Cascade synthesis of a gold nanoparticle-network polymer composite

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Chemistry

Background:

• Developing advanced hydrogel composites with integrated nanoparticles is crucial for novel applications.
• Controlling nanoparticle assembly within a dynamic matrix remains a significant challenge.

Purpose of the Study:

• To describe the synthesis of a self-supporting, hierarchically-structured gold nanoparticle hydrogel composite.
• To investigate the structure-property relationships of the composite during synthesis and swelling.

Main Methods:

• Multi-step cascade synthesis utilizing a lamellar lyotropic mesophase.
• Employing amphiphiles (PEO-PPO-PEO) and chloroaurate ions ([AuCl4](-)).
• Characterization using optical spectroscopy, TEM, ATR/FT-IR, thermal analysis, and X-ray scattering (SAXS/WAXS).

Main Results:

• Successful synthesis of a gold nanoparticle (Au NP) hydrogel composite via auto-reduction and polymerization.
• Observation of Au NP formation, aggregation, and subsequent etching into dispersed spherical NPs.
• Confirmation of polymer network formation and semi-crystalline PEO within water layers.
• Demonstration of reversible swelling with stable Au NP retention and solvent-mediated modulation of surface plasmon resonance (red shift of ~45 nm).

Conclusions:

• The developed method enables the creation of hierarchically structured Au NP hydrogel composites.
• The composite exhibits tunable optical properties based on its swelling state, driven by NP arrangement.
• This material holds potential for applications requiring responsive optical or nanostructured materials.