# Morphological and Spectroscopic Characterization of Multifunctional Self-Healing Systems

## TL;DR

This paper studies a self-healing resin system that combines conductive nanotubes and healing molecules to improve epoxy material properties.

## Contribution

The novel contribution is the integration of self-healing molecules and conductive nanotubes in a resin system, characterized using TUNA and FT-IR.

## Key findings

- FT-IR analysis shows barbiturate acid derivatives interact with epoxy matrix through hydrogen bonding.
- TUNA reveals CNT dispersion and electrical conductivity in the resin matrix at micro- and nanoscale.
- Supramolecular networks formed by hydrogen bonds are detected via electrical current mapping.

## Abstract

Multifunctional self-healing supramolecular structural toughened resins, formulated to counteract the insulating properties of epoxy polymers and integrating auto-repair mechanisms, are morphologically and spectroscopically characterized using Tunneling Atomic Force Microscopy (TUNA) and Fourier transform infrared spectroscopy (FT-IR), respectively. Specifically, the multifunctional resin comprises self-healing molecular fillers and electrically conductive carbon nanotubes (CNTs) embedded in the matrix. The selected self-healing molecules can form non-covalent bonds with the hydroxyl (OH) and carbonyl (C=O) groups of the toughened epoxy matrix through their H-bonding donor and acceptor sites. An FT-IR analysis has been conducted to evaluate the interactions that the barbiturate acid derivatives, serving as self-healing fillers, can form with the constituent parts of the toughened epoxy blend. Tunneling Atomic Force Microscopy (TUNA) highlights the morphological characteristics of CNTs, their dispersion within the polymeric matrix, and their affinity for the globular rubber domains. The TUNA technique maps the samples’ electrical conductivity at micro- and nanoscale spatial domains. Detecting electrical currents reveals supramolecular networks, determined by hydrogen bonds, within the samples, showcasing the morphological features of the sample containing an embedded conductive nanofiller in the hosting matrix.