Ionic Liquid-Cured Epoxy/PCL Blends with Improved Toughness and Adhesive Properties

Area of Science:

• Materials Science
• Polymer Chemistry

Background:

• Epoxy resins are widely used adhesives but often rely on conventional, volatile curing agents.
• Ionic liquids (ILs) offer a sustainable alternative curing agent for epoxy resins due to their low volatility and effective curing at lower concentrations.

Purpose of the Study:

• To investigate the effects of incorporating poly(ε-caprolactone) (PCL) into ionic liquid (IL)-cured epoxy resins.
• To evaluate how the chemical structure of ILs and varying PCL content influence the phase behavior, microstructure, mechanical, and adhesive properties of the modified epoxy resins.

Main Methods:

• Modification of epoxy resins with three different ionic liquids (ILs) and varying contents of poly(ε-caprolactone) (PCL).
• Analysis of phase behavior, microstructure, glass transition temperature (T_g), crosslinking density (ν_e), mechanical properties, and adhesive properties.

Main Results:

• All modified epoxy resins exhibited a single-phase system.
• PCL addition resulted in plasticization, leading to lower T_g and crosslinking densities.
• Low PCL content enhanced adhesive properties, while higher PCL content significantly improved toughness, particularly with imidazolium-based ILs.

Conclusions:

• The IL-cured epoxy/PCL blends demonstrate a favorable balance between mechanical and adhesive properties.
• The use of biodegradable PCL and ILs presents a sustainable approach for developing advanced adhesive materials.
• These findings hold practical significance for the adhesive industry, promoting greener material alternatives.