# Furan–Urethane Monomers for Self-Healing Polyurethanes

## TL;DR

This paper introduces a new method to create self-healing polyurethanes using furan-urethane monomers, which improves the durability and healing efficiency of the material.

## Contribution

The novelty lies in the synthesis of modified self-healing polyurethanes using furan-urethane curing agents and the Diels–Alder reaction.

## Key findings

- Modified polyurethanes showed higher durability and self-healing efficiency compared to traditional methods.
- Materials synthesized with furan-urethane curing agents exhibited improved mechanical properties after damage.
- Spectroscopic and thermal analyses confirmed the structural and thermal stability of the new polyurethanes.

## Abstract

The repair efficiency of various self-healing materials often depends on the ability of the prepolymer and curing agent to form mixtures. This paper presents a synthesis and study of the properties of modified self-healing polyurethanes using the Diels–Alder reaction (DA reaction), obtained from a maleimide-terminated preform and a series of furan–urethane curing agents. The most commonly used isocyanates (4,4′-methylene diphenyl diisocyanate (MDI), 2,4-tolylene diisocyanate (TDI), and hexamethylene diisocyanate (HDI)) and furan derivatives (furfurylamine, difurfurylamine, and furfuryl alcohol) were used as initial reagents for the synthesis of curing agents. For comparative analysis, polyurethanes were also obtained using the well-known “traditional” approach—from furan-terminated prepolymers based on mono- and difurfurylamine, as well as furfuryl alcohol and the often-used bismaleimide curing agent 1,10-(methylenedi-1,4-phenylene)bismaleimide (BMI). The structure and composition of all polymers were studied using spectroscopic methods. Molecular mass was determined using gel permeation chromatography (GPC). Thermal properties were studied using TGA, DSC, and TMA methods. The mechanical and self-healing properties of the materials were investigated via a uniaxial tensile test. Visual assessment of the completeness of damage restoration after the self-healing cycle was carried out using a scanning electron microscope. It was shown that the proposed modified approach helps obtain more durable polyurethanes with a high degree of self-healing of mechanical properties after damage.