Synthesis and characterization of organozirconiums with type-II photoinitiator ligands as multifunctional photoinitiators for free radical photopolymerization

A polymerizable difunctional photoinitiator featuring a bio-based group and its photoinitiating properties

A polymerizable difunctional photoinitiator 2-methylene-succinic acid bis-{2-[4-(2-hydroxy-2-methylpropionyl)phenoxy]ethyl} ester (IAHHMP) based on the commercial photoinitiator 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methylpropanone (HHMP) and a biorenewable itaconic acid is synthesized by esterification. The structure is confirmed by ultraviolet spectroscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR) and thermogravimetric analysis. The photopolymerization behaviour of the photoinitiator is investigated using photo-differential scanning calorimetry and compared with that of two commercial photoinitiators, HHMP (or photoinitiator 2959) and 1-hydroxycyclohexyl phenyl ketone (or photoinitiator 184). The results show that IAHHMP has a strong UV absorption capacity at 245~300 nm and can initiate polymerization of monomers containing a double bond. The relative migration of IAHHMP is less than that of the systems containing an HHMP or 1-hydroxycyclohexyl phenyl ketone photoinitiator. Therefore, IAHHMP is expected to have potential applications in more environmentally friendly materials, such as in food and medical packaging.

Construction of Photoinitiator Functionalized Spherical Nanoparticles Enabling Favorable Photoinitiating Activity and Migration Resistance for 3D Printing

A straight-forward method was exploited to construct a multifunctional hybrid photoinitiator by supporting 2-hydroxy-2-methylpropiophenone (HMPP) onto a nano-silica surface through a chemical reaction between silica and HMPP by using (3-isocyanatopropyl)-triethoxysilane (IPTS) as a bridge, and this was noted as silica-s-HMPP. The novel hybrid-photoinitiator can not only initiate the photopolymerization but also prominently improve the dispersion of nanoparticles in the polyurethane acrylate matrix and enhance the filler-elastomer interfacial interaction, which results in excellent mechanical properties of UV-cured nanocomposites. Furthermore, the amount of extractable residual photoinitiators in the UV-cured system of silica-s-HPMM shows a significant decrease compared with the original HPMM system. Since endowing the silica nanoparticle with photo-initiated performance and fairly lower mobility, it may lead to a reduction in environmental contamination compared to traditional photoinitators. In addition, the hybrid-photoinitiator gives rise to an accurate resolution object with a complex construction and favorable surface morphology, indicating that multifunctional nanosilica particles can be applied in stereolithographic 3D printing.