Acid-PBI

Mamlouk M, Scott K, Hidayati N (2011) High temperature direct methanol fuel cell based on phosphoric acid PBI membrane. J Fuel Cell Sci Technol 8 061009... 

Development efforts at Celanese Research Co. estabHshed soHd-state polymerization as the most practical process for engineering scale-up. Homogeneous solution polymerization of PBI in polyphosphoric acid was eliminated because of the need to work with low soHd compositions (in the range of 3—5%) during the precipitation, neutralization, and washing steps required for isolation of the product. 

PolybenZimidaZoles. The polyben2imida2oles (PBIs) are generally produced by the high temperature, melt polycondensation reaction of aromatic bis-ortho-diamines and aromatic dicarboxylates (acids, esters, or amides) in a reaction such as that shown in equation 11 to form ben2imida2ole [51-17-2] as the repeating unit. 

The PBI molecules studied include pyridyl-(P-PBI), terpyridyl (TP-PBI), and thiol-terminated (T-PBI) perylene-3,4 9,10-tetra-carboxylic acid bisimides, that contain bulky ferf-butylphenoxy substituents at 1,6,7,12 bay positions, and pyridyl-(Py-PBI) and terpyridyl- (TPy-PBI) terminated perylene-3,4 9,10-tetra-carboxylic acid bisimides, that contain bulky pyrrolidinyl substituents at 1,7 bay positions (Fig. 26a) [327-329]. 

To date, much effort has been undertaken to develop new alternatives. For example, sulfonated aromatic polymers, i.e., polymers with the sulfonic acid groups directly attached to the main chain or carrying short pendant side chains with terminal sulfonic acid units, attract increasing interest because of their chemical and thermal stability, and the ease of the sulfonation procedure. Some of the proposed polymers are sulfonated polysulfone (SPSU) [134] sulfonated poly(phenylene oxide) (SPPO) [135] sulfonated poly-(ether ether ketone) (SPEEK) [136] poly(phenylquinoxaline) (PPQ) [137] and poly(benzeneimidazole) (PBI) [138],... 

One of the first examples of this type of blend was composed of SPEEK or SPES as the acidic component and diaminated PES, poly(4-vinylpyridine) (P4VP), poly(benzimidazole) (PBl), or poly(ethyleneimine) (PEI) as the basic component. " For blend lEC values of 1.0 meq/g, conductivity values were reported to be good, as was H2/O2 EC performance. Thermal stabilities for these blends was also demonstrated to be high (>270°C). Other examples of acid-base PEMs include blends of SPPO and PBI, sulfonated poly(phthalazinone ether ketone) and aminated SPES, SPIs and aminated Pls, and SPEEK with PES bearing benzimidazole side groups, ° as well as an unusual example in which the blend is composed of sulfonated, hyper-branched polyether and pyridine-functionalized polysulfone. ... 

Similar to that observed for pure phosphoric acid, the transport properties of PBI and phosphoric acid are also dependent on the water activity, i.e., on the degree of condensation (polyphosphate formation) and hydrolysis. There is even indication that these reactions do not necessarily lead to thermodynamic equilibrium, and hydrated orthophosphoric acid may... 

Figure 22. Proton conductivity of PBI nH3P04 adducts, as a function of temperature T and relative humidity RH for a given phosphoric acid concentration.

Many heterocyclic polymers have been produced in an attempt to develop high-temperature-resistant polymers for aerospace applications. Among these are the polybenzimidazoles (PBIs), which are prepared from aromatic tetramines and esters of dicarboxylic acids (structure 4.63). In standardized procedures, the reactants are heated to below 300°C forming soluble prepolymer, which is converted to the final insoluble polymer by further heating ... 

Drug/Lab test interactions Thiazides may decrease serum PBI levels without signs of thyroid disturbance. Thiazides also may cause diagnostic interference of serum electrolyte, blood, and urine glucose levels (usually only in patients with a predisposition to glucose intolerance), serum bilirubin levels, and serum uric acid levels. In uremic patients, serum magnesium levels may be increased. Bendroflumethiazide may interfere with the phenolsulfonphthalein test due to decreased excretion. In the phentolamine and tyramine tests, bendroflumethiazide... 

Polyimides are obtained from amine and carboxyl reactants when the ratio of amine to acid functional groups is 1 2. If reactants with the reverse ratio of amine to acid functional groups are employed, polybenzimidazoles (PBI) are produced for instance, polymerization of 3,3 diaminobenzidine and diphenyl isophthalate yields poly[(5,5 -bi-liT-benzimidazole]-2,2 -diyl)-l,3-phenylene] (Lilia) (Eq. 2-216) [Buckley et al., 1988 Hergenrother, 1987 ... 

The technical production of poly(benzimidazole) (PBI) is also carried out in two steps. In the first step an aromatic tetramine is condensed with the diphenyl ester of an aromatic dicarboxylic acid at 220-260 °C, yielding a poly(amino amid) with elimination of phenol. Ring closure with elimination of water occurs in the second step (solid-phase polycyclocondensation), conducted at 400 °C and yielding the polybenzimidazole (experimental procedure, see Table 2.3). 

The above reaction may be explained by assuming lead tetroxide as formally equivalent to plumbus plumbate having a structure Pb2 [Pbi 04] in which Pb2+ dissolves in dilute nitric acid forming lead(ll) nitrate whde Pb precipitates out as lead(lV) oxide. 

Fig. 4. Effects of phosphoric acid (PA) treatment on the thermo-oxidative stability of PBI and PBI/PEI blend films aged in air at 315 °C...

Abbreviations AD, asymmetric dihydroxylation BPY, 2,2 -bipyridine DMTACN, 1,4-dimethyl-l,4,7-triazacyclonane EBHP, ethylbenzene hydroperoxide ee, enantiomeric excess HAP, hydroxyapatite LDH, layered double hydroxide or hydrotalcite-type structure mCPBA, meta-chloroperbenzoic acid MTO, methyltrioxorhenium NMO, A-methylmorpholine-A-oxide OMS, octahedral molecular sieve Pc, phthalocyanine phen, 1,10-phenantroline PILC, pillared clay PBI, polybenzimidazole PI, polyimide Por, porphyrin PPNO, 4-phenylpyridine-A-oxide PS, polystyrene PVP, polyvinylpyridine SLPC, supported liquid-phase catalysis f-BuOOH, tertiary butylhydroperoxide TEMPO, 2,2,6,6-tetramethyl-l-piperdinyloxy TEOS, tetraethoxysilane TS-1, titanium silicalite 1 XPS, X-ray photoelectron spectroscopy. 

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