Dodecenyl Succinic Anhydride-Modified PBAT Copolyesters with Enhanced Water Vapor Barrier Property

Poly(butylene adipate-co-terephthalate) (PBAT) possesses mechanical properties and processing advantages comparable to low-density polyethylene (LDPE). However, its poor water vapor barrier properties (~2 orders of magnitude lower than LDPE) limit its applications in agricultural films and packaging. In this study, dodecenyl succinic anhydride (DDSA) was employed as a functional comonomer to synthesize DDSA-modified PBAT-based copolyesters (PBADT) with varying compositions via co-esterification and melt polycondensation, and the effects of the hydrophobic alkylene side chain on surface hydrophobicity, water vapor barrier property, and other physical and mechanical properties of PBADT were systematically investigated. Results indicate that the introduction of DDSA significantly enhanced the surface hydrophobicity and water vapor barrier properties of PBAT. As the DDSA content increased from 0 to 55 mol%, the water contact angle increased from 79° to 101°, and the water vapor barrier performance improved by nearly three times. Crucially, due to the chemical bonding of hydrophobic side chains to the main chains, the PBADT films exhibited excellent stability in its water vapor barrier performance under external mechanical friction. Furthermore, DDSA introduction markedly reduced haze and increased light transmittance, demonstrating improved optical clarity. On the other hand, the existence of the long alkylene side chain of DDSA also significantly inhibited the crystallization and mechanical properties of the copolyesters.