Effect of the Means Used to Synthesize Highly Fluorinated Polyimide on the Properties of an Adsorbent Prepared on Its Basis

Abstract

Selective separating layers based on fluorinated polyimide are synthesized by different methods and employed as a stationary phase for the modification of Chromosorb® P NAW. A comparative estimate is made of the properties of adsorbents modified with polyimide or polyamido acid with subsequent imidization. The textural and chromatographic characteristics of the synthesized materials are measured via low-temperature nitrogen adsorption, high-resolution electron microscopy, and gas chromatography. The specific surface area of the Chromosorb® P NAW adsorbent impregnated with 10 wt % polyimide is found to grow from 31.2 to 78.0 m2/g during thermal treatment in a flow of inert gas in the temperature range of 250 to 700°C, while the size of its pores shrinks from 32.0 to 24.4 A. Chromatographic properties typical of non-polar stationary phases are observed when the adsorbent is subjected to thermal treatment at 250°C, while properties of carbon molecular sieves are exhibited by a support calcined at 700°C.