The role of the ketyl radical in type II photoinitiators
Highly efficient PISWhen adding a triazine derivative to this system, the PIS turns to be highly efficient. High Mn values were found and the D̄ values dramatically increased. This behaviour is attributed to the disappearance of the ketyl radical by virtue of a photocycle. By contrast, the use of a photoactive RAFT agent leads to both high Mn and low D̄. These differences affect the Tg values, a fact which is highlighted when comparing the behavior of the RAFT agent with that of the photocyclic initiating system. The decrease of D̄ leads to higher Tg by avoiding the self-plasticisation due to short chains.
The study has been published in Polymer Chemistry, Issue 9, 2021.