Electro active composite system as hydrogels was prepared from non-conducting polymer and conducting polymer combined together. This type of composite hydrogels has both properties of hydrogel and conducting polymer representing a new material. Polyacrylamide hydrogels was prepared by polymerizing acrylamide (5 mole/L) in an aqueous solution of (NH4)2S2O8(0.20 mole/L) containing a crosslinker N,N’ methylene bisacrylamide (0.2 mole/L) in a test tube at 40oc for 24 hours. After polymerization, the cross linked polymer was isolated from the tube in a long cylindrical shape which was cut into pieces in one cm in length. After getting it washed repeatedly to remove the soluble materials and then dried at room temperature for 48 hours. The hydrogel, so formed, was soaked in an aqueous solution of aniline hydrochloride (1 mole/L) solution to allow the monomer to diffuse inside the hydrogel networks. When 0.25 mole/L FeCL3- an oxidant was added to the solution, the polyaniline was formed inside the porous structure of hydrogel. The resulting hybrid polymer was taken out from polymerizing mixture which was thoroughly washed and dried. The sample appeared deep dark green colour. The average surface resistance (Inverse representation of conductivity) of the sample was estimated about 103 Ohm. Another oxidant like Fe2(SO4)3 gives almost the same results. The reproducibility of conductivity value is poor because it is very difficult to form uniform distribution of the conducting polymer throughout in the hydrogel networks.

Summary The polymerization was carried out under the different concentrations of acrylamide and crosslinker in an aqueous solution of NO2 gas as initiator at 50°C. The resulting polyacrylamide was saponified with NaOH solution. The hydrolysed polymers show high degree of water swelling (>500) than that of unhydrolysed polymers (<100). Swellability of the gel decreases with the increasing concentration of N, N’‐ methylene bisacrylamide − a crosslinker which enhances the degree of crosslinking in the polymer chains. The increased crosslinking restricts the expansion of polymer network which causes the lowering of the water absorbency. It was observed that polymer hydration increased with the molar mass of polyacrylamide. The swellability of polyacrylamide hydrogels is greatly lowered by the addition of ionic salts in the swelling medium. Both ionic strength and valency of the salts are responsible to decrease the water uptaking capacity of the gels which remain unaffected by nondessociating nature of urea. The hydrogels, so prepared, are stable and quite able to undergo swelling − deswelling cycles suggesting their reversible characters.

The electroinitiated polymerization has been described here. The polymerization mixture consisted of monomer dissolved in an aqueous solution of ZnCl2, and was subjected to electrolysis in a divided cell. The rates of polymerization increased linearly with increase in applied current level and monomer concentration. Polymers of high molecular weights (≍105) were obtained from intrinsic viscosity measurements that increased with monomer concentration. The cyclic voltammogram of acrylamide in H2O -ZnCl2 solution suggests that the monomer gets directly reduced at cathode and the polymerization mechanism is anoinic.

The polymerization of toluene was carried out in 1, 2-dichloroethane and nitrobenzene using BF3O(C2H5)2 as supporting electrolyte at platinum electrodes. The polymers were formed as a black mass only at the anode surface. The yield and conductivity of Poly(toluene)or poly(methyl phenylene) depend on the nature of solvents. Cyclic voltammetry measurements suggest that the polymer film is fairly stable.

The polymerization was carried out under the different concentrations of acrylamide and crosslinker in an aqueous solution of NO 2 gas as initiator at 50 º C. The resulting polyacrylamide was saponified with NaOH solution.The hydrolysed polymers show high degree of water swelling (> 500) than that of unhydrolysed polymers (< 100).Swell ability of the gel decreases with the increasing concentration of N, N'-methylene bisacrylamide -a crosslinker which enhances the degree of crosslinking in the polymer chains.The increased crosslinking restricts the expansion of polymer network which causes the lowering of the water absorbency.It was observed that polymer hydration increased with the molar mass of polyacrylamide.The swell ability of polyacrylamide hydrogels is greatly lowered by the addition of ionic salts in the swelling medium.Both ionic strength and valency of the salts are responsible to decrease the water uptaking capacity of the gels which remain unaffected by nondessociating nature of urea.The hydrogels, so prepared, are stable and quite able to undergo swelling -deswelling cycles suggesting their reversible characters.

Electrochemical polymerization of N-vinylcarbazole was carried out in a solution of tetramethyl ammonium chloride in dichloroethane at a constant current. The polymer yields increase with increasing concentration of monomer, impressed current level andelectrolysis time. The inhibition of polymer formation by a free radical scavenger, 2-2-diphenyl-1-picrylhydrazyl supports a free radical mechanism. The free radical species are generated in situ during the electrolysis of polymerizing mixture. Cyclic voltammograms demonstrate the polyvinylcarbazole formed electrochemically in a solution of (C4H5)4NSbC16 or (C4H9)4NClO4 in DCE undergoes oxidation-reduction states. The polymerization of NVCZ resulted in the formation of cross linked conductive polymers on the anode. The conductivity was found to be about 10−6 scm−1.

The redox copolymerization of acrylonitrile with acrylamide in N, N-dimethylformamide (DMF) containing K2S2O8 and AgNO3 was carried out. The resulting copolymers were soluble in this solution. A white floppy mass was obtained, when poltmerizing solution was poured in cold methanol. The copolymers were formed taking different feed ratios of monomers and concentrations of the initiators at 60°C. As the concentration of acrylamide increased in the feed ratio, copolymer yields consierably increased. The copolymerization was completely inhibited by 2, 2-diphenyl-1-picrylhydrazyl suggesting a free radical reaction.

The anodic polymerization of methacrylamide at Fe-electrodes was carried out in the presence of H2O2. No polymer formation occurred in the absence of H2O2. Fe-anode dissolves to furnish Fe (II) ions that decompose H2O2 to produce hydroxyl radicals HO which initiate a free radical polymerization. The reaction continues even after the cessation of electrolysis. The polymer yield increased with the increase of current density and monomer concentration. However the polymer yield initially increased and then began to decrease with the increasing concentration of H2O2. This is because of the decomposition of H2O2 to generate O2 which retards the polymer formation.

Polymer hydrogels are cross linked hydrophilic polymers which are insoluble but absorb, swell and retain large amount of water. They exhibit both liquid and solid like properties. The properties of hydrogels are greatly enhanced by mixing them with metal nanoparticles. Such materials have great promise for technology. We carried out the formation of polyacrylamide hydrogels-metal nanoparticles composites by electrochemical method. The simultaneous reduction of the solution of acrylamide in water and metal ions occurred and subsequently polymer-metal nanoparticles composites were formed insitu at the cathode. Silver, Zinc, Nickel, Iron, Copper and Platinum metals were used as electrodes, anode and cathode being of the same metals. Yields of materials are dependent on the nature of electrode metals. A reaction mechanism is also proposed.

Polymer hydrogels are cross-linked hydrophilic polymers which are insoluble but absorb, swell and retain large amount of water. They exhibit both liquid and solid like properties. Such polymers have wide range applications in biotechnology, biomedical, pharmaceutical, agriculture, water treatment and many other areas. We carried out a free radical polymerization of acrylamide in an aqueous solution of HNO3 where no other initiator was present. A highly crossed linked polymer gel was obtained. The dried gels were brittle and glassy in appearance. They swell in water and equilibrium swelling is obtained after several days. The water intake of the gels substantially increased when the polymer was subjected to an alkaline saponification. The water absorbency of hydrolysed polymer was found to be more than 1000 times their own mass. The polymer chains contain both an amide and a carboxylate groups. The water molecules in the solvent are attracted by dipole-dipole attraction and hydrogen bonding through nitrogen-oxygen and oxygen-oxygen bonding thereby giving a high degree of swelling. The unhydrolysed polyacrylamide is neutral and has a randomly coiled configuration having consequently low swelling. On the other hand the hydrolysed polymer has ionic character with an extended chain configuration. Such polymers display a better swelling behaviour. The degree of swelling of prepared polyacrylamide hydrogels depend on water pH. In neutral medium swelling is also reversible because the same sample of hydrogels undergoes several cycles of swellings and deswellings

The polymerization of thiophene was studied using BF3O(C2H5)2 as a supporting electrolyte at a platinum electrode to obtain conducting polythiophene. The result shows that the electrical conductivity is relatively higher in acetonitrile compare to that obtained 1,2-dichloroethane (DCE). Polymer films formed in DCE were black floppy and brittle but those obtained in acetonitrile were smooth and flexible. The cyclic voltammetric study was also made and the result shows that polymer films are stable.

The electrochemical polymerization of acrylonitrile containing quaternary salts was carried out without any solvent. When an electric current was passed through the solution, polymer formation occurred at cathode. As polyacrylonitrile is not soluble in its monomer, the cathode becomes heavily coated with yellow orange insoluble polymer mass during the course of electrolysis. The polymer yields increased with increasing impressed current levels but molecular weights of polymers decreased. Polymers of high average molecular weights (ca.105) were obtained.The effects of reaction temperature, nature of supporting electrolytes and nature of electrode metals on the polymers yields and molecular weights were investigated. The polymerization mechanism is anionic.

The cyclic voltammograms of polyaniline films prepared electrochemically in the aqueous solution of sulfosalicylic acid, naphthalene -2-sulfonic acid, anthraquinone-2-sulfonic acid and polyacrylic acid were examined in the range of -0.2V to 1.0VvsSCE in the presence and absence of aniline. The multiple cycled voltammograms were recorded with a number of potential scans indicating that the conducting film formed and the thickness increased with potential cycles. The multiple cycled voltammograms confirm that the film is fairly stable without any severe film degradation. The conductivities of polyaniline films prepared at a constant potential electrolysis at +0.85Vvs SCE on a platinum anode in the aqueous solution of aniline with different electrolytes were determined.

The polymerization of pyrrole was carried out in an aqueous solution of oxalic acid on platinum anode at several current densities. Polymer weights formed on the anode increase linearly with the time of electrolysis at a fixed current level. The polymer formation occurs only on the anode and not in the body of the solution because the anolyte remains completely clear during the course of polymerization. The cyclic voltammograms of polypyrrole film made electrochemically were examined in the presence and absence of pyrrole in the aqueous solution of oxalic acid. Cyclic voltammetry studies suggest that the polymeric film suffers no degradation.

The preparation of conducting nylon fibers by electrochemical deposition of polypyrrole onto insulating nylon fibers in an aqueous solution of sulfosalicylic acid has been carried out. The weight gain and the electrical conductivity of the fibers increase with time of electrolysis and impressed current levels. The redox reaction of aniline has been carried out at the conducting nylon fiber anode, as it could be evidenced from cyclic voltametric studies. The results are quite similar to those obtained at platinum electrode.

The electrochemical polymerization of pyrrole and aniline was carried out on some commodity metals such as Fe and Al used as anodes. The result highlights the major role played by both solvents and supporting electrolytes. The formation of insoluble polymer films occurs on the metals in aqueous and organic solvents containing nitric acid, oxalic acid, sulfosalicylic acid and p-toluene sulfonic acids as supporting electrolytes. The cyclic voltammetry studies indicate that the polymerization mechanism on Fe or Al appears to be the same as suggested for a noble metal electrode.