Synthesis and evaluation of new radical photoinitiators bearing trialkoxysilyl groups for surface immobilization

Photoinitiators, which can be readily immobilized on surfaces, e.g. on the surface of nanoparticles, have gained considerable attention of both scientists and engineers. The main reason for this interest is that immobilized initiators lead to a covalent linkage between the surface and the resulting polymer chain. Thus, immobilized photoinitiators are expected not to migrate out of the polymer network, which reduces potential health risks. This paper describes the synthesis of a range of short- and long-wavelength absorbing photoinitiators bearing trialkoxysilyl units. The synthesis starts from commercially available products, Irgacure 2959 or Irgacure TPO-L, and takes 1–4 steps. While some of the reported initiators were previously sparsely described in patents, but lack a systematic study, others are reported for the first time. Both free and immobilized initiators were characterized and tested with regard to their efficiency in acrylic and thiol-ene systems. The findings confirm the good applicability of the nanoparticle-immobilized photoinitiators in the preparation of nanocomposite materials.