Comb-Shaped Polymers as Nanostructure Modifiers of Calcium Silicate Hydrate: A 29Si Solid-State NMR Investigation

TitleComb-Shaped Polymers as Nanostructure Modifiers of Calcium Silicate Hydrate: A 29Si Solid-State NMR Investigation
Publication TypeJournal Article
Year of Publication2013
AuthorsCappelletto, E, Borsacchi, S, Geppi, M, Ridi, F, Fratini, E, Baglioni, P
JournalThe Journal of Physical Chemistry C
Volume117
Pagination22947–22953
Date Publishednov
KeywordsBinding energy, Calcium silicate, Calcium silicate hydrate, Calcium silicate hydrate gel, Degree of polymerization, Mechanical resistance, Molecular architecture, Molecular imprinting, Nanostructures, Nuclear magnetic resonance spectroscopy, Polymers, Portland cement, Silicate minerals, Silicon, Small angle scattering, Solid state physics, Solid-state nuclear magnetic resonance
Abstract

Calcium silicate hydrate gel (C-S-H) is the complex phase mostly responsible for the binding properties and the mechanical resistance of Portland cement. The clarification of the C-S-H nanostructure and how the presence of organic additives affects it is still an intriguing and not trivial task, especially due to C-S-H scarce crystallinity and intrinsic complexity. In this work, we exploited 29Si solid-state nuclear magnetic resonance (NMR) to investigate the effects of different comb-shaped superplasticizers on the silicate structure. The analysis of 29Si solid-state NMR spectra shows that the additives increase the degree of polymerization and hence the average length of the silicate chains in C-S-H. This finding correlates well with the increase of the globule dimensions estimated by means of small angle scattering techniques showing that the comb-shaped polymers are able to tune the overall dimension of the C-S-H globule. This effect is dependent on the molecular architecture of the superplasticizer and allows a molecular imprinting to the globular structure of the C-S-H gel. © 2013 American Chemical Society.

URLhttp://www.scopus.com/inward/record.url?eid=2-s2.0-84889802100&partnerID=40&md5=efeb6c4b92d0072d4ba8d5ecdf633cf3 http://pubs.acs.org/doi/abs/10.1021/jp407740t
DOI10.1021/jp407740t