Abstract
The common knowledge of the crystal structures of nylons dates back to the early 1950s with the work of Bunn and Garner. It describes the packing of sheets made of hydrogen-bonded stems in an extended chain conformation. These alpha phase structures have a specific powder X-ray diffraction pattern with reflections at 4.4 Å and 3.7 Å. On heating, reflections transform progressively and merge at ≈ 4.2 Å at the so-called “Brill transition”. Other diffraction patterns have been recorded for different types of nylons and thermal histories. These patterns were interpreted only as indicating the existence of “variants” of the alpha phase. However, neither their structure, nor the origin of the Brill transition were established. Recent structural analyses and molecular modeling approaches have provided new insights in these long-standing structural puzzles. The “variants” feature chain conformations that are “pleated”. The Brill transition does not involve the standard extended chains of the alpha phase but corresponds to a dynamic interconversion (≈ 1010/s) between mirror conformations of these pleated stems.
Graphic abstract
Similar content being viewed by others
References
Bunn CW, Garner EV. The crystal structures of two polyamides (“nylons”). Proc R Soc Lond Ser A Math Phys Sci. 1947;A189:39–68.
Holmes DR, Bunn CW, Smith DJ. The crystal structure of polycaproamide: Nylon 6. J Polym Sci. 1955;17:159–77.
Brill R. Über das Verhalten von Polyamiden beim Erhitzen. J Prakt Chem. 1942;161:49–64. https://doi.org/10.1002/prac.19421610104.
Ramesh C, Keller A, Eltink SJEA. Studies on the crystallization and melting of nylon-6,6:1. The dependence of the Brill transition on the crystallization temperature. Polymer. 1994;35:2483–7.
Yang X, Tan S, Li G, Zhou E. Dependence of the Brill transition on the crystal size of nylon 10 10. Macromolecules. 2001;34:5936–42.
Ramesh C. New crystalline transitions in nylon 4,6, 6,10 and 6,12 using high temperature X-ray diffraction studies. Macromolecules. 1999;32:3721–6. https://doi.org/10.1021/ma981284z.
Tashiro K, Yoshioka Y. Conformational disorder in the Brill transition of uniaxially-oriented nylon 10/10 sample investigated through the temperature-dependent measurement of X-ray fiber diagram. Polymer. 2004;45:6349–53.
Morales-Gamez L, Ricart A, Franco L, Puiggali J. Study of the Brill transition and melt crystallization of nylon 65: a polymer able to adopt a structure with two hydrogen bonding directions. Eur Polym J. 2010;46(10):2063–77.
Yan D, Li Y, Zhu X. Brill transition in Nylon 10 12 investigated by variable temperature XRD and real time FT-IR. Macromol Rapid Commun. 2000;21(15):1040–3.
Hirschinger J, Miura H, Gardner KH, English AD. Segmental dynamics in the crystalline phase of nylon 66. Solid-state 2H NMR. Macromolecules. 1990;23(8):2153–69. https://doi.org/10.1021/ma00210a009.
Yoshioka Y, Tashiro K, Ramesh C. Structural change in the Brill transition of nylon m/n (2) conformational disordering as viewed from the temperature-dependent infrared spectral measurements. Polymer. 2003;44:6407–17. https://doi.org/10.1016/S0032-3861(03)00593-7.
Yoshioka Y, Tashiro K, Ramesh C. New interpretation of progression bands observed in infrared spectra of nylon-m/n. J Polym Sci B Polym Phys. 2003;41(12):1294–307. https://doi.org/10.1002/polb.10457.
Cooper SJ, Coogan M, Everall N, Priestnall I. A polarised μ-FTIR study on a model system for nylon 6 6: implications for the nylon Brill structure. Polymer. 2001;42:10119–32. https://doi.org/10.1016/S0032-3861(01)00566-3.
Wendoloski JJ, Gardner KH, Hirschinger J, Miura H, English AD. Molecular dynamics in ordered structures: computer simulation and experimental results for nylon 66 crystals. Science. 1990;247(4941):431–6.
Tashiro K, Yoshioka Y. Molecular dynamics simulation of the structural and mechanical property changes in the Brill transition of nylon 10/10 crystal. Polymer. 2004;45:4337–48. https://doi.org/10.1016/j.polymer.2004.03.082.
Jones NAJ, Atkins EDT, Hill MJ. Comparison of structures and behavior on heating of solution-grown, chain-folded lamellar crystals of 31 even-even Nylons. Macromolecules. 2000;33:2642–50.
Vinken E, Terry AE, van Asselen O, Spoelstra AB, Graf R, Rastogi S. Role of superheated water in the dissolution and perturbation of hydrogen bonding in the crystalline lattice of polyamide 4,6. Langmuir. 2008;24(12):6313–26.
Lotz B. Original crystal structures of even-even polyamides made of pleated and rippled sheets. Macromolecules. 2021;54(2):551–64. https://doi.org/10.1021/acs.macromol.0c02404.
Lotz B. Brill transition in nylons: the structural scenario. Macromolecules. 2021;54(2):565–83. https://doi.org/10.1021/acs.macromol.0c02409.
Pauling L, Corey RB. Configurations of polypeptide chains with favored orientations around single bonds: two new pleated sheets. Proc Natl Acad Sci USA. 1951;37:729–40.
Pauling L, Corey RB. Two rippled-sheet configurations of polypeptide chains, and a note about the pleated sheets. Proc Natl Acad Sci USA. 1953;39:253–6.
Kinoshita Y. An investigation of the structures of polyamide series. Makromol Chem. 1959;33:1–20.
Kinoshita Y. The crystal structure of polyheptamethylene pimelamide (nylon 77). Makromol Chem. 1959;33:21–31.
Li Y, Yan D, Zhu X. Crystalline transition in Nylon 10 10. Macromol Rapid Commun. 2000;21:1282–11285.
Lovinger AJ. Crystallographic factors affecting the structure of polymeric spherulites. I. Morphology of directionally solidified spherulites. J Appl Phys. 1978;49(10):5003–13.
Lovinger AJ. Crystallographic factors affecting the structure of polymeric spherulites. II. X-ray diffraction analysis of directionally solidified polyamides and general conclusions. J Appl Phys. 1978;49(10):5014–28.
Tonelli A. Melting of aliphatic nylons. J Polym Sci Polym Phys Ed. 1977;15:2051–3.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Lotz, B. A Fresh Look at the Structures of Nylons and the Brill Transition. Adv. Fiber Mater. 3, 203–209 (2021). https://doi.org/10.1007/s42765-021-00085-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s42765-021-00085-9