Structural Design And Construction Of Cellulose-based Conductive Composite Fibers And Their Multifunctional Applications

Due to their good flexibility,high biocompatibility,and low-cost solution preparation processes,conductive polymers are widely used as conductive materials to endow fibers or textiles with various electronic functions such as gas sensing,motion monitoring,personalized medicine,and human-machine interaction.Compared to two-dimensional planar devices,one-dimensional fiber devices have a high aspect ratio and flexibility,enabling them to adapt to uneven skin morphology and complex motion states,integrate easily with everyday textiles,and thus make them extremely attractive in the field of wearable electronics.Furthermore,they can be further processed into one-dimensional yarns,two-dimensional fabrics,and three-dimensional spacer fabrics through textile technology,which is very suitable for mechanical design of wearable devices.However,existing soft fiber electronic devices based on conductive polymers still face problems such as poor interfacial bonding strength,low conductivity,high production costs,and non-degradability.Therefore,developing degradable high-conductivity composite fibers has important theoretical value and practical significance.This article focuses on utilizing cellulose as the matrix and conductive polymers as the conductive units to fabricate cellulose-based conductive composite fibers through a continuous wet spinning process.Furthermore,a multifunctional fiber sensor is constructed for gas detection,vital signs monitoring,and environmental temperature and humidity sensing.By optimizing the cellulose dissolution method and controlling the morphology and distribution of the conductive polymers,the electrical conductivity and mechanical strength of the composite fibers are significantly enhanced,enabling adaptation to diverse sensing environments.The specific research content is as follows:1.Construction of corn-like polyaniline/regenerated cellulose conductive composite fibers:Regenerated cellulose fibers（RCF）were prepared from waste cotton fabric using an alkaline-urea system.By adjusting the amount of ammonium persulfate（APS）introduced,the morphology and distribution of polyaniline（PANI）particles on the surface of RCF were controlled.Corn-like conductive composite fibers,PANI/RCF（PCF）were successfully constructed by the hydrogen bonding between PANI and cellulose molecules.Thanks to the uniform loading of PANI conductive layer,PCF_0.5（0.5 M APS concentration）exhibited high conductivity（17.30 m S/cm）,and its mechanical strength and sensing performance were significantly enhanced.Based on PCF_0.5,a flexible sensor was developed with the ability to capture multiple signals of organic vapors and human activities,with a high gauge factor（GF）of 23.8.2.Construction of skin-core PCF:With the good dispersibility of PANI,PCF with a skin-core structure were successfully prepared via homogeneous sulfuric acid method under no chemical reaction conditions.The promoting effect of sulfuric acid on the extension of PANI molecular chains was used to build a conductive network at low introduction amount（1 wt%PANI）.Meanwhile,the conductivity and mechanical strength of the conductive composite fibers can be effectively controlled by adjusting the amount of PANI introduced.PCF15（15 wt%PANI）exhibited excellent conductivity（21.50 m S/cm）and high sensitivity to various gases,such as ammonia(2.49×10^-2%/ppm),ethanol(1.74×10^-3%/ppm),and formaldehyde(1.77×10^-3%/ppm).Furthermore,fabrics woven from PCF15 showed good anti-static performance.3.Preparation of high-strength and high-conductivity cellulose-based conductive composite fibers:Polypyrene（PPy）was used as a conductive material to prepare high-strength and high-conductivity RCF-PPy composite fibers using an improved in-situ polymerization and layer-by-layer self-assembly method.By controlling the concentration of reactants and the bath ratio,the embedding and self-assembly growth of PPy on RCF were regulated to construct a continuous and robust conductive network.The RCF-PPy composite fiber exhibited a high conductivity of 87.66 m S/cm and excellent sensing performance,with the ability to monitor strain,pressure,temperature（0.34%/°C）,and humidity（0.895%/RH）.Additionally,the composite fiber had high mechanical strength（1.01 c N/dtex）and excellent tolerance,able to withstand mechanical deformation,friction,and ultrasonic washing,improving the poor interface binding and conductivity stability of conductive fibers.Based on RCF-PPy3（RCF-PPy based on 3times aggregation）,a pressure sensor was constructed as a human-machine interface electronic device,achieving sedentary reminders and fingertip information transmission.In summary,this article provides the support of design ideas,key preparation techniques and other fundamental theories for cellulose-based flexible fiber multifunctional sensors,and constructs cellulose-based conductive composite fibers using surface polymerisation,homogeneous blending and layer self-assembly respectively,and enhances the electrical conductivity and mechanical strength of the composite fibers through structural modulation.The weaveable multifunctional composite fibers have a promising future in the field of wearable electronics.