Imidazolium Ionic Liquids as Compatibilizer Agents for Microcrystalline Cellulose/Epoxy Composites

Area of Science:

• Materials Science
• Polymer Science
• Green Chemistry

Background:

• Microcrystalline cellulose (MCC) is a sustainable bio-resource.
• Improving the compatibility of MCC with polymer matrices is crucial for advanced applications.
• Ionic liquids (ILs) offer tunable properties for material modification.

Purpose of the Study:

• To investigate the use of four imidazolium-based ionic liquids (ILs) as compatibilizers for microcrystalline cellulose (MCC).
• To evaluate the performance of IL-modified MCC as a reinforcement in epoxy bio-based composites.
• To analyze the impact of IL modification on the mechanical and thermal properties of MCC-epoxy composites.

Main Methods:

• Four imidazolium-based ionic liquids were used to treat MCC.
• Ethanolic solutions of IL-modified MCC were prepared and evaporated.
• The modified MCC was characterized using various techniques.
• MCC-epoxy composites were fabricated with 5.0 and 10 phr of modified MCC.
• Mechanical, thermal, and viscoelastic properties of the composites were evaluated.

Main Results:

• Ionic liquids did not significantly alter the morphology or structure of MCC.
• A slight increase in thermal stability was observed due to MCC-IL affinity.
• IL-modified MCC-epoxy composites showed significant improvements in flexural strength (≈22.5%) and toughness (≈18.6%).
• Enhanced storage modulus in the glassy state was observed, dependent on MCC loading and IL type.
• Stronger hydrogen bonding between ILs and the epoxy matrix was identified as the key factor.

Conclusions:

• Imidazolium-based ionic liquids effectively compatibilize microcrystalline cellulose for epoxy composites.
• IL-modified MCC acts as an efficient reinforcement, enhancing mechanical and viscoelastic properties.
• The observed improvements are attributed to enhanced hydrogen bonding and a 'bridging' effect between MCC and the epoxy matrix.