Interpenetration Of Polyethylene Terephthalate With Biocidal Quaternary Ammonium/N-Chloramine Polysiloxane In Supercritical CO₂

Antibacterial modification of surfaces of polymers are very important post-processing process,which can greatly expand the application of materials in medical,clothing and other fields.N-halamine and quaternary ammonium salts are the most commonly used bactericidal groups because of their low price,wide range of sterilization and rich sources.Quaternary ammonium salts use positive charge to attract and penetrate into the negatively charged cell wall of bacteria.They have the following characteristics:no consumption during sterilization,good stability,but low efficiency and insensitivity to Gram-negative bacteria.N-halamines release halogen ion to oxidize receptors of bacteria.They have high germicidal efficiency,good rechargeability,not cause drug resistance.A condition of quaternary ammonium salt and N-halamine can lead to extended biocidal ability since quaternary ammonium salt can attract bacteriaIn this thesis,polysiloxane containing both quaternary ammonium and N-halamine was synthesized.Firstly,the substitution reaction of 5,5-dimethyl hydantoin(DMH)with 3-bromo-1-chloride was used to produce a hydantoin precursor of 3-(3-chloropropyl)-5,5-dimethylhydantoin(CPDMH);secondly,silane alcoholysis between poly(methylhydrosiloxane)(PMHS)and dimethylaminoethyl acrylate,subsequent quaternization with 3-(3-chloropropyl)-5,5-dimethylhydantoin(CPDMH),and chlorination with tert-butyl hypochlorite.The effects of temperature,alcohol sealing agent were investigated using FTIR,NMR,XPS,and SEM,and calculate these yieldsPolyethylene terephthalate(PET)fiber has many advantages including high strength,light weight,stable chemical properties.Because of the excellent properties of PET fiber,it has a wide range of applications in the fields of medical treatment and clothing.In this thesis,PET fiber was used as the template.The synthetire of quaternized N-halamine polysiloxane was impregnated into PET in supercritical carbon dioxide(scCO2)at 50?,28MPa.The PET fibers before and after impregnation were characterized by XPS and SEM.The N-halamine polysiloxane was impregnated into inert PET fibers and formed a 70 nm coating layer for antibacterial.AATCC 1996 standard sterilization method showed quaternized N-halamine polysiloxane impregnated PET fiber provided effective biocidal activities against both S.aureus and E.coli compared with unmodified ones that did not display obvious antibacterial activities.PET coating on fiber was stable toward washing cycled,storage stability and UV irradiation and rechargeable of chlorine was good.Supercritical carbon dioxide(scCO2)impregnation method uses carbon dioxide as the solvent and does not cause pollution to the environment.This method does not require covalent bonding between substrate and biocides,and hence this technique can be applied to inert and reactive substrates.The successful modification of inert PET by supercritical impregnation provides a general and simple approach to functionalize polymeric substrates of chemistry.