Synthesis and properties of SiO2/SiO2@Ag two-phase STFs

Soft body armor with a strain-sensing function using conductive shear thickening fluids (STFs) has gradually gained research interest. In this study, conductive SiO2@Ag core-shell microspheres were synthesized and the influence of process parameters on their properties was evaluated. Subsequently, SiO2 and SiO2@Ag were used as dispersed phases to prepare two-phase STFs, the effect of the core-shell microspheres' proportion on the rheological properties of the STFs was investigated, and its mechanism was discussed. The results indicated that SiO2@Ag core-shell microspheres were coated with elemental silver and when the concentration of sodium hydroxide and glucose were 0.07 and 0.09 mol L-1, respectively, the coating surface was the most uniform and compact, and the conductivity reached the minimum value of 0.56 omega cm. The two-phase STFs exhibited good and reversible shear thickening behaviors and the critical shear rate decreased with increasing core-shell microsphere concentration. Additionally, when the mass fraction of SiO2 and SiO2@Ag core-shell microspheres was 45% and 20%, respectively, the thickening rate was 325%, and the resistance of two-phase STFs decreased simultaneously with the emergence of shear thickening that reached the lowest value of 795.16 k omega. This study provides a novel strategy for synthesizing conductive STFs for strain-sensing flexible stab-resistant composites.

Automated summary

In this study, conductive SiO2@Ag core-shell microspheres were synthesized and their properties were evaluated. Two-phase STFs were prepared using SiO2 and SiO2@Ag as dispersed phases, and their rheological properties were investigated. The results showed that the core-shell microspheres with the most uniform coating and lowest conductivity were achieved when the concentration of sodium hydroxide and glucose were 0.07 and 0.09 mol L-1, respectively. The two-phase STFs exhibited good shear thickening behaviors and the thickening rate reached 325% when the mass fraction of SiO2 and SiO2@Ag core-shell microspheres was 45% and 20%, respectively. This study presents a novel strategy for synthesizing conductive STFs for strain-sensing flexible stab-resistant composites.