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Towards Biomimicking Wood: Fabricated Free-standing Films of Nanocellulose, Lignin, and a Synthetic Polycation
Published on: June 17, 2014
Model films from native cellulose nanofibrils. Preparation, swelling, and surface interactions
S Ahola1, J Salmi, L-S Johansson
1Department of Forest Products Technology, Faculty of Chemistry and Materials Sciences, Helsinki University of Technology, PO Box 3320, FIN-02015 TKK Espoo, Finland. susanna.ahola@tkk.fi
Biomacromolecules
|March 1, 2008
Summary
Researchers developed novel native cellulose model films from wood pulp nanofibrils. These films, featuring crystalline and amorphous regions, mimic pulp fiber surfaces and reveal how charge density influences film structure and swelling behavior.
Area of Science:
- Materials Science
- Surface Chemistry
- Biomaterials
Background:
- Developing accurate model surfaces is crucial for understanding complex biological materials like cellulose.
- Pulp fiber surfaces present a challenge due to their heterogeneous composition of crystalline and amorphous cellulose.
- Existing model cellulose films lack the specific structural and chemical features of native pulp fibers.
Purpose of the Study:
- To create robust native cellulose model films with both crystalline and amorphous cellulose I regions.
- To investigate the influence of cellulose nanofibril charge density on film morphology and surface properties.
- To characterize the swelling behavior and surface interactions of these model films under varying conditions.
Main Methods:
- Spin-coating of aqueous cellulose nanofibril dispersions onto silica substrates.
- Characterization using Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS).
- Swelling and interaction studies via Quartz Crystal Microbalance with Dissipation (QCM-D) and AFM force measurements.
Main Results:
- 3-aminopropyltrimethoxysilane (APTS) effectively improved substrate coverage for low-charged nanofibrils.
- Nanofibril charge density dictated film morphology: low charge yielded network structures, high charge resulted in denser films.
- AFM and QCM-D confirmed film stability and swelling behavior consistent with Donnan theory, with steric forces becoming more prominent upon swelling.
Conclusions:
- The developed cellulose model films accurately represent native pulp fiber surfaces due to their composition and fibrillar structure.
- Nanofibril charge density is a key parameter controlling model film morphology and surface interactions.
- These model films provide a valuable platform for studying cellulose-water interactions and surface phenomena.
