Preparation of polyisoimide powders in suspension

Abstract

It is essential to have simple rapid methods for the determination of fatty acid structures. Traditionally, fatty acids are analysed by gas chromatography using their methyl ester derivatives (FAME). However, their corresponding mass spectra exhibit molecular ions but are usually devoid of ions indicative of structural features and, notably, the position of double bounds on the aliphatic chains [1]. In the most useful approach to structure determination, the carboxyl group is derivatised with a reagent containing a nitrogen atom. Recently, a convenient method for preparing picolinyl esters from intact lipids has been published [2]. However, some problems occurred in our laboratory when this method was used, leading to some modifications and optimisation. Thus, hexane and water have been added while sodium bicarbonate has been removed in order to lower contamination. Temperature and length of the reaction have then been optimised in order to get 100% derivatisation for different kinds of lipids (45 °C and 45 min for FAME). Finally, a comparison of the response factors has confirmed the better sensitivity of the picolinyl derivative against FAME (five times more).

Novel acetylene‐terminated thermosetting polyisoimides with excellent solubility and performed as efficient heat shields composites

“…As well known, polyimides are usually prepared from soluble poly(amic acid) intermediates. Unfortunately, the volatile byproducts (e.g., H 2 O) were produced via rigorous thermal imidization (>300°C) 12 . Then, there are some inherent defects in the obtained polyimides usually, such as high porosity and poor performance stability, which limit the applications of polyimides in high‐precision devices and large size processing 13 .…”

Synthesis and properties of acetylene-terminated isoimide and imide oligomers exhibiting excellent solubility behaviors in low boiling point solvents

“…7,17,18 A class of isoimide oligomers featuring a lower melting point and wider solubility range than the analogous imide oligomers has been reported and can be found in a variety of patents. [19][20][21] Kurita et al 17 have published detailed studies on the structural property influences of model polyisoimides and a facile synthesis of polyisoimides. Meanwhile, Mochizuki et al 22 and Senio et al 23 have developed a new photosensitive polyimide precursor based on polyisoimide.…”

Thermosetting polyimides and composites based on highly soluble phenylethynyl-terminated isoimide oligomers

“…Polyisoimides were considered as attractive precursors of polyimides. [41][42][43][44][45][46] Polyisoimides exhibited greater solubility, lower melt viscosity, and lower melting point than their polyimide analogues. More importantly, polyisoimides can be readily converted to the corresponding polyimides by thermal treatment, without the release of water or other volatile by-products.…”