Polyamides and Polyamines

The present section deals with syntheses of polyamides via formation of amide bonds. Other synthetic strategies are discussed in the preceding and in the following sections. The first approach described by Kim in 1992 [42], was based on SOCI2 as activation/condensing agent. 3,5-Diaminobenzoic acid and 5-amino 

Polycondensations by means od DBOP or TPP also proved useful for the preparation of hb polymides which served as precursors of polyimides [47-49] ((a) Formula 11.6) or polybnezoxazole)s (from (b) or (c) in Formula 11.6 [50-54]. For the best polyimide a DB of 0.48 and a Mw of 188 kDa were determined (by SEC-MALLS). Polycondensations of di or multifunctional aromatic amines and carboxylic acids in the melt are usually not successful, because the high temperatures ( 300 °C) are needed to keep the reaction products in the molten state to cause partial decarboxylation. However, in the case of monomer (c). Formula 11.5, polycondensation at 235 °C proved successful, and a Mw of 74 kDa with a PD of 2.6 was achieved [54]. 

Finally, two syntheses of aromatic polyamines via Pd-catalyzed formation of C-N bonds should be noted [55, 56]. In the first report, 3,5-dibromoaniline served as monomer and a bromo-diaminotriphenylamine in the second study (see Formula 11.6, bottom). However, the molar masses were rather low, and alternative syntheses based on C-C coupling are discussed below. 

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A great many of outstanding adhesive formulations are based on epoxy resins. A broad spectrum of adhesive formulations with a wide range of available properties have resulted from the use of polymeric hardeners such as polyamides and polyamines, phenolics, isocyanates, alkyds, and combinations of amines with polysulfide elastomers, and the alloying of the epoxy with compatible polymeric film-formers, such as poly(vinyl acetate) and certain elastomers. 

Another significant end-use for polyamines is in preparation of paper wet-strength resins. These are polyamide, modified formaldehyde, and polyamine resins used to improve the physical strength of tissue, toweling, and packaging paper products. The cationic formaldehyde resins include both urea—formaldehyde and melamine—formaldehyde types (248,249). Cationic functionaHty is imparted by incorporation of DETA, TETA, and/or TEPA in... 

Three families of polymers have been used to study transfection mechanisms polyamines, polyamides, and polyvinyl type polymers. The transfection efficiencies achievable with these systems vary widely, so an in-depth analysis of each polymer family and subsequent comparison of what affects gene delivery will be discussed in this chapter. In addition to high transfection efficiency, it is important for the polymeric systems to be relatively nontoxic to cells in vitro and not to elicit an immune response in vivo. Thus, the effect of transfection parameters on cytotoxicity and immunogenicity will also be examined. 

High molecular weight aliphatic sulfonamides of alkylene polyamides, and polyalkylene polyamines... 

Table 2.5 summarises typical values of these bulk mechanical properties at around 20 °C for a range of epoxy adhesives. Of particular note is the low strength and stiffness of the epoxy polyamides and polysulphides as compared to those with aliphatic polyamine hardeners. For the design of bonded assemblies, joint tests are often used to determine the relevant mechanical properties. It must be remembered, however, that the results will be highly dependent on the specimen geometry and testing conditions and... 

The adhesive should be a two-part epoxy comprising resin and hardener components. The resin will normally be based on the diglycidyl ether of bisphenol A or bisphenol F or a blend of the two. The hardener, or curing agent, will normally be from the polyamine group, since these tend to result in adhesives with better resistance to moisture than have the polyamides and are likely to... 

In order to improve the physical properties of paper, especially strength and resistance to erasure, natural polymers, like starches and gums, are added to the stock, as well as cellulose compounds, like carboxy-methyl cellulose, or synthetic polymers, e.g. polyacrylamides and polyamines. Wet-strength resins, such as polyamide resins, are also often added to the stock. Urea-formaldehyde and melamine-formaldehyde resins are no longer in wider use for improving wet strength. 

The condensation reaction ofTOFA with a polyalkylene polyamine such as diethyl-enetriamine (DETA), triethylenetetramine (TETA), or tetraethylenepentamine (TEPA) in a molar ratio 1 1 yields amidoamines ofTOFA (also called tall oil fatty acid polyamides). Typically the amidation reaction is conducted at temperatures between 250 and 290 and usually a mixture of tall oil fatty acid polyamide and the corresponding tall oil fatty acid imidazoline is obtained (Figure 3B.12). 

Products of polymerized vegetable oil acids and polyamines, which are highly branched liquid polyamides, are mixed with phenolic resins to produce a thermosetting composition with a wide range of properties. Cure usually is accomplished in 60 min at 300°F. The reaction involves the condensation between methylol groups and amine groups. 

Tris (dimethylaminomethyi phenol) (and its tri-2 ethylhexanoic add salt) Epoxy/polyamide, epoxy/polyamine, epoxy/novolac, epoxy/polysulfide, epoxy/epoxy... 

Examples of catalysts are shown on the first line, whereas all the other compounds are coreactants including dicyandiamide, ureas, imidazoles, aliphatic polyamines, cycloaliphatic polyamides, and cycloaliphatic dicarboxylic acid anhydrides. As all the corresponding reaction mechanisms have been previously disclosed in detail," the following presentation is limited to the initial reaction steps leading to the active species involved in the polymerization or polycondensation processes. These primary attacks are enlightened in Fig. 12.6, which displays only one epoxy group reacting with catalysts or coreactants. 

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