Novel Bifunctional Crosslinkers / Co-initiators Systems for Vinyl Photopolymerization Based on Silsesquioxanes and Riboflavin

PALACIOS R; CHESTA C.A; GALLASTEGUI, A.; GÓMEZ, M. L.

Viña del Mar

Congreso; XIV Elafot; 2019

The development of new aqueous soluble crosslinkers and ecofriendly co-initiators with applications in photopolymerization represent a challenge in the improvement of new materials. However, the use of amines, as co-initiators of photopolymerization, difficult its application in the area of biomaterials. On the other hand, the scarce of water soluble crosslinkers also limit their use, above all in the synthesis of hydrogels and other materials synthesis in aqueous media.In this work, four different functionalized silsesquioxanes (SSOF) are synthesized as novel water soluble crosslinkers containing amines groups in their structures (Figure 1). The developed materials consist of hybrid compounds based on SSOF, functionalized with methacrylate and amine groups. These characteristics allowed using them as co-initiators in aqueous photopolymerization, besides than crosslinkers. In these bifunctional materials, the co-initiators amine groups, inevitably remain attached to the polymer chain, due to crosslinkers reactions. These avoid the undesired effects due to the presence of free amines in the final material. The hybrid nature of the silsesquioxanes came from the Si-O-Si bonds that confer interesting properties such as thermal and chemical resistance, increase in stability, and possibility of functionalization, among others.SSOF were characterized by FTIR, MALDI-TOF MS, 29Si-NMR and 1H-NMR coupled to Si. The efficacy as co-initiators in photopolymerization was evaluated following the kinetic of conversion of C=C of monomers against irradiation time, employing Riboflavin (B2 vitamin) as sensitizer (Figure 2). The bifunctional SSOF synthesized co-initiators present different polymerization rate that could be applied to control the structure and properties of the developed gels. Moreover, the polymerization rate of the photoinitiators systems Rf/SSOF show to be higher than the reference photoinitiation system Rf/TEOHA (see Figure 2).Finally the cross linkers / co-initiators developed here were employed for the synthesized of hydrogels that were evaluated measuring their swelling capacity at different pHs. As expected, hydrogels display different properties according to the SSOF employed in the synthesis.