The influence of photo initiators on refractive index and glass transition temperature of optically and rheologically adjusted acrylate based polymers

A material system with individually adjustable rheological and optical properties is presented. The optical transmission and refractive indices of the material were modified, and viscosities were investigated at different temperatures and shear rates. Furthermore, two UV‐sensitive photo initiators were analysed with respect to their effect on the polymerization behaviour of the material system. The refractive indices of the material system were adjusted between 1.513 < n_D,20 < 1.595, with optical transmittances of up to 90% within the UV‐VIS region (400 nm < λ < 800 nm). Two photo initiators, Diphenyl(2,4,6‐trimethylbenzoyl)phosphine oxide and Bis(2,4,6‐trimethylbenzoyl)phosphine oxide, were investigated, and viscosity was modified at 20 °C between 0.002 Pa · s < η < 87 Pa · s. The glass transition temperature of the polymerized samples was determined to be between 40 °C and 50 °C. Results showed that Diphenyl(2,4,6‐trimethylbenzoyl)phosphine oxide exhibited more effective polymerization compared to Bis(2,4,6‐trimethylbenzoyl)phosphine oxide. The addition of phenanthrene to the mixtures increased the refractive index with ?n = 0.02, whilst the viscosity was decreased by a small amount. Copyright © 2016 John Wiley & Sons, Ltd.