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Towards Biomimicking Wood: Fabricated Free-standing Films of Nanocellulose, Lignin, and a Synthetic Polycation
Published on: June 17, 2014
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Nanocomposites Assembled via Electrostatic Interactions between Cellulose Nanocrystals and a Cationic Polymer
Visuta Engkagul1, Chris Rader1, Nanetta Pon2
1Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland.
Biomacromolecules
|November 4, 2021
Summary
Cellulose nanocrystals (CNCs) are key polymer reinforcements, but aggregation limits their use. This study shows carboxylated CNCs (CNC-COONa) with a cationic polymer (PMETAC) prevent aggregation, significantly enhancing composite strength and stiffness.
Area of Science:
- Materials Science
- Polymer Science
- Nanotechnology
Background:
- Cellulose nanocrystals (CNCs) offer high strength, stiffness, and renewability, making them valuable polymer reinforcing agents.
- A major limitation for CNCs in nanocomposites is their tendency to aggregate, hindering reinforcement.
- Developing methods to incorporate high CNC content without aggregation is crucial for advanced material applications.
Purpose of the Study:
- To investigate the preparation of polymer nanocomposites with very high cellulose nanocrystal (CNC) content.
- To demonstrate the effectiveness of using carboxylated CNCs (CNC-COONa) with a cationic polymer (PMETAC) to prevent CNC aggregation.
- To quantify the mechanical reinforcement achieved in these novel nanocomposites.
Main Methods:
- Preparation of free-standing nanocomposite films via solvent casting from water.
- Utilizing poly[(2-(methacryloyloxy)ethyl) trimethylammonium chloride] (PMETAC) as the cationic polymer matrix.
- Incorporating sodium salt of carboxylated CNCs (CNC-COONa) at high weight percentages.
- Characterization using polarized optical microscopy and electron microscopy.
- Mechanical testing to determine storage modulus and maximum strength.
Main Results:
- Successful preparation of nanocomposite films with very high CNC-COONa content (33 wt %) without observable CNC aggregation.
- Significant enhancement in mechanical properties: storage modulus increased from 1.5 ± 0.3 GPa to 6.6 ± 0.1 GPa.
- Substantial increase in maximum strength from 11 MPa to 32 MPa.
- Demonstrated superior reinforcement compared to nanocomposites made with unmodified CNCs (CNC-OH).
Conclusions:
- Carboxylated CNCs (CNC-COONa) effectively prevent aggregation when combined with the cationic polymer PMETAC.
- This approach enables the creation of highly reinforced polymer nanocomposites with significantly improved mechanical properties.
- The developed method offers a promising route for utilizing CNCs as high-performance reinforcing agents in polymer matrices.
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