Copolyimides block

From a mechanistic point of view, the polyimide synthesis via the polyamic acid is not a convenient method of preparing the block copolyimide for two main... 

Figure 5.15 Naphthalenic copolyimides with sulfonated block.

This method is being increasingly used for the preparation of soluble polyimides, and the rate is faster than in aprotic solvents. This method allows for preparation of block copolyimides.78... 

For the preparation of these segmented polyimides or block copolyimides, diamines rather than dianhydrides are preferred as the monomer bearing the flexible segment. Some of these monomers have been listed in Table 1. 

This class of polymers has great thermal stability and promising short-term perfor-mance. °° The six-membered ring of naphthalenic imides is preferred over the five-membered ring of phthanic imides. The latter is susceptible to acid-catalyzed hydrolysis, which leads to chain scission and membrane embrittlement. An example of six-mem-bered ring polyimides is the block sulfonated copolyimides shown below. ... 

Block and statistical copolyimides (Figure 1.2) were obtained from DNTA and aromatic and aliphatic diamines [39]. 

C.H. Park, C.H. Lee, J.-Y. Sohn, H.B. Park, M.D. Guiver, Y.M. Lee, Phase separation and water channel formation in sulfo-nated block copolyimide. The Journal of Physical Chemistry B2010, 114(37), 12036-12045. 

El-Gendi et al. (2010) studied the PV properties of block ether aromatic copoly-imide series membranes where the ether soft block acted both as a selective and a permeable block. The PV results showed that rubbery copolyimides can lead to promising asymmetric membranes for liquid-liquid separations (water-EtOH). 

Scheme 3.38 Chemical structure of sulfonated block copolyimides [265],...

T. Nakano, S. Nagaoka, H. Kawakami, Preparation of novel sulfonated block copolyimides for proton conductivity membranes, Polym. Adv. Technol. 16 (10) (2005) 753-757. 

K. Yamazaki, Y. Tang, H. Kawakami, Proton conductivity and stabiUty of low-IEC sulfonated block copolyimide membrane, J. Membr. Sci. 362 (1) (2010) 234-240. 

K. Yamazaki, G. Wang, M. Tanaka, H. Kawakami, Sulfonated block-graft copolyimide for high proton conductive and low gas permeable polymer electrolyte membrane, J. Power Sources 216 (2012) 387-394. 

Fig. 7.17 Humidity dependence of the proton conductivity of sulfonated block copolyimide membranes at 80 C...

Zhang et al. of Changchun Institute of Applied Chemistry have also confirmed the similar strategy with their unique multiblock copolyimide ionomers, in which hydrophilic blocks were composed of disulfonated dianhydride and disulfonated diamine (each aromatic ring was sulfonated) (Fig. 7.26) [65]. While they have not... 

Fig. 7.26 Multiblock copolyimides with highly sulfonated hydrophilic block...

Fig. 7.27 (a) Water uptake and (b) proton conductivity of multiblock copolyimides with different lEC as a function of hydrophilic block length (Reprinted from [65] with permission from Elsevier)... 

Kashimura Y, Aoyama S, Kawakami H (2009) Gas transport properties of asymmetric block copolyimide membranes. Polym J 41 961-967... 

Nakano T, Nagaoka S, Kawakami H (2006) Proton conductivity of sulfonated long-chain-block copolyimide films. Kobunshi Ronbunshu 63 200-204... 

The synthesis of polymers from a mixture of several diamines and dianhydrides, and especially the synthesis of block copolyimides, represents wide opportunities of directed regulation of polyimides properties, including giving them solubility. One of the methods of the block copolymers synthesis is getting them on the basis of presynthesized oligomers with determination molecular weight and with different functional groups. 

In this chapter the synthesis of poly (4,4 -dipheniloxide)pyromelht(amic acid) (PAA), fragmented by oligo(amic acid) (OAA), obtained by low-temperature polycondensation of 4,4 -diaminodipheityl oxide and dianhydride 4,4 -diphenyl-l,5-diazo-bicyclo/3,3,0/octane-2,3,6,7-tetracaiboxihc acid and its subsequent chemical imidiza-tion. In the opposition to the original poly-(4,4 -aminodiphenyl)-pyromellitimide (PI) synthesized block copolyimides (BSPI) have a solubility in polar aprotonic solvents. The parameter of B SPI conformation was calculated to explain its solubility. 

The transformation of the synthesized block copolymers which consists of fragments of PAA (A) and OAA fragments (B) into polyimide was realized by two ways - chemical and thermal [13], The research of the spectral characteristics of the synthesized block copolyimide films was performed on FTIR spectrometer Nicolet 7101 in the frequency range 4000-300 cm. ... 

The conformation parameter was calculated to quantify the crookedness and curl of different nature soluble block copolyimides fragments [15-19] ... 

It was studied the kinetics of transformation macromolecules of synthesized BSPI prepolymers by IR spectroscopy [13] in order to optimize the process of obtaining fragmented polyimides. The comparison of the intensity of the absorption bands of imide rings with a peak at 1380 cm before and after the ehemieal imidization showed that the maximum degree of imidization is 92-93% and it is reached within 60 min. In a similar way it was established that after thermal imidization by step increase of temperature up to 320 °C within 120 min maximum degree of imidization of the block copolyimides is 86-87%. 

It is of a great interest to determine the causes of acquisition of block copolyimides solubility. In this respect the analysis of the structural and conformational properties of the polymer dives is useful information. 

TABLE 1 Conformations and stractural characteristics of three-dimensional block copolyimides fragments... 

Block copolyimides Conformation Copolyimides Geometric parameters Identity period Oligo(amic acid) Polyimides... 

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