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Chemistries and Biodegradability of Conducting Polymers
Published in Ram K. Gupta, Conducting Polymers, 2022
Poly 3,4-ethylenedioxythiophene (PEDOT), the most common polythiophene derivative, has been proved as a biocompatible conductive polymer for biomedical applications [19]. PEDOT can be prepared by electrochemical polymerization or chemical-oxidative polymerization. In comparison to other conductive polymers, PEDOT shows excellent chemical and thermal stability. Thus, PEDOT has been proven great potential as an interfacing agent for collecting biological signals. The electrical properties and morphologies of PEDOT polymers are influenced by the counterion incorporation [20]. The most used counterions include inorganic salts (e.g., sodium chloride [NaCl], lithium perchlorate [LiClO4], and ions in PBS) and organic salts (e.g., poly(sodium 4-styrene sulfonate)). In addition, the amino acids, polysaccharides, and proteins, are also used as dopants of the PEDOT for specific biomedical applications. The polyanion PSS incorporated into PEDOT could form a uniform and stable aqueous solution, which have been commercialized due to their excellent processability and biocompatibility [21].
Processing Additives
Published in Mohamed N. Rahaman, Ceramic Processing, 2017
The complex anion species adsorb strongly onto the surface of oxide particles. Adsorption will increase with higher molecular weight of the anion species (higher van der Waals attraction) and with the specific charge (charge per unit anion group). Adsorption, coupled with the formation of a diffuse layer of the counterions (ions of opposite charge), leads to electrostatic stabilization due to repulsion betwe en the double layers (Chapter 6). The valence and radius of the counterions can modify the repulsion between the particles, and so can influence the stability of the suspension. Counterions with higher valence are more effective in causing flocculation (Schulze–Hardy rule), while for ions of the same valence, the smaller ions are more effective. For monovalent cations, the effectiveness of flocculation is in the order Li+ > Na+ > K+ > NH4+, while for divalent cations, it is Mg2+ > Ca2+ > Sr2+ > Ba2+. This sequence is known as the Hofmeister series. For common anions, the effectiveness of flocculation is in the order SO42– > Cl– > NO3–.
The role of polysaccharides and cellulose for modern science and technology
Published in Gennady E. Zaikov, Chemistry of Polysaccharides, 2005
It should be noted that when considering inclusion complexes formation in solutions iodine-iodide-amylose practically in all works the fact that forming complexes including charged particles are similar to macromolecule polyelectrolytes is not considered. And their behavior in solutions will depend on the presence in solutions of counterions-cations. It is known that in polyelectrolytes solutions part of counterions is retained in direct proximity to polymer chains, effectively neutralizing their charge. This phenomenon is called counterions condensation [89]. One may sup- pose that as in the case of polyelectrolytes in the presence of negative charged particles of polyiodide chain inside of amylose molecule counterions-cations "condensation" is possible on its surface. Such complex in its structure will be analogous to "molecular condenser" and driving force of process of polyiodide chains formation inside of amylose molecule in solutions is necessary to consider taking into account counterions influence.
Study of sodium electrolytes on phase behavior of the anionic surfactant/alcohol/model oil system and its application for alkaline-surfactant flooding formulation design
Published in Journal of Dispersion Science and Technology, 2023
Lei Ding, Qianhui Wu, Xuan Zhang, Jijiang Ge
Since the critical micelle concentration (CMC) of the surfactant for enhanced oil recovery (EOR) is typically quite small compared to that practically applied for surfactant flooding, the surfactants are therefore predominately in the form of micelles.[5] The interactions between the surfactant and its counterions can significantly influence the interfacial properties, such as CMC, the micellar size, and interfacial tension, etc.[12,17] Primarily, the counterions are bounded with the surfactants headgroups at the micellar surface by the electrostatic force. It is also reported that the optimal salinity of surfactant in phase behavior tests may be increased with increasing the hydrated radius of its counterions, provided that the valences of the counterions are equal.[12,18]
Thermotropic liquid-crystalline properties of extended viologen bis(triflimide) salts
Published in Liquid Crystals, 2018
Pradip K. Bhowmik, Shane T. Killarney, Jessa Rose A. Li, Jung Jae Koh, Haesook Han, Lewis Sharpnack, Deña M. Agra-Kooijman, Michael R. Fisch, Satyendra Kumar
The field of ILCs is an active area of research for a decade or so that is manifested in a number of reviews on the topic [19–24]. They have the combined properties of both ionic liquids and liquid crystals. The LC phases offer great advantages over liquid phases. For example, ion conduction is enhanced in the SmA and columnar phases when compared to the isotropic liquid phases. The unique properties of ILCs have widespread applications, including display technology, solar cells and ion conductors, templates for the synthesis of nanoparticles. However, they are composed of varied suitably modified cations and anions. Among the common cations are quaternary ammonium, quaternary phosphonium, imidazolium and pyridinium among other cations and the common anions are –Br, –NO3, –BF4, –ClO4, and –PF6 among other anions. The stable –NTf2 counterion has been extensively used in combination of suitable cations for the preparation of many ionic liquids which have superior physical properties including relatively low viscosities, low melting transitions, high conductivity and high thermal stability. However, in contrast to the numerous studies of ILs based on –NTf2 [25–27], reports of ILCs on this fluorinated ion are relatively less studied [5,15,28–32].
Stability of hydrophobic colloids: Perspectives and current opinion
Published in Journal of Dispersion Science and Technology, 2021
Animesh Kumar Rakshit, Bappaditya Naskar, Satya Priya Moulik
For a saturated charged colloid surface, GCL controls the ζ-potential. Addition of salt should decrease ζ by decreasing the thickness of GCL. The CCC here follows an inverse proportionality in terms of their valences (Equation (4)). Counterions can do it more efficiently because of having opposite charges to the colloid surface. They accumulate closer to the plane of slip, whereas the coions accumulate at the rear side of the double layer. Effectively, both decrease the thickness of the GCL with different efficacies. Thus, S-H and iS-H rules are unequal; in terms of the valences of the ions, the former is more efficient.