Synthesis of artificial urushi via ring-opening reaction of benzoxazine with renewable cardanol

A branched urushiol analogue (CBCP) was first prepared by a ring-opening reaction of a benzoxazine containing a phosphazene core with renewable cardanol under solvent-free and catalyst-free conditions. The structure of CBCP was identified using nuclear magnetic resonance (1H NMR, 13C NMR, 31P NMR) a...

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Bibliographic Details
Published in:Polymer (Guilford) 2017-12, Vol.132, p.41-50
Main Authors: Ma, Hong-Xia, Xu, Zhi-Bo, Qiu, Jin-Jun, Liu, Cheng-Mei
Format: Article
Language:English
Subjects:
Adhesion
Adhesive bonding
Artificial urushi
Benzoxazine
Benzoxazines
Bonding strength
Calorimetry
Cardanol
Catalysts
Chemical bonds
Chemical synthesis
Crosslinking
Differential scanning calorimetry
Flame retardants
Fourier transforms
Green fire-retardancy
Hydrogen bonding
Infrared spectroscopy
NMR
Nuclear magnetic resonance
Phosphazene
Polymer films
Solvent-free
Substrates
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Summary:A branched urushiol analogue (CBCP) was first prepared by a ring-opening reaction of a benzoxazine containing a phosphazene core with renewable cardanol under solvent-free and catalyst-free conditions. The structure of CBCP was identified using nuclear magnetic resonance (1H NMR, 13C NMR, 31P NMR) and Fourier transform infrared spectroscopy (FTIR) technique. The preparation process for the cured CBCP film was simple, and the curing reaction of CBCP was monitored using differential scanning calorimetry (DSC) and FTIR methods. CBCP undergoes cross-linking under ambient conditions, resulting in polymeric films (artificial urushi) that are optically transparent, scratch-free and wrinkle-free. The cured film, with a high hardness and glossy surface, showed excellent thermal, excellent adhesion to the metal substrates and good chemical resistances due to strong hydrogen-bonding interactions and a compact, highly cross-linking structure containing a hard phosphazene core. Interestingly, the limited oxygen index (LOI) of cured film is 30, suggesting that the artificial urushi has flame retardant performance. [Display omitted] •A novel solvent-free ring-opening method was proposed to prepare artificial urushi.•Cardanol and 1,3-Benzoxazine reacted readily under mild conditions without any catalyst.•The artificial urishiol showed similar reactivity as natural urushiol.•Fire retardancy of cured films was dramatically improved by incorporating with phosphazene unit.
ISSN:0032-3861
1873-2291
DOI:10.1016/j.polymer.2017.10.053