Tailoring the Performance of Vegetable Oil-Based Waterborne Polyurethanes through Incorporation of Rigid Cyclic Rings into Soft Polymer Networks

Abstract

Vegetable oil-based polymeric materials always suffer from relatively poor performance, such as lower tensile strength and glass transition temperatures, than petroleum-based polymeric materials, which greatly limit their practical applications. In this study, octahydro-2,5-pentalenediol (OPD) was synthesized from naturally occurring citric acid and used together with castor oil as the polyol blends for the production of bio-based waterborne polyurethane (PU) dispersions (PUDs). The effects of the OPD contents on the particle size and ζ potential of the resulting polyurethane dispersion, and the thermal stability, mechanical properties, and hydrophilicity of the resulting polyurethane films were systematically investigated. Taking advantage of the rigid cyclic structures of the OPD and the flexible fatty acid chain of castor oil, waterborne polyurethane (WPU) films with tailorable mechanical performance ranging from elastomeric polymers to rigid plastics were successfully prepared and characterized. The tensile strength of the samples increases from 9.5 to 22.3 MPa with the ratio between OPD and castor oil increasing from 0:10 to 5:5, whereas their elongation at break decreases from 192 to 12%. A significant increase in the glass transition temperature, transparency, and anticorrosive properties was observed for the resulting polyurethane films with increasing the OPD content. However, the thermal stability of the PU films exhibited a slight decrease as the OPD content increased. Moreover, the water contact angle exhibited a slight increase for the polyurethane films prepared from polyol blends compared to the WPU film prepared from pure castor oil. This work provides a novel route to tailor the performance of vegetable oil-based waterborne polyurethanes through the incorporation of rigid cyclic rings into soft polymer networks.

Bio‐Based Polymers Obtained from Modified Fatty Acids and Soybean Oil with Tailorable Physical and Mechanical Performance

“…A more closed examination of the values presented in Table 6 reveals that the contact angles change from 70.2°/67.0° for 30AESO‐70MOA sample to 86.3°/81.3° for 30AESO‐70MLA without a clear tendency. There are several factors influencing the hydrophobicity/hydrophilicity of polymeric surfaces: as higher the amount of hydrophilic groups in the polymers (i.e., ─OH polar groups contained in the pendant chains of the fatty acid derivatives) higher is the hydrophilicity [ 37,38 ] while higher crosslinking density [ 32,37 ] leads to an enhancement in the material hydrophobicity. In our case, the crosslinking density appears to be the most important factor that affects the contact angle values.…”

The Prospering of Macromolecular Materials Based on Plant Oils within the Blooming Field of Polymers from Renewable Resources

“…In this context, castor oil displays one key advantage over other plant oils, namely its inherent polyol character for polyurethane synthesis. A waterborne polyurethane network was synthesized using castor oil, dimethylolbutanoic acid, and isophorone diisocyanate and its structural strength could be tailored by the incorporation of different amounts of octahydro-2,5-pentalenediol [ 64 ]. Furthermore, the same research group prepared high strength self-healing multi-shape memory waterborne polyurethane networks by introducing controlled amounts of dithiodiphenylamine to the castor oil-based polymer chains [ 65 ].…”

Improvement of polyurethane film strength by H‐bonding crosslinking with hydroxylated melamine

“…2,3 However, compared with the conventional organic solvent-based polyurethanes, WPU films have the demerits of poor mechanical properties and poor water resistance. 4 In recent years, the tensile strength of derived WPU films was enhanced by introducing rigid segments into WPU chains [5][6][7] or hybridization of WPU with other polymers, [8][9][10] employing chemical [11][12][13] or physical 14,15 cross-linking agents, adding nanofillers as well. Liang et al employed the rigid cyclic structure of octahedron-2,-5-pentalenediol into polyurethane chain to increase the hard segment contents.…”