Imide polymers

Ch1orocarhony1trime11itic acid 1,2-anhydride [1204-28-0] (9), is used in the preparation of esters and amide—imide polymers. TriaHyl trimellitate [2694-54-4] (10) is used as a cross-linking or co-curing agent for ethylene-derived mbbers and plastics. 

LC polyesters belong to the class of thermotropic main-chain LCPs, which also comprises polymers such as polycarbonates, polyethers, polyphenylenes, polyester-imides, polymers containing azo- or azo V-oxide linking groups, some cellulose derivatives, and polypeptides such as po 1 y (y - be n zy 1 -1. - g 1 u tamate). Both from the academic and industrial points of view, polyesters are by far the most important representatives of this class of polymers. 

Scola et al. [67] studied the kinetics of the MW cure of a phenylethyl-terminated imide polymer model compound and an oligomer using a variable frequency MW source and found that the activation energy of the MW cures were 68% and 51% of the thermal cure respectively. It should be noted that the reactions were performed in the liquid phase in the absence of solvent. 

Fig. 18.6 Upper part - chemical structures of poly(oxyethylene)-segmented (POE) and amides and imides polymer derivatives (POEM). Lower left part - chemical structure of 15-crown-5-functionalized MWCNT. Lower right part - chemical structure of l-(2-acryloyloxy-ethyl)-2-methyl-benzoimidazol-l-ium iodide (AMIml).

It is important to point out that the improvement in adhesion did not result from an increase in the solubihty of the imidized polymer containing the flexible coblock after the Tj cure cycle. In fact, the block copolymers demonstrated less than 2 % swelling (72 h) in the casting solvent, whereas PMDA/ODA polyimide homopolymer swells approximately 20-30 % (72 h). Clearly these data suggest that the improved auto-adhesion results from melt flow at 400 °C [44]. 

Initial investigations of base-catalyzed imidization of polymeric systems, in particular PMDA/ODA based polyfamic alkyl esters), have been difficult due to the insolubility of the polyimide precursor at imidization levels exceeding 40%. Nevertheless, preliminary studies indicate that the base-catalyzed polymer imidization reaction appears to be significantly slower at ambient temperatures as compared to the phthalamide model compounds. It is yet unclear whether this is a direct result of the conformational aspects associated with the polymer chain or solubility considerations arising from the less soluble, partially imidized polymer chain. Since much of the initial work involved IR studies of supported... 

Phthalocyanine Polymers. Phthalocyanin-imide polymers show an initial decomposition temperature > 500 °C both in air and inert atmosphere (Co, Ni, Cu, Zn) as expected. An increase in the concentration of metal phthalocyanine in the copolymer increases the thermal stability [70]. Poly(Cu 2,3,9,10,16,17,23,24-octacyanophthalocyanine) represents an unique polymer showing enhanced thermal stability (1.2% wt loss at 585 °C and 1.5% wt loss at 625 °C, 21.6% at 800 °C) in He atmosphere Rapid oxidation takes place on heating above 560 °C (9% wt loss at 585 °Q [99] in air. The enhanced stability of this material is different from that of monomeric metal phthalocyanine compounds which sublime and loose most of their weight around 600 °C [99]. 

Estimate the Tg of the poly(imide) polymer ULTEM 1000 (produced by General Electric Co)... 

Sekkat et. al. have employed EFISH technique to study photoinduced third-order nonlinearity of some high glass transition temperature (Tg) poly-imide polymers containing azo chromophores. The initial centrosymmetry of the polymer film is preserved at room temperature due to its high Tg even... 

Figure 2. The dipole moment of the absorbed water molecules varies from approximately 1.8 to 0.9 for the polyimides and from 1.1 to 0.7 for the polyamide-imides corresponding to fractional polarizabilities of l.O/i -0.4/x. The low values of p (<0.5p ) as seen in all the amide-imide po ymers and several of the ° polyimides, indicate restricted mobility of the water molecules. In the amide-imide polymers, we believe this is due to increased water-polymer interactions such as hydrogen bonding. Other evidence of hydrogen bonding in polyamide-imides is the water-induced plasticization and Tg lowering frequently observed.

This requirement has been met with soluble, pre-imidized polyimides. It has been found that secondary amines react quite readily with such polyimides in polar solvents such as N-methylpyrrolidinone or dimethylacetamide The reaction was done initially with morpholine for a series of available pre-imidized polymers (see Table I). The reaction was easily followed by infra-red spectroscopy (IR) (see Figure 2), the imide carbonyl absorptions at 1780 and 1723 cm 1 being replaced by amide carbonyls at 1645 cm1. In addition, the aliphatic C-H absorptions at 2880 cm 1 were noted. 

Polyamide Imide Enamels. Aromatic polyamide imide insulations are made from aromatic acids and aromatic diamines. The polyamide imide polymers are primarily present in the form of polyamic acids in the Af-methyIpyrrolidone solutions. During the enameling process the polyamic acids undergo imidization and become essentially fully imidized. Whereas the polyester and polyester imide enamels contain cresylic acids as the major solvent, the polyamide imide enamels are mainly formulated with A/-methylpyrrolidone as solvent. 

F. Biddelestone, A.A. Goodwin, J.N. Hay, G.C. Mouledous, The relaxation spectrum and physical aging ofpoly(ether imide). Polymer 32 (1991) 3119-3125. 

G. T. Brooks and R. E. Bockrath. Injection moldable amide-imide polymers and copolymers containing metal oxides capable of forming hydrates stable at temperatures in excess of 500.degree. f. US Patent 4403 061, assigned to Standard Oil Company (Indiana) (Chicago, IL), September 6, 1983. 

Table 15.12 Examples for Commercially Available Poly(imide) Polymers...

Jan Jang, J.-S., Shin, S.-H. Toughness improvement of tetrafunctional epoxy resin by using hydrolysed poly (ether imide). Polymer 36 (1995) 1199-1207. 

Somboonsub B, Invernale MA, Thongyai S, Praserthdam P, Scola DA, Sotzing GA. Preparation of the thermally stable conducting polymer PEDOT —sulfonated poly(imide). Polymer 2010 51(6) 1231-6. 

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