Diacids, aliphatic

Polyesters are the most important class of synthetic fibers. In general, polyesters are produced by an esterification reaction of a diol and a diacid. Carothers (1930) was the first to try to synthesize a polyester fiber by reacting an aliphatic diacid with a diol. The polymers were not suitable because of their low melting points. However, he was successful in preparing the first synthetic fiber (nylon 66). In 1946, Whinfield and Dickson prepared the first polyester polymer by using terephthalic acid (an aromatic diacid) and ethylene glycol. 

Melt spinning polyesters is preferred to solution spinning because of its lower cost. Due to the hydrophobic nature of the fiber, sulfonated terephthalic acid may be used as a comonomer to provide anionic sites for cationic dyes. Small amounts of aliphatic diacids such as adipic acid may also be used to increase the dyeability of the fibers by disturbing the fiber s crystallinity. 

Morgan and Kwolek33 have described a large number of PA derived from phenylenediamines and aliphatic diacids by low-temperature solution polymerization starting with aliphatic diacid chlorides. 

Aliphatic-aromatic copoly imides, 268 Aliphatic-aromatic polyesters, 18, 19 Aliphatic degradable polyesters, 41 Aliphatic diacids, polyamide synthesis from, 183-184... 

Crystalline polyesters from CHDM and aliphatic diacids are possible, but generally of little interest because of low melting points and low glass transition temperatures. Cyclic aliphatic diacids offer some potentially attractive possibilities. For example, the polyester of CHDM with a high-frans isomer 1,4-cyclohexanedicarboxylate has a melting point ( 225°C) similar to that of PBT [53],... 

Completely aliphatic polyesters, made from aliphatic diacid and aliphatic diol components), are not of major industrial importance because of their low melting temperatures and poor hydrolytic stability. (Low-molecular-weight aliphatic polyesters are used as plasticizers and prepolymer reactants in the synthesis of polyurethanes see Secs. 2-12e, 2-13c-2). 

Kricheldorf and coworkers have found that some heterocyclic compounds containing two reactive bonds behave as bifunctional reactants in a ROP that proceeds by a step polymerization mechanism [Kricheldorf, 2000]. An example is the polymerization of 2,2-dibutyl-2-stanna-l,3-dioxepane with an aliphatic diacid chloride ... 

The probable mechanism for conductance in selected polymers is related to the difficulty of delocalizing electrons. Carraher and colleagues found that antimony polyesters derived from aliphatic diacids are weak semiconductors with bulk specific resistivities in the range of 10"10 ohm cm, whereas analogous polyesters derived from aromatic diacids are good semiconductors with bulk resistivities of about 10"4 ohm cm. The difference in electron conductivity is believed to be due to a difference in ability of the material to delocalize electrons the aromatic polyesters possess the ability to delocalize electrons throughout the polymer chain and thus are more conductive (lower resistivities). 

The diacid dichlorides used so far in rotaxane synthesis all have arene building blocks in common. Nevertheless, the initial amide bond formed between the dichloride and one stopper molecule (cf. 54) is thought to be responsible for successful molecular recognition of the semi-axle and the macromonocycle. Consequently olefinic and aliphatic diacid dichlorides 59a-g were subjected to the threading procedure to test the need for arene units (Figure 25). 

The next approach to incorporate the 12F-diol into a polyurethane matrix was reaction of the m- 12F-diol with aliphatic diacid chlorides (where x = 3 or 4) to give low molar mass polyesters (141) ... 

Other Preparative Reactions. Polyamidation has been an active area of research for many years, and numerous methods have been developed for polyamide formation. The synthesis of polyamides has been extensively reviewed (54). In addition, many of the methods used to prepare simple amides are applicable to polyamides (55,56). Polyamides of aromatic diamines and aliphatic diacids can also be made by the reaction of the corresponding aromatic diisocyanate and diacids (57). 

In order to illustrate this problem, it is interesting to analize the unsubstituted polyamides prepared from aliphatic diamines and aromatic diacids or from aliphatic diamines and aliphatic diacids. They are only soluble in solvents such as sulphuric acid, trifluoracetic acid, m-cresol, etc. 

Bisbenzothiazolylalkanes could be obtained by cyclization of o-aminothiophenol with aromatic and certain aliphatic diacids. Acetic anhydride is used to obtain the most important 2-methylbenzothiazole. The reaction of an o-aminothiophenol with phosgene, and with thiophosgene or carbon disulfide, gives a 2-hydroxy- and a 2-mercapto-benzothiazole, respectively, o-Aminothiophenol adds to alkynecarbonitriles (514) forming vinylamines... 

Domb and Neudelman [393] studied biopolyanhydrides using a polymer series of linear aliphatic diacids, with the following objectives to study systemat-... 

The development of unsaturated polyanhydrides responded to the necessity of improving the mechanical properties of the polymers in applications such as the temporary replacement of bone. " Unsaturated polyanhydrides, prepared by melt or solution polymerization, include homopolymers of fumaric acid (FA), acetylene-dicarboxylic acid (ACDA), and 4,4 -stilbenzenedi-carboxylic acid (STDA). The chemical structures of poly(FA) and poly(ACDA) are shown in Table 1. These polymers are highly crystalline and insoluble in common organic solvents. The double bonds of these monomers make them suitable for further crosslinking to improve mechanical properties of polyanhydrides. When copolymerized with aliphatic diacids, less crystalline polymers with enhanced solubility in chlorinated solvents result. 

It is apparent from the OPV data in Table I that with each additional methylene group in the polymer backbone, OPV at both 0% and 80% RH significantly increases. This trend can also be discerned in a series of copolyesters in which 8-16% of the terephthalic acid portion of poly(ethylene terephthalate) (PET) is replaced by aliphatic diacids of various lengths (6). 

A similar, but less pronounced chain length vs chemical shift dependence is observed for a series of nylon-6,6 type polyamides based on aliphatic or aromatic a,co-diamines and aliphatic or aromatic diacids in trifluoroacetic acid. However, the downfield chemical shift caused by increasing the chain length of aliphatic diacid residues is less pronounced relative to that of aliphatic diamines [12]. 

In another commercial modification, glycols, usually a mixture of ethylene and propylene glycols, are reacted with aliphatic diacids such as adipic acid to produce hydroxyl-terminated polyesters with molecular weights of approximately 2000, The hydroxyl functions are then allowed to react with aromatic... 

In several studies on the behavior of aliphatic diacids of the structure ... 

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