Simultaneous time-resolved measurement of the reaction rates and the refractive index of photopolymerization processes

We explore the use of imaging surface plasmon resonance (iSPR) to simultaneously measure the refractive index and reaction rates of the commercially available Ormocore photosensitive resist during photopolymerization. To this end, we adapted a commercially available iSPR device. We demonstrate good accuracy in the measurement of the refractive index determined independently of the thickness of the polymerized film. Furthermore, we demonstrate that the refractive index is proportional to the degree of cure (double bond conversion) of the resist. This allows the determination of the reaction rates of the polymerization processes, which show reasonable agreement with photodifferential scanning calorimetry measurements.