Study The Antibacterial Mechanism Of Polyethylene Terephthalate(pPET)/Cu₂O-based Nanocomposite Fibers By Designing And Construction Of Cu₂O-based Hybrid Materials

PET is currently the world's largest synthetic fibers,with many excellent properties such as elasticity,crease resistance,electrical insulation,dimensional stability and weak acid and weak alkali,widely used in clothing,home textiles,engineering plastics,etc.As a key application field,the preparation of PET functional antibacterial fiber still faces many problems,such as non-permanent antibacterial,high antibacterial component addition,uneven nano-dispersion,and low antibacterial efficacy.In order to achieve high efficiency,long-lasting and stable antibacterial effect of PET fibers,high-efficiency antibacterial PET nanocomposite fibers were prepared by melt blending and in-situ polymerization.The main means of realization are as follows:(1)Nano-Cu₂O with high antibacterial function was introduced based on blending or in-situ polymerization,and various high-efficiency antibacterial PET/Cu₂O nanocomposites were prepared.(2)To achieve dimensional stability and uniform dispersion of Cu₂O,designed and constructed Cu₂O@ZrP hybrid material with micro-nano structure and high efficiency antibacterial,achieving its high efficiency,stability and long-lasting antibacterial effect.The formation mechanism of small-sized nano-Cu₂O and mechanism of action of Cu₂O@ZrP hybrid material in inhibiting bacterial growth were described.(3)The comparison showed the service performance and antibacterial properties of PET/Cu₂O@ZrP nanocomposites prepared by different processes.The dispersion of Cu₂O@ZrP hybrid materials in PET matrix and the stability of size and performance of small-sized nano-Cu₂O were studied.(4)Based on the organic-inorganic hybrid technology,the organic-inorganic hybrid Cu₂O@ZrP-C18P(octadecyltriphenyl phosphonium bromide)antibacterial materials which meet the high-efficiency antibacterial and stable dispersion of the melt blending process was designed and constructed.The hybrid materials not only had small size nano-Cu₂O(5 nm),but also hybridized with C18P,which realized efficient and stable antibacterial of Cu₂O@ZrP-C18P hybrid materials.PET/Cu₂O@ZrP-C18P composite fibers were prepared by melt spinning.The dispersibility,functional stability of Cu₂O@ZrP-C18P hybrid material in composite fiber and the serviceability,processing property and antibacterial property of PET/Cu₂O@ZrP-C18P composite fibers were studied.The main contents are as follows:1.PET/Cu₂O nanocomposite resin masterbatch was prepared by blending method and in-situ polymerization method respectively.The series of PET/Cu₂O nanocomposite fibers were obtained by melt spinning method.The Cu₂O had the particle size of about 80 nm.This chapter mainly analyzed the influence of preparation process and Cu₂O content on the structure and properties of PET/Cu₂O nanocomposite fibers.The results showed that the agglomeration of Cu₂O in the composite fibers prepared by melt blending was relatively obvious,and one more thermal processing caused thermal degradation of polyester molecules in the fibers.On the other hand,the addition of Cu₂O could improve the heat resistance of the composite resin,and the initial temperature of the resins prepared by the two methods was increased about 7?.During the fiber processing,it was found that the Cu₂O in the composite fibers prepared by the in-situ polymerization method had good dispersibility and more excellent spinnability,and the draw ratio of the fiber could reach 4.6 times.The nanocomposite fibers with Cu₂O content of 0.2 wt%prepared by in-situ polymerization has the best mechanical properties,up to 4.23 c N/dtex.The antibacterial test found that the antibacterial fiber with Cu₂O content of 0.2 wt%prepared by in-situ polymerization could achieve 99%antibacterial activity against Escherichia coli and Staphylococcus aureus,and the antibacterial rate against Candida albicans could reach 85%.When the Cu₂O content was increased to 0.6 wt%,the antibacterial rate against Candida albicans could reach 97%.Therefore,PET/Cu₂O nanocomposite fibers prepared by in-situ polymerization had good mechanical properties and processing properties,their antibacterial properties could also meet national standards and applied in the fields of clothing,home textiles and military protection.2.In order to improve the antibacterial efficiency of Cu₂O,it is necessary to further reduce the particle size of Cu₂O and enhance its dispersion stability.In this chapter,a series of micro-nano structure Cu₂O@ZrP hybrid materials were prepared by in-situ chemical reduction.This chapter systematically characterized the structure,morphology,dispersibility and antibacterial properties of Cu₂O@ZrP hybrid materials.The mechanism of Cu₂O@ZrP hybrid materials in the antibacterial process was summarized and analyzed.The results showed that the amount of Cu SO₄ was the main factor affecting the content of Cu₂O in Cu₂O@ZrP hybrid materials,and the Cu₂O content increased with the change of Cu SO₄ composition.The results of TEM and SEM showed that the particles uniformly dispersed on the surface of the ZrP sheet were Cu₂O with a particle size of about 5 nm.TEM and SEM results showed that Cu₂O with particle size of about 5 nm was uniformly and stably dispersed on the surface of the ZrP sheet.The formation mechanism of small-scale nano-Cu₂O(4?5 nm)was mainly attributed to Cu₂O first forming ultra-small particle size seed crystals.Subsequently,under the synergistic action of EDTA and ZrP,the fixed seed crystal inhibited the agglomeration of the seed crystal,and also limitted the growth of Cu₂O along the vertical ZrP sheet direction,thereby forming a small-scale Cu₂O.The antibacterial test of the oscillating method found that the Cu₂O@ZrP hybrid material not only inhibited the growth of E.coli,but also had an obvious antibacterial effect on super bacteria,and the inhibition rate could reach 99%.The ionic solubility,protein concentration,bacterial ROS and the morphology of the bacteria were characterized.The mechanism of Cu₂O@ZrP hybrid materials on bacterial metabolism and proliferation was proposed.3.Based on the Cu₂O@ZrP hybrid material constructed in the previous chapter,PET/Cu₂O@ZrP nanocomposite fibers were prepared by in-situ polymerization.It was found that Cu₂O@ZrP had good dispersibility in PET/Cu₂O@ZrP nanocomposite fibers,but there was also a small amount of agglomeration when Cu₂O@ZrP content increases to 0.6 wt%.At higher shear rates,Cu₂O@ZrP was oriented with shear,which reduces interaction with the molecular chain and increases fluidity.The fiber strength of Cu₂O@ZrP added by 0.2 wt%could reach 4.24 c N/dtex.The composite fiber had low dissolution ability,thereby reflecting the long-lasting antibacterial ability.After 7 days of dissolution testing,the fiber dissolution amount accounted for about 14%of the total amount.The antibacterial rate of composite fibers with Cu₂O@ZrP content of 0.2 wt%against E.coli and S.aureus could reach 99%,while the inhibition rate of C.albicans reaches 99%only required Cu₂O@ZrP content of 0.4 wt%.The Cu content of the selected Cu₂O@ZrP was only18.6 wt%,and the effective content of copper in PET/Cu₂O@ZrP-0.4%was only 0.07 wt%.This meaned that only small amount of copper presented in PET fiber could achieve excellent antibacterial effect,and further demonstrated the high-efficiency antibacterial ability of the PET/Cu₂O@ZrP nanocomposite fibers.4.In order to improve the dispersibility of nanomaterials when Cu₂O-based antibacterial fibers was prepared by melt blending method,this chapter synthesized benzyltriphenyl phosphonium chloride(BTP)and octadecyltriphenyl phosphonium bromide(C18P)based on the nucleophilic substitution reaction mechanism.High thermal stability organic-inorganic hybrid materials were prepared by intercalation modification of zirconium phosphate.Thereby,a highly efficient Cu₂O-based antibacterial material suitable for melt blending was further constructed.The chemical structures of the two quaternary phosphonium salts were characterized by ¹H NMR and³¹P NMR.The interlayer spacing of ZrP was expanded to more than 1.5 nm,and the thickness of the sheet was significantly reduced.Cu₂O was still well loaded onto the surface of the modified ZrP sheets.Cu₂O@ZrP-C18P had good thermal stability and the initial decomposition temperature was higher than 300?.On the other hand,Cu₂O@ZrP-C18P had a higher Zeta potential value than Cu₂O@ZrP-BTP,which had better compatibility with the polymer matrix.The antibacterial test found that when the concentration of Cu₂O@ZrP-C18P was only 25 mg/L,the inhibition rate was as high as 99%.The activity of Cu₂O@ZrP-C18P hybrid material on NIH3T3 cells showed that the cytotoxicity of C18P was weak.When the concentration of Cu₂O@ZrP-C18P reached 100mg/m L,the cell activity could still be maintained at about 60%,when the concentration was increased to 500 mg/m L,the cell activity was just reduced to about 30%.Therefore,the compatibility of the modified Cu₂O@ZrP-C18P with the PET matrix was increased,and the antibacterial ability of the nanocomposite fiber is improved.