Melt/Solution processalb epolyaniline with functionalized phosphate ester dopants andits thermoplastic blends

摘要

Polyaniline (PANI) was doped with five novel dopants, 3-pentadecyiphe-nyiphosphoric acid (PDPPA), pentadecylphenyl(bis)phosphoric acid [PDP(bis)PAJ, monocardanyiphosphoric acid (MCPA), dicardanyiphosphoric acid (DCPA), and phos-phorylated cashew nut shell liquid prepolymer (PCNSL) and the doping behavior was studied. All dopants were synthesized from inexpensive naturally existing monomers [obtained from cashew nut shell liquid (CNSL)] having a long hydrophobic hydrocarbon side chain in the meta position of the aromatic ring. These dopants can act as plasti-cizing cum protonating agents for PANI so that free-standing films of PANI could be prepared by both thermal processing and solution processing techniques. Protonation was performed either by mechanical mixing of emeraldine base and the dopant or by an in situ doping emulsion polymerization route using xylene or chloroform as the solvent. Further, conductive flexible blends of the protonated PANI with poly(vinyl chloride) (PVC) were also prepared and studied for their conductivity and related properties. The PANI—PDPPA complex obtained by the in situ doping emulsion polymerization route exhibited an exceptionally high degree of crystalline order and orientation. A maximum conductivity value of 1.8 S cm’ was obtained for a PANI—PDPPA film hot-pressed at 1200C. On the other hand, dopants based on cardanol having an unsaturated side chain gave only lower values. This was understood to be due the capability of the saturated analog to contribute to the ordered arrangement of PANI, thus improving the crystal-linity. The conductivity values further decreased when bulky/oligomeric dopants such as PCNSL were used. The thermoplastic blends with PVC exhibited an exceptionally low-level percolation threshold because of the plasticizing nature of the dopants. The doped polymers and blends were characterized by FTIR and UV-visible spectroscopic methods, four-probe conductivity measurements, XRD, SEM, TGA, and DSC.