Condensation polymers summary

Tables 13.4 and 13.5 contain a summary of typical stability values for a number of polymers and elastomers against typical chemical agents. As expected, condensation polymers generally exhibit good stability to nonpolar liquids while they are generally only (relatively) moderately or unstable toward polar agents and acids and bases. This is because of the polarity of the connective condensation linkages within the polymer backbone. By comparison, vinyl type of polymers exhibit moderate to good stability toward both polar and...

In summary, a polymer is classified as a condensation polymer if its synthesis involves the elimination of small molecules, or it contains functional groups as part of the polymer chain, or its repeating unit lacks certain atoms that are present in the (hypothetical) monomer to which it can be degraded. If a polymer does not fulfill any of these requirements, it is classified as an addition polymer. 

The routes give, using well-known condensation and radical reactions, bakelites (I), polyazophenylenes (II), polyimides (III), polyurethanes (IV), nitro compounds and polyamides (V), aromatic polyethers and polyesters (VI), polychalcones (VII), polyphenylene sulfides (IX), ammonia lignin (X), carbon fibers (XI), silicones (XII), and phosphorus esters (XIII). In addition, radiation and chemical grafting can be used to obtain polymers of theoretical interest and practical use. Although the literature on the above subject is very large, there are comprehensive summaries available (1,28,69). 

In summary, the acid-catalyzed condensation polymerization of sugars in methyl sulfoxide results in the formation of copolymers of the sugars with formaldehyde. The glycosyl residues probably occur in blocks, instead of being evenly separated by methylene bridges. The polymers are highly branched, and the glycosyl residues appear to be substituted in a random fashion. 

Summary Two-component room temperature-vulcanizing, condensation-curing systems (RTV-2) are well known in silicone chemistry. Even silicone-based materials caimot fulfill all requirements in diverse applications. It is therefore desirable to combine the curing properties of silicone-based systems with those of other polymer backbones. The use of isocyanatomethyl-dimethylmonomethoxysilane allows the straightforward derivatization of, e.g., hydroxyl-terminated polymers, which yield mono-silanol-terminated polymers upon hydrolysis. 

Summary During the last few years intense research has been focussed on the elaboration of synthetic materials [1-4] based on modified silicon esters. Products with interesting properties were formed by synthesis of a novel group of derived silicon esters. The condensation of carbonyl- and amino groups leads to organotrialkoxysilanes containing azomethine bonds. From these compounds three-dimensional, cross-linked silicon polymers were synthesized by hydrolysis/condensation. 

A summary of the condensable products formed in the RF. powered discharge is presented in Table II. It should be noted that these results are normalized to exclude recovered toluene. Non-condensable gases and polymeric materials in combination accounted for 6 to 16% of the original toluene vapor. The amount of polymer formed was found to vary, unaccountably over a wide range. 

Fig. 4.8. A summary of the three steps of the parylene deposition process. Parylene-C is shown. First, the stable dimer is vaporized at approximately 170°C, and diffuses into the cracker, which is held around 700°C. The cracker breaks the dimer into two reactive monomer units which diffuse into the deposition chamber and condense into a fully reacted polymer at room temperature. Unreacted material is captured in a cold trap to protect the vacuum pump, and the deposition process occurs at approximately 10-50mtorr for parylene-C.

Summary In continuation of our previous contributions concerning the fluorescence behavior of polysiloxanes containing oligosilanyl substructures, the photoluminescence of hydrolysis and condensation products derived from di- and trifiinctional cyclooligosilanes has been investigated. To our present knowledge there are two conditions to be met for our siloxene-like polymers in order to exhibit fluorescence the presence of cyclosilanyl subunits and a two- or three-dimensional polymeric structure. 

As for bulk condensed matter in general, analysis of the microscopic structure of polymer systems is mostly carried out by scattering experiments. This chapter in the Appendix is meant to provide the reader with a summary of results of scattering theory, including both general and specific equations, in a selection suggested by the needs of the considerations in this book. 

The lack of a satisfactory molecular theory for the deformation of polymers has led to the development of mechanical analogues and phenomenological models that represent the material. The task is to find combinations of elastic and viscous elements that reproduce the material behaviour. There is more than one combination that will reproduce the same behaviour. Some combinations are more convenient for a given kind of test and less convenient for another. However, a proper combination of elements should in principle be able to represent all the various tests. A condensed summary of the stress-strain behaviour of the various models is given below. 

Figure 6 Schematic summary of the normal forces F(D) between polymer-modified surfaces as a function of surface separation D. Adapted with slight changes from Klein, J. Molecular Conformation and Dynamics of Macromolecules in Condensed Systems Nagasawa, M., Ed. Elsevier Amsterdam, The Netherlands, 1988 pp 333-352, and Klein, J. Fundamentals of Tribology and Bridging the Gap Between the Macro- and MIcro/Nanoscale Bhushan, B., Ed. Kluwer Academic Publishers The Netherlands, 2001 pp 177-198." At low surface coverage (a), attractive bridging effect (cartoon in a) dominates the interactions. Rg indicates the gyration radius of the free polymer. The interactions in the case of high surface coverage are shown in b.

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