Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

Material Physics 153nature of D 2 O-PAM interaction (stronger) as compared to H 2 O-PAM interaction was found to playa crucial role on the diffusion of polymer, where the diffusion coefficient of the chains was an orderof magnitude higher in D 2 O as compared to that in the H 2 O. A lower value of the excluded-volumeparameter in case of D 2 O also indicates stronger monomer-solvent interactionM Mukherjee, Amarjeet Singh, J Daillant†, Alain Menelle†, F Cousin†SP5.1.2.6 Neutralization kinetics of charged polymer surfaceIn case of photoemission spectroscopy of an insulating material the data obtained from the chargedsurface are normally distorted due to differential charging. Recently we have developed a controlledsurface neutralization technique to study the kinetics of the surface charging. Using this techniqueand the associated data analysis scheme with an effective charging model, quantitative informationfrom the apparently distorted photoemission data from PTFE surfaces were extracted. The surfacecharging was controlled by tuning the electron flood current as well as the X-ray intensity. The effectivemodel was found to describe the charging consistently for both the cases. It was shown thatthe nonlinear neutralization response of differential charging around a critical neutralizing electronflux or a critical X-ray emission current was due to percolation of equipotential surface domains.The obtained value of the critical percolation exponent close to unity indicates a percolation similarto that of avalanche breakdown or chain reaction.Subhrangsu Mukherjee, M MukherjeeSP5.1.2.7 Preparation, Characterisation and Performance of Polysulfone Polypyrrolemembrane in the separation of ionsApart from the electronic properties, conducting polymers are usable in the membrane based separationscience. Evidences are there that the conducting polymers have the potentiality in theselective ion transport in electrical field. Poor mechanical strength of the conducting polymersrestricts their applications in various areas. One of the approaches to increase the applicabilityof conducting polymers is the preparation of composites. Here, in this case we have coupled thePolypyrrole with the polysulfone in composite. Polysulfone is one of the classical polymers for thepreparation of polymeric asymmetric porous membranes by the phase inversion method.S Kundu, A Bhattacharya†SP