Chemical Research in Chinese Universities ›› 2023, Vol. 39 ›› Issue (5): 750-756.doi: 10.1007/s40242-023-3160-8

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High Performance Polylactide Toughened by Supertough Polyester Thermoplastic Elastomers: Properties and Mechanism

FENG Songyang, ZHAO Wuchao, HE Jianghua, ZHANG Yuetao   

  1. State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
  • Received:2023-07-15 Online:2023-10-01 Published:2023-09-26
  • Contact: ZHAO Wuchao, HE Jianghua E-mail:wczhao2022@jlu.edu.cn;hjh2015@jlu.edu.cn
  • Supported by:
    This work was supported by the National Key Research and Development Program of China (No.2022YFB3704900), the National Natural Science Foundation of China (Nos. 22225104, 22071077, 21871107, 21975102) and the China Postdoctoral Science Foundation (Nos. 2022TQ0115, 2022M711297).

Abstract: It is a challenge to develop a biodegradable toughener to toughen polylactic acid (PLA) with both high strength and high toughness, since toughness and strength are mutually exclusive. Here, a series of supertough polyester thermoplastic elastomers (TPEs), poly(L/D-lactide)-b-poly(ε-caprolactone-co-δ-valerolactone)-b-poly (L/D-lactide)s (PLLA-PCVL-PLLA, L-TPEs or PDLA-PCVL-PDLA, D-TPEs), were prepared and blended with a PLLA matrix to toughen PLLA. The mechanical properties of PLLA could be regulated in a wide range by changing blending ratios and TPE structures. For PLLA blends toughened by L-TPEs, the highest elongation at break is up to 425% with the tensile strength of 33.1 MPa and the toughness of 104 MJ/m3. By the stereocomplex crystallization of PLA (sc-PLA), the tensile strength of the PLLA/D-TPE blends further increased to 41.8 MPa with a similar elongation at break (418%) and the toughness up to 128 MJ/m3. The detailed characterizations revealed a toughening mechanism:(I) the added soft segments increased the ductility of the PLLA matrix, (II) the PLLA segments of L-TPEs increased the compatibility between TPEs and PLLA matrix, and (III) the formation of sc-PLA between the PDLA segments in D-TPE and PLLA provided higher tensile strength by enhancing the strength of the crystal skeleton. The toughened PLA using TPEs can maintain original non-toxic and degradable properties, and be applied potentially in surgical sutures, and 3D-printed scaffolds.

Key words: Super-tough polyester elastomer, Poly-L-lactic acid toughening, Biodegradable polymer, Stereocomplex crystallization