Phloretic acid-based multi-benzoxazine monomers: tetramethyl guanidine-triggered synthesis and crosslinking.

A. FORCHETTI; A. MORENO; M. GALIÀ; D ESTENOZ; G. LIGADAS; M. SPONTÓN

JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY

JOHN WILEY & SONS INC

Lugar: New York; Año: 2021

0887-624X

An efficient strategy to synthesize novel biobased multi-functional benzoxazine compounds was developed using the 1,1,3,3-tetramethyl guanidine (TMG)-triggered esterification of natural phloretic acid with organic halides as a key synthetic step. First, phloretic acid was combined with either aniline or furfurylamine to prepare the corresponding carboxylic acid-functional monobenzoxazine monomer. Next, the use of TMG enabled an efficient esterification of these compounds with di-, tri- and tetrafunctional benzyl bromide compounds at room temperature to afford a series of new multi benzoxazine monomers tethered to an aromatic core. The effect of the functionality of the monomers on the curing process was analyzed, indicating that the reactivity during the thermally induced ring-opening increases with the number of furanM and oxazine rings in the monomers. The resulting thermosets revealed goodMcorrelation between the number of oxazine rings in the structure of the monomer and, the properties of the crosslinked materials. Furfurylamine-based polybenzoxazines showed improved thermal behavior compared to the aniline-based systems, due to the role of furan rings. All materials showed high T g , good thermal stability, and promising flame retardancy properties