Waterborne polyurethane acrylate emulsion with dangling chain structure: Simultaneously showing wide damping temperature range and excellent hydrophobic performance

Abstract Waterborne polyurethane (WPU) damping material has been drawing much attention in academic field because of its low toxicity compared with polyurethane (PU) damping material. In order to expand the application range of WPU damping materials, it is necessary to further improve the hydrophobicity and damping properties of WPU. A novel dangling chain polyol‐n (DCP‐n, n expressed as average molecular weight of MPEG) was synthesized from methoxypolyethylene glycol (MPEG), isophorone diisocyanate (IPDI) and 1,1,1‐tris (hydroxymethyl) propane (TMP). Subsequently, a series of dangling chain‐n‐waterborne polyurethane acrylate (DC‐n‐WPUA, n expressed as average molecular weight of MPEG) emulsions were synthesized using DCP‐n as the chain extender. The increase of DCP‐n length will fill in free volume, hinder the entry of water molecules. Therefore, improve the hydrophobic performance. In addition, the increase of DCP‐n length will lead to more intermolecular friction, which can increase the dissipation of energy, and improves the damping performance of DC‐n‐WPUA. The test results show that the hydrophobicity of DC‐n‐WPUA film is improved, and the maximum static water contact angle can reach 110.6°. Dynamic mechanical analysis testing data showed that DC‐500‐WPUA has the best damping performance, and its effective damping temperature range was 77.9°C (−32.0 ~ 45.9°C). The carbamate group on DCP‐n will produce hydrogen bonds to restrict the movement of the chain segments, and the hydrogen bond breakage requires more energy. This ameliorates the thermal stability and mechanical properties of DC‐n‐WPUA. Thus, the initial modulus of DC‐n‐WPUA larger than the initial modulus of WPUA. Therefore, the DC‐n‐WPUA have the potential to be applied to hydrophobic damping coatings in the future.