Construction And Application Of Bonded Polyurethane-based T-ZIF-8 Antibacterial Nanofibers

The outbreak and continuous spread of COVID-19 has sounded the alarm for public health security in China.In order to prevent the spread of the virus and prevent secondary pollution,it is urgent to develop efficient and durable new antibacterial textiles.Zeolite imidazole framework material（ZIF-8）has become the preferred materials for the development of photocatalytic antibacterial fibers due to its large specific surface area,good antibacterial activity,and low biological toxicity.However,there are problems such as low antibacterial efficiency under visible light irradiation and antibacterial function inactivation caused by the dissolution of ZIF-8 in post-finishing technology.This thesis design and synthesis visible light emitted T-ZIF-8 photocatalytic antibacterial materials,employ the electrostatic spinning technology to construct TPU based T-ZIF-8 photocatalytic antibacterial fibers,research and reveal T-ZIF-8 photocatalytic antibacterial mechanism and its bonding type photocatalytic antibacterial fibers microstructure and properties relationship of antibacterial,waterproof,moisture permeability.The research contents and results are as follows:（1）In view of the problem that ZIF-8 has a large band gap and only responds to ultraviolet light,resulting in low antibacterial efficiency under visible light,this paper successfully extended the light response range of ZIF-8 to the visible light region by thermal oxygen sensitization process,so as to solve the problem of low antibacterial efficiency under visible light irradiation.The results show that the crystal structure and morphology of T-ZIF-8are not damaged after thermal oxygen sensitization,but the elements and some functional groups of T-ZIF-8 are changed.After thermal oxygen treatment,the specific surface area of T-ZIF-8 decreases slightly,but it is still up to about 1500 m2/g.The photocatalytic study shows that the band gap of T-ZIF-8 is significantly reduced,and the photogenerated charge separation and migration efficiency of T-ZIF-8 is significantly improved,while the photogenerated electron recombination efficiency is significantly reduced.The photocatalytic antibacterial study shows that the bactericidal rate of T-ZIF-8 against Escherichia coli and Staphylococcus aureus reach 99%within 20 min under visible light irradiation（λ≥420 nm）.Meanwhile,the photocatalytic antibacterial mechanism of T-ZIF-8 against active species such as·O₂^-and h⁺is revealed.（2）In view of the problem of textile antibacterial function failure caused by the dissolution of ZIF-8 antibacterial agent in the post-finishing technology.In this work,the T-ZIF-8 photocatalytic agent excited by visible light was combined with thermoplastic elastic polyurethane with good flexibility and biocompatibility to prepare the bonded polyurethane-based T-ZIF-8 photocatalytic material,and then the bonded polyurethane-based T-ZIF-8antibacterial fiber was constructed by optimizing the properties of electrostatic spinning solution.The structure of the bonded polyurethane-based T-ZIF-8 photocatalytic material was characterized by FTIR and XRD tests,and the results shows that T-ZIF-8 is successfully bonded to polyurethane.The photocurrent and electrochemical impedance measurements show that the photo charge separation and transfer efficiency of PEG/T-ZIF-8 are significantly improved after hydrogen bond association.By optimizing the concentration of electrospinning solution,the optimal concentration of polyurethane-based T-ZIF-8 polymer spinning solution is determined to be 22 wt%.The effects of different contents of"intermediate"PEG on the microstructure of bonded polyurethane-based T-ZIF-8 antibacterial fiber was studied,and the optimal PEG dosage is determined to be 3.3 wt%.In order to further optimize and regulate the micromorphology of bonded polyurethane-based T-ZIF-8 antibacterial fiber,the effect of Zn Cl₂on the micromorphology of the fiber was studied.Finally,the optimal process parameters of the concentration of the spinning solution are 22 wt%,the amount of PEG is 3.3 wt%and the amount of Zn Cl₂ is 0.5 wt%,and the polyurethane-based T-ZIF-8 nano antibacterial fiber with more uniform diameter and tighter structure is constructed.（3）In order to investigate the application value of polyurethane-based T-ZIF-8nanofibers,the structure-property relationship among the fiber microstructure and photocatalytic antibacterial,moisture permeability,waterproof properties were studied.The photocatalytic antibacterial results show that the TPU-PEG/Zn Cl₂/T-ZIF-8 fiber film with more uniform and compact micromorphology have the best photocatalytic antibacterial effect.The antibacterial rates of S.aureus and E coli are 99.99%and 99.57%after visible light irradiation for 30 min and 120 min,respectively.The moisture permeability of TPU-PEG/T-ZIF-8 fiber membrane with abundant hydrophilic groups,larger average fiber diameter and wider distribution range is the best.When the ambient temperature is 40℃,the moisture permeability of TPU-PEG/T-ZIF-8 fiber membrane is higher than 3000 g/（m²·24h）,which meets the standard of Grade I moisture permeability.The water contact angle experiment shows that the water contact angles of the different fibers are both more than 90°,which have a certain waterproof effect.Meanwhile,the hydrophilicity and hydrophobicity of the fiber membrane are closely related to its hydrophilic group and microstructure.In conclusion,the polyurethane-based T-ZIF-8 nanofibers in this work have potential applications in medical dressings,medical protective products,and other fields of health protection.