Molecular self-healing mechanisms between C₆₀-fullerene and anthracene unveiled by Raman and two-dimensional correlation spectroscopy

Abstract

The self-healing polymer P(LMA-co-MeAMMA) crosslinked with C60-fullerene has been studied by FT-Raman spectroscopy in combination with two-dimensional (2D) correlation analysis and density functional theory calculations. To unveil the molecular changes during the self-healing process mediated by the Diels-Alder equilibrium between 10-methyl-9-anthracenyl groups and C60-fullerene different anthracene-C60-fullerene adducts have been synthesized and characterized by time-, concentration- and temperature-dependent FT-Raman measurements. The self-healing process could be monitored via the C60-fullerene vibrations at 270, 432 and 1469 cm(-1). Furthermore, the detailed analysis of the concentration-dependent FT-Raman spectra point towards the formation of anthracene-C60-fullerene adducts with an unusual high amount of anthracene bound to C60-fullerene in the polymer film, while the 2D correlation analysis of the temperature-dependent Raman spectra suggests a stepwise dissociation of anthracene-C60-fullerene adducts, which are responsible for the self-healing of the polymer.

Remendable polymers via reversible Diels–Alder cycloaddition of anthracene‐containing copolymers with fullerenes

“…Nevertheless, the temperature of the rDA reaction cannot be determined by this method, because this transition is not visible in the heating curves. Therefore, this behavior was examined (for CP2F) using FT‐Raman spectroscopy and two‐dimensional correlation analysis in a separate study . The study revealed two pronounced jumps (at 35 and 55 °C) in the Raman peak area for the signals of the anthracene and anthracene‐C 60 ‐fullerene adduct moieties and that the strongest change in these signals starts at 60 °C.…”

“…The band assignments of the monomers (AMMA and MAMMA), copolymers (P1 and P2) as well as fullerene‐containing copolymers (CP1F and CP2F) were depicted in Table S2. Previously, we investigated the self‐healing temperatures as well as the reversibility of CP2F by using Raman and two‐dimensional correlation spectroscopy . In this study, the rebounding behavior of the system in bulk was investigated revealing a stepwise degradation mechanism of anthracene‐C 60 ‐fullerene adducts over a large temperature range.…”

“…of functional monomer unit was utilized for conversion resulting preferably in bis ‐functionalized adducts. In principle, different isomers and higher adducts could be formed, which was investigated in a previous study using FT‐Raman spectroscopy as well . During the conversion study no precipitation of the fullerene‐containing material occurs due to the dilution and, as a result, the presumably intramolecular reaction.…”

Do You Get What You See? Understanding Molecular Self‐Healing

“…[20,34] The use of sophisticated spectroscopic methods, such as CARS microscopy,t os tudy molecular processes during self-healing will lead to an improvement of self-healing materials as well as to a better understanding of the self-healing process and the mechanochemical activation of materials in general. [20,34] The use of sophisticated spectroscopic methods, such as CARS microscopy,t os tudy molecular processes during self-healing will lead to an improvement of self-healing materials as well as to a better understanding of the self-healing process and the mechanochemical activation of materials in general.…”

“…We expect the presented approach of simultaneously acquiring morphological and molecular information to be broadly applicable in the fieldo fs elf-healingm aterials to study for example,o ther self-healing reactions with dynamic covalent bonds like, for example, the Diels-Alder reactions. [20,34] The use of sophisticated spectroscopic methods, such as CARS microscopy,t os tudy molecular processes during self-healing will lead to an improvement of self-healing materials as well as to a better understanding of the self-healing process and the mechanochemical activation of materials in general.…”