Endgroup-based separation and quantitation of polyamide-6,6 by means of critical chromatography

• Published in: Journal of Chromatography A Vol. 949; no. 1; pp. 337 - 349
• Main Authors: Mengerink, Y, Peters, R, van der Wal, Sj, Claessens, H.A, Cramers, C.A
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 08.03.2002; Elsevier
• Subjects: Applied sciences; Caprolactam - analogs & derivatives; Caprolactam - analysis; Caprolactam - isolation & purification; Chromatography, Liquid - methods; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Polyamide; Polymers - analysis; Polymers - isolation & purification; Properties and characterization; Spectrophotometry, Ultraviolet; Structure, morphology and analysis; Polyamide; Gradient elution; Critical chromatography; Elution; Gradient; Flow rate; Phase composition; End group; HPLC chromatography; Temperature effect; Mobile phase; Isocratic condition; Operating conditions; Critical conditions; Amine; Ultraviolet detector; Carboxylic acid; Amide 66 polymer; Quantitative analysis; Functional group; Stationary phase
• ISSN: 0021-9673
• DOI: 10.1016/S0021-9673(02)00030-4

Polyamide-6,6 is a polycondensation product from the two monomers adipic acid and 1,6-hexamethylenediamine. Depending on the reacted amount of these monomers, different ratios of amine and carboxylic acid endgroups can be formed. Besides linear chains, cyclic polyamides will also be formed. Using critical chromatography, polyamide-6,6 can be separated independently of molar mass. Retention is based solely on endgroup functionality. It is demonstrated that high-molecular-mass polyamide-6,6 ( M w≈20 000–30 000) can be separated using this approach. The separation was optimized by using different parameters, such as percentage modifier, temperature and pressure. The concentration of phosphoric acid was used for selective retention of the different endgroup functionalities. Using this property, a new method called critical gradient chromatography was performed where the mobile phase changes from a weak to a strong solvent with respect to the endgroup functionality, while retaining the critical conditions of the backbone unit. Quantification using UV detection is discussed.