Substituent‐controlled energetics and barriers of mechanochromic spiropyran‐functionalized poly([épsilon] ‐caprolactone)

Abstract: In a joint theoretical and experimental study, it is shown that the onset of the mechanically-induced spiropyran (SP) to merocyanine (MC) isomerization can be controlled by both the regiochemistry and the substitution pattern of SP. Four SP-based bifunctional initiators with consistently varied polymer chain anchor point and substituent are used to synthesize poly-ε-caprolactone (PCL). Theoretical calculations (1S and 3S COGEF methods) and in-situ visible light absorption measurements of films during uniaxial stress–strain experiments consistently show varying activation barriers of the force-induced ring-opening reaction of SP to give MC. SPs with PCL chains attached in ortho-position to the pyran oxygen isomerize at lower stress than their para-analogs. NO2-substituted SP mechanophores exhibit a lower activation barrier compared with H-substituted ones, but only if the NO2 substituent is located in para-position relative to the O at the pyran half. These results are consistent with theoretical loading rate-dependent rupture forces required to break the CO bond of SP and may guide mechanophore design

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch
• Notes: Macromolecular chemistry and physics. - 224, 1 (2023) , 2200254, ISSN: 1521-3935

Classification and Topics

• Classification: Ingenieurwissenschaften und Maschinenbau

Contributors, Places and Time

• Event: Veröffentlichung
• (where): Freiburg
• (who): Universität
• (when): 2023
• Creator: Kempe, Fabian ; Metzler, Lukas ; Brügner, Oliver ; Buchheit, Hannah ; Walter, Michael ; Komber, Hartmut ; Sommer, Michael
• Contributor: Albert-Ludwigs-Universität Freiburg. Freiburger Zentrum für interaktive Werkstoffe und bioinspirierte Technologien

Further information

• DOI: 10.1002/macp.202200254
• URN: urn:nbn:de:bsz:25-freidok-2332692
• Rights: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 14.08.2025, 10:48 AM CEST