- Physical Review Journals
All JournalsPhysics Magazine

Physical Review Letters

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

Export citation

Export citation

Choose format for download:

Download Citation
  • Open Access

Polymorphic Self-Poisoning in Poly(Lactic Acid): A New Phenomenon in Polymer Crystallization

Shu-Gui Yang1,2, Xiang-bing Zeng3, Feng Liu1,2, and Goran Ungar1,3

  • 1State Key Laboratory for Mechanical Behavior of Materials, Shaanxi International Research Center for Soft Matter, School of Material Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China
  • 2Institute of New Concept Sensors and Molecular Materials, Shaanxi Key Laboratory of New Conceptual Sensors and Molecular Materials, Xi’an Jiaotong University, Xi’an 710049, China
  • 3School of Chemical, Materials and Biological Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom

PDF

Phys. Rev. Lett. 136, 018101 – Published 6 January, 2026

DOI: https://doi.org/10.1103/yf56-tfhd

Abstract

Self-poisoning is ubiquitous in polymer crystallization but has so far manifested itself visibly only as minima in growth rate vs temperature in either monodisperse systems where, e.g., unstable folded chains obstruct crystallization of stable extended chains, or in periodically segmented chains where unstable stems with n-1 segments disturb deposition of stable stems with n segments. Here, we report a new type of self-poisoning found in poly(lactic acid), where a less stable crystal form (α′) disturbs growth of the stable form (α). While α requires strict up-down order of the polar chains, α’ does not, hence is kinetically favored. Unexpectedly, below the temperature of the growth rate minimum, the lamellar thickness increases rather than drops, as in all other reported cases of polymer crystallization with decreasing temperature. A growth rate equation model is developed, giving good match with experiments, but revealing an unexpectedly low fold surface free energy of α′ form. Delayed crystallization due to self-poisoning of α in practical fast-cooling processing not only gives the low-modulus α′ form, but also leads to an increased glassy amorphous fraction that results in embrittlement of the biofriendly poly(lactic acid) through physical aging.

View figure in article

Physics Subject Headings (PhySH)

Article Text

Supplemental Material

References (51)

  1. G. Ungar and A. Keller, Inversion of the temperature dependence of crystallization rates due to onset of chain folding, Polymer 28, 1899 (1987).
  2. G. Ungar, J. Stejny, A. Keller, I. Bidd, and M. C. Whiting, The crystallization of ultralong normal paraffins: The onset of chain folding, Science 229, 386 (1985).
  3. S. J. Organ, G. Ungar, and A. Keller, Rate minimum in solution crystallization of long paraffins, Macromolecules 22, 1995 (1989).
  4. G. Ungar, P. Mandal, P. G. Higgs, D. S. M. de Silva, E. Boda, and C. M. Chen, Dilution wave and negative-order crystallization kinetics of chain molecules, Phys. Rev. Lett. 85, 4397 (2000).
  5. G. Ungar, E. G. R. Putra, D. S. M. de Silva, M. A. Shcherbina, and A. J. Waddon, The effect of self-poisoning on crystal morphology and growth rates, Adv. Polym. Sci. 180, 45 (2005).
  6. P. G. Higgs and G. Ungar, The dilution wave in polymer crystallization is described by Fisher’s reaction-diffusion equation, J. Chem. Phys. 114, 6958 (2001).
  7. P. G. Higgs and G. Ungar, The growth of polymer crystals at the transition from extended chains to folded chains, J. Chem. Phys. 100, 640 (1994).
  8. K. Leutwyler, Self-poisoning polymer crystals, Sci. Am., https://www.scientificamerican.com/article/self-poisoning-polymer-cr/ (2000).
  9. S. Z. D. Cheng and J. H. Chen, Nonintegral and integral folding crystal growth in low-molecular mass poly (ethylene oxide) fractions. III. Linear crystal growth rates and crystal morphology, J. Polym. Sci. Polym. Phys. 29, 31 (1991).
  10. J. D. Hoffman, L. J. Frolen, G. S. Ross, and J. I. Lauritzen, Jr., On the growth rate of spherulites and axialites from the melt in polyethylene fractions: Regime I and regime II crystallization, J. Res. Natl. Bur. Stand. A Phys. Chem. 79A, 671 (1975).
  11. J. D. Hoffman, Transition from extended-chain to once-folded behaviour in pure n-paraffins crystallized from the melt, Polymer 32, 2828 (1991).
  12. Y. Ma, B. Qi, W. B. Hu, G. Ungar, and J. Hobbs, Understanding self-poisoning phenomenon in the crystal growth of short-chain polymers, J. Phys. Chem. B 113, 13485 (2009).
  13. D. M. Sadler, New explanation for chain folding in polymers, Nature (London) 326, 174 (1987).
  14. T. Verho, A. Paajanen, J. Vaari, and A. Laukkanen, Crystal growth in polyethylene by molecular dynamics: The crystal edge and lamellar thickness, Macromolecules 51, 4865 (2018).
  15. X. Zhang, W. Zhang, K. B. Wanener, E. Boz, and R. G. Alamo, Effect of self-poisoning on crystallization kinetics of dimorphic precision polyethylenes with bromine, Macromolecules 51, 1386 (2018).
  16. X. Zhang, X. Zuo, P. Ortmann, S. Mecking, and R. G. Alamo, Crystallization of long-spaced precision polyacetals I: Melting and recrystallization of rapidly formed crystallites, Macromolecules 52, 4934 (2019).
  17. S. F. Marxsen, D. Song, X. Zhang, I. Flores, J. Fernández, J. R. Sarasua, A. J. Müller, and R. G. Alamo, Crystallization rate minima of polyethylene brassylate at temperatures transitioning between quantized crystal thicknesses, Macromolecules 55, 3958 (2022).
  18. H. Janani, C. W. Kramer, N. R. Boyd, M. Eck, S. Mecking, and R. G. Alamo, Crystallization rate minima of aliphatic polyesters type PE-x,y in a wide range of undercooling. Role of CH2 sequence length and layered crystallites, Macromolecules 58, 5688 (2025).
  19. K. Gabana, G. A. Gehring, X. B. Zeng, and G. Ungar, Quantitative model of multiple crystal growth rate minima in polymers with regularly spaced substituent groups, Macromolecules 57, 1667 (2024).
  20. S. Whitelam, Y. R. Dahal, and J. D. Schmit, Minimal physical requirements for crystal growth self-poisoning, J. Chem. Phys. 144, 064903 (2016).
  21. T. Kandola et al., Pathologic polyglutamine aggregation begins with a self-poisoning polymer crystal, eLife 12, RP86939 (2023).
  22. See Supplemental Material at http://link.aps.org/supplemental/10.1103/yf56-tfhd for gel permeation chromatography traces (Fig. S1), NMR spectra (Fig. S2), results of isothermal DSC runs (Fig. S3), and growth rates of individual spherulites of the plasticized PLLA-9k (Fig. S4), which includes Ref. [23].
  23. K. Suganuma, T. Asakura, M. Oshimura, T. Hirano, K. Ute, and H. N. Cheng, NMR analysis of poly(Lactic Acid) via statistical models, Polymers 11, 725 (2019).
  24. S. G. Yang, X. B. Zeng, F. Liu, and G. Ungar, Polymorphic self-poisoning in poly(lactic acid): A new phenomenon in polymer crystallization, Figshare2025, 10.6084/m9.figshare.29923553.
  25. S. Iannace and L. Nicolais, Isothermal crystallization and chain mobility of poly(L-lactide), J. Appl. Polym. Sci. 64, 911 (1997).
  26. H. Tsuji, T. Miyase, Y. Tezuka, and S. K. Saha. Physical properties, crystallization, and spherulite growth of linear and 3-arm poly(L-lactide)s, Biomacromolecules 6, 244 (2005).
  27. H. Abe, Y. Kikkawa, Y. Inoue, and Y. Doi, Morphological and kinetic analyses of regime transition for poly[(S)-lactide] crystal growth, Biomacromolecules 2, 1007 (2001).
  28. M. L. Di Lorenzo, Crystallization behavior of poly(L-lactic acid), Eur. Polym. J. 41, 569 (2005).
  29. M. Yasuniwa, S. Tsubakihara, K. Iura, Y. Ono, Y. Dan, and K. Takahashi, Crystallization behavior of poly(L-lactic acid), Polymer 47, 7554 (2006).
  30. P. Pan, B. Zhu, W. Kai, T. Dong, and Y. Inoue, Effect of crystallization temperature on crystal modifications and crystallization kinetics of poly(L-lactide), J. Appl. Polym. Sci. 107, 54 (2007).
  31. T. Kawai et al., Crystallization and melting behavior of poly (L-lactic Acid), Macromolecules 40, 9463 (2007).
  32. B. Lotz, Crystal polymorphism and morphology of polylactides, Adv. Polym. Sci. 279, 273 (2018).
  33. T.-Y. Cho and G. Strobl, Temperature dependent variations in the lamellar structure of poly(L-lactide), Polymer 47, 1036 (2006).
  34. K. Jariyavidyanont, C. Schick, and R. Androsch, The bulk enthalpy of melting of α′-crystals of poly(L-lactic acid) determined by fast scanning chip calorimetry, Thermochim. Acta 717, 179349 (2022).
  35. C. M. Guttman, E. A. DiMarzio, and J. D. Hoffman, Modelling the amorphous phase and the fold surface of a semicrystalline polymer—the Gambler’s Ruin method, Polymer 21, 733 (1980).
  36. X. Zeng and G. Ungar, Semicrystalline lamellar phase in binary mixtures of very long-chain n-alkanes, Macromolecules 34, 6945 (2001).
  37. K. Wasanasuk and K. Tashiro, Crystal structure and disorder in poly(L-lactic acid) δ form (α′ form) and the phase transition mechanism to the ordered α form, Polymer 52, 6097 (2011).
  38. K. Wasanasuk, K. Tashiro, M. Hanesaka, T. Ohhara, K. Kurihara, R. Kuroki, T. Tamada, T. Ozeki, and T. Kanamoto, Crystal structure analysis of poly(L-lactic acid) α form on the basis of the 2-dimensional wide-angle synchrotron x-ray and neutron diffraction measurements, Macromolecules 44, 6441 (2011).
  39. M. C. Righetti, M. Gazzano, M. L. Di Lorenzo, and R. Androsch, Enthalpy of melting of α′- and α-crystals of poly(L-lactic acid), Eur. Polym. J. 70, 215 (2015).
  40. J. N. Sherwood, The Plastically Crystalline State: Orientationally Disordered Crystals (John Wiley, New York, 1979).
  41. J. Zhang, K. Tashiro, H. Tsuji, and A. J. Domb, Disorder-to-order phase transition and multiple melting behavior of poly(L-lactide) investigated by simultaneous measurements of WAXD and DSC, Macromolecules 41, 1352 (2008).
  42. B. Kalb and A. J. Pennings, General crystallization behaviour of poly(L-lactic acid), Polymer 21, 607 (1980).
  43. S. Rastogi and G. Ungar, Hexagonal columnar phase in 1,4-t-polybutadiene: Lamellar thickening, chain extension and isothermal phase reversal, Macromolecules 25, 1445 (1992).
  44. M. A. Shcherbina and G. Ungar, Solution of the growth equation for asymmetric crystal faces, Polymer 47, 5505 (2006).
  45. J. M. Cui, S. G. Yang, Q. Zhang, F. Liu, and G. Ungar, Poisoning by purity: What stops stereocomplex crystallization in polylactide racemate?, Macromolecules 56, 989 (2023).
  46. D. Cavallo, L. Zhang, G. Portale, G. C. Alfonso, H. Janani, and R. G. Alamo, Unusual crystallization behavior of isotactic polypropylene and propene/1-alkene copolymers at large undercoolings, Polymer 55, 3234 (2014).
  47. F. Paolucci, D. Baeten, P. C. Roozemond, B. Goderis, and G. W. M. Peters, Quantification of isothermal crystallization of polyamide 12: Modelling of crystallization kinetics and phase composition, Polymer 155, 187 (2018).
  48. A. M. Rhoades, N. Wonderling, C. Schick, and R. Androsch, Supercooling-controlled heterogeneous and homogenous crystal nucleation of polyamide 11 and its effect onto the crystal/mesophase polymorphism, Polymer 106, 29 (2016).
  49. X. Zhang, J. Buzinkai, R. Androsch, R. H. Colby, and A. M. Rhoades, Crystallization of polyamide 66 in blends with a random noncrystallizable poly(hexamethylene isophthalamide-coterephthalamide). Macromolecules 58, 8151 (2025).
  50. A. Toda, Y. Furushima, and C. Schick, Crystal domains and crystallization kinetics of poly(butylene terephthalate), Macromolecules 56, 6891 (2023).
  51. https://cstr.cn/31124.02.SSRF.BL16B1

Outline

Information

Phys. Rev. Lett. 136, 018101– Published 6 January, 2026
  • Received 16 August 2025
  • Accepted 16 December 2025
Crossmark - Check for updates button
Creative Commons Logo

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation