Visible light-induced thione-ene cycloaddition reaction for the surface modification of polymeric materials

High-tech applications often demand the surface modification of polymeric materials using chemoselective reactions that can proceed under mild conditions. In this paper, a feasible method for the surface modification of polymeric materials with low density polyethylene (LDPE) films as model substrates based on visible light-induced thione-ene cycloaddition reaction is proposed. This strategy includes three steps: 3-((6-Hydroxyhexyl)oxy)-9H-xanthene-9-thione (HXT) containing visible light-reactive thiocarbonyl groups was firstly synthesized; Then thiocarbonyl groups were introduced onto LDPE films previously surface-grafted with poly(styrene-co-maleic anhydride) brushes by the reaction between the hydroxyl groups of HXT and anhydride groups; Functional alkenes were finally fixed onto the surface of LDPE films by thione-ene cycloaddition reaction conducted under visible light at room temperature (r.t.). By FTIR, UV–vis spectroscopy, water contact angle test and XPS, we found that four typical functional alkenes, poly(ethylene glycol) methyl ethermethacrylate, 2-(perflurooctyl)ethyl methacrylate, 2, 3-dibromopropyl acrylate, and diethyl vinylphosphonate, can be successfully ligated, which confirmed the effectiveness and versatility of the present method.