Excitation Dependence in Photoiniferter Polymerization

We report on a fundamental feature of photo-iniferter polymerizations mediated with trithiocarbonates and xanthates. The polymerizations were found to be highly dependent on the activated electronic excitation of the iniferter. Enhanced rates of polymerization and greater control over molecular weights were observed for trithiocarbonate-and xanthate-mediated photo-iniferter polymerizations when the n-* pi* transition of the iniferter was targeted compared to the polymerizations activating the pi-* pi* transition. The disparities in rates of polymerization were attributed to the increased rate of C-S photolysis which was confirmed using model trapping studies. This study provides valuable insight into the role of electronic excitations in photoiniferter polymerization and provides guidance when selecting irradiation conditions for applications where light sensitivity is important.

Automated summary

This study reveals that the rates and molecular weight control of photo-iniferter polymerizations heavily rely on the electronic excitation of the iniferter. Enhanced polymerization rates and control were observed when targeting the n-* pi* transition of the iniferter. The increased rate of C-S photolysis was confirmed to be the reason for the disparities in polymerization rates.