Polyamides, alkyl substituted

Let us now consider the structural organization of polyesters and polyamides with alkyl chains [30]. These systems are similar to alkyl-substituted PT and PANi/surfactant. The results obtained for these polymers would be applicable to conducting polymers that also have an aromatic backbone. In the crystalline state, structures of polyesters based on 1,4-dialkyl esters of pyromellitic acid and 4,4 -biphenol (PE-1) were found to depend on the length of the alkyl chains. For n = 12 a layered structure was detected with an interchain distance within layers of 4.55 A. For n = 14, 16, and 18 the interchain distance was 3.45 A. This distance corresponds to the van der Waals radius of the phenyl ring. Such dense packing requires a coplanar arrangement of the aromatic backbone within layers. Coplanar... 

Work reported by Liu and Gregory [35] on alkyl-substituted polythiophenes synthesized with the addition of a urethane group on the /3-substituted alkyl chain shows excellent blending characteristics with hydrogen bonding polymers such as urethanes or polyamides such as nylon. These blends have significantly reduced percolation thresholds and are solution and melt spinnable. 

The basic type of dye closely resembles that used for dyeing polyester fibers, but the selection of compounds is based on other criteria. Requirements regarding sublimation resistance are not as stringent, whereas fastness to ozone, exhaust gases, and washing are important. Substitution by amino, and especially by alkyl-amino, groups tends to decrease lightfastness of the dyes in polyester fibers. This is not the case for acetate and polyamide fibers. 

Cationic polymerization is the only route, however, for the polymerization of iV-substituted (N-alkyl and Af-acyl) lactams the resulting polyamides have much lower melting points than their unsubstituted analogs due to the absence of hydrogen bonding. 

Recent developments in the substitution of completely aromatic LC polyesters have produced polymers which show improved solubilities and reduced transition temperatures (29). The presence of these side groups provides a method for producing polymers that are compatible with other similarly modified polymers. In this way, blends of rigid and flexible polymers can be prepared. Substituents have included alkyl, alkoxy (30) and phenyl alkyl groups (21), some of which lead to mesophases that have been reported as being "sanidic" or board-like. This approach has been used with both polyesters and polyamides and has lead to lyotropic and thermotropic polymers depending on the particular composition used. Some compositions even show die ability to form both lyotropic and thermotropic mesophases (22). 

The selective stationary phases were further divided in the scheme proposed by Horning et al. [79] for the steroid separations into the types selective to alcohols, ketones, multiple bonds, etc. Here, various selective interactions between the column and the separated solutes are utilized. Most importantly, various polyglycols, polyesters, polyphenyl ethers, polyamides and polyimides belong to these categories. In addition, substitution of an alkyl group in a polysiloxane polymer by a more polar... 

The introduction of alkyl groups onto the benzene rings of aromatic polyamides has proved to impart higher solubility to the polymers. The thermostability of these however is reduced because of insufficient resistance of the alkyl substituents towards oxidation. Some studies have therefore been carried out using aromatic substituted monomers, for instance, phenyl [27], phenoxy and thio-phenoxy [28] substituted diamines, and phenyl [27, 29, 70] and phenoxy [30] substituted diacids. These have been used to prepare polyamides 15. In Table 4... 

The polyanion is soluble in DMSO, and different substituents were grafted onto the polyamide backbone via this anion. For instance, Cg-Cig alkyl chain, benzyl, 1-naphthylmethyl, 9-anthrylmethyl, carboxymethyl were succesrfully attached. All the substituted polyamides 47, except the carboxymethyl substi-... 

The largest volumes of phenjienediamines are used for the production of polymers, primarily polyurethanes, where the diisocyanates of toluenediamines (meta isomer) are used. For the manufacture of polyamides both meta and para isomers are used. Another significant use for -phenylenediamines is as antioxidants and antiozonants for elastomers, plastics, and petroleum products. The /V-alkyl-/V-aryl- -phenylenediamines are by far the most commonly used and represent the bulk of the volume of the iV-substituted -phenylenediamines reported in Table 3. Some iV iV-dialkyl compounds ate also stiU used as antiozonants, but they oxidize more rapidly and lose activity sooner. The iV,iV-diaryl-/)-phenylenediamines ate used primarily as antioxidants, especially where copper and other harmful metals might be present. -Dinaphthalenyl- -phenylenediamine is especially effective in this application. The... 

The substituted polyamides with long alkyl- and alkoxychains [33] are highly soluble and form anisotropic melts above their melting temperature. These polyamides are typical examples of sanidic liquid crystalline polymers. Generally, no lyotropic behavior is observed. The temperature stability is obviously substantially lowered due to the substitution with alkyl chains. 

Another recent example (Ford and Conner, 1994) is the alkylation of aniline or a substituted aniline with /j-isopropenylaniline (28) to give bisaniline A (29) with potential applications in polyamides, polyimides, and as a component in epoxy systems. 

The major effects of adding alkyl groups to the amide unit of a polyamide chain are to 1. make the amide more resistant to hydrolysis (9), and 2. make the resulting polymer less hydrophilic, and thus less soluble, than its unsubstituted precursor. The effect on solubility is clearly seen in the behavior of polymer CC when the fraction of N-butyl-substituted, repeat units is high. Such products are water insoluble. 

SUBSTITUTED POLYAMIDES AS PRECURSORS FOR ALKYL AND ALKENYL POLYBENZOXAZOLES... 

As with most groups of compounds, silica gel has generally proved to be the most widely used adsorbent, although cellulose, alumina, and polyamide layers have sometimes had important uses. The main contributions have been summarized in Table 22. The /f/values for alkyl, hydroxyindoles, and a series of 3-substituted derivatives on silica gel are listed in Table 23 with the solvents A to E (197,203), Table 24 records the ) /values for some of the same compounds on cellulose with the solvents A and B shown. The / /values of a group of 3-substituted indoles on silanized silica gel with and without the addition of //-dodecylpyridinum chloride are shown in Table 25. Apart from these types of layers, polyamide has been employed (205). Biogenic amines, including serotinin, have been examined on silica gel in 23 different solvents with detection by means of thiourea (206). Spray... 

Poly(ethylenimine S-alkyldithiocarbamate) polymers were prepared from respective poly(ethylenimine sodium dithiocarbamate) and alkyl chlorides, aralkyl chlorides, substituted alkyl esters of chloroacetic acid, p-chloroethyl esters of carbamic and carboxylic acids, and N-substituted chlorocarboxamides. The derivatives thus obtained were decomposed both physically and chemically to release sulfur and sulfur-containing substances which acted as controlled-release herbicides or fungicides. One author has proposed reactions of the pesticide 2,6-dichlorobenzaldehyde with diols and amines to form polyamide polycondensation products. ... 

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