Surface Analytical Study of Poly(acrylic acid)-Grafted Microparticles (Beads): Characterization, Chemical Derivatization, and Quantification of Surface Carboxyl Groups

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• 作者：Paul M. Dietrich ; Andreas Hennig ; Markus Holzweber ; Thomas Thiele ; Heike Borcherding ; Andreas Lippitz ; Uwe Schedler ; Ute Resch-Genger ; Wolfgang E. S. Unger
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：September 4, 2014
• 年：2014
• 卷：118
• 期：35
• 页码：20393-20404
• 全文大小：617K
• ISSN：1932-7455

文摘

We report a surface analytical study of poly(methyl methacrylate) (PMMA) microparticles (beads) with a grafted shell of poly(acrylic acid) (PAA) with thicknesses up to 4 nm using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and near-edge X-ray adsorption fine structure (NEXAFS) spectroscopy. These polymer microparticles were analyzed before and after reaction of the surface carboxyl (CO₂H) groups with 2,2,2-trifluoroethylamine (TFEA) to gain a better understanding of methods with use of covalently bound probe molecules for surface group analysis. The results obtained with chemical derivatization XPS using TFEA are discussed in terms of surface quantification of reactive CO₂H groups on these PAA-coated microparticles. A labeling yield of about 50% was found for TFEA-derivatized particles with amounts of surface-grafted CO₂H groups of 99 渭mol/g or more, which is consistent with predicted reaction yields for homogeneously dispersed PAA hydrogels.