# Bio-Based, Degradable, and Tunable Epoxy Thermosets from Homogenized Acids and Epoxidized Linseed Oil or Glycerol Triglycidyl Ether

## TL;DR

This paper introduces a new type of eco-friendly epoxy material made from natural sources that can be easily broken down and customized for different uses.

## Contribution

The paper presents a novel method to create tunable, degradable epoxy thermosets using bio-based ingredients like epoxidized linseed oil and acid hardeners.

## Key findings

- Epoxy thermosets made from epoxidized linseed oil and acid mixtures show tunable thermomechanical properties.
- Materials are readily degradable under basic aqueous conditions without needing solvents.
- Replacing linseed oil with glycerol triglycidyl ether improves thermomechanical performance.

## Abstract

Epoxy thermosets continue to be seen as desirable materials
for
high-performance applications, given their excellent thermomechanical
properties. However, commercial epoxides are generally derived from
non-renewable feedstocks and are highly resistant to chemical decomposition.
Accordingly, the provision of readily degradable, bioderived alternatives
offering both high performance and tunable thermomechanical properties
is urgently necessary for the development of sustainable composite
materials. In this work, such materials are prepared by the reaction
of epoxidized linseed oil (ELO) with different quantities of organic
acid hardeners, comprising eutectic mixtures of (trifunctional) citric
acid (CA) and various concentrations of two different linear aliphatic
diacids, pimelic acid (PA), and glutaric acid (GA). Variation of both
acid chain length and diacid:triacid ratio permits controlled manipulation
of the resulting materials’ thermomechanical properties, with
extensive cross-linking in high-triacid systems yielding increases
in both glass transition temperature and mechanical strength. The
presence of diacid species ensures homogeneity of the reaction mixture
during resin curing, without requiring exogenous solvents or other
diluents to solubilize the CA, and all materials are shown to be readily
degradable under aqueous basic conditions. Finally, preliminary studies
indicate that replacement of ELO with glycerol triglycidyl ether (GTE)
yields materials with further enhanced thermomechanical properties
comparable to Bisphenol A diglycidyl ether-derived
materials.