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Aniline was polymerized under different experimental conditions such as interfacial polymerization, rapid mixing in hydrochloric acid medium and classical bulk polymerization method using p-toluene sulphonic acid. The resulting polyanilines were characterized by infrared, X-ray diffraction, conductance and scanning electron microscopic analysis. The main emphasis of the paper is to study the thermal response of the synthesized polyanilines by thermogravimetric analysis and differential scanning calorimetry (DSC). The DSC data were utilized further to calculate the specific heat capacities of the synthesized polyanilines as a function of temperature.

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Density data of good precision for binary aqueous solutions containing salt of a homologous series of alkyltrimethylammonium bromides [hexyl (C6TAB), octyl (C8TAB), decyl (C10TAB), dodecyl (C12TAB), tetradecyl (C14TAB), and hexadecyl (C16TAB)] at 293.15, 298.15, and 303.15 K are reported. Using the density data, the apparent molar volumes of solutes at finite concentration (ϕV) and at infinitely dilute solutions (ϕV 0) have been calculated. The partial molar volumes (V̅ 2), apparent molar expansivity (ϕE) and limiting molar expansivity (ϕE 0) parameters at 298.15 K are also reported. The pseudophase separation model has been utilized to estimate critical micelle concentration (cmc) and aggregation number (n) of the studied surfactant molecules. The main result of our studies is the observation that the expansivity parameter goes through a maximum at cmc except in the case of C6TAB and C8TAB surfactants at 298.15 K. The volume changes due to micellization (ΔV x mic) and standard unitary free energy changes for micellization (ΔG m *) have been estimated and their magnitudes found to depend upon the chain length of the alkyltrimethylammonium ions.

Studies of water contents of solid -cyclodextrin (-CD) in crystallized and vacuum dried conditions are reported. Water contents were estimated using Karl-Fischer (KF) titration and thermo-gravimetric analysis (TGA) techniques. It was found that the water contents for crystallized and vacuum-dried samples were 6.93 and 0.86 moles of water per -CD molecule respectively. TGA studies gave values of 6.83 and 0.52 moles of water per -CD molecule respectively. The results agree with those reported from X-ray diffraction studies. Also, the molecular weight of the vacuum dried sample was determined using vapour pressure osmometry, which agrees well with the actual molecular weight of -CD. The thermal profiles of -cyclodextrin (-CD) and -CD are presented. The differential scanning calorimetry data was used to calculate specific heat at constant pressure (C p ) at different temperatures (338.15-468.15 K). These results are compared with similar data for -CD and discussed in terms of motional contribution to C p values and related conformational effects.