Preparation And Performance Of Multifunctional Thermoplastic Polyurethane Composite Fiber Membrane

Wearable electronic materials have promising applications in areas such as personal health management,sports tracking and human-computer interaction.Thermoplastic polyurethane（TPU）,with its high elasticity,low-temperature flexibility and abrasion resistance,is often used as an elastic substrate in the wearable field,but TPU’s flammability and insulating properties limit its application in special applications.Therefore,improving the flame retardancy of TPU and reducing the release of toxic gases has become an urgent problem to be solved while ensuring the comfort of human wear.In addition,with the application of TPU in the wearable field,the waterproof and breathable,mechanical and electrical properties of TPU also need to be improved.In this paper,multifunctional composite fiber films were prepared using inorganic flame retardant nanomaterials in combination with TPU and their flame retardant,thermal management and electrical properties were investigated as follows:（1）The TPU/MXene/APP_SGcomposite fiber membrane was obtained by spraying Ti₃C₂T_xMXene nanosheets on the surface of TPU fiber membrane prepared by electrostatic spinning and using the sol-gel method to prepare ammonium polyphosphate nanoparticles(APP_SG),which were dip-coated on the TPU/MXene surface.The inorganic material component imparted flame retardancy,thermal stability（residual carbon in argon atmosphere of 49.55%）and water resistance and breathability to the composite fiber membrane;the coating of MXene on the one hand made the fiber membrane significantly stronger,and on the other hand provided a conductive pathway.The conductive network of the fiber membrane is deformed by external forces,resulting in a change in electrical resistance,thus enabling deformation sensing（GF=1.6）.However,the APP particles sprayed on the surface of the fibers are prone to peeling off during use and testing resulting in a reduction in the durability of the fabric.（2）The APP nanoparticles obtained by ball milling were co-blended with TPU spinning solution,followed by electrostatic spinning to obtain the TPU/APP composite fiber membrane in one step.Finally,MXene nanosheets were sprayed to obtain the TPU/APP/MXene composite fiber membrane.The synergistic charring effect,gas dilution and barrier effect between the flame retardant APP and MXene improves the fire resistance of the polymeric material（Argon atmosphere carbon residue of 41.16%,limiting oxygen index LOI value of 28%）.The co-spinning method solves the problems of surface peeling and poor fabric durability when spraying APP.At the same time,the composite achieves excellent strain sensitivity（GF=4465）due to better interfacial contact between MXene and the fibers.This multifunctional composite fiber membrane,which combines flexibility,flame resistance,deformation sensitivity and breathability,has a wide range of applications in practical wearable applications.（3）The application of montmorillonite（MMT）,a flame-retardant compound containing silicon,in multifunctional fiber membranes was investigated.Multifunctional flame retardant TPU composites with excellent electrical conductivity and waterproof and breathable properties were obtained by electrostatic spinning.The optimised process resulted in TPU/MMT/MXene fiber membrane with carbon formation of up to 43.85%and 48.57%and the LOI value of 27.9%.It opens up a new way to design polymeric nanocomposites with excellent mechanical properties,waterproof and breathable properties and fire resistance.