• Bulletin of the Korean Chemical Society
• /
• v.9 no.4
• /
• pp.248-251
• /
• 1988

Mechanism of electrochemical polymerization of pyrrole (Py) on a Pt electrode in acidic aqueous solutions was studied by means of potentiostatic measurements, cyclic voltammetry and chronopotentiometry. Pyrrole molecule appeared to be initially oxidized via two-electron transfer step to produce oxidized pyrrole ion ($Py^+$), which was coupled with a non-oxidized pyrrole to yield a dimerized species, Py-Py. The Py-Py thus formed was further oxidized again via two-electron transfer step, which was followed by coupling with non-oxidized monomer and by concomitant expulsion of a $H^+$. Then the latter chain extension process was repeated. The chain extension and polypyrrole oxidation reactions occurred competitively.

• Advances in materials Research
• /
• v.1 no.4
• /
• pp.299-310
• /
• 2012

This article describes the synthesis of a novel N-substituted pyrrole monomer containing an azobenzene group. The 2-[N-ethyl-N-[4-[(4-nitrophenyl) azo]-phenyl] amino] ethyl-3-chloropropionate (RedII) compound was synthesized via reaction of 4-nitro-4'-[N-ethyl-N-(2-hydroxyethyl)-amino] azobenzene (RedI) and 3-chloropropionic acid. RedII was reacted with the potassium salt of pyrrole then 2-[N-ethyl-N-[4-[(nitro phenyl) azo] phenyl] amino] ethyl-N-pyrrolyl propionate (Py-RedII) was prepared. Chemical polymerization of Py-RedII and copolymerization of Py-RedII with pyrrole carried out using $FeCl_3$. Poly (2-[N-ethyl-N-[4-[(nitro phenyl) azo] phenyl] amino] ethyl-N-pyrrolyl propionate) (PPy-RedII) was characterized by UV, IR, $^1HNMR$, $^{13}CNMR$ spectroscopies. Electropolymerization of Py-RedII and electroco-polymerization of Py-RedII and pyrrole were studied using conventional three electrodes system, Ag/AgCl reference electrode, platinum counter electrode and GC disk working electrode. Scanning electron microscopy (SEM), thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC) were used for thermal and rheological studies. The TGA curve of PPy-RedII demonstrated a high thermal stability up to 200°C and its DSC thermogram showed two endothermic peaks at 88 and $122^{\circ}C$. The glass transition temperature of the polymer was found to be above the room temperature. Electrical conductivities of PPy-RedII and it's copolymer with pyrrole (PPy-RedII-co-Py) were studied by the four-probe method and produced conductivities of $7.5{\times}10^{-4}$ and $6.5{\times}10^{-3}Scm^{-1}$, respectively.

• Applied Chemistry for Engineering
• /
• v.7 no.6
• /
• pp.1061-1068
• /
• 1996

The conducting polymer composites were prepared by imbibing the porous particle wish the $FeCl_3$ oxidant solution, drying the imbibed porous particle, and imbibing again with pyrrole solution for polymerization to take place in the pore of porous particles. The effect of synthesis conditions on the conductivity of composite polymers were investigated. It was found that the conductivity of composite polymers was dependant on the concentration of pyrrole monomer, nature of the oxidants and solvents used for the oxidant and pyrrole, which influence the degree of penetration/distribution of polyprrole in the composite and reaction of dopant with pyrrole.

• Korean Chemical Engineering Research
• /
• v.46 no.4
• /
• pp.777-782
• /
• 2008

Using ultrasonic-induced polymerization of pyrrole, mesoporous $TiO_2$ thin film with polypyrrole nanoparticles was prepared. Polypyrrole nanoparticles were ultrasonically synthesized in the mother solution of mesoporous $TiO_2$ before spin-coating. The polypyrrole particles were well dispersed in the solution. After spin-coating and calcinations process, the nanocomposite films have well-organized pore channels without pore-collapse, and polypyrrole nanoparticles are well dispersed in mesoporous $TiO_2$ matrix. The pore size and light absorbance of the mesoporous nanocomposite thin films were controlled by using different template materials, and by using different amount of pyrrole monomer, respectively.

• Journal of Sensor Science and Technology
• /
• v.26 no.2
• /
• pp.73-78
• /
• 2017

A tetrode is one of the neural electrodes, and it is widely used to record neural signals in the brain of a freely moving animal. The impedance of a neural electrode is an important parameter because it determines the signal-to-noise ratio of the recorded neural signals. Here, we developed a modification technique using carbon nanotube-polypyrrole composite nanostructures to decrease the impedances of tetrodes. The synthesis of the carbon nanotube and polypyrrole nanostructures was performed in two steps. In the first step, randomly dispersed carbon nanotubes and pyrrole monomers were gathered and aligned on the tetrode electrode. Next, they were electro-polymerized on the electrode surface. As the applied time (step-1 and step-2) and the offset voltage increased, the impedances of the tetrodes decreased. The modification technique is, therefore, an important and useful of lowering the impedances of tetrodes.

• Applied Chemistry for Engineering
• /
• v.10 no.6
• /
• pp.923-928
• /
• 1999

Polycarbonate(PC)/polypyrrole(PPy) conducting composites were prepared by precipitation polymerization. $FeCl_3$, pyrrole and chloroform were used as oxidant, monomer, and solvent, respectively. The electrical conductivity was increased with increasing the amount of PPy, while the mechanical property was decreased. When the PPy content was 25 wt %, the electrical conductivity of the composites was increased up to 0.23 S/cm. The electrical conductivity, the stability of conductivity in air and mechanical properties of the composites of different PPy content were investigated and the morphology of the composite films was observed.

• Macromolecular Research
• /
• v.16 no.3
• /
• pp.200-203
• /
• 2008

A conducting polymer layer was introduced into the pore surface of mesoporous carbon via vapor infiltration of a monomer and subsequent chemical oxidative polymerization. The polypyrrole, conducting polymer has attracted considerable attention due to the high electrical conductivity and stability under ambient conditions. The mesoporous carbon-polypyrrole nanocomposite exhibited the retained porous structure, such as mesoporous carbon with a three-dimensionally connected pore system after intercalation of the polypyrrole layer. In addition, the controllable addition of pyrrole monomer can provide the mesoporous carbon-polypyrrole nanocomposites with a tunable amount of polypyrrole and texture property. The polypyrrole layer improved the electrode performance in the electrochemical double layer capacitor. This improved electrochemical performance was attributed to the high surface area, open pore system with three-dimensionally interconnected mesopores, and reversible redox behavior of the conducting polypyrrole. Furthermore, the correlation between the amount of polypyrrole and capacitance was investigated to check the effect of the polypyrrole layer on the electrochemical performance.

• Applied Chemistry for Engineering
• /
• v.5 no.4
• /
• pp.616-623
• /
• 1994

Conductive Polypyrrole films have been synthesized by electrochemical method in nucleophilic solvent such as N, N-dimetylformamide(DMF), dimethylsulfoxide(DMSO). The effect of protic acid as supporting electrolyte to decrease the nucleophilicity of the solvent was studied. Cyclic voltammetry, I-t transients were carried out to investigate the electrodeposition of conductive polypyrrole film on platinum electrode. Three peaks of 0.65V, 0.85V, and 1.2V vs. $Ag/AgNO_3$ indicated oxidation of monomer, oxidation of pyrrole to the platinum electrode and decomposition of polypyrrole film, respectively. With the I-t transients, nucleation process was confirmed and from obtained linear fits of I vs.t2resembles the metal film formation, and 2.15-2.26 of n-value could be calculated. As concentration of pyrrole or prolic acid was increased, the conductivity of polypyrrole film increased linearly. Tensile strength and elongation were investigated for comparing the mechanical properties and also SEM was performed for morphology investigation.

• Fibers and Polymers
• /
• v.3 no.1
• /
• pp.24-30
• /
• 2002

Wool yams were coated with conducting Polypyrrole by chemical synthesis methods. Polymerization of pyrrole was caned out in the presence of wool yarn at various concentrations of the monomer and dopant anion. The changes in tensile, moisture absorption, and electrical Properties of the yam upon coating with conductive polypyrrole are Presented. Coating the wool yams with conductive Polypyrrole resulted in higher tenacity, higher breaking strain, and lower initial modulus. The changes in tensile properties are attributed to the changes in surface morphology due to the coating and reinforcing effect of conductive Polypyrrole. The thickness of the coating increased with the concentration of p-toluene sulfonic acid, which in turn caused a reduction in the moisture regain of the wool yin. Reducing the synthesis temperature and replacing p-toluenesulfonic acid by anthraquinone sulfonic acid resulted in a large reduction in the resistance of the yam.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.03a
• /
• pp.133-133
• /
• 2003

가스센서는 인간의 오감 중에 후각 기능을 대신하는 것으로 사회 여러 분야에 응용범위가 확대되고 있다. 유기화합물(VOC; volatile organic compounds) 가스는 대기환경을 오염시켜 스모그를 발생하며 인체에 발암을 유발하는 물질이기 때문에 많은 문제와 규제가 예상되고 있다. 따라서 VOC를 감지하고 정확히 분석할 수 있는 환경 측정용 센서에 대한 요구가 절실해지고 있다. 최근에는 고온에서 동작하는 산화물 반도체 센서와는 달리 상온에서 유해성 가스를 감지할 수 있는 전도성 고분자의 특성이 알려지면서 센서 물질로 각광을 받고 있으며, 특히 유해성 가스인 VOC 가스를 검지 할 수 있는 센서로서 주목을 받고 있다. 전도성 고분자인 Polypyrrole를 pyrrole monomer, APS, DBSA를 사용하여 $0^{\circ}C$, 1기압에서 화학중합을 하였다. 만들어진 powder를 chloroform과 DBSA를 사용하여 용액을 만들어 전극에 dipping하고 7$0^{\circ}C$, 질소 분위기에서 1시간동안 건조를 하고 methanol에서 1시간동안 soaking 처리를 한 뒤 7$0^{\circ}C$, 질소 분위기에서 4시간동안 열처리 과정을 통해 센서를 제조하였다.