Molecular Orientation-Regulated Bioinspired Multilayer Composites with Largely Enhanced Mechanical Properties

Area of Science:

• Materials Science
• Biomimetic Engineering
• Polymer Science

Background:

• Natural nacre's structure inspires inorganic platelet/polymer composites for enhanced mechanical properties.
• Current strategies focus on platelet size, alignment, and interfacial interactions.

Purpose of the Study:

• To introduce a new strategy for enhancing bioinspired multilayered composites through polymer chain orientation.
• To investigate the effect of polymer chain orientation on mechanical properties and failure mechanisms.

Main Methods:

• Fabrication of multilayer films using sodium carboxymethyl cellulose and alumina platelets.
• Utilized water evaporation-induced gelation, high-ratio prestretching, and Cu2+ infiltration.
• Controlled polymer chain orientation to study its impact on material properties.

Main Results:

• Regulating sodium carboxymethyl cellulose chain orientation significantly enhanced mechanical properties: Young's modulus (2.3x), tensile strength (3.2x), and toughness (2.5x).
• Increased chain orientation led to a failure mode transition from platelet pull-out to platelet fracture.
• Experimental and theoretical predictions confirmed enhanced stress transfer to platelets.

Conclusions:

• Polymer chain orientation is a viable strategy for enhancing bioinspired multilayered composites.
• This approach offers effective improvements in modulus, strength, and toughness.
• Opens new avenues for designing polymer aggregation states in composite materials.