Thermally curable benzoxazine monomer with a photodimerizable coumarin group

Abstract

AbstractA new monomer, 4‐methyl‐9‐p‐tolyl‐9,10‐dihydrochromeno[8,7‐e][1,3]oxazin‐2(8H)‐one, possessing both benzoxazine and coumarin rings in its structure was synthesized by the reaction of 4‐methyl‐7‐hydroxycoumarin, paraformaldehyde, and p‐toluidine in methanol at 40 °C and characterized with spectral analysis. Upon photolysis around 300 nm, this monomer underwent dimerization via the [2πs+2πs] cycloaddition reaction. Photodimerization reactions were investigated with UV and 1H NMR spectroscopy measurements. The thermal ring‐opening reaction of the benzoxazine ring was demonstrated with differential scanning calorimetry measurements. The thermal behavior of the cured product was also investigated with thermogravimetric analysis. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1670–1676, 2007