Fabrication Of Antibacterial Surfaces Via Ionic Liquids Grafting

Bacteria are a common microorganism in our daily life.The infection and inflammation caused by bacteria has a serious impact on many areas.The researches on antibacterial materials attracts lots of interests.Cationic bactericide as an efficient bactericide has been used widely.Among them,ionic liquid or poly(ionic liquid)not only possess good antibacterial property,chemical and thermal stability,but also obtain the ability to change the hydrophilic-hydrophobic property and antibacterial property via changing anions types.It makes ionic liquid and poly(ionic liquids)becoming a designable cationic compound to create multifunctional antibacterial surfaces.In this paper,we try to modify the substrate with ionic liquid to form an antibacterial coating via simple and fast methods,and research for the antibacterial activity of ionic liquid molecule,poly(ionic liquid)and cyclic poly(ionic liquid).Firstly,we synthesized an imidazolium ionic liquid derivative containing benzophenone group.Through one-step UV irradiation,this ionic liquid derivative can be bonded to various substrates containing C-H bonds in a short time.We also applied this method to polymer substrate,like polyvinyl chloride(PVC)surfaces.Surface antibacterial test showed that the modified surfaces obtained a great killing efficiency to gram-negative bacteria E.coli and gram-positive bacteria S.aureus.The dead bacteria on the surfaces can be released by exchanging the anion.Then,we synthesized a polymerizable 1-(2-methacryloyloxyhexyl)-3-methylimidazolium bromide ionic liquid monomer.A kind of alkyl bromine initiator was added to polydimethylsiloxane(PDMS).Later,the antibacterial surfaces were prepared via visible-light-induced surface grafting polymerization.Antibacterial test showed that the modified PDMS surfaces had a great killing efficiency.When the surface hydrophilic bromide anion was changed to hydrophobic bis(trifluoromethanesulfonyl)amide anion,dead bacteria on surfaces could be released and the killing and releasing efficiency remained unchanged in three cycles.The water contact angle and thickness test before and after anion switching showed that the surface wettability and the conformation of the grafted polymers are the main reason for bacteria releasing.Finally,we combined the reversible addition-fragmentation chain transfer(RAFT)polymerization with sulfur(VI)fluoride exchange(SuFEx)"Click " reaction to prepare cyclic poly(ionic liquid)homopolymer C-1.The characterization of polymers showed that the linear and cyclic polymer have been synthesized successfully.In order to study the antibacterial property of linear and polymer,we reinitiated homopolymer L-1 to introduce catechol group into the polymer and synthesized linear block polymer L-2.Then,the cyclic block polymer C-2 was prepared after the ring closure reaction.These two kinds of poly(ionic liquid)was grafted to the surfaces via the deposition of catechol group.The results showed that the cyclic poly(ionic liquid)had a better antibacterial effect whether in the solution or on the surfaces when it compared to linear poly(ionic liquid).All the results provide a theoretical basis for researching the influence of topology on antibacterial property of poly(ionic liquid).