Supporting Document
Synthesis, Charge Transport Studies and Microwave Shielding Behavior of Nanocomposites of Polyaniline with Ti-Doped--Fe2O3
Anoop Kumar Sa,b, Avanish Pratap Singha, Parveen Sainia, Fehmeeda Khatoonb and S.K. Dhawana*
aPolymeric & Soft Materials Section, National Physical Laboratory (CSIR),New Delhi-110 012, India
bDepartment of Applied Sciences, Faculty of Engineering & Technology, Jamia Millia Islamia, New Delhi-110025, India
*E-mail:
Fax: 91-11-25726938
The band gap calculation
The optical band energy of the polymer was obtained from the given relation
Whereis the absorption coefficient, his the photon energy and Eg is the optical band gap. The band gap is calculated by the slopeof curve between shows that as the amount of FT increases, the band gap increases. The band gap of transition for FPT0, FPT1,FPT2 respectively are 2.26eV,2.30eV,2.49eV and band gap of polaron transition for FPT0, FPT1,FPT2 respectively are 1.30eV,1.43eV,1.44 eV.
Figure.1The curve between for the calculation of band gap.
FTIR spectra of polymer composite
Figure.2 shows the FTIR spectra of pure polyaniline and doped composites. The spectra of all composites gives the characteristic bands of both benzenoid and quinoid units which confirms the presence of polyaniline. FTIR spectra of polyaniline doped with DBSA( FPT0) , FPT1, FPT 2 and FT.The main characteristics bands for the polyaniline doped with DBSA are found at 1550 and 1400cm-1which are assigned for the C=C bond stretching vibrations of quinoid and benzenenoid rings respectively. Bands at 1257 cm-1 and 1064cm-1 are due to C=N stretching and in-plane bending of the C- H bond . The peak at 1639cm-1 may be due to the formation of the carbonyl group arising due to the over oxidation of the alkyl chain of the DBSA. In case of titanium doped ferric oxide , the main peaks are observed at 1636, 1419, 1363, 637 and 558.8cm-1. The presence of the peaks at 637cm-1 and 558.8cm-1 which are the characteristic band of Fe–O & Ti-O band stretching respectively and these peaks are also found in polymer composite clearly indicate the presence of titanium doped ferric oxide in the polymer matrix while the shifting in the main peaks arises due to the interaction of the titanium doped ferric oxide with N-atom of the aniline ring.
Figure.2 The FTIR spectra of pure polyaniline,FT and polyaniline composites.
Variation of reduced activation energy (W) with temperature (T)
The reduced activation energy (W) can defined as:
(1)
Further according to VRH theory:
(2)
The differentiation of eqn. 2 and putting the vales in eqn. 1 gives:
(3) Taking log both sides gives:
(4)
Therefore, the slope of the graph between ln W and ln T plot gives the actual value of VRH exponent ().It was observed that for FPT2 ‘’ was ~0.245
Figure.3Shows the variation of reduced activation energy (W) against temperature (T) on a double logarithmic scale.