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Title: A 13C NMR Spectroscopic Study on the Reparation of Acid and Ester Groups in MPEG Type PCEs Prepared via Radical Copolymerization and Grafting Techniques

Author(s): Julia Pickelmann; Huiqun Li; Robert Baumann; and Johann Plank

Publication: Symposium Paper

Volume: 302


Appears on pages(s): 25-38

Keywords: copolymerization; dispersing force; grafting; microstructure; polycarboxylates

DOI: 10.14359/51688082

Date: 6/1/2015

The microstructure of MPEG-type polycarboxylate (PCE) copolymers, i.e. the distribution of side chains along the main chain was investigated via 13C NMR spectroscopy and the effect on the interaction with cement was determined. For this purpose, two series of polycarboxylate samples (one series synthesized by radical copolymerization, the other one via grafting/esterification) at molar ratios of –COO– to side chain of 2 to 10 were compared. The 13C NMR spectra suggest that the copolymerized PCEs possess a gradient-like distribution of side chains along the main chain while the grafted PCEs exhibit a statistical (random) repartition. Owed to those microstructural differences the grafted PCE copolymers show a tendency to adsorb in lower amount on cement. The reason is that in the copolymerized PCEs, large blocks of –COO– groups are present which exhibit high affinity to the surface of cement and therefore promote adsorption.