Polyimides copolyimides

A number of phosphorus containing polyimides were synthesized by Varma and coworkers and their properties were studied [137-141]. Polyimides have also been synthesized by the reaction of benzophenonetetra-carboxylic dianhydride (BTDA) and bis(3-aminophen-yl)methylphosphine oxide [142]. Copolyimides were... 

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... 

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... 

Blend systems with significantly improved thermo-oxidative performance can be achieved through incorporation of carefully designed polyimide molecules. As shown in Table 1, a copolyimide containing the sulfone and 6F moieties which exhibits a Tg above 300 °C (see Fig. 5), as well as extraordinary short-term thermo-oxidative stability can be synthesized. 

The fluorinated copolyimides (including homopolyimides) are all more transparent than the nonfluorinated PMDA/ODA. The color of 10-pm-thick films changes gradually from bright yellow to colorless as the 6FDA/TFDB content increases. All these copolyimide films are also homogeneous compared with polyimide blends of 6FDA/TFDB and PMDA/TFDB. 

The fluorinated polyimides PMDA/TFDB and 6FDA/TFDB and the copolyimides have the high optical transparency, controllable refractive index. 

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. 

Furukawa N, Yamada Y, Kimura Y (1997) Lap shear bond strength of thermoplastic polyimides and copolyimides. High Perform Polym 9(1) 17... 

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. ... 

Carboxylic Groups Pervaporation separation of toluene/i-octane mixmres using copolyimide membranes containing 3,5-diaminobenzoic acid (DABA) was investigated in Ref. [128]. It was established that introduction of diaminobenzoic acid into the 6FDA-TrMPD polyimide improves membrane selectivity. The sorption component of the separation factor /3s is hnearly correlated with the membrane solubility parameter and with DABA content in the copolymer (/3s = 3.2, 3.3,4.3, 5.2 for DABA contents 0%, 10%, 33%, 60%, respectively). 

Since the first commercialization of Kapton polyimide nearly three decades ago, an impressive number of new polyimides of unique properties have been introduced for various industrial and consumer product applications. Commercial and semi-commercial production of numerous new monomers have made it possible to explore seemingly infinite varieties of structurally different polyimides and copolyimides. As a result we seem to have a more finely tuned understanding of structure-property relationship necessary for a specific application. Research and development activities in new polyimides seem to be intensifying rather than reaching its maturity. In this article, recent advances in polyimides are reviewed in the area of scientific activity as well as commercial developments. 

The polyimides derived from the dianhydrides had high Tg s of 238 to 466 °C and they were soluble in chlorinated hydrocarbon solvents. Because of their solubility, copolyimides containing the following acetylene substituted diamine monomere were readily prepared by homogeneous high temperature solution polycondensation in m-cresol. 

The 6FDA/BDAF polyimide was modified using PPD in an effort to "stiffen" the polymer backbone and improve thermal performance (Tg). A better overall property balance was achieved in several of these 6FDA/BDAF/PPD copolyimides. A series of random copolymers was prepared in which the level of PPD was varied from 0% to 100% based on the total moles of diamine. The incorporation of PPD had little effect on the dielectric constant but did result in improved thermal performance and was accompanied by increased moisture uptake (Figures 1,2, and 3). This behavior is consistent with the overall reduction in the amount of bound fluorine in the polymer backbone however, additional work is required to establish a direct correlation. A reasonable property balance was realized over a range of 40 to 60 mole% PPD which displayed dielectric constants from 2.85 to 2.90, moisture absorption from 1.5% to 2.0%, and Tg from 280°C to 290°C. In addition, the 6FDA/BDAF/PPD copolyimides displayed somewhat less solvent sensitivity than the 6FDA/BDAF homopolymer as described above. 

The author s work on polyimide synthesis and its use to derive MI values for polyimides has been described in the previous section [43, 45-46]. These are virtually the only strictly true mesogenic polyimides which have been reported in the literature to date. However, in addition, there have been many reports of modified copolyimides such as copoly(etherimide)s, copoly(amide-imide)s, co-poly(esterimide)s or copoly(imide-carbonate)s which are discussed below. 

The temporal stability of SHG was measured at 180 C. The copolyimides exhibit a much improved stability, compared with the original PI 1 and other polyimides wq synthesized (2). Few polymers can survive at such high temperatures for a long time. The polymer with higher Tg possessed a higher stability. Figure 4... 

Mikroyannidis, J. A. Fire resistant polyimides and copolyimides based on l-[(dialkoxy-phosphinyl)methy 11-2,4- and -2,6-diaminobenzenes. /. Polym. Sci. Polym. Chem. Ed.y 22, 1065 (1984)... 

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