(628d) Analysis of Reaction Kinetics and Oxygen Inhibition Processes in the Polymerization of Patterned Hydrogel Microstructures Using FTIR Imaging

Fourier transform irfrared (FTIR) imaging has been utilized for a wide variety of applications such as tissue analyses, drug diffusion, polymer dissolution, etc. Here, we have reported in situ studies to spatially resolve kinetics of micropatterning reaction using FTIR imaging. The differences in reaction rates across the patterned region were successfully resolved and characterized. Oxygen inhibition often plays a critical role in polymerization process occurring in thin films and micro/nano- structures where oxygen is able to rapidly transport through the short diffusion paths. There have been limited or no methods applied to analyze the oxygen inhibition at microscale. In particular, the effect of oxygen inhibition during the photopolymerization reaction of a patterned region was observed via FTIR imaging system by varying initiator concentration, UV intensities, monomer functionality and additives. It has been observed that the oxygen inhibition was reduced by using high UV intensity and higher initiator concentration. Also for methacrylate and acrylate monomer systems, reduction in oxygen inhibition was observed for the monomers with higher molecular weight of poly(ethylene glycol) units in the backbone chain. The oxygen inhibition was also reduced by using different types of additives n the reaction systems, such as amines and borane complexes.