Development Of Vinyl Sulfone-based Surface Initiated Polymerization Method And Its Application

Surface-initiated polymerization is key for preparing polymer-inorganic composite materials.Currently,four methods are used commonly for surface-initiated polymerization,including atom transfer radical polymerization,reversible addition-fragmentation chain transfer,nitroxide-mediated polymerization and photoiniferter-mediated polymerization.However,these methods have limitations,such as strict reaction conditions and complex catalytic system.Development of a new method to address the above limitations will be beneficial.Research has shown that the vinyl sulfone group has high reactivity due to the strong electron-withdrawing effect of the sulfone group.In this study,we have developed a new method to initiate polymerization on surfaces bearing vinyl sulfone groups.Specifically,the following work has been carried out:Firstly,we established a new method on planar substrates of silicon wafers.Vinyl sulfone functionalization was achieved on the surface of silicon wafers through the two-step method and one-step method,followed by surface polymerization of sulphobetaine methacrylate(SBMA)via the "grafting-from" approach.The water contact angle results showed that the surface had strong hydrophilicity after polymerization.X-ray photoelectron spectroscopy could confirm that there were polymerization products on the surface.The polymer film thickness measured by ellipsometer was 11 nm.The above results verified the success of the new surface initiated polymerization method.Next,we examined the newly developed method on substrates of 100 nm silicon nanoparticles(SiNP).Two-step and One-step method was used to functionalize the surface of silicon nanoparticles with vinyl sulfone groups(SiNP-VS).Then,the zwitterionic polymer of SBMA was grafted to achieve anti-fouling samples(SiNP-PSBMA).The results of Dynamic light scattering showed that as the reaction proceeded,the particle size of the silicon nanoparticles continued to increase.Fourier transform infrared spectroscopy showed polymerization products on the surface.Thermogravimetric analysis of two-step modified silicon nanoparticles polymer weight loss 7.5%.Combined with gel permeation chromatography data,the average molecular weight of the grafted polymer was shown to be1476 g/mol.Thermogravimetric analysis of one-step modified silicon nanoparticles polymerweight loss 8.8%.The average molecular weight of the grafted polymer was shown to be1848 g/mol.Finally,we studied the anti-fouling and emulsion ability of the silicon nanoparticles with or without the grafted zwitterionic polymers.Using Bovine serum albumin(BSA)as model proteins,anti-fouling property of the functionalized samples was evaluated.The results showed that BSA protein adsorption on SiNP-PSBMA samples was only 1.67 μg / mg NPs,which corresponds to a reduction by 93.6% and 90.6% on SiNP and SiNP-VS samples.We studied silicon nanoparticles with or without the grafted zwitterionic polymers stabilized toluene/water emulsion system.As the increase of nanoparticles concentration,the emulsion stability gradually improved.The oil yield of 2 mg/ml SiNP-PSBMA was only 15%,and it was stable for 12 hours under pH = 5-7.It could be demulsified under strong alkaline conditions.This paper presented a novel surface-initiated polymerization method that has been successfully verified on the surface of silicon wafers and silicon nanoparticles.We explored the grafted polymer nanomaterials has good anti-fouling and emulsifying properties.It shows a certain application prospect in the field of oil field chemistry.