Poly 2,6-dimethylphenylene

Membranes and Osmosis. Membranes based on PEI can be used for the dehydration of organic solvents such as 2-propanol, methyl ethyl ketone, and toluene (451), and for concentrating seawater (452—454). On exposure to ultrasound waves, aqueous PEI salt solutions and brominated poly(2,6-dimethylphenylene oxide) form stable emulsions from which it is possible to cast membranes in which submicrometer capsules of the salt solution ate embedded (455). The rate of release of the salt solution can be altered by surface—active substances. In membranes, PEI can act as a proton source in the generation of a photocurrent (456). The formation of a PEI coating on ion-exchange membranes modifies the transport properties and results in permanent selectivity of the membrane (457). The electrochemical testing of salts (458) is another possible appHcation of PEI. 

Attractive interactions are also the reason for the self-assembly of PS-fo-PB-fo-PMMA at the interface of poly(styrene-co-acrylonitrile), SAN, and poly(2,6-dimethylphenylene ether), PPE. In this blend, PS and PPE are miscible on one side and PMMA and SAN are miscible on the other one, with negative / parameters. This blend, in which the rubbery domain is located at the interface between SAN/PMMA and PPE/PS, was originally prepared by coprecipitation of all components from a common solution [195]. From a processing point of view, in this system the difficulty was to get the dispersion of PPE in SAN via melt mixing of SAN, PPE and the triblock terpolymer. 

We have recently demonstrated the synthesis of poly(2,6-dimethylphenylene oxide) (PPO) via oxidative coupling in a C02 continuous phase (see Scheme 7) [76]. These reactions proceeded at 345 bar and either room temperature or... 

To this type of reaction belongs the synthesis of poly(phenylene ether)s from substituted phenols, for example, poly(2,6-dimethylphenylene ether), PPE, from 2,6-dimethylphenol in the presence of pyridine and copper(I) chloride ... 

Poly(2,6-dimethylphenylene ether) can be prepared by dehydrogenation of 2,6-dimethylphenol with oxygen in the presence of copper(l) chloride/pyridine as catalyst at room temperature. It is known that the mechanism involves a stepwise reaction, probably proceeding via a copper phenolate complex that is then dehydrogenated. 

Poly(2,6-dimethylphenylene ether) is amorphous and has a glass transition temperature of about 170 °C. It is soluble in chlorinated hydrocarbons such as chloroform, carbon tetrachloride, as well as tetrachloroethane,and also in nitrobenzene and toluene. 

Of the diluents known to affect the dynamic relaxation behavior of polymers in the glassy state, water has so far received the greatest attention. Many polymers, which in the dry state are lacking any secondary relaxation process at temperatures from 77 to 273 K, e.g. poly(methyl methacrylate)135, polymethacrylamide136, cellulose and its derivatives137, collagen138, polysulfones139, poly(2,6-dimethylphenylene oxide)139, and others,... 

Kressler J, Kammer HW (1987) Miscibility behavior of poly(2,6-dimethylphenylene oxide) and poly(styrene-co-acrylonitrile). Acta Polym 38 600-602... 

Organic compounds having labile hydrogens, such as phenols [41,42], phenylene-diamines [43], and acetylenes [44], can be oxidatively coupled in the presence of specific metal complexes to form polymeric compounds. The oxidative polymerization of 2,6-disubstituted phenols with a copper-amine complex produces poly(2,6-disubstituted phenylene ether) [45-51], Poly(2,6-dimethylphenylene ether) and poly(2,6-diphenylphenylene ether) are commercially produced from 2,6-dimethyl phenol and 2,6-diphenylphenol, respectively (Figure 5). These polymers exhibit excellent performance as engineering plastics. 

Figure 5 (a) Poly(2,6-dimethylphenylene ether) (b) poly(2,6-diphenylphenylene ether). 

A series of Japanese patent applications concerns addition of BPA/DC to poly(2,6-dimethylphenylene oxide) (PPO). Electroinsulating coatings with elevated heat resistance were obtained from PPO and BPA/DC [43]. As a rule, maleimide monomers are used together with BPA/DC. According to [44], the following reaction (Scheme 10) between BPA/DC and maleimide takes place ... 

Touring the last decade, catalyzed oxidative coupling has gained wide-spread interest as a novel and general polymerization method. Various polymer systems of scientific and commercial interest have been prepared by this novel technique. Such polymer systems include polyphenylene oxides) (9, 13, 25), of which poly(2,6-dimethylphenylene oxide) (PPO) is produced commercially polyphenylenes (21) poly-... 

FIGURE 10-65 The approximate glass transition temperatures of polyethylene, polydimethylsiloxane and poly(2.6-dimethylphenylene oxide). 

First experiments which focused on the variation of the conformational properties have been performed by Brown et al. [240], who studied the role of the interactions between matrix and brush polymers (enthalpy driven brush swelling, see Eq. 59). They used a series of polystyrene (PS)-poly(methyl methacrylate) (PMMA) symmetric diblock copolymers with different blocks labeled by deuterium, placed at the interface between PMMA and poly(2,6-dimethylphenylene oxide) (PPO) homopolymers. A double brush layer was created with PMMA blocks dangling into (neutral) PMMA homopolymer and PS blocks immersed in favorably interacting PPO melt (x=Xps/ppo<0)- The SIMS profiles obtained showed that the PS side of the block copolymer is stretched by at least a factor of 2 with respect to the PMMA side. 

Scalco, Huseby, and Blyler (8), Zosel (9), and Bergen and Morris (10). Prest and Porter (23) applied the same principle to homopolymer blends [poly (2,6-dimethylphenylene oxide)-polystyrene]. Recently some papers were published on triblock copolymers of styrene-butadiene-styrene and on their blends with polybutadiene (24, 25). Triblock copolymers can be considered heterophase material as the different constituent blocks are thermodynamically incompatible with each other, and, consequently, polystyrene domains are enclosed in polybutadiene (continuous matrix). The findings indicate that these systems are in general thermorheologically complex, so that the shift factor ar depends not only on temperature but also on time. These conclusions have been extrapolated to other two-phase systems. 

Polyacrylonitrile Poly(oxyethylene) Poly(2,6"dimethylphenylene oxide) Poly(ethylene terephthalate)... 

---