Gelves G A, Lin B, Sundararaj U, Haber J A
Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, T6G 2G6, Canada.
Nanotechnology. 2008 May 28;19(21):215712. doi: 10.1088/0957-4484/19/21/215712. Epub 2008 Apr 23.
The morphological, electrical and rheological characterization of polystyrene nanocomposites containing copper nanowires (CuNWs) functionalized with 1-octanethiol is presented. Characterization by SEM and TEM shows that surface functionalization of the nanowires resulted in significant dispersion of CuNWs in the PS matrix. The electrical characterization of the nanocomposites indicates that functionalized CuNWs start to form electrically conductive networks at lower concentrations (0.25 vol% Cu) than using unfunctionalized CuNWs (0.5 vol% Cu). The organic coating on the nanowires prevents significant changes in the electrical resistivity in the vicinity of the percolation threshold. Percolated nanocomposites showed electrical resistivity in the range of 10(6)-10(7) Ω cm. The transition from liquid-like to solid-like behavior (rheological percolation) of the nanocomposites was studied using dynamic rheology at 200 °C. Unfunctionalized CuNWs result in electrical and rheological percolation at similar concentrations. Functionalized CuNWs show rheological percolation at higher concentration (1.0-2.0 vol%) than that required for electrical percolation. This is attributed to the decrease in the interfacial tension between nanowires and polymer chains and its effect on the viscoelastic behavior of the combined polymer-nanowire networks.
本文介绍了含有用1-辛硫醇功能化的铜纳米线（CuNWs）的聚苯乙烯纳米复合材料的形态、电学和流变学特性。扫描电子显微镜（SEM）和透射电子显微镜（TEM）表征表明，纳米线的表面功能化导致CuNWs在聚苯乙烯（PS）基体中显著分散。纳米复合材料的电学特性表明，与使用未功能化的CuNWs（铜含量为0.5 vol%）相比，功能化的CuNWs在较低浓度（铜含量为0.25 vol%）时就开始形成导电网络。纳米线上的有机涂层可防止在渗流阈值附近电阻率发生显著变化。渗流后的纳米复合材料的电阻率在10(6)-10(7) Ω·cm范围内。在200 °C下使用动态流变学研究了纳米复合材料从类液体行为到类固体行为的转变（流变学渗流）。未功能化的CuNWs在相似浓度下导致电学和流变学渗流。功能化的CuNWs显示出流变学渗流的浓度（1.0-2.0 vol%）高于电学渗流所需的浓度。这归因于纳米线与聚合物链之间界面张力的降低及其对聚合物-纳米线组合网络粘弹性行为的影响。
