Enhanced Water Resistance Performance of Castor Oil—Based Waterborne Polyurethane Modified by Methoxysilane Coupling Agents via Thiol-Ene Photo Click Reaction

Abstract

Nowadays, waterborne polyurethanes (WPUs) prepared from renewable resources has attracted more and more attention. However, due to its structure, the prepared films easily swells in water and greatly affects the application range of WPUs. Therefore, solving the problem of water resistance is a way to improve the application range of WPUs. In this study, a series of WPU dispersions were prepared using castor oil as the bio-based polyol. Besides, the thiol-ene photo click reaction was carried out on the WPU films for silane modification. The effect of the silane modification on the chemical structures of the WPU dispersions and the properties of the WPU films was investigated and discussed. The results revealed that the WPU dispersions had a smaller particle size and potential, showing excellent stability. In addition, the modified WPU films showed highly water resistance which 72 h water absorption could be reduced to 1.94% and the contact angle was up to 99.34 . Moreover, the modified WPU films also exhibited excellent solvent resistance (in acid and salt solution) and thermal stability. This study can provide a new way to improve the water-resistance, hydrophobicity, and thermal stability of bio-based waterborne polyurethane for potential application in painting, adhesives and inks.

Synthesis and Application of Silane-Modified Castor Oil-Based Waterborne Polyurethane as a Fluorine-Free and Durable Water Repellent

“…The melting enthalpy of the finished fabric is 67 J/g, an increase of 30 J/g compared to the raw fabric. The increase in the crystallinity of the polyamide fabric after finishing is likely due to the eutectic interaction occurring between the polyurethane segments in SiCO-WPU and the polyamide chains of fabric at high temperatures. , Such interactions have augmented the adhesion and durability of SiCO-WPU on the polyamide fabric surface …”

“…The increase in the crystallinity of the polyamide fabric after finishing is likely due to the eutectic interaction occurring between the polyurethane segments in SiCO-WPU and the polyamide chains of fabric at high temperatures. 2,42 Such interactions have augmented the adhesion and durability of SiCO-WPU on the polyamide fabric surface. 25 Despite widespread reports on water-repellent agents, most treatments typically lead to a significant decrease in the tactile properties of fabrics such as hardness and softness.…”

“…41 He et al employed CO as a biobased polyol to prepare a series of WPU dispersions and carried out the thiol− ene photo click reaction for silane modification on WPU films. 42 The modified WPU films exhibited high water resistance, with a water absorption rate of 1.94% and a contact angle of up to 99.3°. Parvathy and Sahoo successfully modified the epoxidized CO to develop a silanized CO and methyl ricinoleate bioresins through a transesterification and silanization process.…”

“…As the CO content increased from 0 to 8.97%, the hydrophobicity of the film was significantly improved with a maximum contact angle of 89.5° and a water absorption rate of 7.60% . He et al employed CO as a biobased polyol to prepare a series of WPU dispersions and carried out the thiol–ene photo click reaction for silane modification on WPU films . The modified WPU films exhibited high water resistance, with a water absorption rate of 1.94% and a contact angle of up to 99.3°.…”

Preparation and Properties of Hydrophobic Polyurethane Based on Silane Modification

“…Therefore, the addition of a certain amount of A172 can enhance the surface hydrophobicity of coatings to a certain extent. In the last decade, there are few studies on enhancing the hydrophobicity of polyurethane with silicon modification, and some data on hydrophobicity studies of polyurethane in the last decade at home and abroad were briefly listed in Figure 9 [ 12 , 18 , 20 , 25 , 30 , 31 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 ].…”