Dendritic carbosilane-based macrophotoinitiator: Synthesis, characterization, and photoinitiating behavior

A novel radical dendritic macrophotoinitiator, bearing alkyl pheone moieties linked to the surface of the dendrimer, was synthesized via alcoholysis of carbosilane dendrimer and the small-molecule photoinitiator 2-hydroxy-2-methyl-1-(4-tert-butyl)phenylpropane-1-one. The structure of the dendritic carbosilane-based macrophotoinitiator (MPI) was characterized using Fourier transform infrared spectroscopy, ¹H NMR, ¹³C NMR ²⁹Si NMR, elemental analysis, size exclusion chromatography/multi-angle laser light scattering, UV-visible spectroscopy, and differential photocalorimetry (DPC). UV-visible analysis indicates that the absorption band of photosensitive moieties shifts towards high wavelength by introducing the carbosilane dendrimer core. The DPC results demonstrate that the initiating efficiency of MPI is effective when using epoxy acrylate (EA) as a model resin. Furthermore, thermogravimetric analysis of cured EA resin indicates that the thermal stability can be improved markedly by the incorporation of MPI in the curing formulation.