Sonochemical Processing of Gallium-based Soft Composites

Abstract

Gallium-enabled soft materials have emerged as promising systems for flexible electronics and sustainable devices due to their metallic conductivity, low melting point, and deformability. This thesis investigates how sonochemical processing and interfacial engineering can address key limitations of gallium-based particles while enabling the design of soft, conductive, and biomass-integrated composites.

Thiol-functionalized gallium nano- and microparticles are developed to suppress oxidation and achieve sintering-free conductivity via metal–molecule junctions, with conjugated ligands enabling tunable electrical performance. Liquid gallium nanoparticles are further integrated into PEDOT:PSS, significantly enhancing electrochromic switching kinetics through improved interfacial charge transport.

The role of sonochemistry in intensifying mass transport is demonstrated through a coffee-brewing sonoreactor, where extraction efficiency is improved while preserving chemical integrity. Building on this, sustainable composites incorporating spent coffee grounds (SCGs) and gallium nanoparticles are fabricated, forming flexible films with integrated biomass functionality. Preliminary NO₂ sensing results further demonstrate the potential of these materials for functional applications.

Overall, this thesis establishes sonochemical interface engineering, molecular functionalization, and biomass integration as complementary strategies for designing next-generation gallium-based soft materials, advancing both fundamental understanding and practical applications in flexible and sustainable systems.