Synthesis and Characterization of Structurally Uniform Model Oligomers of Polybenzoxazine

Abstract

The controlled synthesis of a series of polybenzoxazine model oligomers is described. A synthetic strategy is developed in which bromine is used as an ortho position blocking group allowing a stepwise synthesis of structurally uniform compounds. Debromination and subsequent hydrogenation is achieved in high yields by using activated Raney nickel catalyst in a methanol/aqueous base reaction medium. An effective hydrogenation procedure that does not require the addition of hydrogen gas is described. Polybenzoxazine oligomers as large as the model tetramer are synthesized. Applications for these strategies and procedures toward the synthesis of a variety of polybenzoxazine structures are described. Model oligomeric compounds of polybenzoxazines have been characterized by Fourier transform infrared spectroscopy (FT-IR), UV−visible spectroscopy, nuclear magnetic resonance spectroscopy (NMR), high performance liquid chromatography (HPLC), and size exclusion chromatography (SEC). Those oligomers used are the dimer, trimer, and tetramer of a monofunctional benzoxazine resin. Additional model compounds have also been synthesized. They are 2,6-bis(dimethylaminomethyl)-4-methylphenol and 2,6-bis(N-ethyl-N-methylaminomethyl)-4-methylphenol, which were used as model compounds to aid infrared band assignments.

Shape memory polybenzoxazines based on a siloxane-containing diphenol

“…In general, benzoxazines polymerize via a cationic ring‐opening polymerization . In most cases, the thermally activated polymerization of benzoxazines proceeds through an attack by the ortho ‐position of the benzene ring with respect to the oxygen of oxazine on the activated methylene between the oxygen and the nitrogen on the oxazine ring . However, TMDSBPDP‐a and TMDSBPDP‐m belong to a 8‐substituted‐3,4‐dihydro‐2 H ‐1,3‐benzoxazine, and their ortho ‐positions are blocked.…”

Study of the characterization and curing of a phenyl benzoxazine using15N solid-state nuclear magnetic resonance spectroscopy

“…17,18 Further, it has been shown that there is significant hydrogen bonding in these kinds of benzoxazine compounds. 19 However, in solid-state NMR, it is expected that hydrogen bonding may shift resonances only slightly, but, more importantly, may lead to an increased line width. Referring to Table I, there is good agreement between the observed resonances and the calculated chemical shifts as shown in Figure 11.…”

Poly(hydroxyether of bisphenol A)-block-polydimethylsiloxane alternating block copolymer and its nanostructured blends with epoxy resin

“…This reaction possesses some important features such as high selectivity and high conversion of reaction under mild conditions. This reaction has been employed to prepare a variety of benzoxazine monomers to access high performance polybenzoxazine, a modified phenolic thermoset [60][61][62][63][64][65][66][67][68][69][70][71][72]. To the best of our knowledge, nonetheless, there has no precedent report on the application of this reaction for polymerization to synthesize alternating block copolymers.…”