Molecular structure and thermal stability of dye-doped polyurethanes for laser technologies.

This article investigates the thermal stability of two types of polyurethane resins (PUR)—polyurethane (PU) and polyurethane acrylate (PUA)—and the influence of doping them with two xanthene-type dyes, Rhodamine 6G (RG) and Rhodamine B (RB). Using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR), the study finds that PUA exhibits higher thermal resistance than PU due to greater crosslinking from its radical photopolymerization synthesis. The incorporation of RB dye into PU notably improves its thermal stability through covalent and hydrogen bonding that enhance cross-linking between polymer chains, whereas RG dye has a lesser effect due to its molecular structure. In contrast, PUA’s high initial crosslink density limits the impact of dye doping on its thermal properties.