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This study presents a method to polymerize aniline in styrene-divinylbenzene copolymer pores using benzoyl peroxide as an initiator. The composites are sulfonated, impregnated with tin oxide (IV) and used as heterogeneous catalysts in the direct polycondensation synthesis of PLGA. Evaluation of parameters such as molar proportion, temperature, time, quantity and type of catalyst were carried out. The characterization of composites and PLGA's were performed by: elemental analysis, DRX, FTIR, nitrogen adsorption-desorption, Bronsted acid site determination, SEM, ICP/OES, and inherent viscosity. The polyaniline deprotonation before thermal treatment enhances crosslinking, increasing surface area and stability of the porous structure. The composite acts as a catalyst, increasing PLGA molar mass, reducing oxidation and tin contamination. The process has several advantages like PLGA production without solvent contamination, lower tin content, and no high-cost cyclic dimmers use. So far, the results show promising catalytic performance of the developed composite. KEYWORDS catalyst, composite, poly (lactic-co-glycolic acid), polyaniline, polycondensation, styrene-divinylbenzene, 1 | INTRODUCTION Polymers are present in human lives and have been widely used in the industrial area for packaging, food, medicine, and construction. They are an alternative material for [...]

Polyaniline nanostructures have been synthesized by self-assembly method by varying the dopant to monomer molar ratio. High resolution transmission electron micrographs show how the dopant to monomer molar ratio influences on the morphology and structure. The temperature dependence of dc conductivity study shows semiconducting behavior. From dc conductivity study it has been observed that conductivity increases with increasing dopant concentration and maximum conductivity is attained at dopant to monomer molar ratio of 3:4. From the slope of the reduced activation energy versus temperature plot it is confirmed that the charge transport in polyaniline nanostructures is in insulating regime and dominated by variable range hopping mechanism. In particular, a crossover from 1D to 3D variable range hopping conduction is observed by changing the dopant to monomer molar ratio. With increasing the dopant concentration the 680 nm absorption peak shifted towards higher wavelength range. The red shifting of this peak indicates the increased extent of π-conjugation length. The enhancement of characteristic band intensity at 1336 [cm.sup.-1] in Micro-Raman spectra indicates the increase of delocalization degree. Temperature profiles of the degradation processes have been mapped using thermogravimetry analyzer and it is observed three-step weight losses for all the samples., INTRODUCTION Conducting polymers are a class of functional materials having alternating single and double carbon-carbon bonds along the polymeric chains. The highly conjugated polymers possess reversible chemical, electrochemical, and physical [...]

Polyaniline (PANI) electrode was synthesized on a conducting indium tin oxide glass by in situ oxidative polymerization to construct a low production cost counter electrode of dye-sensitized solar cell (DSSC). The scanning electron microscopy image showed that PANI electrode was a porous state with the particles diameter in 20-30 nm. The cyclic voltammogram measurement revealed that PANI electrode had smaller charge transfer resistance and higher electrocatalytic activity for [I.sub.3.sup.-]/[I.sup.-] redox reaction. The Brunauer-Emmett-Teller (BET) surface area of PANI was high to 53.114 [m.sup.2]/g, and the high surface area of PANI electrode benefited for the absorption of electrolyte. Finally, we compared the photoelectric properties of DSSC using the PANI counter electrode and platinized counter electrode. The results indicated the efficiency of DSSC with PANI electrode reached 2.64%, which was higher than that with platinized electrode (1.75%). Therefore, the PANI counter electrode with excellent catalytic performance is a potential substitute for platinized electrode to save cost of DSSC. POLYM. ENG. SCI., 51:663-669, 2011. [C]2010 Society of Plastics Engineers, INTRODUCTION Dye-sensitized solar cells (DSSCs) are one of the most promising photovoltaic devices owing to their high conversion efficiency and low cost [1-4]. The photovoltaic device is composed of a [...]

Substituted polyaniline, poly(N-ethyl aniline) (PNEA), doped with camphor sulphonic acid (CSA) and p-toluene sulphonic acid (p-TSA), was synthesized by single-step chemical polymerization method using ammonium persulphate as an oxidizing agent. This is a single-step polymerization process to synthesize directly the conducting emeraldine salt phase of the polymer using CSA and p-toluene sulphonic acid as dopants. The synthesized polymers were characterized by UV-vis and FTIR spectroscopy, scanning electron microscopy, TGA/SDTA, DSC, and conductivity measurements. This single-step chemical synthesis method offers a polymer having very good physicochemical properties with good electrical conductivity. High temperature conductivity measurements show 'thermal activated behavior.' The change in resistance with respect to % relative humidity (% RH) is observed, when pressed pellets of the polymer were exposed to the broad range of humidity (ranging between 20 and 100% RH). POLYM. ENG. SCI., 47:1621-1629, 2007. © 2007 Society of Plastics Engineers, INTRODUCTION In the past few decades, inherently conducting polymer (ICP) polyaniline, (Pani) has been paid considerable attention because of its high electrical conductivity [1], thermal stability [2], ease of preparation [...]