Polymer blends poly based

Pasupathi et al. fabricated an acid-base polymer blend membrane based on sulfonated poly(etheretherketone) and poly(benzimidazole) for direct methanol fuel cells. A SPEEK/PBI membrane demonstrated a noticeable enhancement in the DMFC performance compared with Nafion 117. The maximum power densities (45 mW cm ) obtained with SPEEK/PBI membranes were twice that of Nafion 117 at 60 °C. This membrane maintained high power densities for more than 50 days of operation and therefore is seen as a potential candidate for portable DMFC applications [89]. 

Common conductive polymers are poly acetylene, polyphenylene, poly-(phenylene sulfide), polypyrrole, and polyvinylcarba2ole (123) (see Electrically conductive polymers). A static-dissipative polymer based on a polyether copolymer has been aimounced (124). In general, electroconductive polymers have proven to be expensive and difficult to process. In most cases they are blended with another polymer to improve the processibiUty. Conductive polymers have met with limited commercial success. 

Blends of yellowish-green-light emissive carbazole-containing PPV-based copolymer 105 (Apl = 490, 520 nm, AEL = 533 nm) with blue-emissive oxadiazole- poly-/ -phenylene (PPP) copolymer 106 (AEL = 426 nm) allowed to tune the emission of PLEDs (ITO/polymer blend/Al) from AEL = 533 nm to AEL = 451 nm, although the device turn-on voltage was essentially higher for the blends with increased content of 106 [149] (Chart 2.22). 

H Jagt, Y Dirix, R Hikmet, and C Bastiaansen, Linear polarizers based on polymer blends oriented blends of poly(ethylene-2,6-naphthalenedicarboxylate) and a poly(styrene/methylmethacrylate) copolymer, Jpn. J. Appl. Phys., 37 4389-4392, 1998. 

S. Patachia, Blends based on poly(vinyl alcohol) and the products based on this polymer , in Handbook of Polymer blends and composites , C. Vasile and A.K. Kulshreshtha (eds.), Chap. 8, RAPRA Technology LTD., England, Chap.8. 2003. p. 288-365. 

Swier, S., Ramani, V., Fenton, J. M., Kunz, H. R., Shaw, M. T. and Weiss, R. A. 2005. Polymer blends based on sulfonated poly(ether ketone ketone) and poly(ether sulfone) as proton exchange membranes for fuel cells. Journal of Membrane Science 256 122-133. 

Gao, Y., Robertson, G. R, Guiver, M. D., Jian, X. G., Mikhailenko, S. D. and Kaliaguine, S. 2005. Proton exchange membranes based on sulfonated poly(phthalazinone ether ketone)s/aminated polymer blends. Solid State Ionics 176 409-415. 

Figure 5.19 Homogenous polymer blend of 2,7-diamido-l,8-naphthyridine (DAN) functionalized polystyrene and urea of guanosine (UG) functionalized poly(butyl methacrylate) (14), based on the four-point complementary complex formation between DAN and UG.

One method of reducing crystallinity in PEO-based systems is to synthesize polymers in which the lengths of the oxyethylene sequences are relatively short, such as through copolymerization. The most notable hnear copolymer of this type is oxymethylene-linked poly(oxyethylene), commonly called amorphous PEO, or aPEO for short. Other notable polymer electrolytes are based upon polysiloxanes and polyphosphazenes. Polymer blends have also been used for these applications, such as PEO and poly (methyl methacrylate), PMMA. The general performance characteristics of the polymer electrolytes are to have ionic conductivities in the range of cm) or (S/cm). 

Knaub P, Camberlin Y (1988) Gerard JF, New reactive polymer blends based on poly(urethane ureas) (PUR) and polydisperse poly(dimethylsiloxane) (PDMS) control of morphology using a PUR-b-PDMS block copolymer. Polymer 29(8) 1365-1377... 

Morphology evolution during solution casting of polymer blends has been studied to some extent in recent years [93-96]. More than 10 blend solutions comprising immiscible polymers and random copolymers such as poly(methyl methacrylate) and different styren-based copolymers were studied in Ref. [93]. The results can be summarized as follows ... 

Miscible Blends. Both Components Amorphous. Certainly one of the most commercially important and publicized examples of a miscible polymer blend system is that based on polystyrene and poly(phenylene oxide), which is sold under the trade name Noryl by General Electric. Many fundamental studies of this system have been published, many of which were devoted to proving that these two components are miscible in a thermodynamic sense (see chapter 5 of Ref. 10 by MacKnight, Karasz, and Fried). Commercial interest in this system involves both... 

A preliminary screening indicated that excellent impact could be obtained using 15-20 wt % butadiene based on the total polymer blend. At 20 wt % butadiene, several block polymers were screened for optimum impact and overall balance of properties. Two-component systems (block polymer-polystyrene) and three-component systems (block poly-mer-polybutadiene-polystyrene) were tried. The impact varied with the styrene content of the block polymer in both two- and three-component systems as shown in Figure 1. Subsequent work showed that the best overall balance of impact, flexural modulus, and heat distortion was obtained at 15% butadiene. 

The only single phase, miscible IPNs reported are homopolymer IPNs, in which both networks are composed of the same polymer, and IPNs based on poly (2,6-dime thy Iphenylene oxide) (PPO) and polystyrene (PS) (18). The corresponding blend of the latter system is miscible and does not undergo thermally induced phase separation below its degradation temperature (19). 

As reported by Diehl et al. [58], interpolymers are also compatible with a broader range of polymers, including styrene block copolymers [59], poly(vinyl chloride) (PVC)-based polymers [60], poly(phenylene ethers) [61] and olefinic polymers such as ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer and chlorinated polyethylene. Owing to their unique molecular structure, specific ESI have been demonstrated as effective blend compatibilizers for polystyrene-polyethylene blends [62,63]. The development of the miscibility/ compatibility behavior of ESI-ESI blends differing in styrene content will be highlighted below. 

Conducting polymer blends based upon polyaniline (PANI) are a new class of materials in which the percolation threshold for the onset of electrical conductivity can be reduced to volume fractions well below that required for classical percolation (16% by volume for globular conducting objects dispersed in an insulating matrix in three dimensions) [277,278], The origin of this remarkably low threshold for the onset of electrical conductivity is the self-assembled network morphology of the PANI poly blends, which forms during the course of liquid-liquid phase separation [61],... 

Polymer blends based on a polyester and a polycarbonate have been shown to be immiscible provided no transesterification reaction occurs (Porter Wang, 1992). Heat treatment of the same blends yielded different degrees of compatibility depending on the temperature and duration of the treatment, as well as on the presence and type of catalyst. This method has been successfully used to increase the compatibility of different polymers with poly(bisphenol-A-carbonate) (PC). 

Eisenberg and coworkers have employed acid-base interactions to improve the miscibility of a number of polymer-polymer pairs. Miscible blends were prepared using acid-base interactions, e.g., with SPS (acid derivative) and poly (ethylacrylate-co-4-vinylpyrldine) (91), sulfonated polyisoprene and poly (styrene-co-4-vinylpyridine) (92), and using ion-dipole interactions, e.g., poly (styrene-co-llthium methacrylate) and poly (ethylene oxide) (93). Similarly, Weiss et al. (94) prepared miscible blends of SPS(acid) and amino-terminated poly (alkylene oxide). In addition to miscibility improvements, the interactions between two functionalized polymers offers the possibility for achieving unique molecular architecture with a polymer blend. Sen and Weiss describe the preparation of graft-copolymers by transition metal complexation of two functionalized polymers in another chapter. 

Solid-state NMR has been applied successfully in a few cases for the study of poly(imide) blends. It can be said, however, that the techniques arising from recent advances in the analysis of polymer blends, such as selection techniques based on multipulse methods, and improvements in the modelling methods of spin diffusion, have yet to be applied to the study of blends containing poly(imide)s. It is suggested that these techniques will have an important role to play in future studies of poly(imide) blends, particularly for blends such as impact-modified BMI resins. 

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