High-performance water-based UV-curable soft systems with variable chain architecture for advanced coating applications

Silicone-based materials and systems have played a key role over a century. In this work, surface and bulk characteristics of siloxane-modified water-based urethane-acrylate dispersions containing hydrophilic and hydrophobic soft segments with variable molecular weight and also a hard segment were tailored. Feeding and synthesis conditions were changed systematically to control over compatibility and softness of samples. FTIR, elemental analyses by proton and silicon nuclear magnetic resonances and dynamic light scattering were used to describe microstructure of dispersions. The effects of PDMS content and molecular weight on the composition property relationship was discussed in terms of contact angle, water absorption and mechanical properties. Addition of PDMS having high-molecular-weight as hydrophobic soft segment in polyurethane-acrylate system improved water repellency, as featured by a rise in contact angle from 72 to 102 degrees. The effect of photoinitiators type on C = C conversion rate was monitored by changing the polarity and hydroxyl group by real-time FTIR (RT-IR) spectroscopy. Physical and mechanical properties of UV-cured coatings like hardness, adhesion and flexibility were also examined. Siloxane-modified crosslinked films exhibited excellent flexibility and hydrophobic surface depending on soft segment type and content. Siloxane-modified water-based urethane-acrylate UV-cured film revealed high thermal-stability with negligible weight loss unless well-above 200 degrees C.