| UV-induced surface-grafted modification is abroadly applied in various applications for its non-pollution,easy control,economical,and no damage to the bulk properties of the substrates.The "smart grafting" process carried out through the coupling reaction can introduce specific functional groups onto the surface of the unactivated polymer substrates,thereby tailoring the surface performance.This study consists of two parts:(1)firstly,using p-dimethylaminobenzene ring as synthetic building blocks,and bonding specific functional groups onto the surface of the substrate via the α-amino radicals coupling under the UV irradiation;and(2)achieving UV-induced surface radical grafting polymerization of vinyl ethers(VEs)with the "naked"Li+as a catalyst.Follows are the main results:1.The first part presents a versatile blueprint to transfer unactivated surface C-H bonds of polymeric substrates to C-R-F groups by UV light-assisted surface free radical coupling.With p-dimethylaminophenyl radical as a building block,various reactive groups,such as-CHO,-SH,-B(O)OH,-CN and-SO3-,are successfully grafted onto typical commercial polymer substrates including BOPP,PET,ETFE and silicone rubber.Fluorencence microscope images,X-ray photoelectron spectroscopy,UV-vis and fluorescence spectra support that the above functional groups are covalently bonded to the polymer substrates.The concentration of the reactive groups immobilized on the different substrates is in the order of 10-8 to 10-7 mmol/mm-2 determined by UV-vis spectrometry.2.As a proof-of-concept,the reactivity of the induced surface functional groups is demonstrated by their special reactions.For example,-CHO reacting with-NH2 to synthesize Schiff base,-SH to detect silver ions,and the complexes of-C=N and Zn2+to degrade Rhodamine B.The results indicate that one can fabricate an integrated molecular library on the surface of polymeric substrates at the molecular level by selecting the building blocks.3.The related work of UV-assisted construction of functional coatings on the surface of the substrate was expanded,and the photo-induced surface radical grafting polymerization of vinyl ether on the surface of the substrate under the catalysis of Li+was studied.The structure,morphology and surface properties of grafted polymer layer were characterized using CA,XPS,FTIR-ATR,SEM,AFM and the other test methods.Moreover,ellipsometry data implied that the thickness of the PVEs was about 20-60 nm,the grafting densities was 0.65-1.15 chain/nm2,and DCA data decreased from 84.4°to 45.3°.No hydrolysis was observed after the surface exposure to phosphate-buffered saline(PBS)solution,0.1 mol/L NaOH(eq)and 0.1 mol/LHCl(eq)for 30 days.The surface coatings are of excellent hydrolysis resistance and long service life.4.In addition,as a proof-of-concept,the side hydroxyl groups of grafted PVEs provide efficient fixation sites for bioactive molecules e.g.,glycosaminogly can react with serum protein.Antibacterial experiments show that the functionalized substrate has a good antibacterial effect.The surface-OH group was oxidized to-CHO group with the Collins reagent.Furthermore,the-CHO could react with bovine serum albumin,and the protein chip was successfully prepared. |
