Poly , ionic plastic

Figure 11.12. Effect of fraction of stoichiometric concentration of 2-ethylhexyl-p-dimethylaminobenzoate used for ionic plasticization of poly(styrene-b-isobuty-lene-b-styrene), having 4.7% sulfonated phenyl units, on glass transition temperature, Tg, and temperature at which tan6=3. [Data from Storey R F Bau D W, Polym. Eng. Sci., 39, No.7, July 1999, p. 1328-34.]...

In Fig. II the effect of plasticizer is shown for the system poly(vinyl chloride)/tricresyl phosphate. Water also affects the conductivity considerably but its precise function is by no means clear particularly at low moisture contents (135). The presence of ionic impurities causes increased conductivity but the effect of organic impurities is less apparent. For instance, the addition of plasticizers of differing purity to poly-... 

In the works of Ferruti et al.83,84), there has been reported a method for heparinization of plasticized polyvinyl chloride which was pre-modified by grafting of poly-aminoamines. The surface concentration of ionically bound heparin was 1.2 ng/cm2. Heparin can be eluted off the polymer in a narrow pH range of 10.8 to 11.4. 

Prepare the cocktail for the potassium sensor membrane mixing in a 3mL glass vial the following substances 0.0025 g of valinomycin (ionophore), 0.075 g of poly(vinyl chloride) (PVC), 0.165g of bis(2-ethylhexyl)sebacate (plasticizer), 0.0015 g of potassium tetrakis(4-chlorophenyl)borate (ionic additive) and 1.5 mL of tetrahydrofuran (THF). Cover the vial and shake it well, preferably in an orbital shaker for 30 min in order to dissolve and to homogenize the mixture. The resultant cocktail will suffice to prepare 10 sensors. 

A prime need for a solid ionic conductor arises in the design of electrochemical fuel cells (Alberti and Casciola, 2001). Perhaps the most important type is the hydrogen fuel cell, shown diagrammatically in Fig. 8.5. Here the membrane which separates the two electrodes must be able to transfer protons efficiently. A material which combines the flexibility and toughness of a plastic with high protonic conductivity would be an ideal candidate. Prototype cells were successfully operated with membranes made from poly(styrenesulphonate),... 

Specialty polymers achieve very high performance and find limited but critical use in aerospace composites, in electronic industries, as membranes for gas and liquid separations, as fire-retardant textile fabrics for firefighters and race-car drivers, and for biomedical applications (as sutures and surgical implants). The most important class of specialty plastics is polyimides. Other specialty polymers include polyetherimide, poly(amide-imide), polybismaleimides, ionic polymers, polyphosphazenes, poly(aryl ether ketones), polyarylates and related aromatic polyesters, and ultrahigh-molecular-weight polyethylene (Fig. 14.9). 

Very recently, the self-assembly of poly(y-benzyl-i,-glulamalc)-fo-poly(i,-lysine) rod-coil copolypeptide via ionic complexation was reported by Ikkala, Hadjichristidis and coworkers [65]. Complexation between the anionic surfactants dodecyl benzenesulfonic acid and the cationic poly(L-lysine) chains occurs via proton transfer from the acid group to the base, resulting in electrostatically bonded comb-like structures, and fluid-like liquid crystalline structures at room temperature due to efficient plasticization of dodecyl benzenesulfonic acid. 

A rigid backbone was used by Wegner to build ion-conductive PEO-based polymers [63]. 01igo(ethylene oxide) chains were grafted from poly(p-phenylene) as shown in Fig. 6. The mixtures of polymers 5 and lithium salts show conductivities in the order of 10-6 Son 1 at ambient temperature. The ionic conductivities can be improved to the order of 10-5 S cm-1 by plasticization of the materials with oligo(ethyleneglycol)-dimethylether. 

A variety of dimensionally stable solid electrolytes consisting of a mixture of organic plasticizers such as EC, PC etc., along with structurally stable polymers such as poly( acrylonitrile) (PAN) or poly( vinyl sulfone) (PVS), or polyvinyl pyrrolidine (PVP) or polyvinyl chloride (PVC) and several lithium salts have been tested and found to have excellent ionic conductivities at ambient temperatures [155-156]. In these gel type electrolytes the primary role of the polymers PAN, PVS, PVP or PVC is to immobilize the lithium salt solvates of the organic plasticizer liquids. However, with polymers such as PAN a coordination interaction with Li+ is also quite likely. 

Other polymers such as MEEP, poly MEEM A and polysiloxanes are completely amorphous polymers and remain amorphous even in the polymer-metal salt complexes at least upto certain concentrations of the metal salt. The question of the amorphous nature of the polymer electrolytes is important in view of Berthi-er s demonstration in the PEO-polymer electrolyte system that the ionic conductivity occurs mostly in the amorphous phase [59]. Thus the room temperature ionic conductivities of the completely amorphous MEEP-LiX complexes is at least three orders of magnitude higher than the corresponding PEO-LiX complexes. This has led to the use of plasticizers and other modifications to suppress crystallinity and increase free volume as discussed above. 

Sudhakar, Y. N., M. Selvakumar, and D. K. Bhat. 2013. LiC104-doped plasticized chitosan and poly(ethylene glycol) blend as biodegradable polymer electrolyte for supercapacitors. Ionics 19 277-285. 

Plasticization of poly(styrene-b-isobutylene-b-styrene) ionomer by 2-ethylhexyl-p-dimethylaminobenzoate causes a decrease in the glass transition temperature, Tg, as the amount of plasticizer increases (Figure 11.12). This lowering of the Tg indicates that there is a slight plasticization of the non-ionic polystyrene phase. A much larger shift is observed in temperature at which tan5 = 3. This indicates a prefererrtial plasticization of the ionic clusters. 

In a typical microfluidic setting, the most power absorbing material is the liquid sample in the microchannels. The common materials for microfluidic chips are glass, quartz, and thermal plastics such as polydimethylsiloxane (PDMS), poly(methyl methacrylate) (PMMA), and polycarbonate, which usually have very small absorption as compared to liquid materials. The absorption of the liquid medium increases with its ionic content which increases the conductivity and with the operating frequency. Take water as an example. 

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