Polymer nanocomposites (PNCs) of poly(3-hexylthiophene) (P3HT) with organically modified montmorillonite (om-MMT) clay have been prepared by the solvent casting method. WAXS and TEM studies indicate exfoliated clay structure for lower clay content, but at higher clay content (5%, w/w) intercalated structures appear. The interchain lamella of P3HT exists in the nanocomposite, and the P3HT crystals become more ordered, showing better X-ray diffraction peaks. The thermal stability of PNCs increases significantly, and 1% clay content PNC exhibits the maximum thermal stability. The glass transition temperature (T g), β-transition temperature (Tβ), the melting point (Tm), and the enthalpy of fusion (∆H) of the PNCs are increased as compared to those of pure P3HT. The storage modulus (G′) of PNCs showed a dramatic increase from that of pure P3HT, and the increase is larger in the temperature range 20-50 °C. The FTIR study indicates a decrease in Si-O-Si and Si-O stretching frequency for the exfoliated clay structure. The UV-vis study showed a blue shift of the π-π* transition band of P3HT in the PNCs, and they exhibit photoluminescence quenching which increases with increase in clay concentration. The dc conductivity of undoped PNCs remains almost the same as that of pure P3HT, but iodine-doped PNCs, however, exhibit 2.5-3 times greater conductivity than that of iodine-doped P3HT.

Highly dense arrays of ordered and aligned nanorods of polyaniline with 10 nm diameter on transparent ITO substrate have been successfully fabricated using supramolecular assemblies of block copolymer as scaffold material; the ordered arrays of polyaniline nanorods so fabricated were found to exhibit excellent electrochemical properties with an electrochemical capacitance value of 3407 F g(-1).

Poly(3-hexyl thiophene) (P3HT) organically modified montmorillonite (om-MMT) polymer nanocomposites (PNCs) are prepared in the melt-cooled state. Hierarchical structures up to third order, namely, side chain mesomorph formation followed by the interchain lamellar structure of P3HT and finally its intercalation within the clay tactoids are observed. The structures are supported by transmission electron microscopy (TEM) and wide-angle X-ray scattering (WAXS) experiments. The TGA curves show two-stage degradation corresponding to those of the side chain and main chain of P3HT, and both temperatures decrease with an increase in clay concentration in the PNCs. The melting points of PNCs have increased by 2-3 degrees C higher than that of P3HT. The glass-transition temperature (Tg) and beta-transition temperature (Tbeta), measured by DMA, increase with an increase in clay concentration. The storage modulus (G) of PNCs has also increased more dramatically than that of P3HT. The UV-vis spectra of the PNCs show a blue shift in the pi-pi* absorption peak of the conjugated chain, but the photoluminescence spectra showed a red shift with an increase in the clay concentration. The quantum yield of the photoluminescence process also increases in the melt-cooled PNCs, and this is in sharp contrast to that of solvent cast PNCs where photoluminescence quenching was observed. Fibrillar network structure of the solvent cast PNCs promotes energy transfer of the charge carriers, but its absence in the melt-cooled films inhibits such energy transfer, increasing the quantum yield. The room-temperature dc conductivity of the PNCs decreased by an order compared to that of P3HT in both the doped and undoped states. The I-V characteristic curve shows semiconducting behavior, and it slowly transforms into insulator with increasing clay concentration.

Soluble poly(3-hexylthiophene) (P3HT)-multiwalled carbon nanotube (MWNT) nanocomposites (PCNCs) are prepared by the in-situ oxidative polymerization of 3-hexylthiophene (3HT) in a dispersion of MWNT in CHCl 3 . The MWNT-P3HT nanocomposite produces blackish-brown solution in chloroform, making it an easily processable system. With increase in MWNT concentration the molecular weight of P3HT has increased, but at higher MWNT concentration (8% w/w) the molecular weight has decreased. The head-tail (H-T) regioregularity of the samples remains the same with that of pure P3HT. The TEM pictures of PCNC-1 and PCNC-8 [the number indicates percentage (w/w) of MWNT with respect to monomer in the composite] show uniform wrapping of MWNT with P3HT. The increase of outer diameter in wrapped MWNT decreases with increase in MWNT concentration, but the PCNC-2.5 exhibits phase segregation by the formation of separate spheroid-like species on the partially wrapped MWNT surface. The higher molecular weight P3HT produced in the PCNC-2.5 has been attributed to this difference in morphology. Type 1 P3HT crystal is formed in all the PCNCs, and melting temperature shows an increase with increasing MWNT concentration except for the PCNC-2.5 sample. The glass transition temperature (T g ) remains unchanged in the PCNCs, but the β-transition temperature (T β ) varies differently in the different PCNCs. The storage modulus of PCNCs has increased abruptly (maximum increase 158%) in the PCNCs than that of pure P3HT. The UV-vis spectra of PCNCs show a red shift in the π-π* transition band while the emission spectra show a small blue shift with increase in MWNT concentration. Fluorescence quenching occurs in the PCNCs, and it increases with increase in MWNT concentration except for the PCNC2.5 sample. The conductivity values of both undoped and doped PCNCs have increased significantly with increase in MWNT concentration. FT-IR spectra and NMR spectra indicate the presence of both CH-π and π-π interaction between P3HT and MWNT. Thus, the increased conductivity and mechanical properties of P3HT in the easily processable MWNT-P3HT nanocomposite are interesting for its probable use in different optoelectronic appliances.

CH 2 OH-terminated regioregular poly(3-hexylthiophene) (P3HT) was grafted onto carboxylic groups of acid-oxidized carbon nanotubes (CNTs) via esterification reaction. The P3HT-attached CNTs (P3CNTs) are soluble in common organic solvents, facilitating an intimate mixing with free P3HT chains for strong electronic interactions. The optical and electrochemical properties of the resultant nanocomposite were found to be different from the conventional composite, in which the pristine CNT and P3HT were physically mixed together (P3HT/CNT). Electrochemical measurements on the onset oxidation and reduction potentials of the P3CNT showed positive shifts by 0.06 and 0.1 eV, respectively, with respect to the corresponding values of pure P3HT, indicating that P3CNT has a lower highest occupied molecular orbital (HOMO) energy level and a lower lowest unoccupied molecular orbital (LUMO) energy level than those of pure P3HT. Bilayer photovoltaic devices with a thin film of pure P3CNT as the electrondonor and C 60 as the electron-acceptor layer showed an increase in the power conversion efficiency by about 40% with respect to their counterpart based on pure P3HT.