Research On Thiol-ene/yne Click Reaction Based Antibacterial Polymers

Infection caused by pathogenic microorganisms on material surfaces has been a long-term problem for public health hygiene.Using antibacterial polymer coatings to protect the material surface is an effective antibacterial method.In recent years,antibacterial polymers with biocidal groups covalently bonded to their chains have attracted a tremendous amount of attention due to their advantages with reduced residual toxicity,increased efficiency and selectivity,no drug resistance and prolonged active lifetime.In this study two kinds of imidazolium antibacterial agents were synthesized by connecting long alkyl chains and alkenyl and alkynyl onto the two N atoms on imidazole molecular ring,specifically.Antibacterial polymer coatings were prepared by thiol-ene and thiol-yne photopolymerization.The physical and chemical properties and antimicrobial properties of antibacterial films were evaluated in detail.The results and conclusions are listed as below.Firstly,a series of side-chain antibacterial polymers with polysiloxane backbones PMMS0-g-ADIm,PMMS0.1-g-ADIm,PMMS0.25-g-ADIm and PMMS0.5-g-ADIm have been synthesized by grafting ADIm monomers to poly[3-mercaptopropylmethylsiloxane](PMMS)in the first-step thiol-ene click process,meanwhile leaving spare mercapto groups,which could be further used as cross-linking sites to form Film-0,Film-10,Film-25 and Film-50 antibacterial polymer coatings in the second-step thiol-ene click process.The structures were characterized and the physical properties were investigated by FT-IR,~1H-NMR,TGA,DMA,contact angle and pencil hardness.It turns out that with the increase of ADIm content in the films the crosslinking degree,thermal stability,glass transition temperature,elastic modulus and pencil hardness of films decrease.In addition,with the increase of ADIm content in the films,cation density of the film surface increases,which is easier to attract water molecules and enhance hydrophilicity.Secondly,four imidazolium quaternary ammonium salts [PHIM]Br,[POIM]Br,[PDIM]Br and [PDODIM]Br were synthesized on the foundation of molecular design,characterized by ~1H-NMR and FT-IR.Four antibacterial films Film-6C,Film-8C,Film-10 C and Film-12 C were synthesized through thiol-yne photopolymerization using [PAIM]Br as antibacterial monomers,PETMP as reactive monomer and DMF as solvent.We take [PHIM]Br/PETMP photopolymerization system as an example and study the the curing process by FT-IR and ATR-FTIR,it was found that photopolymerization was almost finished within 100 seconds.The influence of alkyl chain length on the physical properties were investigated by TGA and DMA.It turns out that alkyl chain length will have little impact on the physical properties such as thermal stability,glass transition temperature and elastic modulus.Thirdly,for a series of antibacterial films Film-0,Film-10,Film-25 and Film-50 S.aureus was selected to evaluate the antimicrobial properties of antibacterial films by dynamic shake methed.The results show that with the increase of ADIm content in the films,bactericidal activity increased.Film-50 exhibited the strongest bactericidal activity,killing all the bacterias within 90 min.for a series of antibacterial films Film-6C,Film-8C,Film-10 C and Film-12 C S.aureus and E.coli were selected to evaluate the antimicrobial properties of antibacterial films by dynamic shake methed.It was found that the antibacterial ability increase with the alkyl length,which relate to the hydrophobic ability of alkyl chain.Comparing to E.coli,the biocidal efficiency towards S.aureus was much higher.