Ultralight And Antibacterial Fibrous Sponges For High-Efficiency Warmth Retention

It is difficult for human body to resist long-term cold in low temperature environment.Wearing warmth retention materials can effectively reduce the loss of human heat in low temperature environment.Natural warmth retention materials such as cotton and down have become the mainstream materials for people to keep warm from the cold.However,these materials are easy to absorb moisture and deform,resulting in decreased warmth retention performance and gradually replaced by synthetic thermal materials that are moisture-proof and moth-proof.Warmth retention performance of synthetic thermal materials is limited by their coarse fiber diameters（generally greater than 10μm）.Electrospinning is simple and controllable,and are able to eventually produce electrospinning fibers of small diameters,which has the potential to produce fluffy fiber materials.Unfortunately,their fluffy and porous structure also provides living and breeding space for viruses and bacteria.Also,existing three-dimensional electrospinning warmth retention materials have no antibacterial properties,which cannot effectively avoid the cross infection and disease transmission brought by bacteria and viruses.And their fluffy structure is unstable,which inevitably leads to the decline of their warmth retention performance.Therefore,the successful preparation of fiber sponges with stable and fluffy structure and excellent antibacterial and warmth retention performance has great practical application value.In this paper,acrylonitrile styrene copolymer（AS）and polyurethane（PU）were used as polymers to prepare fluffy fiber sponges with excellent warmth retention performance by direct electrospinning.And then the morphology,structure and comprehensive properties of fiber sponges with different AS/PU concentration were compared.When the concentration of AS/PU was 38wt%,the fiber sponge had the smallest volume density(4.5 mg cm^-3)and the highest porosity（99.61%）.The average diameter of its fiber was 4.0μm,and its thermal conductivity was only 23.3 mW m^-1K^-1,which indicates that it had excellent warmth retention performance.At the same time,AS/PU fiber sponge could quickly recover the original shape after 60%compression strain,and the compressive stress it could withstand was 980 Pa,showing good compression performance.In order to give AS/PU fiber sponges excellent antibacterial properties,this paper introduced the antibacterial agent chlorhexidine（CHX）into the spinning solution to produce AS/PU/CHX fiber sponges,and then discussed the effects of different CHX content on the morphology,structure and comprehensive properties of AS/PU/CHX fiber sponges.With the successful introduction of 1.0 wt%CHX,the average diameter of the fiber sponge was reduced to 2.6μm,and the mechanical property was improved.The compressive stress of the fiber sponge under 60%strain reached 1048 Pa.After 100 times of compression,the plastic deformation of the fiber sponge was 6.4%,which indicated that the fiber sponge had good compressive resilience.The thermal conductivity of AS/PU/CHX-1.0 fiber sponge was as low as 24.1 mW m^-1K^-1,and the antibacterial rate was 99.9%.After 10washing cycles,its thermal conductivity was 25.7 mW m^-1K^-1,and its bacteriological inhibition rate was 95.6%,which proved the stability of its thermal and antibacterial properties.Finally,the microstructure and comprehensive properties of AS/PU/CHX-1.0 fiber sponges were compared with common commercially antibacterial and warmth retention felts.It can be seen that the average fiber diameter and mean pore diameter of AS/PU/CHX-1.0 fiber sponges were much smaller than the three kinds of commercially antibacterial and warmth retention felts.At the same time,it had the smallest thermal conductivity and the largest antibacterial rate,showing excellent thermal and antibacterial properties.