unidirectional transport mechanism.The thesis consists of three parts as follows:1.MXene nanosheets were assembled by impregnation onto the surface of PU nanofiber films to construct a conductive network,and then chitosan(CS)was adsorbed on the MXene surface to enhance hydrophilicity while protecting MXene from oxidation to obtain CS/MXene@PU nanofiber composites,which were electrosprayed as a substrate with a"bead-like" structure of polyvinylpyrrolidone(PVP)/PU hydrophobic thin layer to obtain nanofiber films(ANM)with asymmetric structure."The introduction of PVP can improve the interfacial interaction between the hydrophobic and hydrophilic layers,and the one-way transport time from the hydrophobic side to the hydrophilic side can reach 30 s and the water diffusion time on the hydrophilic side is 2.5 s.The nanofiber films can be obtained after ultrasonic cleaning,cyclic After several wear tests such as ultrasonic cleaning,cyclic stretching and sand impact,its unidirectional transport performance is almost unchanged,showing excellent interfacial stability and durability.2.A core-shell structure was formed by ultrasonically inducing the assembly of MXene and CS on the surface of PU nanofibres,which was then electrostatically spun as a substrate for a thin hydrophobic layer of low-concentration PU,and modified by impregnating the hydrophobic side with a low concentration of MXene.The unidirectional transport time was 18 s and the water diffusion time on the hydrophilic side was 1.5 s.The unidirectional transport performance was significantly improved compared to the first part,and the JNM also had excellent photothermal and temperature-sensitive properties.3.The superhydrophilic CS/MXene@PU nanofibre composite was prepared using the same method as in Study 2,and a thin layer of MXene/PU fibres was electrostatically spun on its surface as a substrate,resulting in a composite nanofibre membrane(JCNM)with different distribution states of MXene,with a JCNM unidirectional transport time of 10.5 s and a water diffusion time of 1.5 s on the hydrophilic side.The unidirectional transport performance was further improved compared to the second part.The mechanism of JCNM unidirectional transport was analysed,the temperature-sensitive response behaviour and durability of JCNM under multiple photothermal cycles were tested,the stability of JCNM unidirectional transport behaviour under multiple tensile cycles and abrasion resistance tests were evaluated,and its application in temperature sensing and temperature warning was explored.