POS4-0403
Salt-Induced Silica Nanoparticle Aggregation Decouples Mechanical Reinforcement and Ionic Transport in Polymer Nanocomposite Electrolytes
Topic
S4. Colloids, Interfaces, and Molecular Assemblies for Functional Soft Materials
When and Where
Sep 30, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Heesuk KIM
Jinhye BAE
Presenter(s)
Seunghan Yun (Seoul National University)
Co-Author(s)
Abstract
Achieving mechanical reinforcement without sacrificing ionic conductivity (σdc) remains a main challenge in polymer electrolyte design. Polymer nanocomposite (PNC) electrolytes offer a promising route by exploiting polymer-ion-particle interactions, but particle aggregation is often regarded as detrimental to structural homogeneity and σdc of electrolyte. In salt-containing PNC electrolytes, dissociated ions can screen charged particle surfaces and alter particle dispersion, yet how this structural heterogeneity affects mechanical reinforcement and ion transport remains unclear.
Here, we use PEG-salt-silica PNC electrolytes as a model system to examine the effects of cation chemistry (Li+ and Na+), PEG molecular weight (0.4k and 10k), and silica nanoparticle size (36.5 and 15.8 nm). SAXS and zeta potential measurements on PEG-free silica-ethanol dispersions show that dissociated ions screen negatively charged silica surfaces and promote aggregation. After PEG matrix incorporation and subsequent solvent removal, particle aggregation still observed in dried PNC electrolytes, indicating that salt-driven heterogeneity persists in the final state.
Rheological measurements reveal that these aggregates are mechanically coupled into stress-bearing networks through PEG-cation-silica interactions. This reinforcement is strongest for PEG-0.4k and smaller silica nanoparticles, reflecting efficient interaggregate coupling through short chains and large interfacial area. In contrast, σdc is governed mainly by the PEG-salt phase rather than by the aggregated network. Temperature-dependent σdc and dielectric relaxation analyses indicate that crystallization, segmental dynamics, and cation-EO coordination dominate ion transport. Overall, this model study shows that salt-induced aggregation can provide mechanical reinforcement without severely disrupting σdc, offering design guidelines for balancing modulus and σdc in PEG-based PNC electrolytes.
Here, we use PEG-salt-silica PNC electrolytes as a model system to examine the effects of cation chemistry (Li+ and Na+), PEG molecular weight (0.4k and 10k), and silica nanoparticle size (36.5 and 15.8 nm). SAXS and zeta potential measurements on PEG-free silica-ethanol dispersions show that dissociated ions screen negatively charged silica surfaces and promote aggregation. After PEG matrix incorporation and subsequent solvent removal, particle aggregation still observed in dried PNC electrolytes, indicating that salt-driven heterogeneity persists in the final state.
Rheological measurements reveal that these aggregates are mechanically coupled into stress-bearing networks through PEG-cation-silica interactions. This reinforcement is strongest for PEG-0.4k and smaller silica nanoparticles, reflecting efficient interaggregate coupling through short chains and large interfacial area. In contrast, σdc is governed mainly by the PEG-salt phase rather than by the aggregated network. Temperature-dependent σdc and dielectric relaxation analyses indicate that crystallization, segmental dynamics, and cation-EO coordination dominate ion transport. Overall, this model study shows that salt-induced aggregation can provide mechanical reinforcement without severely disrupting σdc, offering design guidelines for balancing modulus and σdc in PEG-based PNC electrolytes.
