Controlled Synthesis and Crystallization-Driven Self-Assembly of Poly(<i>ε</i>-caprolactone)-<i>b</i>-polysarcosine Block Copolymers

Poly(ε-caprolactone)-<i>b</i>-polysarcosine (PCL-<i>b</i>-PSar) block copolymers (BCPs) emerge as a promising alternative to conventional poly(<i>ε</i>-caprolactone)-<i>b</i>-poly(ethylene oxide) BCPs for biomedical applications, leveraging superior bi...

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Main Authors: Zi-Xian Li, Chen Yang, Lei Guo, Jun Ling, Jun-Ting Xu
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/30/15/3108
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author Zi-Xian Li
Chen Yang
Lei Guo
Jun Ling
Jun-Ting Xu
author_facet Zi-Xian Li
Chen Yang
Lei Guo
Jun Ling
Jun-Ting Xu
author_sort Zi-Xian Li
collection DOAJ
description Poly(ε-caprolactone)-<i>b</i>-polysarcosine (PCL-<i>b</i>-PSar) block copolymers (BCPs) emerge as a promising alternative to conventional poly(<i>ε</i>-caprolactone)-<i>b</i>-poly(ethylene oxide) BCPs for biomedical applications, leveraging superior biocompatibility and biodegradability. In this study, we synthesized two series of PCL-<i>b</i>-PSar BCPs with controlled polymerization degrees (<i>DP</i> of PCL: 45/67; <i>DP</i> of PSar: 28–99) and low polydispersity indexes (<i>Đ</i> ≤ 1.1) and systematically investigated their crystallization-driven self-assembly (CDSA) in alcohol solvents (ethanol, <i>n</i>-butanol, and <i>n</i>-hexanol). It was found that the limited solubility of PSar in alcohols resulted in competition between micellization and crystallization during self-assembly of PCL-<i>b</i>-PSar, and thus coexistence of lamellae and spherical micelles. To overcome this morphological heterogeneity, we developed a modified self-seeding method by employing a two-step crystallization strategy (i.e., <i>T</i><sub>c1</sub> = 33 °C and <i>T</i><sub>c2</sub> = 8 °C), achieving conversion of micelles into crystals and yielding uniform self-assembled structures. PCL-<i>b</i>-PSar BCPs with short PSar blocks tended to form well-defined two-dimensional lamellar crystals, while those with long PSar blocks induced formation of hierarchical structures in the PCL<sub>45</sub> series and polymer aggregation on crystal surfaces in the PCL<sub>67</sub> series. Solvent quality notably influenced the self-assembly pathways of PCL<sub>45</sub>-<i>b</i>-PSar<sub>28</sub>. Lamellar crystals were formed in ethanol and <i>n</i>-butanol, but micrometer-scale dendritic aggregates were generated in <i>n</i>-hexanol, primarily due to a significant Hansen solubility parameter mismatch. This study elucidated the CDSA mechanism of PCL-<i>b</i>-PSar in alcohols, enabling precise structural control for biomedical applications.
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spelling doaj-art-a4b60ab2d2fd4d03ae8cbb579274a5da2025-08-20T03:02:55ZengMDPI AGMolecules1420-30492025-07-013015310810.3390/molecules30153108Controlled Synthesis and Crystallization-Driven Self-Assembly of Poly(<i>ε</i>-caprolactone)-<i>b</i>-polysarcosine Block CopolymersZi-Xian Li0Chen Yang1Lei Guo2Jun Ling3Jun-Ting Xu4State Key Laboratory of Biobased Transportation Fuel Technology, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310058, ChinaState Key Laboratory of Biobased Transportation Fuel Technology, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310058, ChinaState Key Laboratory of Biobased Transportation Fuel Technology, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310058, ChinaMOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310058, ChinaState Key Laboratory of Biobased Transportation Fuel Technology, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310058, ChinaPoly(ε-caprolactone)-<i>b</i>-polysarcosine (PCL-<i>b</i>-PSar) block copolymers (BCPs) emerge as a promising alternative to conventional poly(<i>ε</i>-caprolactone)-<i>b</i>-poly(ethylene oxide) BCPs for biomedical applications, leveraging superior biocompatibility and biodegradability. In this study, we synthesized two series of PCL-<i>b</i>-PSar BCPs with controlled polymerization degrees (<i>DP</i> of PCL: 45/67; <i>DP</i> of PSar: 28–99) and low polydispersity indexes (<i>Đ</i> ≤ 1.1) and systematically investigated their crystallization-driven self-assembly (CDSA) in alcohol solvents (ethanol, <i>n</i>-butanol, and <i>n</i>-hexanol). It was found that the limited solubility of PSar in alcohols resulted in competition between micellization and crystallization during self-assembly of PCL-<i>b</i>-PSar, and thus coexistence of lamellae and spherical micelles. To overcome this morphological heterogeneity, we developed a modified self-seeding method by employing a two-step crystallization strategy (i.e., <i>T</i><sub>c1</sub> = 33 °C and <i>T</i><sub>c2</sub> = 8 °C), achieving conversion of micelles into crystals and yielding uniform self-assembled structures. PCL-<i>b</i>-PSar BCPs with short PSar blocks tended to form well-defined two-dimensional lamellar crystals, while those with long PSar blocks induced formation of hierarchical structures in the PCL<sub>45</sub> series and polymer aggregation on crystal surfaces in the PCL<sub>67</sub> series. Solvent quality notably influenced the self-assembly pathways of PCL<sub>45</sub>-<i>b</i>-PSar<sub>28</sub>. Lamellar crystals were formed in ethanol and <i>n</i>-butanol, but micrometer-scale dendritic aggregates were generated in <i>n</i>-hexanol, primarily due to a significant Hansen solubility parameter mismatch. This study elucidated the CDSA mechanism of PCL-<i>b</i>-PSar in alcohols, enabling precise structural control for biomedical applications.https://www.mdpi.com/1420-3049/30/15/3108amphiphilic block copolymerssemicrystalline block copolymerscrystallization-driven self-assemblypoly(<i>ε</i>-caprolactone)polysarcosineself-seeding
spellingShingle Zi-Xian Li
Chen Yang
Lei Guo
Jun Ling
Jun-Ting Xu
Controlled Synthesis and Crystallization-Driven Self-Assembly of Poly(<i>ε</i>-caprolactone)-<i>b</i>-polysarcosine Block Copolymers
Molecules
amphiphilic block copolymers
semicrystalline block copolymers
crystallization-driven self-assembly
poly(<i>ε</i>-caprolactone)
polysarcosine
self-seeding
title Controlled Synthesis and Crystallization-Driven Self-Assembly of Poly(<i>ε</i>-caprolactone)-<i>b</i>-polysarcosine Block Copolymers
title_full Controlled Synthesis and Crystallization-Driven Self-Assembly of Poly(<i>ε</i>-caprolactone)-<i>b</i>-polysarcosine Block Copolymers
title_fullStr Controlled Synthesis and Crystallization-Driven Self-Assembly of Poly(<i>ε</i>-caprolactone)-<i>b</i>-polysarcosine Block Copolymers
title_full_unstemmed Controlled Synthesis and Crystallization-Driven Self-Assembly of Poly(<i>ε</i>-caprolactone)-<i>b</i>-polysarcosine Block Copolymers
title_short Controlled Synthesis and Crystallization-Driven Self-Assembly of Poly(<i>ε</i>-caprolactone)-<i>b</i>-polysarcosine Block Copolymers
title_sort controlled synthesis and crystallization driven self assembly of poly i ε i caprolactone i b i polysarcosine block copolymers
topic amphiphilic block copolymers
semicrystalline block copolymers
crystallization-driven self-assembly
poly(<i>ε</i>-caprolactone)
polysarcosine
self-seeding
url https://www.mdpi.com/1420-3049/30/15/3108
work_keys_str_mv AT zixianli controlledsynthesisandcrystallizationdrivenselfassemblyofpolyieicaprolactoneibipolysarcosineblockcopolymers
AT chenyang controlledsynthesisandcrystallizationdrivenselfassemblyofpolyieicaprolactoneibipolysarcosineblockcopolymers
AT leiguo controlledsynthesisandcrystallizationdrivenselfassemblyofpolyieicaprolactoneibipolysarcosineblockcopolymers
AT junling controlledsynthesisandcrystallizationdrivenselfassemblyofpolyieicaprolactoneibipolysarcosineblockcopolymers
AT juntingxu controlledsynthesisandcrystallizationdrivenselfassemblyofpolyieicaprolactoneibipolysarcosineblockcopolymers