14265 IUPAC Gold Book - homoepitaxy 10.1351/goldbook.14265 14265 current 1 Epitaxy between crystals of the same substance. Homoepitaxy may occur between crystals of the same crystal polymorph but different morphology as in the crystallization of chain-folded crystals on fibril-like extended-chain crystals in shish-kebabs. Similarly, in non-isothermal crystallization, lamellar crystals of lower thickness are often nucleated on thicker crystals, preserving a unique orientation of the crystal lattice. A less frequent homoepitaxy may occur, as for the \(\ce{\upalpha\mbox{-}polymorph}\) of isotactic polypropylene, between crystals of the same crystal polymorph and morphology but with a different, well-defined orientation of the crystal lattice. Homoepitaxy may allow the development of crystals of the same polymer but in two distinct crystal polymorphs with well-defined mutual orientations, as in the case of \(\ce{\upgamma\mbox{-}isotactic}\) polypropylene grown on \(\ce{\upalpha\mbox{-}isotactic}\) polypropylene. A new crystal layer, initiated by secondary nucleation, or the formation of a twinned polymer crystal, can be seen as a form of homoepitaxy. crystal polymorph https://goldbook.iupac.org//terms/view/14219 non-isothermal crystallization https://goldbook.iupac.org//terms/view/14267 twinned polymer crystal https://goldbook.iupac.org//terms/view/14260 PAC, 2011, 83, 1831. 'Definitions of terms relating to crystalline polymers (IUPAC Recommendations 2011)' on page 1861 (https://doi.org/10.1351/PAC-REC-10-11-13) https://goldbook.iupac.org/terms/view/14265/html https://goldbook.iupac.org/terms/view/14265/json https://goldbook.iupac.org/terms/view/14265/plain Citation: 'homoepitaxy' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.14265 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-05-17T21:39:53+00:00