Preparation Of Haloamine Polymers And Their Application In Antibacterial Cotton

In recent decades,the diseases caused by bacterial infection pose a serious threat to human health and safety.In order to control the spread of infectious diseases caused by bacterial infection,researchers have palyed much attentions on antibacterial materials due to their abilities to effectively inhibit the growth of microorganisms.Among them,Antimicrobial N-halamine polymers have been extensively studied due to their broad-spectrum bactericidal activities,long-term stability,regenerability,and safety to humans and environment.In this thesis,a kind of N-halamine polymeric nanoparticles and a precursor of the acyclic N-halamine polymer were sysnthesized and a kind of acyclic N-halamine grafted cotton fabrics was prepared.The main contents are as follows:3-allyl-5,5-dimethylhydantoin(ADMH)was achieved by a reaction between 5,5-dimethylhydantoin and allyl bromide,and characterized by Fourier Transform Infrared Spectroscopy and Nuclear Magnetic Resonance.N-halamine polymeric nanoparticles [P(ADMH-Cl-AA)NPs] were synthesized via a solution polymerization of ADMH and acrylic acid(AA),followed by a simple chlorination process using sodium hypochlorite.The particle size of the as-synthesized P(ADMH-Cl-AA)NPs can be controlled by adjusting the amount of initiator and ADMH,and the average particle size is between 22-736 nm.The oxidative chlorine contents of P(ADMH-Cl-AA)NPs with different particle sizes were between 0.23-6.08%.The chemical structure and composition of P(ADMH-Cl-AA)NPs were analyzed by FTIR and XPS.The morphology and size distribution of P(ADMH-Cl-AA)nanoparticles were analyzed by field emission electron microscopy(FE-SEM)and particle size analyzer(DLS).The results of UV irradiation stability test showed that the stability of N-halamine functional groups in P(ADMH-Cl-AA)NPs with a small particle size under UV irradiation is better than that of P(ADMH-Cl-AA)NPs with a large particle size.The experimental results of the regeneration and storage stability of P(ADMH-Cl-AA)NPs showed that the Nhalamine functional groups in P(ADMH-Cl-AA)NPs with different particle sizes had good regenerability and storage stability.The results of antibacterial test showed that all P(ADMH-Cl-AA)NPs with different particle sizes showed excellent bactericidal activities against Escherichia coli and Staphylococcus aureus.The minimum bactericidal concentrations(MBCs)of P(ADMH-Cl-AA)NPs with average particle sizes of 22,375,and 736 nm are 64,20,4 ppm for Escherichia coli and 128,20,4 ppm for Staphylococcus aureus,respectively.When P(ADMH-Cl-AA)NPs contained the same oxidative chlorine contents,the bactericidal speed of P(ADMH-Cl-AA)NPs with a small particle size was faster than that of P(ADMH-Cl-AA)NPs with a large particle size.The P(ADMH-Cl-AA)NPs with an average particle size of 22 nm could kill almost all Escherichia coli and Staphylococcus aureus within 1 and 5 min of contact time,respectively;The P(ADMH-Cl-AA)NPs with an average particle size of 375 nm could kill almost all Escherichia coli and Staphylococcus aureus within 10 min.of contact time;The P(ADMH-Cl-AA)NPs with an average particle size of 736 nm could kill almost all Escherichia coli and Staphylococcus aureus within 15 min.of contact time.Acrylic acid(AA)and methylene-bis-acrylamide(MBAA)were copolymerized in solution to produce an acyclic N-halamine precursor P(AA-MBAA).The assynthesized P(AA-MBAA)was grafted onto cotton fabrics under the catalysis of 1-ethyl-(3-dimethylaminopropyl)phthalimide hydrochloride(EDC)and 4-dimethylaminopyridine(DMAP)at room temperature to form P(AA-MBAA)grafted cotton fabrics [P(AA-MBAA)-cotton].After a facile chlorination in diluted NaOCl solution,the amide functional groups in P(AA-MBAA)-cotton were converted to Nhalamine ones and durable antibacterial cotton fabric containing stable acyclic Nhalamine groups [P(AA-MBAA-Cl)-cotton] was achieved.The as-prepared P(AAMBAA)-cotton was characterized by X-ray photoelectron spectroscopy(XPS)and Scanning Electron Microscope(SEM).The antimicrobial test showed that the asprepared P(AA-MBAA-Cl)-cotton could completely inactivate 5.78×107 CFU/m L of S.aureus and 7.58×108 CFU/mL of E.coli within 30 min.Furthermore,it was found that the tensile strength of cotton fabrics didn't change a lot after grafting and chlorination processes,indicating that the grafting and chlorination processes didn't damage the structure of the cotton fabrics.