Interdigitated Three-Dimensional Heterogeneous Nanocomposites for High-Performance Mechanochromic Smart Membranes

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Mechanochromic smart membranes are crucial for applications like smart windows and camouflage.
• Achieving high-contrast optical modulation via light scattering at low strain is a significant challenge.

Purpose of the Study:

• To design and demonstrate a novel mechanochromic scattering membrane with high optical modulation at low strain.
• To explore the underlying mechanisms of strain-induced light scattering in heterogeneous materials.

Main Methods:

• Fabrication of a periodic 3D structure with interdigitated polydimethylsiloxane phases exhibiting Young's modulus mismatch and weak interfaces.
• Utilizing refractive index-matched interfaces for high initial optical transparency.
• Employing experimental and computational studies to analyze nanogap formation and light scattering under tension.

Main Results:

• The designed membranes achieve high optical transparency (93%) due to refractive index-matched interfaces.
• Nanoscale debonds (nanogaps) form at modulus-mismatching interfaces under tension, enabling light scattering.
• A high transmittance contrast (>50% at 15% strain, 82% maximum) was achieved.

Conclusions:

• The 3D heterogeneous design effectively enables mechanochromic light scattering at low strain.
• The membranes show potential for smart windows, providing moderate indoor illumination.
• The design principles can be adapted for other mechanochromic applications, such as enhancing mechanophore-dyed nanocomposites.