One-Pot Synthesis of Marine-Biodegradable Poly(Ethylene Succinate)-Based Ester Amide Copolymers Containing Amino Acid

High Resolution Image Download MS PowerPoint Slide We developed a cost-effective one-pot method for synthesizing marine-biodegradable poly(ethylene succinate) (PES)-based ester amide copolymers containing natural amino acids, while suppressing the formation of N -succinimide rings. In conventional batch copolymerization, N -succinimide rings are easily formed when succinic acid (SA) and primary amines react at high temperatures, inhibiting the extension of the polymer chains. In this study, we synthesized prepolymers, which do not easily undergo imide cyclization, using an amino acid, ethylene glycol (EG), and dodecanedioic acid, followed by the one-pot addition of SA and EG. L -Valine and L - and β-alanine were used as amino acids with different substituents, and the numbers of N -succinimide rings in the resulting copolymers were calculated using 1 H nuclear magnetic resonance spectroscopy. This strategy successfully suppressed the formation of N -succinimide rings in several of the copolymers. Conversely, the use of amino acids with smaller substituents favored the formation of N -succinimide rings compared to the use of those with larger substituents. In biochemical oxygen demand biodegradability assessments utilizing seawater, the obtained polymers exhibited marine biodegradability comparable to that of cellulose, even though they contained amide bonds, indicating that the introduction of amide moieties did not affect the marine biodegradability of the original PES-based copolyester. Poly(ester amide)s can be biodegradable materials with high-performance properties. The results obtained may contribute to developing industrially advantageous SA-based materials copolymerized with other monomers bearing amino groups.