New Bifunctional Cross-Linkers/Co-Initiators For Vinyl Photopolymerization: Silsesquioxanes-B2 Vitamin As Eco-Friendly Hybrid Photoinitiator Systems

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 coinitiators 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??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.