The present work reports an easy route for synthesis of polyaniline (PAn) in stable aqueous solution/dispersion form, using poly(vinyl alcohol) (PVA) as an efficient steric stabilizer. Resulting composite successfully combines desirable physical properties like mechanical strength, solution processibility and electrical conductivity of PVA and PAn components. The composite was subjected to versatile characterizations and its different physical properties (especially optical, thermal, mechanical and electrical) were explored. Free standing films can be obtained from the solutions, which exhibit important microwave shielding property over the X-band. This has enhanced the importance of this material to a large extent. © 2001 Elsevier Science B.V. All rights reserved.

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University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Polyaniline-poly(vinyl alcohol) conducting composite : material with easy processability and novel application potential

Synthetic Metals

Interpenetrating polymer network (IPN) composites of polypyrrole (PPy) and poly(vinyl acetate) (PVAc) were prepared by dipping FeCl3 impregnated PVAc films into solutions of pyrrole in water. PVAc becomes colored due to partial dehydroacetylation and also insoluble due to FeCl3 treatment. These properties do not change on leaching out FeCl3 from the films. However, differential scanning calorimetry shows that the Tg of PVAc remains unchanged in the FeCl3 treated films indicating that the dehydroacetylation did not proceed to significant extent. The FeCl3 impregnated films however swell rapidly with simultaneous leaching of FeCl3 when they are immersed in water. The extent of swelling decreases with decrease in temperature. Considerable swelling occurs even below the Tg of the polymer. PPy forms inside the swollen films when the impregnated films are dipped into aqueous solutions of pyrrole instead of water. The DSC studies of the composite films reveal that the Tg of PVAc is increased to higher temperatures with increased incorporation of PPy indicating that there may be some mixing between PPy and PVAc. The percolation threshold for electrical conductivity occurs between 3.5 to 5 wt.% of PPy in the composites. The threshold values are found to be insensitive to the degree of swelling of the FeCl3 impregnated films. The low values of fp have been attributed to fractal growth of PPy phase in the water channels of the swollen films. This view is supported by the SEM images of the cryofracture surface of the composites which reveal the formation of PPy particles in the channels formed by water during swelling of the films. The effects of O2, moisture and temperature on the conductivity of the films have also been studied. The present method is not universally applicable. Thus, with PMMA or polycarbonate used as the matrix polymers FeCl3 goes quickly into solution in water without swelling of the films and no composite is formed. © 1999 Elsevier Science S.A. All rights reserved.

Interpenetrating polymer network composites of polypyrrole and poly(vinyl acetate)

Peroxodisulfate-induced polymerization of aniline in aqueous acidic (HCl) media using the support of a water soluble polymer polyacrylamide, PAAm produced polyaniline (PANI) in aqueous dispersion/solution having high stability and easy processability. PAAm support apparently allows limited grafting of PANI on it in addition to causing a template effect through hydrogen bonding between segments of the two polymers; this explains fairly uniform and high degree of dispersion or solubility of PANI with exceptional storage stability. Aqueous and isolated dry PANI-PAAm composites were characterized spectroscopically (UV-Vis and FTIR), thermally (TGA, DSC) and with respect to their electrical conductivity at different PANI loadings and temperatures. The morphology of the composites were studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). © 1999 Elsevier Science Ltd. All rights reserved.

European Polymer Journal

Studies on stable aqueous polyaniline prepared with the use of polyacrylamide as the water soluble support polymer

Polyaniline (PANI) of high stability and good processibility was prepared in acidic aqueous dispersion/solution, using the support of a water soluble polymer poly(vinyl pyrrolidone) (PVP). The high degree of dispersion and near solubility and storage stability of the PANI prepared, are explained on the basis of the synchronized establishment of hydrogen bonding, between segments of PANI being formed during the polymerization of aniline and the PVP present in the solution. Studies of the prepared dispersions/solutions of the PANI-PVP composites, by viscometry and UV-visible spectrophotometry, lend support to this view. Results of studies of the isolated PANI-PVP composites of different PANI loadings by FTIR spectroscopy, also support this view. The PANI-PVP composites were also thermally characterized, employing thermogravimetric analysis and differential scanning calorimetry (TGA and DSC, respectively). They were characterized microscopically, by transmission electron microscopy (TEM), for the prepared dispersion or solution of PANI in the presence of PVP, and by scanning electron microscopy (SEM) for selected isolated PANI-PVP composites. © 1999 Elsevier Science Ltd. All rights reserved.

Journal	Synthetic Metals
Publisher	-
ISSN	0379-6779