Novel properties of PMMA/PVAc matrix, slightly doped with MDMO-PPV
Ishwar Naik, Rajashekhar Bhajantri, Vinayak Bhat
AIP Conference Proceedings 2104, 030040 (2019)
We have prepared 1:1 blend of PMMA /PVAc in chloroform as the common solvent, the blend is doped with the light emitting polymer Poly [2-methoxy-5-(3’,7’-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) at a very low concentrations of 0.1%, 0.2%,0.3%, 0.4% and the films are prepared by solution cast method. Samples are subjected to UV-Visible spectroscopy using Jasco UV-Vis 700 spectrometer in which the spectrum confirmed a red shift in max absorption wavelength(λmax) towards higher doping concentration. The optical band gap is calculated using Tauc’s plot that indicated a drastic reduction in the band gap of pure PMMA/PVAc from 5.03 eV to 1.98 eV. Fluorescence spectral study is carried out using Fluoromax Plus CP Spectrofluorometer, 0124D-1816-AFMPLUS,HORIBA by exciting the samples with 340nm. The samples exhibit the maximum emission at 585nm and a small red shift in the emission maximum towards 0.4% doped film. Relatively small emission peak is also observed at 540nm which is pronounced for 0.1% and getting suppressed with higher doping concentrations. Considerable Stokes shift is also noticed in the absorption – emission spectral analysis. The ac electrical conductivity and dielectric properties are studied using Agilent 4294A Precision Impedance Analyzer. The conductivity increases with increase in frequency and also with increase in doping concentration. Dielectric constant and dielectric loss decrease with the increase in frequency and with increase in doping level of LEP. The thermal stability of the samples is investigated using Universal TA-SDT Q600 in which TGA and DTGA curves indicate that doped samples are more stable than the pure polymer matrix. The Structural studies carried out using IR –Prestige-21 FTIR Spectrometer SHIMADZU, confirmed small interaction between the host and dopant. DC conductivity studies done with Keithly -236 source measure unit shows an increase in conductivity with the increased doping level. This enhancement in conductivity is attributed to the induced free charge carriers (holes) by the dopant into the host matrix. We conclude that the new material has several novel properties like, transparency, light harvesting, red light emitting, conducting and also enough stability. These properties can be used in the construction of plastic electronic devices along with scope for future research.
PMMA, light emitting polymer, Poly [2-methoxy-5-(3’,7’-dimethyloctyloxy)-1,4-phenylenevinylene