Poly imide acetylene terminated

Rezac, M. E., and Schoberl, B. (1999). Transport and thermal properties of poly (ether imide)/acetylene-terminated monomer blends, J. Membrane Sci. 156, 211. 

Sefcik and coworkers [80] were the first to use solid-state NMR to study the curing of poly(imide) oligomers terminated with reactive groups. The authors observed a clearly-resolved peak at 84 ppm in the spectrum of the unreacted poly(imide) resin, Thermid 600, due to terminal acetylene groups. On curing at 450-640 K, the decrease in intensity of this peak allowed facile... 

Murphy et al. [73] studied the cure and degradation of an acetylene-terminated N-labelled poly(imide) using N CPMAS NMR. Initially, the conversion of the amic acid to the imide precursor was followed. Four resolved peaks are observed due to amide and imide either attached to a phenyl ring or at the terminal position. Measurements of the rate of crosspolarization, and the dipolar dephasing experiment, assisted in the assignment to the spectra. Very different rates of cross-polarization (1/Tnh), and values of Ti, were measured for the various structures. Imidization was incomplete after heating to 670 K for 1 h, a result at variance with the results of... 

In a later study. Swanson and coworkers [81] studied the cure of acetylene-terminated poly(imide)s selectively labelled at various positions with nuclei. Curing of the sample, labelled at the imide carbonyl group, confirmed the completion of the imidization reaction on heating. The product of addition onto the carboxyl group was not observed. Four new peaks were identified in the spectrum of the cured sample labelled at the Ci-acetylene group, while a similar result was obtained for the sample labelled at the C2-acetylene position. Analysis of these results rules out the participation of coupling reactions and the biradical mechanism, which would produce triple-bond structures, but confirms the presence of the product of cyclotrimerization and Friedel-Crafts reactions. The latter mechanism is confirmed from the presence of small peaks due to aliphatic carbons in the spectra of the materials labelled at the acetylene groups. 

NMR spectroscopy and in particular solid-state NMR spectroscopy proved to be a powerful method for studying the mechanism and extent of reaction in complex poly(imide) materials. In particular, during the cure of BMI resins, careful use of C CPMAS NMR indicated that measurements of the extent of cure by DSC were significantly overestimated [86, 87]. This article demonstrates that NMR spectroscopy has been able to characterize the structure of condensation poly(imide)s and, more successfully, the cure of BMI, PMR and acetylene-terminated resins. 

St. Clair et used the concept of sequential semi-IPNs to produce two unique IPNs which are based on acetylene-terminated imide oligomers and thermoplastic polyimides, particularly a material designated LARC-TPI. Pater and others used the concept of simultaneous semi-IPNs to make semi-IPNs which are based on PMR-15 mixed with such materials as LARC-TPI, NR150B2 and Thermid 600 polyimides. Other examples of semi-IPNs which fit into the category of high temperature materials include thermoplastic modified bismaleimides (BMI). As one example, BMI has been mixed with condensation polyimides such as PI20280 or with terminated poly (arylene ether ketone) oligomers. The observed miscibility in semi-IPNs which are based on thermoplastic BMIs was found to be further improved when a BMI and thermoplastic both prepared from aromatic diamines were blended. ... 

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