A 13C NMR spectroscopic study on the reparation of acid and ester groups in MPEG Type PCEs prepared via Radical copolymerization and grafting techniques

Julia Pickelmann, Huiqun Li, Robert Baumann, Johann Plank

Research output: Contribution to journalConference articlepeer-review

8 Scopus citations

Abstract

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.

Original languageEnglish
Pages (from-to)25-37
Number of pages13
JournalAmerican Concrete Institute, ACI Special Publication
Volume2015-January
Issue numberSP 302
StatePublished - 2015
Event11th International Conference on Superplasticizers and Other Chemical Admixtures in Concrete - Ottawa, Canada
Duration: 10 Jul 201513 Jul 2015

Keywords

  • Copolymerization
  • Dispersing force
  • Grafting
  • Microstructure
  • Polycarboxylates

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