Correlation of the Abbe Number, the Refractive Index, and Glass Transition Temperature to the Degree of Polymerization of Norbornane in Polycarbonate Polymers

Abstract

The influences of the average degree of polymerization (Dp), which is derived from Mn and terminal end group, on optical and thermal properties of various refractive indexed transparent polymers were investigated. In this study, we selected the alicyclic compound, Dinorbornane dimethanol (DNDM) homo polymer, because it has been used as a representative monomer in low refractive index polymers for its unique properties. DNDM monomer has a stable amorphous phase and reacts like a polymer. Its unique reaction allows continuous investigation from monomer to polymer. For hydroxy end group and phenolic end group polymers, the refractive index (nd) decreased with increasing Dp, and both converged to same value in the high Dp region. However, the Abbe number (νd) of a hydroxy end group polymer is not dependent on Dp, and the νd of a phenolic end group polymer is greatly dependent on Dp. As for glass transition temperatures (Tg), both end group series were increased as Dp increased, and both converged to the same value.