Synthesis of novel L-lactic acid-based plasticizers and their effects on the flexibility, crystallinity, and optical transparency of poly(lactic acid)

• Published in: International journal of biological macromolecules Vol. 273; no. Pt 2; p. 132826
• Main Authors: Hou, Boyou, Wang, Yanning, Li, Bingjian, Gong, Tianyang, Wu, Jianming, Li, Jinchun
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.07.2024
• Subjects: Flexibility; Plasticizers; Poly(lactic acid); Flexibility; Plasticizers; Poly(lactic acid)
• ISSN: 0141-8130; 1879-0003; 1879-0003
• DOI: 10.1016/j.ijbiomac.2024.132826

Using bio-based plasticizers derived from biomass resources to replace traditional phthalates can avoid the biotoxicity and non-biodegradability caused by the migration of plasticizers during the application of plastics. In this study, L-lactic acid and levulinic acid were employed as the major biomass monomer to successfully fabricate L-lactic acid-based plasticizers (LBL-n, n = 1.0, 1.5, 2.0, 2.5) containing a diverse number of lactate groups. The plasticizing mechanism was explained, manifesting that L-lactic acid-based plasticizers containing a substantial number of lactate groups could effectively improve the flexibility of poly (lactic acid) (PLA), and the elongation at break was 590 %–750 %. Compared to LBL-1.5 plasticized-PLA films, the tensile strength and modulus of ketonized-LBL-1.5 (KLBL-1.5) plasticized-PLA films increased to 59 % and 163 %, indicating the ketal functionality of plasticizers enhanced the strength of PLA. Meanwhile, the increment of lactate groups and the introduction of the ketal group in the plasticizer increased the crystallization, migration, and volatilization stability of plasticized-PLA films and also kept their outstanding optical transparency. Besides, the biodegradability of KLBL-1.5 was investigated by active soil and Tenebrio molitor experiments, and its degradation products were characterized. The findings indicated that KLBL-1.5 was fully decomposed. Taken together, this paper offers new promise for developing high-efficiency and biodegradable plasticizers. [Display omitted] •A strategy for bio-based plasticizers derives from L-lactic acid was developed.•The L-lactic acid-based plasticizers have endowed PLA with remarkable flexibility and well-preserved transparency.•The KLBL-1.5 could be degradable with active soil and Tenebrio molitor.•The degree of crystallinity and crystallization rate of PLA is effectively improved by the introduction of L-lactic acid-based plasticizers.