China
Africa
Explore chapters and articles related to this topic
P
Published in Joseph C. Salamone, Polymeric Materials Encyclopedia, 2020
Electrically conducting polypyrrole is prepared by electrochemical or chemical oxidative polymerization of pyrrole. In chemical oxidative polymerization, ferric chloride is the initiator (oxidant) of choice. It also acts as the dopant. The polymer is insoluble and infusible and hence difficult to process. Preparing the polymer in dispersion form greatly increases its processability. The dispersion may be used alone or blended with latexes or solutions of other polymers. Required amounts of the stabilizer and initiator are dissolved in the appropriate solvent. The solution is brought to the desired temperature. Pyrrole is added. The beginning of polymerization is recognized from the change in color of the medium which ultimately becomes black. The polypyrrole particles isolated from the original dispersion can be redispersed in solvents with soluble stabilizers. Dried particles are difficult to redisperse, perhaps because drying renders the stabilizer distribution nonuniform.
Adsorbents for DNA separations
Published in A. K. Haghi, Lionello Pogliani, Eduardo A. Castro, Devrim Balköse, Omari V. Mukbaniani, Chin Hua Chia, Applied Chemistry and Chemical Engineering, 2017
Some composites were also reported as DNA adsorbents such as polypyrrole (PPy)-silica monocomposite particles,57, 58 polymers, and hydrogels.61 Polypyrrole is a conductive polymer, stable and biocompatible compared with other polymers.33 Its good thermal and mechanical stability let its use in biological areas such as biosensor design. Composite form of it, with DNA absorbable material, makes them acceptable for DNA adsorption. Therefore, polypyrrole-silica nanocomposites (untreated and amine or carboxylic powder acid functionalized) were studied at neutral pH in sodium phosphate buffer by Saoudi and coworkers. 57, 58 DNA adsorption was measured to be 32 and 22 mg/g for the aminated silica sol and the aminated PPy-silica particles, respectively, and 6.5 mg/g for the carboxylated particles. DNA adsorption is not applied only for purification of DNA but also for therapies of autoimmune diseases. DNA-immobilized supports, such as polymeric adsorbent, have been used. Amount of immobilized DNA on the material is directly related to antibody removal rate. For instance, poly-L-lysine-immobilized poly(2-hydroxyethyl methacrylate) (pHEMA) membrane was used for that purpose.61 At 4°C from phosphate-buffered salt solution, maximum DNA adsorption was obtained as 5849 mg/m2.
Preparation of Conductive Nanofibers
Published in A. Sezai Sarac, Nanofibers of Conjugated Polymers, 2017
Due to its easy synthesis and long-term ambient stability, polypyrrole has been investigated for different applications, i.e., antistatic, electromagnetic shielding, actuators and polymer batteries. Its monomers are soluble in water. The inherently poor solubility of polymer in common solvents, which originates from the strong inter- and intra-chain interactions is the disadvantage that restricts practical applications of polypyrrole in some areas.
Development of choline biosensor using toluidine blue O as mediator
Published in Preparative Biochemistry & Biotechnology, 2020
Rüya Baskin, Elif (Aynaci) Koyuncu, Halit Arslan, Fatma Arslan
Platinum plate was cleaned mechanically and chemically before coating.[23] Then it was coated with PPy in PVS medium[24]. During the coating, polypyrrole was deposited on the electrode surface by electropolymerization of pyrrole. The coating process was done as follows; cleaned Pt electrode, auxiliary, and the reference electrode were dipped in a 10 mL solution of 0.1 M pyrrole and 2.5 mL (25%) of sodium polyvinylsulphonate. Argon gas was passed through the solution for 10 min to remove the oxygen. One cycle was obtained at a scanning speed of 50.0 mV/s between −1.0 and 2.0 V with a cyclic voltammetry (CV) technique (vs. Ag/AgCl electrode (3.0 M KCl)).[25] After coating, PPy–PVS film electrode was lavaged with pure water to remove unreacted pyrrole.
A review on the recent progress, opportunities, and challenges of 4D printing and bioprinting in regenerative medicine
Published in Journal of Biomaterials Science, Polymer Edition, 2023
Parvin Pourmasoumi, Armaghan Moghaddam, Saba Nemati Mahand, Fatemeh Heidari, Zahra Salehi Moghaddam, Mohammad Arjmand, Ines Kühnert, Benjamin Kruppke, Hans-Peter Wiesmann, Hossein Ali Khonakdar
Polypyrrole is another conductive polymer with high electrical conductivity and stability, biocompatibility, and facility for synthesis [43]. Vijayavenkataraman et al. [44] developed a new conductive bioink for neural tissue engineering. The hydrogel was based on collagen and polypyrrole block copolymer and polycaprolactone (PCL) (PPy-block-poly (caprolactone)) for encapsulating cells during 3D bioprinting. Their study aimed to overcome the previous problems of conductive hydrogels, such as non-biodegradability or long-term cytotoxicity of nano-metals. This system had elastic-solid behavior and the best continuous line, and 3D printing could be obtained at a printing speed of above 3 mm/s and 5 ml/min. Furthermore, adding PPy-block-PCL to collagen enhanced the mechanical properties and showed no cell cytotoxicity. Zhao et al. [45] suggested another electrical response construct for neural tissue engineering. Silk fibroin and polypyrrole conductive scaffolds were fabricated, and Schwann cells were cultured on the scaffolds’ surface after fabrication. An electrical stimulus was applied to the printed scaffold and improved cell viability, proliferation, and migration. Furthermore, neurotrophic factors expression was increased, and in-vivo investigations demonstrated better axonal regeneration and remyelination. In addition, extracellular signal-regulated kinase (ERK) as one of the mitogen activated protein kinases (MAPKs) signal pathways were activated by electrical response material. It is assumed that ERK is involved in neuronal plasticity and activation of MAPK signal pathway plays a critical regulatory role in controlling cytological activities. Therefore, this composite could serve as a promising candidate for bioprinting in peripheral nerve regeneration.
Modification of the elemental composition of iron(III) oxide as an asymmetric supercapacitor anode: A minireview
Published in Instrumentation Science & Technology, 2020
Among the various polymers, polypyrrole (PPy) has reasonable thermal and environmental stability, high electrical conductivity and simple synthesis. Bashir et al.[49] reported that a polypyrrole-Fe2O3 nanocomposite was prepared by adding Fe2O3 particles into the polypyrrole matrix by chemical oxidation polymerization. The selected samples were observed by transmission electron microscopy (TEM) based upon the detailed surface characterization of the polypyrrole-Fe2O3 nanocomposite.