| Surface modification not only endows the material with specific functions,but also does not change its original properties,and has been widely used in the fields of environmental protection,biomedicine and preparation of special materials.The surface modification mathod based on the polymer molecular brushes has the advantages of simple process and great versatility.Bilayer / bimodal molecular brushes,V-type molecular brushes,ring molecular brushes and cross-linked molecular brushes have special conformation and chemical composition,therefore,they not only present more excellent performances,but also have dynamic adjustable performance.However,there are few reports on the application of cross-linked molecular brushes in the field of the surface modification.The stimulation response properties of cross-linked molecular brushes are mostly caused by temperature stimulation and pH stimulation,which makes the application of cross-linked molecular brushes unable to be accurately controlled and difficult to be applied to the biological field.Light is precisely controlled in time and space,efficient and clean.Therefore,there are great practical significance and application value to develop a cross-linked molecular brush respodsing only to light stimulation.Based on this,the aim of this study is to prepare a series of polymer brushes with photoreversible crosslinking properties on the surface of materials and obtain the surface with excellent hydrophobicity,controllable wettability and anti-protein adhesion through firstly grafting an atom transfer radical polymerization(ATRP)initiator onto the surface of materials by using polydopamine with excellent adhesion properties as a secondary functionalization reaction platform, then grafting fluorinated monomers and the photoreversible coumarin monomer.In addition,this project also explored the multiple stimulus response properties of the surface grafted disulfide bonds in order to provide theoretical basis and technical support for further preparation of multi responsive cross-linked molecular brush-modified surface.The main researches and contents are as follows:(1)The PDA-coated material surface(PDA-Glass)was prepared by the oxidation of dopamine.Then,2-(perfluorobutyl)ethyl acrylate(PFBEA)and2-(perfluorohexyl)ethyl acrylate(PFHEA)were grafted onto the surface of PDA-Glass by the surface initiates atom transfer radical polymerization(SI-ATRP)method to prepare polymer molecular brush modified material 4F-G and 6F-G.The structure and particle size of PDA were characterized by a infrared spectrometer(FTIR)and dynamic light scattering(DLS).The effects of the fluorine chain length and polymerization time on the surface properties of polymer brushes were investigated by grafting rate test,X-ray photoelectron spectrometer(XPS)and water contact angle test.The experimental results show that with the increase of polymerization time,the grafting rate of the monomers and the content of F element on the surface of the material increased,while the surface water contact angle first increased and then tended to be constant.When the same polymerization time was the same,with increase monomer fluorine chain length,the grafting rate of the monomers,the content of F element and the water contact angle of the materials surface all increased,and the maximum contact angle reached 138±1.5°.(2)A photopoly merizable coumarin monomer(AMYCM)was synthesized from acryloyl chloride and 7-hydroxy-4-methylcoumarin.A series of photo reversible crosslinking polymer brushes modified materials(CUM-F-G)with different ratio of AMYCM to PFBEA was prepared by the copolymerization of AMYCM and PFBEA by SI-ATRP.The water contact angle of the material surface decreased with the decrease of PFBEA content,and the lowest value was 73.6°.The wettability of the material surface containing AMYCM can be controlled through crosslinking and decrosslinking of polymer molecular brushs under 365 nm and 254 nm light.In addition,with the crosslinking of polymer molecular brush containing AMYCM under 365 nm light,the anti-protein adhesion of the material surface was enhanced,and the anti-protein adhesion of CUM10-F0-G crosslinked polymer molecular brush with AMYCM/PFBEA ratio of 10:0 was the strongest,and the polymer molecular brush-modified surface as an anti-fouling surface has a great application potential in ship,biomedical and other fields.(3)Bis-[3-(trimethoxysilyl)propyl] disulfide(TPDS)was synthesized by using mercaptopropyltrimethoxysilane and grafted onto PDA-Glass with excellent photothermal conversion ability.The disulfide bond on the surface can be broken under the stimulation of near-infrared light,ultraviolet light and temperature,and reduced to hydrophilic thiol,resulting in the decrease of water contact angle from 78°to 55°.The thiol group on the surface was oxidized by ferric chloride to reform disulfide bond,and the water contact angle of the surface could rise to about 78° again,thereby realizing the controllable wettability of the surface based on multiple stimulus response,which enables materials to choose stimuli freely in different environments and have a wider range of applications. |
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