Bioderived Rubber-Cellulose Nanocrystal Composites with Tunable Water-Responsive Adaptive Mechanical Behavior

Area of Science:

• Materials Science
• Polymer Science
• Biomaterials Engineering

Background:

• Nature-inspired adaptive composites are crucial for advanced applications, especially in biomedicine.
• Water-responsive polymer nanocomposites, often using cellulose nanocrystals (CNCs), are promising but typically rely on petroleum-based matrices.
• There is a need for sustainable, bio-derived alternatives to petroleum-based elastomers in these advanced materials.

Purpose of the Study:

• To investigate the feasibility of using bioderived rubbers, specifically natural rubber (NR) and epoxidized natural rubber (ENR), as matrices for CNC-based nanocomposites.
• To evaluate the water-responsive adaptive mechanical behaviors of these novel bioderived nanocomposites.
• To understand the underlying mechanisms governing the water-response in these bio-based systems.

Main Methods:

• Fabrication of nanocomposites using cellulose nanocrystals (CNCs) dispersed within natural rubber (NR) and epoxidized natural rubber (ENR) matrices.
• Characterization of the mechanical properties and water-responsive behaviors of the fabricated NR-CNC and ENR-CNC composites.
• Analysis of the CNC-polymer interactions, filler dispersion, and network structures to correlate with observed mechanical responses.

Main Results:

• Epoxidized natural rubber (ENR) composites demonstrated significantly more pronounced and reversible water-responsive mechanical behaviors compared to natural rubber (NR) composites.
• Enhanced CNC-polymer interactions, primarily through hydrogen bonding in ENR, led to improved filler dispersion and the formation of a dual network structure (CNC-CNC and CNC-polymer).
• The synergistic effect of these dual networks in ENR composites was key to tuning mechanical properties and water sensitivity.

Conclusions:

• Bioderived rubbers, particularly ENR, can be effectively used as matrices to create water-responsive adaptive nanocomposites with cellulose nanocrystals.
• The enhanced CNC-polymer interactions in ENR-based systems are critical for achieving superior water-responsive mechanical properties.
• This research offers a sustainable pathway for producing high-value, water-responsive nanocomposites from renewable resources for potential biomedical applications.