New bifunctional cross-linkers / co-initiators for vinyl photopolymerization: Silsesquioxanes - B2 vitamin as eco-friendly hybrid photoinitiator systems

Abstract

The development of new and improved aqueous soluble cross-linkers and eco-friendly co-initiators for photopolymerization applications represents a significant challenge. In this work, novel water-soluble eco-friendly hybrid photoinitiator systems were prepared and characterized. The developed photoinitiators consist of hybrid compounds based on silsesquioxanes, functionalized with acrylate and amine groups with dual capacity as co-initiators and cross-linkers; and B2 vitamin (riboflavin) that performs as a biocompatible photosensitizer. The materials were characterized by FTIR, MALDI-TOF MS, and 29Si-NMR. The efficiency of co-initiators in photopolymerization was evaluated monitoring C[dbnd]C conversion using FTIR as a function of irradiation time. The photoinitiator systems showed different polymerization rates depending on the employed silsesquioxane. Polymerization rates of the new photoinitiator systems are higher than that of a reference system based on riboflavin/triethanolamine. Hydrogels and nanogels were successfully synthesized, demonstrating the versatility of the developed photoinitiators.