Interpenetration composition

Interpenetrating Composite Aerogels by Supercritical Solvent Evacuation A related procedure was reported for the preparation of highly porous, low-density composites. This process relies on the selection of a cosolvent that is suitable for the preparation of interpenetrating organic-inorganic composites, and can also be replaced by carbon dioxide under supercritical... 

The component with the lower viscosity tends to encapsulate the more viscous (or more elastic) component (207) during mixing, because this reduces the rate of energy dissipation. Thus the viscosities may be used to offset the effect of the proportions of the components to control which phase is continuous (2,209). Frequently, there is an intermediate situation where a cocontinuous or interpenetrating network of phases can be generated by careflil control of composition, microrheology, and processing conditions. Rubbery thermoplastic blends have been produced by this route (212). 

The chapter is organized as follows the second section will discuss the photophysics of conjugated polymer/fullerene composites as a standard model for a charge-generating layer in plastic solar cells. Pristine polymer devices will be discussed in the third section while bilayer and interpenetrating network devices are presented in Sections 4 and 5. Section 6 contains some remarks on large area plastic solar cells and Section 7 conclusions. 

Consequently, interpenetrating phase-separated D/A network composites, i.e. bulk heterojunction , would appear to be ideal photovoltaic materials [5]. By controlling the morphology of the phase separation into an interpenetrating network, one can achieve a high interfacial area within a bulk material. Since any point in the composite is within a few nanometers of a D/A interface, such a composite is a bulk D/A heterojunction material. If the network in a device is bicontinuous, as shown in Figure 15-26, the collection efficiency can be equally efficient. 

The toughest challenge and the greatest opportunity in chemical engineering for high-performance materials lie in the development of wholly new designs for composite solids. Such materials are typified by composites reinforced by three-dimensional networks and trass-works—microstractures that are multiply cormected and that interpenetrate the multiply cormected matrix in which they are embedded. In such materials, both reinforcement and matrix are continuous in three dimensions the composite is bicontinuous. Geometric prototypes of... 

The ultimate goal of bulk modification endows with the polymer-specific surface composition or a specific property for a given application. The bulk modification can be classified into blending, copolymerization, interpenetrating polymer networks (IPNs), etc. 

The use of interpenetrating donor-acceptor heterojunctions, such as PPVs/C60 composites, polymer/CdS composites, and interpenetrating polymer networks, substantially improves photoconductivity, and thus the quantum efficiency, of polymer-based photo-voltaics. In these devices, an exciton is photogenerated in the active material, diffuses toward the donor-acceptor interface, and dissociates via charge transfer across the interface. The internal electric field set up by the difference between the electrode energy levels, along with the donor-acceptor morphology, controls the quantum efficiency of the PV cell (Fig. 51). 

The G phase is a complex phase possessing a bicontinuous structure which is located in or close to the compositional range of the PL phase. The minority component forms two interpenetrating threefold coordinated networks [10]. 

KyHg3i, which is not too far from K2Hg7 in chemical composition, is better characterized by an interpenetrating complex arrangement of K-centered high coordination number polyhedra [d(Hg-Hg) > 300 pm, Figure 2.4-8(c)] than by its mercury partial structure alone [4], thus leading into the essential aspects of Section 2.4.2.5. 

A group of crystals show diffraction patterns in which two or more 3D lattices having periods commensurate or incommensurate to each other may be recognized. In other words, the crystal consists of two or more interpenetrating substructures (two or more different atom sets) with different periods at least along one direction (see Fig. 3.42). Names such as composite crystals, vernier structures, misfit-layer structures, and chimney-ladder structures have been used for this group of structures. 

Tautomerism on polymer should be quite sensitive to neighbouring group effects (composition and unit distribution, steric hindrance and tacticity) and to the microenvironment polarity in solution (copolymer-solvent interactions, critical concentration c of coil interpenetration). The determination of the tautomerism constant KT=(total conjugated forms)/(keto form) in dilute (csemi-dilute (c>c ) solution from H-NMR at 250 MHz and from UV spectroscopy has been reported elsewhere (39,43). The following spectrometric data related to keto-2-picolyl and keto-qui-naldyl structures are quite illustrative ... 

The volume fraction of each phase was taken from the fractional area in the transmission electron micrographs. Combined with the values shown in Table 1, the compositions within each phase were calculated and are shown in Table 2. Overall, the results suggest variably 0-20% actual molecular mixing. Noting the probable errors in estimating the experimental Tg s, the and W2 values are probably correct to within +0.05. Thus mixing plays an important role in interpenetration and influences the reinforcement within each phase. 

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