Fabrication and interfacial characteristics of surface modified Ag nanoparticle based conductive composites

The recent emergence of wearable electronics has driven the advancements of flexible and elastic conductive metal-polymer composites as electrodes and sensors. Surface modification of the conductive metal fillers are required to achieve a good dispersion within the matrix to obtain suitable conductivity and sensing properties. Additionally, it would be critical to ensure that the inclusion of these fillers does not affect the curing of the pre-polymers so as to ensure sufficient filler loading to form functional composites. In this work, a one-step approach is used to modify Ag-PAA nanoparticles via hydrogen bonds to form PAA-PVP complex modified Ag nanoparticles. The interfacial characteristics and thermal stability of these surface-modified Ag nanoparticles were studied to elucidate the underlying chemistries that governed the surface modification process. After surface modification, we successfully improved the dispersion of Ag nanoparticles and enabled curing of PDMS to higher Ag loadings of similar to 25 vol%, leading to much lower electrical resistivity of similar to 6 U cm. Our studies also showed that Ag nanoparticles modified at a PAA/PVP molar ratio of 1 : 10 resulted in a minimal particle aggregation. In a preliminary testing of our conductive composites as electrodes, clear electrocardiography signals were obtained. The facile surface modification method introduced here can be adapted for other systems to modify the particle interfacial behavior and improve the filler dispersion and loading without adversely affecting the polymer curing chemistry.