title: Separation and characterization of functional poly(n-butyl acrylate) by critical liquid chromatography.
abstract: The separation of functional poly(n-butyl acrylate) (PnBA) polymers based on the number of end-groups under critical liquid chromatography (LC) conditions has been studied using a bare-silica column. The (near-) critical solvent compositions for non-, mono-, and difunctional (telechelic) carboxyl-PnBAs were determined in normal-phase LC, using mixtures of acetonitrile, acetic (or formic) acid, and dichloromethane of varying composition. Some formic or acetic acid had to be added to the mobile phase to elute PnBA polymers with carboxyl end-groups. The critical solvent compositions obtained were not exactly the same for non-, mono-, and difunctional PnBA polymers. These were unusual experimental observation, but they were in agreement with theoretic predictions. Nevertheless, low-molecular-mass PnBA samples were successfully separated according to the carboxyl functionality at (near-) critical conditions. With the aid of mass spectrometry (MS), the (near-) critical separation of low-molecular-mass PnBA polymers was confirmed to be mainly based on the carboxyl functionality. Calibration curves for evaporative light-scattering detection (ELSD) were used for quantitative analysis of carboxyl-functional PnBA polymers. The results proved that nearly ideal functionalities (average number of carboxyl end-groups per molecule up to 1.99) were achieved for telechelic PnBAs prepared by one-step reversible addition-fragmentation chain-transfer (RAFT) polymerization of PnBA.
authors.affiliation: Polymer-Analysis Group, Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands. xljiang@science.uva.nl
authors.forename: Xulin
authors.initials: X
authors.lastname: Jiang
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Schoenmakers
authors.forename: Xianwen
authors.initials: X
authors.lastname: Lou
authors.forename: Vincent
authors.initials: V
authors.lastname: Lima
authors.forename: Joost L J
authors.initials: JL
authors.lastname: van Dongen
authors.forename: José
authors.initials: J
authors.lastname: Brokken-Zijp
mesh_terms: D000179:Acrylates / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000379:methods*; D008027:Light; D008970:Molecular Weight; D011108:Polymers / Q000737:chemistry*; D012542:Scattering, Radiation; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D000179:Acrylates; D011108:Polymers; C498324:poly(n-butyl acrylate)