Condensation polymerization definition

The general definition of a condensation reaction is a one that involves product formation by expulsion of water (or other small molecule) as a by-product. By this definition, activation and methylolation are also condensations. In more precise terms the chain-building process should be described as a condensation polymerization, however, in the jargon of the phenolics industry, the term condensation is usually reserved for the chain-building process. This terminology is not necessarily observed in the literature [88]. Many literature reports correctly refer to methylolation as a condensation reaction. The molecular weight development of the phenol alcohol adducts may also be classified as a step-polymerization. 

Representative condensation polymers are listed in Table I. The list is by no means exhaustive, but it serves to indicate the variety of condensation reactions which may be employed in the synthesis of polymers. Cellulose and proteins, although their syntheses have not been accomplished by condensation polymerization in the laboratory, nevertheless are included within the definition of condensation polymers on the ground that they can be degraded, hydrolytically, to monomers differing from the structural units by the addition of the elements of a molecule of water. This is denoted by the direction of the arrows in the table, indicating depolymerization. 

The free amino group of the amino ester may then react analogously with another molecule of the monomer, etc. The kinetics of the polymerization are in harmony with a mechanism of this sort. The final polypeptide may contain up to 300 or more structural units. While the polymerization of N-carboxyanhydrides is closely analogous to the addition polymerizations of ethylene oxide and of other cyclic substances, definition unfortunately classifies it as a condensation polymerization inasmuch as carbon dioxide is eliminated in the process. 

The difficulties of devising a basis for conveniently classifying various polymerizations in an appropriate manner have been discussed earlier in this chapter and several borderline examples which offer particular difficulty have been mentioned. One of these, the polymerization of the N-carboxyanhydrides, falls within the definition of a condensation polymerization, proceeds by a mechanism resembling a vinyl addition polymerization, and yields a product which possesses the structure of a typical condensation polymer. Definitions have been... 

Note 2 The earlier term polycondensation was synon5nnous with condensation polymerization. It should be noted that the current definitions of polycondensation and eondensative chain polymerization were both embraced by the earlier term polycondensation. 

While this particular reaction fulfils one of the early definition requirements of the term condensation polymerization , i.e., that another molecule was eliminated as a by-product, polyurethane formation... 

Definition Sodium salt of the prod, obtained by condensation polymerization of naphthalene sulfonic acid and formaldehyde Formula (CkFIsOjS CFIjO), xNa Properties Anionic... 

Polymerizations are classified by lUPAC as either addition polymerizations, or condensation polymerizations. According to this definition, addition polymerizations consist of repeated addition processes, and condensation... 

But all these definitions are purely phenomenological, and provide no information on the elementary processes in polymerization. Thus, three other definitions of addition and condensation polymerization are to be found in the literature. 

Cloud point n. (1) In condensation polymerization, the temperature at which the first turbidity appears, caused by water separation when a reaction mbcture is cooled. (2) In petroleum and other oils, the falling temperature at which the oil becomes cloudy, from precipitation, of wax or other solid. (3) Point at which a definite lack of clarity (cloudiness) appears when a liquid is... 

Synonyms Naphthalenesulfbnic acid-formaldehyde condensate, sodium salt Naphthaienesuifonic acid, poiymer with fonnaldehyde, sodium salt Sodium naph-thaiene-formaidehyde suifonate Sodium naphthalene-fonnaldehyde sulfonate polymers Sodium naphthalene sulfonate Sodium polynaphthalenemethane sulfonate Sodium salt of sulfonated naphthalene-fonnaldehyde condensate Definition Sodium salt of the prod, obtained by condensation polymerization of naphthalene sulfonic acid and formaldehyde ionic Nature Anionic Formuia (C uHjOjS CHjOj -xNa... 

A stochastic system is one whose behavior is not purely deterministic and predictable, but rather has (assumed inherent) randomness. The theory of probability provides a mathematical fi amework for understanding and modeling such systems. Rather than provide abstract definitions, we introduce the subject through an example modeling the distribution of polymer chain lengths in condensation polymerization. 

The chemical and physical properties of the polymers obtained by these alternate methods are identical, except insofar as they are affected by differences in molecular weight. In order to avoid the confusion which would result if classification of the products were to be based on the method of synthesis actually employed in each case, it has been proposed that the substance be referred to as a condensation polymer in such instances, irrespective of whether a condensation or an addition polymerization process was used in its preparation. The cyclic compound is after all a condensation product of one or more bifunctional compounds, and in this sense the linear polymer obtained from the cyclic intermediate can be regarded as the polymeric derivative of the bifunctional monomer(s). Furthermore, each of the polymers listed in Table III may be degraded to bifunctional monomers differing in composition from the structural unit, although such degradation of polyethylene oxide and the polythioether may be difficult. Apart from the demands of any particular definition, it is clearly desirable to include all of these substances among the condensation... 

Few definitive studies have been reported for the reduced catalyst. One of the earliest studies which was made attempted to relate activity for aldol condensation of n-butylaldehyde to Mo5+ concentration on reduced Mo/Al catalysts (39). The catalysts contained varying amounts of Mo and were prereduced under identical conditions. Aldol conversions were approximately linear with Mo5+ signals (by ESR) up to about 10% Mo. Morris et al. (101) also report a correlation between Mo5+ and catalytic activity for ethylene polymerization over reduced Mo/Al catalysts. Unfortunately, in both studies, tests were not done on a catalyst having the same Mo content but prereduced under different conditions (to give different Mo5+ values). Therefore, the correlation obtained was not unequivocal since other parameters besides Mo5+ might also be proportional to Mo level. 

Based on the classical definitions given in organic chemistry, the step-growth polymerization process can involve either condensation steps or addition steps. The former proceeds with elimination of by-products while the latter takes place without elimination of by-products. This is illustrated by Eqs (2.1) and (2.2), for the particular case of difunctional molecules ... 

Assuming the above statements are correct, any two p-xylylene species should be capable of copolymerization in any desired ratio. This is somewhat of a simplification since it has been observed that for each substituted p-xylylene there is a definite ceiling condensation temperature above which it will not condense and polymerize at any appreciable rate. Thus, if the monomer does not condense, it is not available for copolymerization. This was demonstrated in the studies described earlier of the pyrolysis of acetyl-di-p-xylylene and separation of the monomers VI and VII on the basis of widely differing Tc s. 

The segment condensation approach is now one of the rapidly developing techniques in the solid phase method. The possibility of the isolation, purification and characterization of the intermediates in this approach is definitely a notable advantage over the stepwise synthesis on the polymeric support. 

The propensity of NCAs to polymerize has substantially limited their routine use for sequential peptide synthesis. Upon first reports on the reaction of NCAs with amines or amino acid esters,Baileyt provided a definitive study of the reaction of amino acid esters with a variety of NCAs at —65 °C to give A-carbamoyl dipeptides which on warming to room temperature liberated carbon dioxide to give the free amino dipeptide. The mixture is then recooled to —65°C and condensed with a second NCA to give the tripeptide (Scheme 11). 

Published kinetic data were generally obtained in batch reactors (1-5). The data obtained were observed to fit first order kinetics notwithstanding the complexity of the feeds studied and the constant change in the nature of the product-forming intermediates. It has been shown (3,5) that batch coking has a definite induction period and that the usually observed first order coking behavior of complex feeds is only apparent. Also it was determined that the rates observed could fit third order kinetics for decomposition and fourth order for polymerization/ condensation (5). Clearly, kinetics of batch coking are only approximations. 

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