Correlation between cellulose thin film supramolecular structures and interactions with water

Area of Science:

• Materials Science
• Biomaterials Science
• Surface Science

Background:

• Understanding water interactions with bio-based materials is crucial for their application.
• Wood-derived polysaccharides like cellulose exhibit complex behaviors influenced by their nanostructure.
• Surface-sensitive techniques are key to probing these interactions at the molecular level.

Purpose of the Study:

• To investigate the water interactions of ultra-thin cellulose films.
• To clarify the influence of cellulose film structural features (crystallinity, porosity) on water uptake and swelling.
• To explore the impact of xylan modification on cellulose water interactions.

Main Methods:

• Quartz Crystal Microbalance with Dissipation (QCM-D) for characterizing water uptake and swelling.
• Atomic Force Microscopy (AFM) for evaluating film structural features (crystallinity, porosity, roughness).
• Spin-coating and Langmuir-Schaefer deposition for preparing cellulose thin films with varying supramolecular structures.

Main Results:

• More crystalline cellulose films exhibited higher water binding capacity and retained rigidity due to nanoporosity and increased surface area.
• Amorphous cellulose films absorbed less water, leading to softening and viscoelastic behavior under high humidity.
• The supramolecular structure of cellulose influenced both xylan adsorption and the subsequent water interactions of the modified films.

Conclusions:

• Cellulose film's supramolecular structure, particularly crystallinity, significantly dictates its water interaction properties.
• Nanoporosity in crystalline cellulose enhances water binding and maintains mechanical integrity.
• Surface modification with xylan further modulates the water interactions, highlighting the tunability of these bio-based materials.