Understanding the vibrational structure, ring-opening kinetics of oxazine ring, hydrogen bonding system and smart ortho-structure molecular design of higher performance polybenzoxazines

HAN, LU; IGUCHI, DANIELA; SEDWICK, VICTORIA M.; OHASHI, SEISHI; FROIMOWICZ, PABLO; HEYL, TYLER R.; ARZA, CARLOS R.; ISHIDA, HATSUO; ZHANG, KAN; GIL, PHWEY; SALUM, MARIA LAURA; LACKS, DANIEL J.

Nueva Orleans

Simposio; PMSE: Third International Symposium on Polybenzoxazines: Towards Diamond Jubilee of Benzoxazine Chemistry; 2018

American Chemical Society

Polybenzoxazine is a newly developed thermal set resin which shows a lot of excellent properties. A lot of research has been done focusing on a variety new molecular structures. However, much less work has been done on the fundamental study of understanding the vibrational structure, ring-opening kinetics, hydrogen bonding system of oxazine ring, which will be a great guidance on future molecular design and higher performance materials, resins, composites. Oxazine ring-related vibrational modes of benzoxazine monomers is studied by using fully aromatically substituted, deuterated, 15N isotope exchanged and oxazine-ring-substituted compounds and theoretical calculations. This study shows that the band in question is a mixture of the O-C2 stretching of the oxazine ring and the phenolic ring vibrational modes. Intrinsic self-initiating thermal ring-opening polymerization of 1,3-benzoxazines is demonstrated using single-crystal resins without the influence of impurities. The study reveals that polybenzoxazines can be obtained by both the traditional thermally accelerated (or activated) polymerization, where impurities or purposefully added initiators are involved in the reaction; or, by the classic thermal polymerization, where only heat is enough to initiate the reaction. The effects of intramolecular and intermolecular hydrogen-bonding systems on the polymerization of amide-containing benzoxazines is also studied. Based on all the fundamental studies, smart ortho-structure molecular design is proposed. The polybenzoxazine shows many excellent properties including lower polymerization temperature, high thermal stability, low dielectric constant, and latent catalysis.