Choosing the ideal photoinitiator for free radical photopolymerizations: predictions based on simulations using established data

Abstract

We present a tool for predicting the initiation efficiency of various type 1 (α-cleavage) photoinitiators for free radical photopolymerization. The amount of initiated polymer chains is crucial for the successful outcome of radical polymerizations. This is based on a subtle combination of intrinsic photoinitiator characteristics, i.e. quantum yields for dissociation, the absorption spectrum of the initiator in terms of its absorption bands and the corresponding absorption coefficients (ε), the rate constants of the primary radicals toward the monomer, and side reactions such as oxygen quenching. Equally important are the emission properties of the utilized light source (irradiation wavelengths, light intensity). We highlight that a balanced combination of all these factors is crucial for achieving optimal initiation performance.