Preparation and properties of silane-modified cardanol–benzoxazine for hydrophobic coating

Abstract

Cardanol is a kind of green industrial raw material, refined from cashew nut shell oil by advanced technology, which has shown potential for anticorrosion coating application. A new cardanol-based benzoxazine monomer (CB) was synthesized by Mannich condensation of a cardanol, paraformaldehyde, and cardanol aldehyde amine (Carala), which was prepared based on cardanol, paraformaldehyde, and triethylenetetramine, and finally, the cardanol-based benzoxazines containing amino group were modified by silane (CBSi). Cardanol, Carala, and CB were characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. Furthermore, the cured films have been evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The result of DSC of CB and CBSi showed that curing behavior of CBSi was similar to that of CB; however, the enthalpy of polymerization reaction corresponding to CB and CBSi is 84.7 J g−1 and 91.3 J g−1, respectively, and exothermic enthalpy of CBSi is slightly higher than that of CB. TGA results illuminated that the thermal stability and char yield of cardanol-based polybenzoxazine could be enhanced due to increment of silane, and residual char yield at 700°C of CBSi30 is 13%. Especially, incorporation of silane could improve the water contact angle, which can increase from 78.7° to 98.9° when the ratio of γ-(2,3-epoxypropoxy) propytrimethoxysilane to CB increases from 0% to 30%.

Development of Nanofree, Silane-Free, and Fluorine-Free Cardanol-Based Multifunctional, Superhydrophobic Wood Coating

“…15 Zhang et al developed cardanol-based benzoxazine with silane modification and achieved 98.9°static contact angle. 17 Superhydrophobicity is the next level of hydrophobic coatings and requires additional nanomicro scale roughness as well as strongly hydrophobic chemical functionalities. 18 In the last decades, functionalized nanoparticles have drawn huge attention by academies and industries as a multifunctional material integrated with the polymer system.…”

“…Zhang et al. developed cardanol-based benzoxazine with silane modification and achieved 98.9° static contact angle …”

Construction novel polybenzoxazine coatings exhibiting corrosion protection of mild steel at different concentrations in a seawater solution

“…Using it in carbon materials is due to its high char yield following carbonization [ 29 ]. Currently, two approaches suggested to soften polybenzoxazine coatings are introducing nanofiller (e.g., carbon nanotube) [ 30 ] or plastic polymers to alloy polybenzoxazine [ 31 ], the other is introducing flexible silane or alkyl long-chain segments to the branched-chain or backbone of benzoxazine monomers [ 32 , 33 ]. This study focuses on introducing an effective Schiff base moiety into a benzoxazine precursor through molecular design.…”

Tetramethyl guanidine‐assisted synthesis and thermal crosslinking of multifunctional benzoxazine monomers based on natural phloretic acid

“…5 Due to the environmental and economic concerns, in the last decades both academic and industrial sectors have engaged in exploring the design of biobased polybenzoxazines, since trials on developing other biobased polymers succeeded and are already available in market. 6 Most recent efforts have focused on producing phenols from renewable biomass, that is, cardanol, [7][8][9][10][11] arbutin, 12 sesamol, 13 guaiacol, 14 coumarin, 15 eugenol, 16,17 among others, [18][19][20][21][22][23][24] as well as biobased amines such as furfurylamine and amino acids into mono-and bisoxazine precursors. [25][26][27][28][29][30][31][32] However, the limitation of not having natural biobased multi-phenols and/or multiamines has restricted the development of benzoxazine monomers with oxazine ring functionality greater than two, and only few monomers were developed.…”