Mild condition lignin modification enabled high-performance anticorrosive polyurethane coating.

Area of Science:

• Materials Science
• Polymer Chemistry
• Corrosion Science

Background:

• Lignin's diverse hydroxyl groups hinder the development of effective lignin-based polyurethane coatings for corrosion resistance.
• Existing methods face challenges in controlling lignin reactivity and preventing molecular weight increases during modification.

Purpose of the Study:

• To develop a facile and effective method for preparing high-performance lignin-based polyols for anticorrosive polyurethane coatings.
• To investigate the impact of hydroxypropyl modification on lignin's reactivity and the resulting coating properties.

Main Methods:

• Mild hydroxypropyl modification of lignin using propylene oxide and an alkali solution under ambient conditions.
• Synthesis of dense, defect-free lignin-based polyurethane coatings (25 ± 5 μm thickness).
• Evaluation of barrier properties (impedance modulus |Z| > 10^9 Ω cm²) and long-term anticorrosive performance (>120 days).

Main Results:

• Successfully converted phenolic hydroxyl groups to aliphatic ones, increasing reactivity.
• Achieved high crosslinking density in the lignin polyurethane coatings.
• Demonstrated outstanding barrier properties and superior long-term corrosion resistance.

Conclusions:

• Mild hydroxypropyl modification is an effective strategy for creating highly reactive lignin-based polyols.
• This approach is crucial for developing advanced bio-based polyurethane anticorrosive coatings.
• The resulting coatings offer excellent protection against corrosion due to their dense structure and barrier properties.