A fast , efficient, inexpensive and green way to outdoor photopolymerization

M. PAULA MILITELLO; GABRIELA V. PORCAL; SONIA G. BERTOLOTTI; CARLOS M. PREVITALI; ERNESTO M. ARBELOA

SOLAR ENERGY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2023

0038-092X

A series of environmentally friendly photoinitiating systems operating under mild conditions of visible light (Vis - PIs) were tested for vinyl polymerization using sunlight as a free of charge radiation source . These Vi s -PI s base d on water soluble xanthene dyes showed good performances after deaerating with an inert gas, obtaining colorless polymers with gravimetric yields up to 80 –90 % after short irradiation time s (2 –15 min) . Aqueous solutions of the materials were highly viscous and viscosimetric measurements yielded molecular weights up to 106. Surprisingly, the evaluated Vi s -PI s also worked successfully under ambient air atmosphere, obtaining similar polymer yields in the same irradiation times. Photolysis experiments and transient spectroscopy were used to shed light on the mechanism of the process, allowing both triplets and radicals formation of the dyes to be identified even in the presence of air. The kinetics of photopolymerization was studied following the monomer conversion at several irradiation times by FTIR . The results were interpreted based on kinetic data collected as competitive quenching mechanisms between the co-initiator and oxygen for the excited dyes. The present report represents a breakthrough in the search for fast, efficient and inexpensive Vis -PIs with low ecological impact, which can be very useful in outdoor coating applications among others.