Vanillin derived partially bio-based benzoxazine resins for hydrophobic coating and anticorrosion applications: Studies on syntheses and thermal behavior

ABSTRACT

The study mainly focuses on the synthesis, thermal, hydrophobic, and anticorrosion properties of environmentally friendly polybenzoxazines based on vanillic acid for applications such as water repellent coatings and anticorrosion. Vanillic acid (VA) was individually reacted with cyclohexylamine (cha), dodecylamine (dda), furfurylamine (ffa), and 3-trifluoromethylaniline (tfma) in order to develop structurally distinct benzoxazines. The synthesized monomers molecular structure was examined using ATR-FTIR and ¹H-NMR. Thermal characteristics were also described using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The polymerization temperature (T_p) of benzoxazines synthesized was observed in the range of 203–245°C from DSC analysis. The polymerization temperature of VA-ffa was found to be 203°C, which has lower than that of other benzoxazine monomers. Typically, the early decomposition temperatures of all the developed polybenzoxazines were over 250°C, demonstrating remarkable thermal stability. Poly(VA-tfma), one of the polybenzoxazines, exhibits highest value of char yield of 43% at 850°C. Additionally heat resistance index obtained for all the polybenzoxazines was ranged between 147 and 158°C. The value of water interface angle noticed for polybenzoxazine ranges from 142° to 145°. Among the synthesized polybenzoxazines, poly(VA-tfma) showed excellent hydrophobicity with highest value of 145°. In addition, hydrophobicity of the benzoxazine coated cured cotton fabric was analyzed for its durability at various time intervals. SEM analysis was performed for all the four VA-based polybenzoxazines. Benzoxazines were coated on mild steel (MS) plates to study the corrosion resistant property. Poly(VA-tfma) has better corrosion resistant behavior than that of poly(VA-cha), poly(VA-dda) and poly(VA-ffa) according to electrochemical impedance measurements. Further, salt spray test was conducted on polybenzoxazine coated MS for 96 h, minimum weight loss was observed for initial and after 96 h. Data from several studies indicate that benzoxazine, which is based on vanillic acid, can be utilized for applications demand hydrophobic condition with corrosion protection.

GRAPHICAL ABSTRACT

KEYWORDS:

• Anti-corrosion behavior
• curing behavior
• hydrophobic cotton fabric
• vanillic acid
• water interface angle

Acknowledgments

The authors thank the PSG Management and Secretary and Principal, PSG Institute of Technology and Applied Research, Neelambur - 641 062, Coimbatore, India for their moral and financial support.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplemental data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/25740881.2023.2283772

Additional information

Funding

None of the authors received any financial compensation for this work.

Notes on contributors

Subasri Appasamy

Subasri Appasamy is a Ph.D. scholar working under the supervision of Prof. Balaji Krishnasamy. Her field of interest is the development of photosensitive bio-benzoxazines for high performance applications.

Guruselvalakshmi M

Guruselvalakshmi M is a post graduate project student from Polymer Engineering laboratory working under the guidance of Prof. Balaji Krishnasamy. She is working in the field of benzoxazine for hydrophobic and anti-corrosion applications for her post graduate dissertation work.

Balaji Krishnasamy

Balaji Krishnasamy is working as Associate Professor and team member in Polymer Engineering laboratory, PSG Institute of Technology and Applied Research. He is working in the field of sustainable bio-based photosensitve polymers for optical and material science applications.

Sasikumar Ramachandran

Sasikumar Ramachandran is working as Assistant Professor and team member in Polymer Engineering laboratory, PSG Institute of Technology and Applied Research. His field of interest is development of bio-based benzoxazines for engineering applications.

Alagar Muthukaruppan

Alagar Muthukaruppan is research mentor of PSG Institute of Technology and Applied Research. He has got 30 years of both academic and research experience. He has published more than 400 research articles in international journals. He has guided more than 50 Ph.D. students. He has got wide variety of research interest in the field of materials sciences, chemistry and engineering applications.