Abstract
Stereocomplex (SC) crystallization has been an effective way to improve the physical performances of stereoregular polymers. However, the competition between homo and SC crystallizations can lead to more complicated crystallization kinetics and polymorphic crystalline structure in stereocomplexable polymers, which influences the physical properties of obtained materials. Herein, we select the medium-molecular-weight (MMW) poly(L-lactic acid)/poly(D-lactic acid) (PLLA/PDLA) asymmetric blends with different PDLA fractions (fD=0.01–0.5) as the model system and investigate the effects of fD and crystallization temperature (Tc) on the crystallization kinetics and polymorphic crystalline structure. We observe the fractionated (i.e., multistep) crystallization kinetics and the formation of peculiar β-form homocrystals (HCs) in the asymmetric blends under quiescent conditions, which are strongly influenced by both fD and Tc. Precisely, crystallization of β-form HCs is favorable in the MMW PLLA/PDLA blends with high fD (≥0.2) at a low Tc (80–100 °C). It is proposed that the formation of metastable β-form HCs is attributed to the conformational matching between β-form HCs and SCs, and the stronger constrain effects of precedingly-formed SCs in the early stage of crystallization. Such effects can also cause the multistep crystallization kinetics of MMW PLLA/PDLA asymmetric blends in the heating process.
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
References
Auras, R.; Harte, B.; Selke, S. An overview of polylactides as packaging materials. Macromol. Biosci. 2004, 4, 835–64.
Lassalle, V.; Ferreira, M. L. PLA nano- and microparticles for drug delivery: an overview of the methods of preparation. Macromol. Biosci. 2007, 7, 767–783.
Zhu, Y.; Romain, C.; Williams, C. K. Sustainable polymers from renewable resources. Nature 2016, 540, 354–362.
Zheng, Y.; Zhang, C.; Bao, Y.; Shan, G.; Pan, P. Temperature-dependent crystallization and phase transition of poly(L-lactic acid)/CO2 complex crystals. Chinese J. Polym. Sci. 2021, 39, 484–492.
Rocca-Smith, J. R.; Pasquarelli, R.; Lagorce-Tachon, A.; Rousseau, J.; Fontaine, S.; Aguié-Béghin, V.; Debeaufort, F.; Karbowiak, T. Toward sustainable PLA-based multilayer complexes with improved barrier properties. ACS Sustain. Chem. Eng. 2019, 7, 3759–3771.
Pan, P.; Yang, J.; Shan, G.; Bao, Y.; Weng, Z.; Cao, A.; Yazawa, K.; Inoue, Y. Temperature-variable FTIR and solid-state 13C NMR investigations on crystalline structure and molecular dynamics of polymorphic poly(L-lactide) and poly(L-lactide)/poly(D-lactide) stereocomplex. Macromolecules 2012, 45, 189–197.
Tsuji, H. Poly(lactic acid) stereocomplexes: a decade of progress. Adv. Drug Deliv. Rev. 2016, 107, 97–135.
Liu, G.; Zhang, X.; Wang, D. Tailoring crystallization: towards high-performance poly(lactic acid). Adv. Mater. 2014, 26, 6905–6911.
Pan, P.; Han, L.; Bao, J.; Xie, Q.; Shan, G.; Bao, Y. Competitive stereocomplexation, homocrystallization, and polymorphic crystalline transition in poly(L-lactic acid)/poly(D-lactic acid) racemic blends: molecular weight effects. J. Phys. Chem. B 2015, 119, 6462–6470.
Pan, P.; Kai, W.; Zhu, B. Polymorphous crystallization and multiple melting behavior of poly(L-lactide): molecular weight dependence. Macromolecules 2007, 40, 6898–6905.
Hu, D.; Chen, M.; Yang, Y.; Li, H. Texture induced by molecular weight dispersity: polymorphism within poly(L-lactic acid) spherulites. Chinese J. Polym. Sci. 2020, 38, 1365–1373.
Wei, X.; Bao, R.; Cao, Z.; Yang, W.; Xie, B.; Yang, M. Stereocomplex crystallite network in asymmetric PLLA/PDLA blends: formation, structure, and confining effect on the crystallization rate of homocrystallites. Macromolecules 2014, 47, 1439–1448.
Tsuji, H.; Ikada, Y. Stereocomplex formation between enantiomeric poly(lactic acids). 9. Stereocomplexation from the melt. Macromolecules 1993, 26, 6918–6926.
Ju, Y.; Li, X.; Diao, X.; Bai, H.; Zhang, Q.; Fu, Q. Mixing of racemic poly(L-lactide)/poly(D-lactide) blend with miscible poly(D,L-lactide): toward all stereocomplex-type polylactide with strikingly enhanced SC crystallizability. Chinese J. Polym. Sci. DOI: https://doi.org/10.1007/s10118-021-2588-x.
Bao, R.; Yang, W.; Wei, X.; Xie, B.; Yang, M. Enhanced formation of stereocomplex crystallites of high molecular weight poly(L-lactide)/poly(D-lactide) blends from melt by using poly(ethylene glycol). ACS Sustain. Chem. Eng. 2014, 2, 2301–2309.
Bao, R.; Yang, W.; Jiang, W.; Liu, Z.; Xie, B.; Yang, M. Polymorphism of racemic poly(L-lactide)/poly(D-lactide) blend: effect of melt and cold crystallization. J. Phys. Chem. B 2013, 117, 3667–3674.
Hu, J.; Wang, J.; Wang, M.; Ozaki, Y.; Sato, H.; Zhang, J. Investigation of crystallization behavior of asymmetric PLLA/PDLA blend using Raman Imaging measurement. Polymer 2019, 172, 1–6.
Henmi, K.; Sato, H.; Matsuba, G.; Tsuji, H.; Nishida, K.; Kanaya, T.; Oda, A.; Endou, K. Isothermal crystallization process of poly(L-lactic acid)/poly(D-lactic acid) blends after rapid cooling from the melt. ACS Omega 2016, 1, 476–482.
Xie, Q.; Bao, J.; Shan, G.; Bao, Y.; Pan, P. Fractional crystallization kinetics and formation of metastable β-form homocrystals in poly(L-lactic acid)/poly(D-lactic acid) racemic blends induced by precedingly formed stereocomplexes. Macromolecules 2019, 52, 4655–4665.
Saeidlou, S.; Huneault, M. A.; Li, H.; Sammut, P.; Park, C. B. Evidence of a dual network/spherulitic crystalline morphology in PLA stereocomplexes. Polymer 2012, 53, 5816–5824.
Xie, Q.; Guo, G.; Lu, W.; Sun, C.; Zhou, J.; Zheng, Y.; Shan, G.; Bao, Y.; Pan, P. Polymorphic homocrystallization and phase behavior of high-molecular-weight poly(L-lactic acid)/poly(D-lactic acid) racemic mixture with intentionally enhanced stereocomplexation ability via miscible blending. Polymer 2020, 201, 122597.
Yang, C.; Huang, Y.; Ruan, J.; Su, A. Extensive development of precursory helical pairs prior to formation of stereocomplex crystals in racemic polylactide melt mixture. Macromolecules 2012, 45, 872–878.
Chang, L.; Woo, E. M. A unique meta-form structure in the stereocomplex of poly(D-lactic acid) with low-molecular-weight poly(L-lactic acid). Macromol. Chem. Phys. 2011, 212, 125–133.
Shao, J.; Sun, J.; Bian, X.; Cui, Y.; Zhou, Y.; Li, G.; Chen, X. Modified PLA homochiral crystallites facilitated by the confinement of PLA stereocomplexes. Macromolecules 2013, 46, 6963–6971.
Ru, J.; Yang, S.; Zhou, D.; Yin, H.; Lei, J.; Li, Z. Dominant α-form of poly(L-lactic acid) obtained directly from melt under shear and pressure fields. Macromolecules 2016, 49, 3826–3837.
Sawai, D.; Takahashi, K.; Sasashige, A.; Kanamoto, T.; Hyon, S. H. Preparation of oriented α-form poly(L-lactic acid) by solid-state coextrusion: effect of extrusion variables. Macromolecules 2003, 36, 3601–3605.
Sawai, D.; Yokoyama, T.; Kanamoto, T.; Sungil, M.; Hyon, S. H.; Myasnikova, L. P. Crystal transformation and development of tensile properties upon drawing of poly(L-lactic acid) by solidstate coextrusion: effects of molecular weight. Macromol. Symp. 2006, 242, 93–103.
Brizzolara, D.; Cantow, H. J.; Diederichs, K.; Keller, E.; Domb, A. J. Mechanism of the stereocomplex formation between enantiomeric poly(lactide)s. Macromolecules 1996, 29, 191–197.
Brochu, S.; Prud’homme, R. E.; Barakat, I.; Jerome, R. Stereocomplexation and morphology of polylactides. Macromolecules 1995, 28, 5230–5239.
Sun, J.; Yu, H.; Zhuang X.; Chen X.; Jing X. Crystallization behavior of asymmetric PLLA/PDLA blends. J. Phys. Chem. B 2011, 115, 2864–2869.
Pulst, M.; Samiullah, M. H.; Baumeister, U.; Prehm, M.; Balko, J.; Thurm-Albrecht, T.; Busse, K.; Golitsyn, Y.; Reichert, D.; Kressler, J. Crystallization of poly(ethylene oxide) with a well-defined point defect in the middle of the polymer chain. Macromolecules 2016, 49, 6609–6620.
Huang Y.; Zhang Z.; Li Y.; Xu, J.; Xu, L.; Yan, Z.; Zhong, G.; Li, Z. The role of melt memory and template effect in complete stereocomplex crystallization and phase morphology of polylactides. Cryst. Growth Des. 2018, 18, 1613–1621.
Michell, R. M.; Muller, A. J. Confined crystallization of polymeric materials. Prog. Polym. Sci. 2016, 54–55, 183–213.
Zhang, P.; Huang, H.; He, T.; Hu, Z. Long-range ordered crystallization structure in the micromolded diblock copolymer thin film. ACS Macro. Lett. 2012, 1, 1007–1011.
Huang, C.; Jiao, L.; Zeng, J.; Zhang, J.; Yang, K.; Wang, Y. Fractional crystallization and homogeneous nucleation of confined PEG microdomains in PBS-PEG multiblock copolymers. J. Phys. Chem. B 2013, 117, 10665–10676.
Wu, B.; Yang, W.; Niu, D.; Dong, W.; Chen, M.; Liu, T.; Du, M.; Ma, P. Stereocomplexed poly(lactide) composites toward engineering plastics with superior toughness, heat resistance and anti-hydrolysis. Chinese J. Polym. Sci. 2020, 38, 1107–1116.
Pan, P.; Zhao, L.; Yang, J.; Inoue, Y. Fractional crystallization and phase segregation in binary miscible poly(butylene succinate)/poly(ethylene oxide) crystalline blends: effect of crystallization temperature. Macromol. Mater. Eng. 2013, 298, 201–209.
Pan, P.; Zhao, L.; Inoue, Y. Fractional crystallization kinetics of poly(ethylene oxide) in its blends with poly(butylene succinate): Molecular weight effects. Macromol. Mater. Eng. 2013, 298, 919–927.
Xie, Q.; Han, L.; Zhou, J.; Shan, G.; Bao, Y.; Pan, P. Homocrystalline mesophase formation and multistage structural transitions in stereocomplexable racemic blends of block copolymers. Polymer 2020, 189, 122180.
Yu, C.; Han, L.; Bao, J.; Shan, G.; Bao, Y.; Pan, P. Polymorphic crystallization and crystalline reorganization of poly(L-lactic acid)/poly(D-lactic acid) racemic mixture influenced by blending with poly(vinylidene fluoride). J. Phys. Chem. B 2016, 120, 8046–8054.
Hoogsteen, W.; Postema, A. R.; Pennings, A. J.; Brinke, G. T.; Zugenmaier, P. Crystal structure, conformation and morphology of solution-spun poly(L-lactide) fibers. Macromolecules 1990, 23, 634–642.
Lorenzo, A. T.; Arnal, M. L.; Albuerne, J.; Muller, A. J. DSC isothermal polymer crystallization kinetics measurements and the use of the Avrami equation to fit the data: Guidelines to avoid common problems. Polym. Test. 2007, 26, 222–231.
Li Y.; Han C. Isothermal and nonisothermal cold crystallization behaviors of asymmetric poly(L-lactide)/poly(D-lactide) blends. Ind. Eng. Chem. Res. 2012, 51, 15927–15935.
Tol, R. T.; Mathot, V. B. F.; Groeninckx, G. Confined crystallization phenomena in immiscible polymer blends with dispersed micro- and nanometer sized PA6 droplets, part 3: Crystallization kinetics and crystallinity of micro- and nanometer sized PA6 droplets crystallizing at high supercoolings. Polymer 2005, 46, 2955–2965.
Chen, L.; Jiang, J.; Wei, L.; Wang, X.; Xue, G.; Zhou, D. Confined nucleation and crystallization kinetics in lamellar crystalline-amorphous diblock copolymer poly(ε-caprolactone)-b-poly(4-vinylpyridine). Macromolecules 2015, 48, 1804–1812.
Palacios, J. K,; Zhao, J.; Hadjichristidis, N.; Muller, A. J. How the complex interplay between different blocks determines the isothermal crystallization kinetics of triple-crystalline PEO-b-PCL-b-PLLA triblock terpolymers. Macromolecules 2017, 50, 9683–9695.
Zhang, J.; Duan, Y.; Sato, H.; Tsuji, H.; Noda, I.; Yan, S.; Ozaki, Y. Crystal modifications and thermal behavior of poly(L-lactic acid) revealed by infrared spectroscopy. Macromolecules 2005, 39, 8012–8021.
Acknowledgments
This study was financially supported by the National Natural Science Foundation of China (No. 21873083). WAXD measurement were performed on the beamline BL16B1 of SSRF.
Author information
Authors and Affiliations
Corresponding authors
Additional information
Notes
The authors declare no competing financial interest.
Rights and permissions
About this article
Cite this article
Xiang, WK., Xie, Q., Xu, SS. et al. Fractionated Crystallization Kinetics and Polymorphic Homocrystalline Structure of Poly(L-lactic acid)/Poly(D-lactic acid) Blends: Effect of Blend Ratio. Chin J Polym Sci 40, 567–575 (2022). https://doi.org/10.1007/s10118-022-2658-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10118-022-2658-8