Preparation of Ag nanochain and its application for polyurethane-based flexible conductive composites

In consideration of the two key issues for the poor conductivity and poor flexibility of flexible polymer matrix conductive composites, flexible conductive fillers were prepared and the amount of fillers were reduced to solve these issues simultaneously. Deoxyribonucleic acid (DNA) molecule chains were utilized as template to fabricate Ag nanochains and Ag nanochains filled polyurethane-based flexible conductive composites. The interface structures of the Ag nanochains/Ag-coated Cu flakes/polyurethane conductive composites were studied by SEM. The mechanism of the conductivity and flexibility for Ag nanochains/Ag-coated Cu flakes/polyurethane conductive composites were discussed. Research shows that when the total mass fraction of conductive fillers is keep at 76% and the mass fraction of Ag nanochains is 4%, the optimum resistivity and the resistance change ratio of Ag nanochains/Ag-coated Cu flakes/polyurethane conductive composites before and after deformation were achieved, which are 2.13×10^-4 Ω·cm and 3.6 respectively. When the Ag nanochains were used as single fillers, the Ag nanochains/polyurethane conductive composites possess excellent flexibility. The Ag nanochains/polyurethane conductive composite prepared by foam template method achieves better conductivity at lower filler mass fraction. When the mass fraction of Ag nanochains is 60%, the sheet resistance is 56 Ω/sq, less than that of the Ag nanochains/polyurethane conductive composites prepared by blending method whose mass fraction of filler is 65% (98 Ω/sq).