Materials simultaneous interpenetrating

The first type, termed sequential IPN s, involves the preparation of a crosslinked polymer I, a subsequent swelling of monomer II components and polymerization of the monomer II in situ. The second type of synthesis yields materials known as simultaneous interpenetrating networks (SIN s), involves the mixing of all components in an early stage, followed by the formation of both networks via independent reactions proceeding in the same container (10,11). One network can be formed by a chain growth mechanism and the other by a step growth mechanism. 

Castor oil and styrene were polymerized to make simultaneous interpenetrating networks. On reaction, the materials phase separate and sometimes phase invert. 

Simultaneous Interpenetrating Networks Based on Epoxy/Acrylic Materials... 

IPN s and related materials) in fact) have a long history. For example) IPN s were first synthesized to produce smooth sheets of bulk polymerized homopolymers (11), IPN s were next used as solution polymerized ion exchange resins. (12) 13) Further development of IPN s included the syntheses oT interpenetrating elastomer networks (lEN s) and simultaneous interpenetrating networks (SIN s) (14). lEN s consist of a mixture of different emulsion polymerized elastomers which are both crosslinked after coagulation. SIN s are formed by the simultaneous polymerization of mixed monomers by two noninterfering reactions (3 ) 16). 

In those years, Edison had switched from the cylinder-type phonograph records to the platter type. The latter ones were made of the new phenol-formaldehyde material, just invented by Leo Baekeland. The problem with the new material was that it was extremely biitfle, hence the new platters needed to be very thick. Aylsworth s solution to the problem was to mix in natural rubber and sulfur, which on heating forms a network. Since the phenol-formaldehyde compositions are all densely crosslinked, the overall composition was a simultaneous interpenetrating network. 

R. E. Touhsaent, D. A. Thomas, and L. H. Sperling, Simultaneous Interpenetrating Networks Based on Epoxy/Acrylic Materials, in Toughness and Brittleness of Plastics, R. D. Deanin and A. M. Crugnola, Advances in Chemistry Series No. 154, American Chemical Society, Washington, D.C. (1976), Epoxy/P (n-BA) SINs. 

If appreciable mixing between the component polymers occurs, the inward shift in the Tg of the two phases can each be expressed by the equations of Section 8.8.1 (125). Using equation (8.73), the extent of mixing within each phase in a simultaneous interpenetrating network of an epoxy resin and poly(n-butyl acrylate) was calculated (see Table 8.10). The overall composition was 80/20 epoxy/acrylic, and glycidyl methacrylate is shown to enhance molecular mixing between the chains. Chapter 13 provides additional material on the glass transition behavior of multicomponent materials. 

There are several kinds of such composites, including the polymers filled in situ by inorganic particles, hybrids formed on simultaneous formation of interpenetrating organic and inorganic networks, and materials obtained by the introduction of organic substances into the polymer inorganic networks. 

In this type of material, two networks are formed, either simultaneously or sequentially, in such a way as to interpenetrate one another. They thus communicate with one another through interchain interactions, including entanglements, rather than through... 

This can be achieved either by impregnation of a preformed gel, or by adding these monomers to the alkoxide solution. In this case, the simultaneous polymerization of organic and inorganic precursors leads to IPN (Interpenetrating Polymer Network) hybrids where both cross-linked gels are associated at the molecular level, as demonstrated for PDMAAm- and polystyrene-silica materials (Figure 4b). ... 

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