Analysis of Double Bond Conversion of Photopolymerizable Monomers by FTIR-ATR Spectroscopy

An experiment for the calculation of the degree of double bond conversion, after a polymerization reaction, of photopolymerizable liquid monomers using FTIR-ATR spectroscopy is reported. The experiment was successfully conducted with undergraduate students in materials engineering during the Fundamentals of Polymeric Material course. Students synthesized a Bis-GMA and TEGDMA copolymer through radical chain polymerization using visible light as the energy source (photopolymerization). Through the quantitative analysis of two absorption bands in the FTIR spectra of the monomer and the polymer, the νC═C of the alkene group at 1638 cm–1 and the νC═C of the aromatic ring at 1610 cm–1, students calculated the degree of double bond conversion after the polymerization reaction. Students acquired competencies in the synthesis and qualitative and quantitative characterization of polymeric materials through FTIR spectroscopy.