Condensation polymerizations Condensed structural formulas

Haward et al.t have reported some research in which a copolymer of styrene and hydroxyethylmethacrylate was cross-linked by hexamethylene diisocyanate. Draw the structural formula for a portion of this cross-linked polymer and indicate what part of the molecule is the result of a condensation reaction and what part results from addition polymerization. These authors indicate that the crosslinking reaction is carried out in sufficiently dilute solutions of copolymer that the crosslinking is primarily intramolecular rather than intermolecular. Explain the distinction between these two terms and why concentration affects the relative amounts of each. 

Identify the monomers that form specific polymers, and draw structural formulas for polymers made from given monomers. Differentiate between condensation and addition polymerization reactions. Summarize the relationship between structure and properties of polymers. 

The structural formulae are COOH (CH 2) if COOH (adipic acid) and H2N(CH2) 6NH2 This polymer was larought about by condensation polymerization with the loss of a small molecule (H2O), which is a characteristic of all condensation polymerizations. 

Polysaccharides are naturally occurring polymers, which can be considered as derived from aldoses or ketoses by condensation polymerization. A polysaccharide derived from hexoses, for example, has the general formula (C6H]oOs)n. This formula, of course, tells us very little about the structure of the polysaccharide. We need to know what the monosaccharide units are and how many there are in each molecule how they are joined to each other and whether the huge molecules thus formed are straight-chained or branched, looped or coiled. 

It was, therefore, decided that we would study thermal polymerization of bisdichloromaleimides at 300°C for 30 min. The resulting product was soluble in DMF to a great extent (Table III) with the exception of compound (b). This indicates the absence of thermal polymerization under these conditions. Anaerobic char yields of these thermally treated bisdichloromaleimides depended on their backbone structure a very low value was obtained in compounds (a) and (c) compound (b), which contained phosphorus, was most stable. Condensed phase reactions are influenced by the presence of phosphorus in these polymers. An almost linear relationship is observed between anerobic char yields at 800°C and bridge formula weight of bisdichloromaleimide (Fig. 3). 

A number of aluminium aspirin preparations have also been described, to which different structures have been assigned . One of these compounds, aluminium aspirin NF, was found to be poorly absorbed compared with acetylsalicylic acid. Aloxiprin (Palaprin) is a different form of aluminium aspirin, being a polymeric condensation product of aluminium oxide and acetylsalicylic acid, with the formula Al302(C8H4(o-OCMe)-COO)s 9B. This compound is therapeutically as effective as acetylsalicylic acid it produces less gastric irritation and gastro-intestinal blood loss, but has a slight tendency to cause constipation. ... 

Carothers defined addition polymers as those in which the molecular formula of the monomer is identical to that of the structural unit, so that the monomer can be obtained back from the polymer by thermolysis and, vice versa, the polymer can be synthesized from the monomer by self-addition. Condensation polymers, according to Carothers, are those where the molecular formula of the monomer differs from that of the structural unit in this case, the monomer can be obtained from the polymer by hydrolysis or an equivalent reaction, and the polymer can be synthesized from the monomer by poly-intermolecular condensation. In this type of polymerization, the elimination of simpler molecules (H2O, HCl, NaCl, etc.) is common [1]. 

Molecules of a difiinctional monomer such as X-R-Y (where X and Y are mutually reactive functional groups) are polymerized via the elimination of small molecule by-products of XY, a linear condensation polymer with a general formula of X-(-R-)w-Y is formed, whereas when molecules of an olefinic monomer such as H2C=CHR are polymerized, a vinyl polymer with a structure of -[-H2C-CH(R)-]w- is produced. The difunctional and olefinic monomers have been the major monomer sources, and their step and chain polymerization reactions have been the main synthetic routes to the conventional polymers such as polyester and polystyrene, respectively [27]. 

In 1929 Carothers made the proposition that all polymers could be divided into two types, namely condensation polymers and addition polymers. A condensation polymer was defined as a polymer in which the structural unit contains fewer atoms than the monomer (or monomers) from which the polymer is derived. An addition polymer was defined as a polymer in which the structural unit has the same molecular formula as the monomer. A limitation of this classification is that some polymers may be included in both categories. For example, polyethylene is usually prepared by the polymerization of ethylene ... 

If pyrrole formation occurs with an amino acid, this product can react further (Formula 4.63) to yield a bicychc lactone (V in Formula 4.59). Other secondary products of 3-deoxyosone are compounds with a pyranone structure. In fact, P-pyranone (VI in Formula 4.59) is under discussion as the most important intermediate. It can be formed from the pyranose hemiacetal form of 3-deoxyosone (Formula 4.64). This compound has been identified only in the full acetal form (e. g., with carbohydrates on drying) because only this structure makes a relatively stable end product possible. The compounds mentioned have acidic hydrogen atoms in position 4, easily allowing condensation reactions with aldehydes and polymerization or the formation of brown dyes. 

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