A Simplified Preparation Method for PCEs Involving Macroradicals


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Title: A Simplified Preparation Method for PCEs Involving Macroradicals

Author(s): Lei Lei and Johann Plank

Publication: Special Publication

Volume: 302


Appears on pages(s): 1-14

Keywords: Polycarboxylate; Admixture; Synthesis; Graft copolymer; Polymerization mechanism; Dispersion

Date: 6/1/2015

Polycarboxylate superplasticizers are known to be most powerful admixtures which exhibit superior dispersing force even at extremely low water-to-cement ratio. In this study, a simplified one-pot synthesis method for a PCE using only maleic anhydride and methoxy polyethylene glycol as sole raw materials was developed. Compared to conventional synthetic routes, the new method constitutes a much simpler process which performs esterification and grafting in one reactor. Macromonomers are no longer needed for the synthesis of this PCE. The resulting copolymer was characterized by size exclusion chromatography and anionic charge density measurement. Performance of the polymer in cement was probed via ‘mini slump test’. To detect a potential retarding effect of the copolymer, time-dependent heat evolution was monitored. Finally, a model for the formation of this PCE is proposed. According to this, maleic anhydride and MPEG maleate monoester are grafted onto MPEG macroradicals which present the backbone of this PCE.