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Abstract <p>Dynamic covalent networks (DCNs) based on the thermoreversible Diels–Alder (DA) reaction offer a unique combination of reprocessability, recyclability, and tunable mechanical properties. When dynamic bonds are introduced on semi-crystalline polymers such as poly(<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\varepsilon\)</EquationSource> </InlineEquation>-caprolactone) (PCL), their solidification is governed by the interplay of the chemical crosslinking reaction and the physical crystallization. However, conventional characterization techniques typically probe these mechanisms separately on distinct samples, whereas both mechanisms are convoluted in the rheological response. This makes it difficult to disentangle their simultaneous effects under processing-relevant conditions. Therefore, a hyphenated rheo-Raman technique is proposed that enables the <i>in situ</i> and simultaneous monitoring and correlation of both macroscopic rheological properties and microscopic molecular-level transformations during DA network formation and PCL crystallization. Isothermal experiments reveal an excellent agreement between Raman-derived and rheological gelation, confirming the reliability of spectroscopic tracking for dynamic network formation. Crystallization studies reveal that pre-existing crosslinks slow down crystallization. However, the Raman spot size highlights spatial restrictions arising from spherulitic growth and nucleation density, which can cause delays in local crystallinity tracking relative to bulk crystallization. Additionally, non-isothermal cooling experiments demonstrate how thermal history and cooling rate dictate the relative progression of crystallization and DA crosslinking. Together, these findings establish rheo-Raman spectroscopy as a powerful technique to decouple and quantify complex and interacting solidification pathways in semi-crystalline DCNs. The resulting insights provide a new experimental foundation to tailor improved structure–property relationships in dynamic covalent networks, with direct relevance to advanced processing methods such as additive manufacturing.</p> Graphical abstract <p></p>

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Simultaneous rheo-Raman characterization of crosslinking and crystallization in semi-crystalline Diels–Alder polymer networks

  • 期刊论文

  • 发表日期：

    2026年3月31日

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  • Jelle De Ceulaer,
  • Ruth Cardinaels,
  • Peter Van Puyvelde

摘要

Abstract

Dynamic covalent networks (DCNs) based on the thermoreversible Diels–Alder (DA) reaction offer a unique combination of reprocessability, recyclability, and tunable mechanical properties. When dynamic bonds are introduced on semi-crystalline polymers such as poly( \(\varepsilon\) -caprolactone) (PCL), their solidification is governed by the interplay of the chemical crosslinking reaction and the physical crystallization. However, conventional characterization techniques typically probe these mechanisms separately on distinct samples, whereas both mechanisms are convoluted in the rheological response. This makes it difficult to disentangle their simultaneous effects under processing-relevant conditions. Therefore, a hyphenated rheo-Raman technique is proposed that enables the in situ and simultaneous monitoring and correlation of both macroscopic rheological properties and microscopic molecular-level transformations during DA network formation and PCL crystallization. Isothermal experiments reveal an excellent agreement between Raman-derived and rheological gelation, confirming the reliability of spectroscopic tracking for dynamic network formation. Crystallization studies reveal that pre-existing crosslinks slow down crystallization. However, the Raman spot size highlights spatial restrictions arising from spherulitic growth and nucleation density, which can cause delays in local crystallinity tracking relative to bulk crystallization. Additionally, non-isothermal cooling experiments demonstrate how thermal history and cooling rate dictate the relative progression of crystallization and DA crosslinking. Together, these findings establish rheo-Raman spectroscopy as a powerful technique to decouple and quantify complex and interacting solidification pathways in semi-crystalline DCNs. The resulting insights provide a new experimental foundation to tailor improved structure–property relationships in dynamic covalent networks, with direct relevance to advanced processing methods such as additive manufacturing.

Graphical abstract