Electrical Conductivity Of Miscible Polymer Blends/Multiwalled Carbon Nanotube Composites

Polymer-MWNTs composites has always been the central issue in materials and energy area, since they possess not only the excellent mechanical properties of polymers at low loading of MWNTs but also good conductivity, thus can be applied in many fields. Until now conductive miscible polymer blends/CNTs composites has been barely reported.We herein did the following work:1, We synthesized quasi-block copolymer to ameliorate the conductivity of immiscible polymer blends PMMA-PS/MWNTs composites and proposed an optimized double-percolation theory based on the classic double-percolation concept. Quaisi-block copolymer (qb) FMMA-qb-VS were synthesized by two step of prepolymerization-copolymerization, with block PDI of1.8and can be deemed to be miscible polymer blends. We also fabricated immiscible polymer blends/MWNTs composites and random copolymers to investigate systematically. The characterization of the composites includes Hall effect detection, field effect scanning electronic microscopy (FESEM), Fourrier transformation infrared spectrum (FTIR), X-ray photoelectron spectrum (XPS). Results from Hall effect detection demonstrated that enhancement of carrier concentrations are main factor of improvement of conductivity. FESEM results attested that carbon nanotubes distribute in the pre-PMMA blocks to detour micro-and nanoscale blocks of pre-PS blocks and construct a regular network frame. Both FTIR and XPS testified that CNT in qb/CNTs composites has the most potent doping effect.2, Based on the first work, we designed miscible polymer blends polyvinyl choloride (PVC)/qb/MWNTs composites in solution situation that has lowered the electrical percolation threshold to0.071wt%. The characterization mainly includes FESEM and XPS. The proposed mechanism is based on the1st work of qb/MWNTs composites, which were continuous phase with PVC as the dispersed phase, forming a localization of qb/MWNTs regular network frame in the composite as a whole. And the compatibility between PVC and PMMA-segments diminishes as the CNTs content grows. XPS results indicate that carrier concentration in the composites increases as the network frame forms, and the carrier mobility enlarges as the doping CNTs grows. DSC (Differential scanning calorimetry) results indicates that Tg (glass transition temperature) is reduced drastically as percolation threshold is established (1035℃/wt%) before it reaches a plateau with some fluctuations. Therefore, the compatibility and dynamics in this regime requires more work to be done.3, We fabricated both miscible PMMA/PVC/CNTs composites and immiscible PMMA/PS/CNTs composites through solution-mixing and annealing process and obtained ultralow electrical percolation threshold of0.0005wt%, which is so low and has not been reported yet.