聚吡咯/多壁碳纳米管及其聚氨酯导电复合材料的制备和性能

以羧基化多壁碳纳米管(MWCNTs)做模版剂,采用化学氧化法将吡咯(Py)在羧基化MWCNTs表面聚合制备PPy/MWCNTs导电材料,将其添加到溶剂型聚氨酯(PU)溶液中制备了PPy/MWCNTs/PU导电复合材料,研究了Py用量对PPy/MWCNTs及其PU复合材料性能的影响.研究表明,随Py用量的增加,PPy/MWCNTs的长度不变,管径增大,sp~2和sp~3杂化C含量先提高后减少,N的掺杂梯度降低,PPy/MWCNTs的导电率高于羧基化MWCNTs和PPy.当Py用量为羧基化MWCNTs的20%时,其导电率最大.PPy/MWCNTs中N元素的掺杂程度及其管径变化是引起PPy/MWCNTs/PU复合材料的性能不同的主要原因.增加Py用量,MWCNTs中亲水的羧基因对PPy掺杂而消耗,相同导电材料用量时纳米导电粒子数目相对减少,PPy/MWCNTs/PU复合材料的耐水性能提高,定向应力、储能模量和玻璃化温度降低,导电率先增加后减小.当Py用量为羧基化MWCNTs的15%时,导电率最大.

Preparation and Properties of Polypyrrole/Multi-walled Carbon Nanotubes and Their Polyurethane Composites

Polypyrrole/multi-walled carbon nanotubes (PPy/MWCNTs) conductive fillers and their polyurethane (PU) composites were synthesized via chemical oxidative polymerization of pyrrole (Py) on the surface of carboxylated MWCNTs in the presence of FeCl3 oxidant at 0 ℃.The effects of Py dosage on the properties of PPy/MWCNTs and on their PU composites were investigated.FTIR results suggested that an interaction force existed between the-COOH carboxylated groups of MWCNTs and the NH groups of PPy.Thermogravimetric analysis (TGA) demonstrated that carboxylated MWCNTs made a noticeable improvement in thermal stability compared with PPy.Test of scanning electron microscopy (SEM) showed that Py polymerization of occurred on the surface of the carboxylated MWCNTs and Py content changed the aspect ratio of PPy/MWCNTs.Deconvolution of the C 1 peak of X-ray photoelectron spectroscopy (XPS) suggested that an increase in Py dosage led to a first increase and then decrease in the content of sp2 and sp3 hybrid carbons,with a decrease in the ratio of doping nitrogen.Accordingly,the electrical conductivity of PPy/MWCNTs increased first and then decreased.The highest conductivity was obtained when Py content was 20％ based on the weight of the carboxylated MWCNTs.The change in PPy doping and the aspect ratio of PPy/MWCNTs played a significant role in the properties of PPy/MWCNTs/PU composites.Increasing Py dosage resulted in an improvement in the water resistance of the PPy/MWCNTs/PU composites,with a decrease in their tensile stress,storage modulus and glass transition temperature.The conductivity of PPy/MWCNTs/PU showed a similar trend to that of PPy/MWCNTs,and the highest electrical conductivity was obtained with Py content of 15％.It is suggested that PPy/MWCNTs possess better thermal stability,electric conductivity and reinforcing properties than PPy,and their PU composites have good processability,mechanical properties and electrical conductivity.