Development of Novel Cardanol-Derived Reactive Dispersing Agents for Bio-Based Anionic-Nonionic Waterborne...

Area of Science:

• Materials Science
• Polymer Chemistry
• Sustainable Chemistry

Background:

• Development of high-performance waterborne polyurethane dispersions (WPUDs) is crucial for environmentally friendly coatings.
• Existing chain extenders often rely on non-renewable resources and may lack advanced functionalities.
• Need for sustainable, functional additives to enhance WPUD properties, particularly for UV-curable applications.

Purpose of the Study:

• To synthesize and characterize a novel bio-based, photocurable, anionic-nonionic dual-functional chain extender, sulfonated cardanol-based polyethylene glycol (SCP).
• To investigate the preparation of WPUDs using SCP and evaluate the impact of SCP on dispersion properties and film formation.
• To assess the performance enhancement of WPUD coatings after UV irradiation, focusing on mechanical strength, water resistance, and thermal stability.

Main Methods:

• SCP was synthesized from renewable cardanol and polyethylene glycol.
• WPUDs were prepared via an acetone process using poly(butylene adipate) (PBA), isophorone diisocyanate (IPDI), ethylene diamine (EDA), and SCP.
• Effects of polyethylene glycol molecular weight and SCP dosage were studied; particle size, stability, film properties, tensile strength, water absorption rate (WAR), water vapor transmission rate (WVTR), and thermal stability were measured.

Main Results:

• Optimal dispersion stability and film-forming properties were achieved with a polyethylene glycol molecular weight of 1500 and a PBA to SCP molar ratio of 4:1, resulting in a particle size of 0.326 ± 0.010 μm and six-month storage stability.
• UV irradiation significantly increased tensile strength from 11.4 MPa to 16.8 MPa due to semi-interpenetrating network formation.
• UV cross-linking markedly improved water resistance (WAR reduced from 18.68% to 4.21%; WVTR reduced from 6.59 × 10⁻⁵ to 2.26 × 10⁻⁵ g·m⁻¹·Pa⁻¹·d⁻¹) and thermal stability.

Conclusions:

• SCP is a highly effective, bio-based, photocurable dual-functional chain extender for WPUDs.
• SCP enables the development of high-performance WPU coatings with enhanced mechanical properties, superior water resistance, and improved thermal stability through UV cross-linking.
• This study presents a sustainable pathway for advanced functional coatings derived from renewable resources.