Diamine component

Polyamides containing a-aminoacid units are readily obtained by reaction of bisazlactones (2-oxazolin-5-ones) with diamines. When polyamines such as diethylenetriamine (DETA) or triethylenetetramine (TETA) are used as the diamine component, the resultant polyamides readily cyclodehydrate above 200°C to produce polymers containing 2-imidazolin-5-one units in the backbone. Polyamides derived from simple diamines (e.g. 1,6-hexanedi amine) cyclodehydrate only in the presence of a suitable catalyst. Carboxylate salts and certain Lewis acids have been found to be efficient catalysts for this transformation. 

A different approach to quinoxalines and heterocycle-fused pyrazines has been described by the Lindsley group, based on the cyclocondensation of 1,2-diketones and aryl/heteroaryl 1,2-diamines (Scheme 6.260) [450]. Optimized reaction conditions involved heating an equimolar mixture of the diketone and diamine components for 5 min at 160 °C in a 9 1 methanol/acetic acid solvent mixture, which furnished the substituted quinoxalines in excellent yields. This approach could also be applied equally successfully to the synthesis of heteroaryl pyrazines, such as pyr-ido[2,3-b]pyrazines and thieno[3,4-b]pyrazines. The same group has employed 1,2-diketone building blocks for the preparation of other heterocyclic structures (see Schemes 6.198, 6.268, and 6.269). 

Hexafluoroisopropylidene-unit-containing copoly(azomethine)s are also prepared under similar reaction conditions using an equimolar mixture of 2,2-bis[4-(4-aminophenoxy)phenyl]-l, 1,1,3,3,3-hexafluoropropane (17) and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (21) or of 2,2-bis(4-aminophenyl)-l, 1,1,3,3,3-hexafluoropropane (18) and 2,2-bis(4-aminophenyl)propane (22) as the diamine components with terephthalaldehyde (19) or isophthalaldehyde (20) (Scheme 12).20... 

It has become the custom to name linear aliphatic polyamides according to the number of carbon atoms of the diamine component (first named) and of the dicarboxylic acid. Thus, the condensation polymer from hexamethylenedi-amine and adipic acid is called polyamide-6,6 (or Nylon-6,6), while the corresponding polymer from hexamethylenediamine and sebacoic acid is called polyamide-6,10 (Nylon-6,10). Polyamides resulting from the polycondensation of an aminocarboxylic acid or from ring-opening polymerization of lactams are indicated by a single number thus polyamide-6 (Nylon-6) is the polymer from c-aminocaproic acid or from e-caprolactam. 

Interfacial polycondensation can be also performed in dispersion (Example 4-13) For this purpose the solution of acid dichloride is dispersed in the aqueous solution of diamine by vigorous stirring (if necessary in the presence of a water-soluble dispersion stabilizer). The polycondensation then takes place at the surface of the droplets. Water is especially suitable as solvent for the diamine component, while aliphatic chlorinated hydrocarbons are best for the dicarbox-ylic acid dichlorides. 

Although Eq. (2) is not adequate to fully describe ablation processes, the absorption coefficient is still a useful parameter as it provides a quantitative evaluation of the level of interaction between a given medium and photons of a specific wavelength and, to a first-order approximation, their propensity to laser ablation. 5 different materials can have different chemical compositions and structural arrangements, it is not surprising that they have different absorption coefficients and thus can exhibit different ablation characteristics. This is indeed found to be the case. For instance, PMMA is readily structured at 193 run ( 193 2 X 10 cm I) although it is essentially transparent and unaffected at 308 nm (a 308 < 1 x 10 cm i). However, for an aromatic polyimide such as the system whose dianhydride/diamine components are pyromelletic dianhy-dride/oxydianiline (PMDA-ODA), ablation occurs readily not only at 193 nm... 

Lindsley and co-workers developed a general procedure towards the collection of diverse heterocyclic scaffolds from common 1,2-diketone intermediates 96. Substituted quinoxalines 97, fused pyrazolo [ 4,5-g ] quinoxalines 98 and imidazolo[3,4-g]quinoxalines 99 as well as pyrido[2,3-fo]pyrazines 100 and Ihicno[3,4-fo Ipyrazincs 101 have been prepared in excellent yields [132] (Scheme 54), employing optimized reaction conditions (microwave heating of equimolar mixtures of 1,2-diketone 96 and diamine components at 160 °C for 5 min in 9 1 MeOH - AcOH). The use of microwave irradiation resulted in reduced reaction times (5 min vs. 2-12 hours), improved yields as well as the suppressed formation of polymeric species a characteristic of traditional... 

As the VDP of polyimides involves two precursors, diamine and dianhydride, the relative amounts of fluxes of the precursor vapors need to be controlled carefully to obtain high quality polyimide thin films. The effects of both excess dianhydride as well as the diamine components have been studied and reported in literature, It was observed that, excess dianhydride (PMDA) undergoes desorption when cured after deposition leading to poor thermal stability. 

Both Tg and thermal stability of PADS/ODAN copolymers were increased when the ODA diamine component was replaced with m- or p-phenylenediamine (MPD, PPD) or a mixture of the two diamines (Table VII). A solvent resistant material prepared from PADS/ODAN/PPD/MPD 3 7 5 5 had a Tg of 260°C and exhibited outstanding thermal stability by TGA analysis, volatilizing less than 2 wt % per hour at 480°C under nitrogen. 

Devasahayam et al. (72) have also carried out Raman studies of the changes in the functional group concentrations at high dose for several other transparent polyimides. In this study the polyimides were irradiated in an inert atmosphere by e-beam over a range of temperatures from ambient temperature to 503 K. The Raman study indicated that the principal centres for radiation damage in these polyimides were located at the phenyl ether units in the diamine components and at the fluorinated isopropylidine units in the dianhydride components. 

Selar PA, poly(hexamethylene isophthalamide/terephthalamide) or 6-I/T (the diamine components are listed first, then the diacid components), is an amorphous polyamide which is marketed by Du Pont. As shown in Figure 1, it has unique properties for a barrier resin in that the oxygen barrier properties actually... 

Ringsdorf s research group have prepared novel types of rigid-rod polyesters and polyamides 56 with a disc-like mesogen in tte mainchain [75]. Most polymers with six lateral substituents appear to be thermotropic liquid crystals. Polyamides with Z = H and having four substituents on the diamine component are not liquid crystalline. The two substituents on the diacid component seem to contribute to decrease further the intermolecular hydrogen bonding. 

Hn designating nylons, the first number refers to the number of carbon atoms in the diamine component, the second number to the number of carbon atoms in the dicarboxylic acid component. Single numbers refer to poly-Q-amino acids. hNumber of ends per million grams of polymer. 

Diamine Components Diaidehyde Components tinh dL/ginH,SO. Polymer iNeit Temperature, °C... 

Interestingly, the chirality of the diol and diamine components controls the tertiary structure of the complex, in other words the sense of chirality with which the cyclohexane rings wrap around the central core in the triple-stranded helicate. Thus, whereas the (S,S)-diamine 22 gives a left-handed helicate 25 with the (S,S)-diol 23, the (J ,J )-diamine 24 gives a right-handed helicate 26 with the same diol. 

Analysis of polymer solubility in chloroform indicates that the solution of polymer XV shows a tendency toward precipitation. On the contrary, polymer XTV, bearing a more flexible diamine component, forms solutions up to a concentration of 0.2%, and polyimides xi-xm are soluble up to a concentration of 0.5%. Water-soluble polymer XVII was produced by the selective sulfonation of PPI XVI which is soluble in organic solvents. 

For the formation of polyurethane (PU) or polyurea (PUR) shells in miniemulsion systems, usually the diol- or diamine component is water soluble, while the diisocyanate is hydrophobic and thus soluble in organic media. For direct miniemulsions, mostly isophorone diisocyanate (IPDI) [186,187] was used, as this compound... 

Which of these four potential advantages, if any, actually occurs with the platinum polymers is currently being studied. Approximately two dozen platinum polyamines have been synthesized, and some show biological activity while others do not (126-128). Several of the polymers properties are being explored and correlated with polymer activity in an effort to discover why certain polymers are active while others are inactive. Such factors as the nature of the diamine component, the extent to which a polymer is transported into the cell, the rate of aquation, etc., could all influence the biological activity of a polymer. Two other properties that could control polymer activity are the size of a polymer and the tendency of a polymer to degrade, and these will be the subject of discussion here. 

However, the diamine component does not determine a polymer s activity in any simple fashion. The biological activities of the diamines themselves have been measured, and there is no direct relationship between the activity of the diamine and the activity of a polymer containing that diamine. In some cases a diamine is more active than its polymer in some cases the diamine is less active than its polymer. There are numerous other factors which might influence the biological activity of a polymer, such as the rate at which the polymer is transported into the cell, the rate at which it is aquated within the cell, the rate at which it reacts with cellular macromolecules, etc. Two other possible factors which could determine biological activity are the size of the polymer and its ability to degrade into smaller molecules. 

Apparent molecular weights were measured by light scattering photometry using 0.1% polymer solutions. Table 3 summarizes the results for a number of the polymers. A wide variation in molecular weight is seen, ranging from 7100 daltons for polymer 13 to 584,000 daltons for polymer 14 (136). At least part of this variation is probably due to the different diamine components which produce polymers of different sizes. Polymer 19 (with tryptophan as the diamine component) has a molecular weight of only 960 and so is really only a dimer. 

Alternatively, instead of the acids, the corresponding esters can be used as starting materials. Esterification of the dicarboxylic acid advantageously lowers its melting point to a temperature that allows melting of the acid while nunimizing the thermal degradation. The admixture of the dicarboxylic acid component and the diamine component in the form of a melt is thereby facilitated. 

Commercial products are frequently referred to as nylons without further differentiation, and are distinguished from each other by numbers or letters. The numbers indicate the number of carbon atoms per aliphatic monomeric unit. Thus, nylon 6 or polyamide 6 is poly( -caprolactam). In the authentic nylon series, there are two numbers the first number refers to the number of carbon atoms in the diamine component and the second number to the number of carbon atoms in the dicarboxylic acid component. Consequently, nylon 6,6 or nylon 66 is poly(hexamethylene adipamide). Letters are often used to designate cyclic units, i.e., T for the terephthalic acid residue. 

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