Polyimides aliphatic-aromatic

Polyamide or polyimide polymers are resistant to aliphatic, aromatic, and chlorinated or fluorinated hydrocarbons as well as to many acidic and basic systems but are degraded by high-temperature caustic exposures. 

Asano, N., Aoki, M., Suzuki, S., Miyatake, K., Uchida, H. and Watanabe, M. 2006. Aliphatic/aromatic polyimide ionomers as a proton conductive membrane for fuel cell applications. Journal of the American Chemical Society 128 1762-1769. 

However, the starting point of polyimide synthesis dates away back to the mid 1950s, when Edwards and Robinson had synthesized aliphatic-aromatic polyimides (hereafter referred to as aliphatic polyimides) by the melt polycondensation of nylon-salt-type monomers composed of aliphatic diamines and aromatic tet-racarboxylic acids or their diacid-diesters (Eq. 2) [6,7]. 

The polycondensation of the salt monomers of both aliphatic-aromatic and wholly aromatic types proceeds according to Eqs. (5) and (3), giving aliphatic and aromatic polyimides, respectively. 

In a brief summary, we have developed a facile and versatile asalt monomer method for the rapid synthesis of both aliphatic and aromatic polyimides. The salt monomer method has the following advantages over the conventional two-step method. First, the aliphatic-aromatic salt monomers as well as all aromatic, composed of diamines (both aliphatic and aromatic) and aromatic tetracarbox-ylic acids (or their half diesters) are highly reactive and rapidly produce polyimides with high molecular weights in one step by the solid-state thermal poly-... 

The results of the high-pressure polycondensations of the aliphatic-aromatic salt monomers XPMA, XBPA, XTPE, XOPA, and XBTA under 200-600 MPa at 220-320°C for 3-30 h leading to the formation of a series of aliphatic polyimides (see Eq. 5) are summarized in Table 1 [22,24-26]. 

According to literary data, the following mixtures of aromatic/aliphatic-aromatic hydrocarbons were separated toluene/ n-hexane, toluene/n-heptane, toluene/n-octane, toluene/f-octane, benzene/w-hexane, benzene/w-heptane, benzene/toluene, and styrene/ethylbenzene [10,82,83,109-129]. As membrane media, various polymers were used polyetherurethane, poly-esterurethane, polyetherimide, sulfonyl-containing polyimide, ionicaUy cross-linked copolymers of methyl, ethyl, n-butyl acrylate with acrilic acid. For example, when a composite polyetherimide-based membrane was used to separate a toluene (50 wt%)/n-octane mixture, the flux Q of 10 kg pm/m h and the separation factor of 70 were achieved [121]. When a composite mebrane based on sulfonyl-containing polyimide was used to separate a toluene (1 wt%)/ -octane mixture, the flux 2 of 1.1 kg pm/m h and the separation factor of 155 were achieved [10]. When a composite membrane based on ionically cross-linked copolymers of methyl, ethyl, w-butyl acrylate with acrilic acid was used to separate toluene (50 wt%)//-octane mixture, the flux Q of 20-1000 kg pm/m h and the separation factor of 2.5-13 were achieved [126,127]. 

By using monomers other than dianhydrides and diamines, a number of methods has been outlined to synthesize polyimides, for instance from tetracarboxylic acids and their half diesters. This method can be successfully applied to the preparation of aliphatic-aromatic polyimides by melt polycondensation of the salt from the diamine and an aromatic tetracarboxylic acid or half-diester (Scheme 8). The reaction achieved some importance when polyimides appeared in the 1950s as an alternative for uses such as... 

Cosutchi AI, Nica S-L, Hulubei C, Homocianu M, loan S. Effects of the aliphatic/aromatic stmcture on the miscibility, thermal, optical and rheological properties of some polyimide blends. Polym. Eng. Sd. 2012 52(7) 1429-1439. 

S.-L. Nica, G. Hulubei, I. Stoica, G. E. loanid, and S. loan. Surface properties and blood com-patibihty of some aliphatic/aromatic polyimide blends. Polym. Eng. Sci. 53,263-272 (2013). 

Dicyclic polyimide - - Aliphatic and aromatic products TGA also applied [81]... 

In addition to the research on fluorinated and cardo polyimides, an important work was devoted to the semiaromatic cycloaliphatic polyimides. Volk-sen points out the potential interest of these materials in electronic industry.64 He reports that the simplest procedure to prepare these materials is to use a cycloaliphatic dianhydride and an aromatic diamine (Fig. 5.9) instead of an aliphatic diamine and an aromatic dianhydride, which leads to formation of gels. 

Some examples concerning the polyimide synthesis by condensation of the crystalline salts obtained with the aliphatic or aromatic diamines and aromatic tetraacids will be discussed in Section 5.4.1. 

Alicyclic dianhydrides are interesting for electronic applications. The polyimides obtained from them are colorless with high transparency in the visible range, exhibit low birefringence,125 and have a low dielectric constant.126 The reactivity of the polycyclic aliphatic dianhydride has been investigated. For example, bicyclo-[2,2,2]-oct-7-ene tetracarboxylic dianhydride reacts quickly with an aromatic amine because the bicyclo-imide is less strained than the corresponding dianhydride.127... 

The competition at 200°C between an aliphatic and an aromatic amine toward the formation of an imide is a very selective reaction (Fig. 5.1) for the formation of an aliphatic imide.141 This reaction suggests that the reactive processing in extruder, for example, could be used to transform a melt-processable polyimide with an oligomer end capped with an aliphatic amine. In order to get a perfecdy alternate block polyimide-block siloxane, Rogers et al. used low-temperature transimidization.142 An oligomeric aromatic imide was end capped... 

Phthalazinone, 355 synthesis of, 356 Phthalic anhydride, 101 Phthalic anhydride-glycerol reaction, 19 Physical properties. See also Barrier properties Dielectric properties Mechanical properties Molecular weight Optical properties Structure-property relationships Thermal properties of aliphatic polyesters, 40-44 of aromatic-aliphatic polyesters, 44-47 of aromatic polyesters, 47-53 of aromatic polymers, 273-274 of epoxy-phenol networks, 413-416 molecular weight and, 3 of PBT, PEN, and PTT, 44-46 of polyester-ether thermoplastic elastomers, 54 of polyesters, 32-60 of polyimides, 273-287 of polymers, 3... 

Aromatic nitrations, 17 160-161 by-products of, 17 161 kinetics of, 17 162 Aromatic nitriles, 17 243 Aromatic nucleophilic displacement, polyimide synthesis via, 20 273 Aromatic phosphines, 19 60, 62 Aromatic poly(monosulfide ketone)s, 23 709 Aromatic poly(monosulfide)s, 23 706 Aromatic polyamide copolymers, laboratory synthesis of, 19 720 Aromatic polyamide fibers, 24 614 Aromatic polyamides, 10 210-212 19 713-738. See also Aliphatic polyamides (PA)... 

The preparation of imides from reaction of isocyanates with anhydrides dates back to the early days of organic chemistry [96]. With the advent of polyimide chemistry in the early 1960s, this chemistry was soon explored for the synthesis of polyimides. However, in contrast to the preparation of polyimides via thejr poly(amic acid) intermediate, the reaction of aromatic dianhydrides with aromatic diisocyanates is much less understood. The reaction of aromatic dianhydrides with aliphatic or aromatic diisocyanates is believed to form a cyclic seven-membered intermediate which then splits out C02 to form the polyimide [97], see Scheme 27. The addition of water, which has been reported to accelerate the anydride/isocyanate reaction, can result in several transformations of either the anhydride or the isocyanate reagent, see Scheme 28... 

For highly polar polymers, Hs < —Hw, and the equilibrium concentration is a decreasing function of temperature. This is often found in the most hydrophilic networks, based, for example, on the aromatic amine -aliphatic diepoxide of diglycidyl ether of butane diol (DGEBD) type (Tcharkhtchi et al., 2000), or on particular polyimides (Hilaire and Verdu, 1993). 

The membrane used depends on the nature of the organics. Poly(vinyl alcohol) and cellulose acetate [14] have been used to separate alcohols from ethers. Polyurethane-polyimide block copolymers have been used for aromatic/aliphatic separations [17]... 

Nevertheless, further detailed information was unavailable on the polyimide synthesis from nylon-salt-type monomers that is referred to as salt monomer method , and this method was not really recognized as a simple synthetic method of both aromatic and aliphatic polyimides. In addition, many polyimide investigations have mainly been concentrated on aromatic polyimides, and little information is available about aliphatic polyimides [13-18] that are also potential candidates for engineering plastics. 

---