Bio-based monomers have become considerably popular in polymer industries. Here we present a new family of bio-based polyamides with properties comparable to nylon-6,6 that can be readily differentiated to express a range of desirable attributes such as enhanced hydrophobicity or flame retardancy.

The good properties of nylon 6,6, high strength, stiffness, and thermal stability, make it a high performance thermoplastic widely applicable in automotive, electronics, and food packaging industries, amongst others. However, despite its widespread utility, nylon 6,6 is moisture-sensitive, resulting in undesirable softening, dimensional instability, and susceptibility to corrosive environments. Therefore, there are unmet needs for hydrophobic variants of nylon 6,6.

Due to significant interest of bio-based resources, here, we present a value opportunity for “bioadvantaged” polymers that can be derived from biologically-produced intermediates, such as muconic acid. In this study, we demonstrate the introduction of unsaturated trans-3 hexenedioic acid (t3-HDA) as a platform that provides unique advantages in differentiating nylon 6,6 through copolymerization. Different composition range of BAN salts were prepared, followed by melt polycondensation reaction in tube furnace.

The thermal and mechanical properties of “bioadvantaged nylon” (BAN) were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide angle X-ray scattering (WAXS), and dynamic mechanical analysis (DMA).

Findings indicate that HDA decreases the melting point, ultimately suppressing it completely at greater than 50% substitution, while negligibly impacting the thermal stability.

Furthermore, we illustrate the functionalization of t3-HDA and implication of the monomer in the structure of nylon 6,6. The resultant BAN shows enhancement in hydrophobic properties. In addition, the properties of the hydrophobic bioadvantaged nylon (HBAN) fully studied using the broad range of techniques for thermal, mechanical, and structure characterization. Our results illustrate the utility of unsaturation sites in polymer property customization by demonstrating a reduction in hygroscopicity of up to 93% without deleterious effects on the thermal and mechanical properties. Moreover, the chemical stability of HBAN against aggressive corrosive agents such as zinc chloride is dramatically improved.