Exotic polymer

In several cases the formation of a special morphology imparts mechanical properties to "simple" macromolecules which hitherto have only be obtained with "exotic" polymers (e.g. high strength polyethylene fibers). 

A key challenge is figuring out how to get less exotic polymers to self-assemble. Physical scientists are a long way from being able to control polymer syntheses so that the self-assembly of complicated, three-dimensional molecules is possible. This is a very active area of research, one that promises eventually to result in interesting new scientific understanding, new technological tools, and new materials with unique properties. 

The number N of vertices in the hydrogen-suppressed graph, the zeroth-order connectivity indices and °%v, and the first-order connectivity indices l% and 1xv, are listed in Table 2.2 for a diverse set of 357 polymers. All of the common polymers are included in this table. Many specialized and/or exotic polymers are also included. The polymers are listed in the order of increasing N. The easiest way to look up the connectivity indices of a polymer in Table 2.2 is to draw the stmcture of the repeat unit of the polymer, count the number of non-hydrogen atoms in this repeat unit, and search among the polymers with that value of N. For example, poly(vinyl fluoride), which is shown in Figure 2.3, has N=3. Its connectivity indices can be... 

The structures of some of the more exotic polymers from this dataset are shown in Figure 15.3. 

The false monomeric unit content can often be determined by spectroscopic procedures, such as infrared or nuclear magnetic resonance spectroscopy. In the special cases of acrylamide or styrene p-sulfonamide polymers, it can be determined by hydrolysis as well. Polymers for which no monomer corresponding to the actual monomeric unit exists are called phantom or exotic polymers. 

For general purpose rubbers, the quantity and type of monomer incorporated for cure may be of vital importance. This will determine the method and rate of cure that is possible. Several of the more exotic polymers have recently become available with termonomers incorporated to allow crosslinking by peroxides rather than by the use of more exotic chemicals. This has provided a greater degree of latitude to the chemist in polymer choice. 

Thus I as the result of the lucky accident associated with the work on HFPO, the ultimate in thermoplastic perfluorocarbon polymers was commercialized in 1972, over ten years later. The long time between initial discovery and commercialization was only in part due to the enormous amount of new technology that had to be developed. Of equal importance was the lack of a clear cut market for this exotic polymer. 

The most significant change that could occur in the usage pattern of NBRs would be an increasing use of the thermoplastic alternatives, where the production cost reductions possible in the moulding process would be difficult to resist. Even though some final application conditions have warranted a move to more exotic polymers, the... 

In space environments, temperature extremes require exotic polymers as adhesives and sealants for spacecraft, and bombardment by particles, such as molecules, ions, and atoms, requires special coatings on the surface of spacecraft. 

In Chapters 3 and 4 the basic plastics materials were described. In reinforced plastics both thermosetting and thermoplastic polymers are used although their method of use is very different. Very many thermoset resins can and have been used with reinforcements. Unsaturated polyester resins are normally looked upon as the main material used in conjunction with reinforcements, and the majority of this chapter will be devoted to the use of these materials. Many other thermosetting resins, epoxides, phenolics, silicones, and some of the exotic polymers such as the polyimides have been used extremely successfully. 

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