A multifunctionalized macromolecular silicone-naphthalimide visible photoinitiator for free radical polymerization

A multifunctional silicone-naphthalimide visible macrophotoinitiator (SND) not only exhibits improved initiating activity and high performance in the migration stability, but also could change the surface property of the photo-cured films of urethane diacrylate prepolymer (PUA) from hydrophilic to hydrophobic with the dramatically enhanced resistance against water and ethanol. [Display omitted] •A multifunctional macrophotoinitiator SND was prepared.•It shows higher activity than CQ.•It changes the properties of PUA after its induced photo-curing. Multifunctionalization strategy in the photoinitiator design keeps in step with the requirement of the green chemistry in photopolymerization techniques. Therefore, a multifunctional macromolecular silicone-naphthalimide visible photoinitiator (SND) has been designed and prepared by a convenient thermal polymerization process of 4-(1,3-dioxo-6-(piperidin-1-yl)-1H-benzo[de]isoquinolin-2(3H)-yl)phenyl acrylate (ND-PA) and 3-bis(trimethylsilyoxy)methylsiyl-propylmethacrylate (TSMSPM). Its structure has been confirmed by 1H NMR, 13C NMR, FT-IR and GPC analysis. On one hand, SND has been evidenced as a visible photoinitiator by its successfully initiating the free radical polymerization of acrylate monomers in the presence or absence of a hydrogen donor under the irradiation of different LEDs (405nm, 455nm and 470nm). Furthermore, SND/MDEA (N-methyldiethanolamine) system shows higher photoinitiating activity than that of the commercial CQ (camphorquinone)/MDEA system. On the other hand, this multifunctionalization strategy also brings about some desired modification for cured-materials. After employing only 5wt% SND as the photoinitiator, for example, a photo-cured film of urethane diacrylate prepolymer (PUA) increases its water contact angles from 70.1° to 101.2°, implying that SND could change the surface property of the PUA cured film from hydrophilic to hydrophobic. Meanwhile, the use of SND as an initiator could significantly improve the resistance against water and ethanol. When the mass fraction of SND increases to 15%, the water and ethanol absorption ratios of the cured PUA films decrease from 4.4% to 1.0% and 8.9% to 2.8%, respectively.