Synthesis and Characterization of Polyurethane Networks Derived from Soybean-Oil-Based Cyclic Carbonates and Bioderivable Diamines

Abstract

Nonisocyanate polyurethane (NIPU) thermoset networks were produced from a novel soybean-oil-derived poly­(vinyl ether) (i.e., poly­[(2-vinyoxy)­ethyl soyate]) possessing cyclic carbonate functional groups in the fatty acid ester side chains of the polymer. Three different linear aliphatic diamines, namely, 1,6-hexamethylenediamine, 1,9-nonanediamine, and 1,13-tridecanediamine, were used to cross-link the cyclic carbonate-functional poly­[(2-vinyoxy)­ethyl soyate] [C-poly­(2-VOES)]. All three of these diamines can be readily obtained from renewable resources. For comparison purposes, analogous NIPU networks were produced using cyclic carbonate-functional soybean oil (CSBO) in place of the C-poly­(2-VOES). The chemical, thermal, viscoelastic, and mechanical properties of the six NIPU networks were characterized. With regard to the chemical nature of the soy-based, carbonate-functional component, it was found that the polymeric nature of C-poly­(2-VOES) resulted in very different NIPU properties compared to analogous cross-linked networks based on CSBO. While the CSBO-based NIPU networks exhibited lower Young’s moduli and ductile behavior, the networks based on C-poly­(2-VOES) showed significantly higher Young’s moduli and brittle behavior. In addition, measurements using dynamic mechanical analysis showed significantly high cross-link densities for the networks based on C-poly­(2-VOES), which can be attributed to a much higher number of methine carbon atoms per molecule in C-poly­(2-VOES) as compared to CSBO. In addition to the cross-links resulting from the reaction of the amine groups of the cross-linker with the cyclic carbonate groups of the soy-based carbonate-functional materials, these methine carbon atoms serve as cross-links in the NIPU networks. The higher cross-link densities achieved with the use of C-poly­(2-VOES) explain the thermal and mechanical property differences observed between networks based on the two different soy-based carbonate-functional materials. With regard to the influence of the diamines on NIPU network properties, as expected, increasing the chain length of the diamine cross-linker decreased cross-link density, which, in general, resulted in decreases in Young’s moduli and glass transition temperature.

From the Synthesis of Biobased Cyclic Carbonate to Polyhydroxyurethanes: A Promising Route towards Renewable Non‐Isocyanate Polyurethanes

“…Functionality of the carbonated vegetable oils strongly affects the stiffness and T g values of PHU materials synthesized from CSBO, if cured with aliphatic amines, leading to soft and flexible materials with T g <20 °C. Even with short triamines, such as tris(2‐aminoethyl)amine (TDA), CSBO‐based materials remain soft ( T g =6 °C, E =3.7 MPa) . The use of carbonated linseed oil (CLSO) as unique monomers or mixed with CSBO increases the stiffness of materials, with T g up to 60 °C and a Young's modulus above 1000 MPa .…”

“…Even with short triamines, such as tris(2-aminoethyl)amine (TDA), CSBO-based materials remain soft (T g = 6 8C, E = 3.7 MPa). [89] The use of carbonated linseed oil (CLSO) as unique monomers or mixed with CSBO increasest he stiffness of materials, with T g up to 60 8Ca nd a Young's modulus above 1000 MPa. [86] Webster et al developed biobased and highly functional CCs from epoxidized sucrose soyate (a combinationo fs ucrose and vegetable oil fatty acids) under supercriticalc onditions.…”

Utilization of cyclocarbonated lignin as a bio-based cross-linker for the preparation of poly(hydroxy urethane)s

“…Bio-based bis-cyclic carbonates were obtained by epoxidation and following carbonation of terminal and internal double bonds of a variety of plant seed oils, such as sunower, linseed and soybean oil. 8,9 However, the exible nature of vegetable oils oen results in poor mechanical and thermal properties of the resulting PHU, requiring the use of more rigid scaffolds to match the performance of traditional polyurethane resins. In this respect, the utilization of stiffer monomers like terpenes were investigated and a bis-cyclic carbonate was successfully prepared from epoxidized limonene and employed for the preparation of PHU resins 10 with improved properties.…”

Perspective: green polyurethane synthesis for coating applications

“…Vegetable oils represent ideal substrates as their unsaturations can be epoxidized and carbonated. After these modifications, thermosets were produced directly from triglycerides and thermoplastics from fatty acid derivatives . The same strategy was adapted for terpenes for the preparation of limonene‐based bis‐cyclic carbonates and derived thermoplastics …”