Hybrid polymer blends

Although this definition still fits most materials called IPNs, now some hybrid polymer blends, such as thermoplastie ayyarent IPNs, call for a broader concept [3,7,8]. In contrast to the chemically crosslinked IPNs, physical bonds are characteristic of the crosslinking in thermoplastic apparent IPNs. These physical bonds are glassy domains of block copolymers, ionic clusters in iono-mers, or crystalline domains in semicrystalline polymers. The components of thermoplastic IPNs are capable to form physical networks and are characterized by interpenetration of phases. Thermoplastic apparent IPNs take an inter-... 

Interaction parameters for polymer blends, 20 322 in surfactant adsorption, 24 138 Interaortic balloon pump, 3 746 Intercalated disks, myocardium, 5 79 Intercalate hybrid materials, 13 546-548 Intercalation adducts, 13 536-537 Intercalation compounds, 12 777 Intercritical annealing, 23 298 Interdiffusion, 26 772 Interdigitated electrode capacitance transducer, 14 155 Interesterification, 10 811—813, 831 Interest expense, 9 539 Interface chemistry, in foams, 12 3—19 Interface metallurgy materials, 17 834 Interfaces defined, 24 71... 

Pearce, E. Kwei, T. K. Lu, S. Hydrogen Bond Interactions and Self-Condensation of Silanol-Containing Polymers in Polymer Blends and Organic-Inorganic Polymeric Hybrids. In Silicones and Silicone-Modified Materials-, Clarson, S. J., Fitzgerald, J. J., Owen, M. J., Smith, S. D., Eds. ACS Symposium Series 729 American Chemical Society Washington, DC, 2000 pp 419-432. 

Choi S.-H., Song H., Park 1. K., Yum J.-H., Kim S.-S., Lee S. and Snng Y.-E. (2006), Synthesis of size-controlled CdSe qnantum dots and characterization of CdSe-conjngated polymer blends for hybrid solar cells , J. Photochem. Photobiol. A 179, 135-141. 

One extensively studied material system among the nanocrystal-polymer blends is zinc oxide (ZnO) in combination with MDMO-PPV or P3HT [273-282]. Beek et al. presented the first polymer solar cells containing ZnO nanoparticles, reaching power conversion efficiencies of 1.6% [273]. In this case the nanoparticles were prepared separately and then intermixed with MDMO-PPV in solution. Shortly after this study the Janssen group presented another route to ZnO-polymer hybrid solar cells by forming the nanocrystals in situ inside the film by applying a precursor [274]. Here, diethylzinc served as the precursor and was spin cast in blends with MDMO-PPV. Process-... 

The linear viscoelastic properties in the melt state of highly grafted polymers on spherical silica nanoparticles are probed using linear dynamic oscillatory measurements and linear stress relaxation measurements. While the pure silica tethered polymer nanocomposite exhibits solid-like response, the addition of a matched molecular weight free matrix homopolymer chains to this hybrid material, initially lowers the modulus and later changes the viscoelastic response to that of a liquid. These results are consistent with the breakdown of the ordered mesoscale structure, characteristic of the pure hybrid and the high hybrid concentration blends, by the addition of homopolymers with matched molecular weights. 

The polymer tethered silica hybrids were blended with a homopolymer with similar molecular weight to the one attached to the silica nanoparticles (Table... 

Figure 5. Blend composition dependence of the value of the storage modulus at a fixed frequency of 1 rad/s at a reference temperature of 30 °C. The frequency corresponds to a time scale significantly larger than the relaxation time of the polymer. The plateau at long times observed for the three highest hybrid concentration blends occur at frequencies lower than the frequency chosen here.

Thermoplastic IPN. When physical crosslinks rather than chemical crosslinks are utilized, the materials may flow at elevated temperatures. As such, they are hybrids between polymer blends and IPNs. Such crosslinks commonly involve block copolymers, ionomers, and/or semicrystallinity. 

Chem. Descrip. Proprietary polymers blend Uses Surf, modifier for powd. coatings based on urethanes, epoxies, hybrids, polyesters... 

Numerous polymers have been studied for their potential apphcation in PEMFCs. Based on their chemical structure, these polymers can be categorized into (a) vinylic polymers, (b) aromatic polymers, and (c) polymer blends and composite/hybrid polymers. Generally, vinylic polymers are synthesized by addition polymerization, while aromatic polymers are synthesized by step-growth polymerization. The most studied vinylic polymers for PEMFC applications are perfluorosulfonic acid ionomers (PFSls), in particular Nation , and styrene sulfonic acid-based polymers. Chemical structures of representative vinyhc PEMs are shown in Scheme 2. 

M.-C Wu, et al, Nanostructured polymer blends (P3HT/PMMA) Inorganic titania hybrid photovoltaic devices. Solar Energy Materials and Solar Cells, 2009. 93(6-7) p. 961-965. 

In practice, methods (2) and (3) seem to be the most commonly used. Recently, yet another method of preparation of hybrid polymer dispersions, called an active blending has been reported [18]. The components of such active blends or active mixtures remain inactive when in the presence of water, and cross-react during film formation. 

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