title: Influence of Conducting Polymer as Filler and Matrix on the Spectral, Morphological and Fluorescent Properties of Sonochemically Intercalated poly(o-phenylenediamine)/Montmorillonite Nanocomposites.
abstract: BACKGROUND
  Nanocomposites consisting of spatially confined polymeric chains are of great interest due to their application in optoelectronic and photonics devices. Polymer layered silicate nanocomposites have attracted much attention in industry as well as academia owing to their remarkable physical and chemical properties as compared to conventional polymer nanocomposites.
  
  
  METHODS
  In present study, comparative investigation of the in-situ polymerization of poly(ophenylenediamine) intercalated montmorillonite has been done via two methods i.e using poly(o-phenylenediamine) as filler for MMT in one case and as matrix in the other. Intercalation and in-situ polymerization was confirmed by FT-IR, UV-Visible spectroscopy and XRD studies. TEM and optical microscopy studies confirmed the self-assembled morphology of nanocomposites while the fluorescence properties revealed that controlled emission could be achieved by confining poly(o-phenylenediamine) in MMT galleries.
  
  
  RESULTS
  Intercalation and in-situ polymerization of o-phenylenediamine within MMT was successfully carried out using sonochemical technique. The growth of conducting polymers in the interlayer region of the clays has been shown to dramatically improve the properties of conducting polymers. Also, the loading of the polymer in the MMT has shown to influence the optical properties of the nanocomposite. IR spectra and XRD analysis confirmed the intercalation of POPD and its polymerization within the clay galleries. UV spectra revealed the doped state of POPD within clay galleries. Highest oscillator strength of 0.0137 was observed for POPD:MMT-1:0.25. Spherical self-assembled morphology was attained for POPD:MMT-1:0.25. XRD revealed major shift of 82.5 Å for the nanocomposite POPD:MMT-1:1, POPD:MMT-1:0.5 and MMT:POPD-1:0.25. Blue shift of 20 nm was noticed in the fluorescence spectra of POPD:MMT-1:0.25 and POPD:MMT-1:0.5 which was correlated to the intense interaction between NH of POPD with SiO of MMT. Highest quantum yield of 0.345 was achieved in case of POPD:MMT-1:0.25. The gallery confinement was found to control the optical as well as morphological characteristics of the nanocomposite. The controlled growth of POPD chains and their minimum aggregation resulted in the formation of self-assembled morphology. Thus, by choosing the optimum filler loading and by controlling its interaction with the matrix, nanocomposites with controlled architecture can be designed.
  
  
  CONCLUSIONS
  It can be concluded that intercalation and exfoliation of nanocomposites largely depends on the experimental conditions such as type of conducting monomer, clay and organic modifier etc. The preparation technique and processing conditions influence the overall properties of the nanocomposites. Thus, by choosing the optimum filler loading and by controlling its interaction with the matrix, nanocomposites with controlled architecture can be designed. Few relevant patents to the topic have been reviewed and cited.
authors.affiliation: Department of Chemistry, Jamia Millia Islamia (A Central University), New Delhi-110025, India. uriaz@jmi.ac.in.
authors.forename: Ufana
authors.initials: U
authors.lastname: Riaz
authors.forename: Syed M
authors.initials: SM
authors.lastname: Ashraf
authors.forename: Anurakshee
authors.initials: A
authors.lastname: Verma