Poly-p-phenylene oxide

Among other in vitro enzymatic polymerizations that have been studied are the oxidative polymerizations of 2,6-disubstituted phenols to poly(p-phenylene oxide)s (Sec. 2-14b) catalyzed by horseradish peroxidase [Higashimura et al., 2000b] and the polymerization of P-cellobiosyl fluoride to cellulose catalyzed by cellulase [Kobayashi, 1999 Kobayashi et al., 2001],... 

In general, regularity in polymer structure and strong intermolecular forces favor high Tm values. Phenylene groups, such as those in polyphenylene, poly-p-phenylene oxide (PPO), and poly-p-phenylene sulfide (PPS), increase Tm values. 

Poly(p-phenylene oxide) is also a processible polymer, but its treatment with AsF5 leads only to rather poor conductivity77). The synthesis of poly(p-phenylene selenide) has been described by Jen et al. 78) and by Sandman et al. 79) but the polymer does not conduct even on prolonged exposure to AsF5. 

Poly(p-phenylene) also fascinated many workers due to its cheap cost, good mechanical strength and high stability for use in electrochemical systems. In anodic oxidation and over-oxidation studies in aqueous acidic solutions of different nucleophilicity by cyclic voltammetry, two peaks were observed. The reversible first peak was attributed to poly(p-phenylene) oxidation and formation of some insertion compound, whereas the strong and irreversible second peak at higher potentials was attributed to over-oxidation of the polymer [291] and the polymer anode started degrading at acid concentrations below 13 M [292], Accordingly, the microanalytical, IR spectroscopic and acid-base titration studies showed evidence of the formation of aromatic dicarboxylic acid, phenolic compound and carbondioxide via a p-benzoquinone intermediate [291],... 

The polymer from 2,6-dimethylphenol is the commercial product referred to as poly(p-phenylene oxide) or PPO. The lUPAC name is poly(oxy-2,6-dimethyl-l,4-phenylene). PPO... 

Figure 8 Simulated adsorption by molecular dynamics of (A) poly (p-phenylene) oxide (PRO), (B) poly(methyl-l,4-phenylene) (PMP) and (C) poly(iso-propyl-l,4-phenylene) (PIPP) on an alumina surface showing substantial structural changes during the adsorption process (upper figure initial conformation lower figure = adsorbed conformation) (From Ref. 71.) Note the formation or absence of adsorption loops in the polymer chains for the different cases.

PREPARATIVE TECHNIQUES Poly(p-phenylene oxide) is prepcired from mono p-bromo-... 

The similarities between the molecular structure of the emeraldine base and those of poly(p-phenylene sulfide),poly(p-phenylene oxide),and even poly(p-phenylene terephthalamide) suggest that a sinular interchain packing might be expect. Indeed, the two strongest equatorial peaks in Figurelb(at 20=19.5 and 20=22.8 ) correspond to the similar peaks observed in all three materials. 

The phenyl ether polymers are a class of polyethers containing aromatic cycles in their main chain. The examples include polyphenyl ether (PPE) and poly (p-phenylene oxide) (PPO). 

Connecting Benzene Rin s. The possibility that -benzoquinone diazide would decompose in the appropriate solvent with the loss of nitrogen to yield poly(p-phenylene oxide) was intriguing. However, complicated reaction products were obtained in non-polar solvents. Because the monomer was not appreciably soluble in nonpolar solvents, Pat Cassidy carried out these reactions in tetra-hydrofuran. Analysis of the polymer revealed that the polymer was not the expected poly(phenylene oxide), and by the time we had become convinced that solvents had been incorporated into the polymer, Charlie Price, who was present when these results were discussed at a symposium in Tucson for Marvel had also reached the same conclusion. Thus, an alternating copolymer of phenylene oxide and tetra-hydrofuran was obtained. When other cyclic ethers were used as solvents, alternating copolymers were also formed. 

Another example is poly p-phenylene oxide (PPO) and polystyrene. The General Electric Noryl is a blend of PPO with rubber modified polystyrene (i.e., high impact polystyrene, often known as HIPS) (see Section 6.8). HIPS is much tougher than glassy polystyrene but HIPS miscibility with PPO (Formula 5.13) is based upon HIPS polystyrene content. The improvement in toughness of the brittle PPO by HIPS makes this blend a commercial success. 

Poly(p-phenylene sulphide) (commonly called poly(phenylene sulphide) or PPS) is the sulphur analogue of poly(p-phenylene oxide) and is prepared from p-dichlorobenzene and sodium sulphide ... 

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