| Photoinitiators are the compounds which can absorb the UV light and/or visible light and produce active species used for converting the monomer and/or prepolymer into polymer. In recent years, it has been focused on preparing some photoinitiators which have desirable properties such as higher activity or greater curing speed coupled with lower migration rates and/or water solubility. Considering to the excellent properties of silicone, it has been applied to the area of photopolymerization, especially in the area of photoinitiator. This paper reported a polysiloxane-based photoinitiator which can not only solve the yellowing, toxicity and other issues, but also allow the surface to be fully cured.The details and conclusions are described as follows:1,A polysiloxane-based photoinitiator was prepared with Michael addition reaction. Its structure was confirmed by 1H NMR and real-time infrared spectroscopy. The UV absorption spectra and the kinetics of photopolymerization showed it was an effective photoinitiator.2,The difference in the surface tension between silicone and non-silicone moieties of the polymer backbone is the main driving force for the enrichment of silicone groups at the material surface, which will result in the gradually decrease of silicone concentration from the outermost surface to the inner bulk. In the present paper, a new method to prepare the gradient material by using this property of polysiloxane-based photoinitiator was explored. The gradient polymerization was investigated by XPS, mapping-EDS, GPC and UV spectrum.3,Considering to the unique properties of silicone, poly siloxane-containing photoinitiator will migrate to the surface after standing some time, which will lead to high photoinitiator concentration on the surface. Therefore, there are redundant photoinitiators on the surface of polymer. The excess photoinitiators still have activity, they can continue to polymerize under UV irradiation. In this work, a novel room-temperature UV-assisted process via free radical polymerization initiated by the above redundant polysiloxane-containing photoinitiator has been reported for attachment of thin polymeric layers onto the other polymeric surface. For photografting procedure, the measurements of SEM, EDS and contact angle indicated the feasibility of this method. |
