Abstract
This work details the scalable and solventless synthesis of a potential fully biobased monobenzoxazine resin derived from tyrosol and furfurylamine. The structure of the monomer was studied by nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FTIR). The curing of the precursors was characterized by differential scanning calorimetry (DSC), rheological measurements, and thermogravimetric analysis (TGA). The properties of the resulting biobased polybenzoxazine were then determined by thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMA). A thermally stable resin was obtained with 5% and 10% weight-reduction-temperature (Td5 and Td10) values of 349 and 395 °C, respectively, and a char yield of 53%. Moreover, the low melting temperature, low viscosity, and excellent thermomechanical behavior make this fully biobased resin a promising candidate for coating applications.
Highlights
The interest for polybenzoxazines from both academia and industry has been rising and has intensified in the past few decades
Polybenzoxazines are usually obtained through a ring-opening polymerization process of heterocyclic six-membered 1,3-benzoxazine monomer most commonly synthesized by a Mannich-like condensation of a phenol, a primary amine, and formaldehyde [3]
The design flexibility results in numerous novel constantly increasing structures of monomers; traditional and unfunctionalized benzoxazine resins demonstrated high curing temperatures that limit their use in practical applications [4]
Summary
The interest for polybenzoxazines from both academia and industry has been rising and has intensified in the past few decades. Furfurylamine was chosen as the amine source because of its intrinsic valuable properties: (1) the furan ring participates in polymerization as additional crosslinking reaction to enhance the crosslink density and thermal resistance of the resulting resins [23]; (2) the cooperative activation effect of furan could lower the ring-opening polymerization temperature. This effect was studied by Froimowicz et al with a comparative experiment between a coumarin-containing benzoxazine U–fa (synthesized from umbelliferone and furfurylamine) and U–a (made from umbelliferone and aniline). The low melting temperature, low viscosity, and excellent thermomechanical behavior make this fully biobased monobenzoxazine a promising candidate for practical application, such as anticorrosion coatings on aluminum
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