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Conducting Polymers
Published in Ram K. Gupta, Conducting Polymers, 2022
Suba Lakshmi Madaswamy, N. Veni Keertheeswari, Ragupathy Dhanusuraman
Chemical synthesis of polymerization was done by either reduction or oxidation of consistent monomers. Chemical polymerization occurs when conjugated monomers are mixed with an excess of oxidant in a suitable solvent, such as acid. The process of polymerization occurs quickly but requires constant stirring. A numerical analysis was used to improve the quality and yield of the synthesized product obtained through the oxidative polymerization technique. Most of the CPs like PANI and PPy are synthesized by chemically using oxidizing agents like ammonium persulfate ((NH4)2S2O8), hydrogen peroxide (H2O2), and potassium permanganate (KMnO4). One of its benefits is the possibility of mass manufacturing at a reasonable cost [19]. For example, PANI is synthesized by the oxidative polymerization method. When aniline monomer is mixed with hydrochloric acid, then ammonium persulfate is used as an oxidizing agent, a dark green color PANI is obtained.
Advances in Preparations and Applications of Polymeric Microsphers
Published in Kunio Esumi, Polymer Interfaces and Emulsions, 2020
In emulsion polymerization, water-soluble persulfate initiators and azo initiators are usually used. Potassium persulfate (KPS), ammonium persulfate (APS), and 2,2'-azobis(2-methylpropionamidine)dihydrochloride (V-50) are typical examples. An initiator-surfactant (inisurf) which acts as both an initiator and emulsifier was developed and used in emulsion polymerization; for example, an azo initiator [17] containing emulsifier groups, as shown in (VII). As the case of an reactive emulsifier, inisurf has the advantage that it can be incorporated in the microsphere by a covalent bond, so that it does not desorb from the microspheres. In the recent years, new initiators were developed to introduce a new functionality to microspheres, corresponding to the specific purpose. For example, Sugiyama et al. [18] used an azo initiator containing a phosphatidylcholine group (VIII), which is present on the external surface of blood cells, in the emulsion polymerization of ST to obtain the microspheres with the phospholipid on the surface. The microspheres obtained showed excellent biocompatibility.
Polymers in Special Uses
Published in Manas Chanda, Plastics Technology Handbook, 2017
PNIPAAm has been synthesized from N-isopropylacrylamide (NIPAAm) by a variety of techniques, the most widely used being free-radical initiation of organic solutions [171] and redox initiation in aqueous media [172]. Redox polymerization of NIPAAm in aqueous media typically uses ammonium persulfate or potassium persulfate as the initiator and either sodium metabisulfite or N,N,N′N′- tetramethylethylenediamine (TEMED) as the accelerator. In addition, the solutions are usually buffered to constant pH since in the absence of buffer much greater polydispersity is obtained. Whether one polymerizes NIPAAm in organic or aqueous solution also affects polymer properties [173].
Synthesis of DBSA-doped Polyaniline by Emulsion Polymerization and PANI/PLA Electrospun Fiber Membrane Conductivity
Published in The Journal of The Textile Institute, 2019
Taohai Yan, Mohan Zhang, Jinhua Jiang, Nanliang Chen
The primary methods for synthesizing polyaniline are electrochemical polymerization and chemical oxidation polymerization (Huang, Humphrey, & MacDiarmid,1986; Huang, Virji, Weiller, & Kaner, 2003). Chemical oxidative polymerization is conventionally used to prepare polyaniline (Zhang, Goux, & Manohar, 2004), which includes solution polymerization, emulsion polymerization, and microemulsion polymerization (Huang & Kaner,2004; Reddy, Sin, Yoo, Sohn, & Lee, 2009; Shao, Zhang, Fu, Zhou, & Fan, 2014). Solution polymerization is the oxidative polymerization of aniline monomers with an oxidizing agent in an acidic solution. Hydrochloric acid is typically used as the doping acid, and ammonium persulfate is typically used as the oxidizing agent, although the solubility and the conductivity of the products are not ideal and its application is complicated (Kim, Oh, Han, & Im, 2000). The microemulsion polymerization system consists of water, aniline, surfactant, co-surfactant, and organic solvent. The polyaniline chain structure that is prepared by this method demonstrates good regularity and high crystallinity. The polyaniline particles will agglomerate and have a litter low electrical conductivity after the product becomes demulsified and vacuum dried (Jang, Ha, & Kim, 2007; Xia & Wang, 2001). The emulsion polymerization method synthesizes polyaniline by selecting an organic macromolecular acid with a specific hydrophilic functional group and the protonic acid is doped in one step. This method has a rapid reaction rate, easy operation control, easy removal of residual monomers, and avoids practical problems such as low volatility and poor solubility of small-molecule acids that are present in the solution polymerization methods. This method boasts great advantage in the synthesis of polymer materials, such as polyaniline (Kim, Jung, Kim, Choi, & Joo, 2001; Österholm, Cao, Klavetter, & Smith, 1994; Palaniappan & John, 2008).