十二烷基硫酸钠对碳纳米管悬浮液分散性能的影响

以十二烷基硫酸钠(SDS)为分散剂,制备碳纳米管悬浮液。通过测定SDS在碳纳米管表面的等温吸附曲线和悬浮液的Zeta电位,研究SDS对碳纳米管表面性质的影响。结果表明:SDS的加入使Zeta电位由-28 mV变为-48 mV左右,SDS浓度c(SDS)为2.0×10-3 mol/L左右时达到最大电位值并最终趋于稳定;SDS在碳纳米管表面的等温吸附曲线为典型的双平台型(LS型)吸附曲线。SDS吸附量在低浓度下(0.7×10-3~1.2×10-3 mol/L范围内)处于第一平台吸附值;随后SDS浓度进一步增大,吸附量迅速上升,在2×10-3 mol/L处趋近饱和吸附,吸附量达到第2个平台。悬浮碳纳米管浓度测定结果表明SDS可作为水性体系碳纳米管的分散剂,SDS的最佳浓度范围为2.0×10-3~8.0×10-3 mol/L,通过静电排斥和位阻效应有效阻止碳纳米管的团聚。

Effect of sodium dodecyl sulfate on dispersion properties of carbon nanotubes

Stable homogeneous dispersions of carbon nanotubes were prepared by using sodium dodecyl sulfate(SDS) as dispersant.Surface chemistry of the carbon nanotube was investigated by measuring isotherm adsorption and zeta potential.In the SDS solutions,the zeta-potential of carbon nanotube surface progressively increases with increasing the SDS concentration,in which the zeta potential of carbon nanotube changes from –28 mV to-48 mV.The adsorption isotherms of SDS adsorpting on carbon nanotubes was investigated,the curves of adsorption isotherms indicate a two-step mechanism of adsorption,and the isotherms reach the saturation plateau at SDS concentration of about 2.0×10-3 mol/L.The optimum concentration of SDS is 2.0×10-3~8.0×10-3 mol/L.The dispersion and stabilization of the carbon nanotubes in SDS aqueous solution is attributed to an electrostatic stablization mechanism.