writer：Wenyuan Xie,* Chenguang Jiang, Xing Yu, Xinyu Shi, Shubin Wang, Yu Sun, Ming Yin, Defeng Wu
keywords：poly(lactide), amphiphilic block copolymer, self-assembly, stereocomplex crystallization, vesicles
source：期刊
specific source：ACS Applied Polymer Materials
Issue time：2021年

ACS Applied Polymer Materials, 2021, 3(12), 6078-6089. 

Biodegradable polymersomes that can potentially be employed in drug delivery systems were fabricated by blending poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-PEG-PLLA) and poly(D-lactide)-b-poly(ethylene glycol)-b-poly(Dlactide) (PDLA-PEG-PDLA) block copolymers in a weight ratio of 1:1 in an aqueous solution. A series of amphiphilic PLLA-PEGPLLA and PDLA-PEG-PDLA triblock copolymers were synthesized with different hydrophobic chain lengths through ring-opening polymerization. The self-assembly of pure PLLA-PEG-PLLA and an equimolar mixture of enantiomers of PLLA-PEG-PLLA and PDLA-PEG-PDLA was investigated by transmission electron microscopy, X-ray diffraction, and dynamic light scattering. Various nanostructures including spherical micelles, worm-like micelles, and vesicles were obtained by controlling the hydrophobic chain length and the incubation temperature. In the pure PLLA-PEG-PLLA systems, the hydrophobic-hydrophilic balance dominated the self-assembled morphologies. In equimolar enantiomer mixtures, self-assembled morphologies were greatly affected by the formation of the PLLA-PDLA stereocomplex (SC). There was an inverse correlation between the SC crystallinity and the curvature of the self-assembled structures - the higher the SC content, the smaller the curvature. This rule was not applicable when the SC content was too high (50%), which produced spherical micelles as the main nanostructures. Since the SC-induced self-assembly could be controlled by changing the incubation temperature, the polymersomes can potentially be used in many applications, such as nanoreactors and nanovehicles.

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https://pubs.acs.org/doi/abs/10.1021/acsapm.1c00879