Stereocomplex-Driven Morphological Transition of Coil-Rod-Coil Poly(lactic acid)-Based Cylindrical Nanoparticles

Yujie Xie; Wei Yu; Tianlai Xia; Rachel K O'Reilly; Andrew P Dove

doi:10.1021/acs.macromol.3c00653

Stereocomplex-Driven Morphological Transition of Coil-Rod-Coil Poly(lactic acid)-Based Cylindrical Nanoparticles

Macromolecules. 2023 Sep 25;56(19):7689-7697. doi: 10.1021/acs.macromol.3c00653. eCollection 2023 Oct 10.

Authors

Yujie Xie^{1

2}, Wei Yu¹, Tianlai Xia¹, Rachel K O'Reilly¹, Andrew P Dove¹

Affiliations

¹ School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
² School of Medicine, Shanghai University, Shanghai 200444, China.

Abstract

The stereocomplexation of poly(lactic acid) (PLA) enantiomers opens up an avenue for the formation of new materials with enhanced performance, specifically regarding their mechanical and thermal resistance and resistance to hydrolysis. Despite these useful features, the study of the stereocomplexation between block copolymers based on PLA in solution is limited, and a comprehensive understanding of this phenomenon is urgently needed. Herein, triblock copolymers of poly(N-hydroxyethyl acrylamide) and PL(or D)LA in which PLA was midblock (PHEAAm_y-b-PL(D)LA_x-b-PHEAAm_y) were synthesized and assembled into cylindrical micelles via crystallization-driven self-assembly . The stereocomplexation between enantiomeric micelles facilitates the morphological transition, and the transformation process was investigated in detail by varying the aging temperature, block composition, and solvent. It was found that the solubility of the copolymers played a vital role in determining the occurrence and the speed of the chain exchange between the micelles and the unimers, which thereafter has a significant impact on the shape transition. These results lead to a deeper understanding of the stereocomplex-driven morphological transition process and provide valuable guidance for further optimization of the transition under physiological conditions as a new category of stimuli-responsive systems for biomedical applications.