Alexandria Digital Research Library

Understanding and controlling hydration and crystallization of inorganic structural materials

Sangodkar, Rahul P.
Degree Supervisor:
Bradley F. Chmelka and Michael F. Doherty
Place of Publication:
[Santa Barbara, Calif.]
University of California, Santa Barbara
Creation Date:
Issued Date:
Chemistry, Chemical engineering, and Materials science
Online resources and Dissertations, Academic
Degree Grantor:
University of California, Santa Barbara. Chemical Engineering
Ph.D.--University of California, Santa Barbara, 2016

Hydration and crystallization processes in inorganic materials are typically initiated at particle surfaces in the presence of water and are central to the development of important macroscopic properties, which enable diverse applications, including in optoelectronics, catalysis, therapeutics, and building materials. In particular, for silicate, aluminate and carbonate structural materials, the macroscopic mechanical and structural properties depend on the morphologies, structures, compositions, and interactions of the various inorganic species and the hydrated and/or crystallized products that are formed in the presence of water. Importantly, the hydration and crystallization processes can be modified or controlled by using certain exogenous organic molecules or inorganic species that typically interact at particle surfaces to competitively exclude water, which exhibits strong influences on the macroscopic properties. Despite the enormous importance of silicates, aluminates, and carbonates as hydraulic cements and biogenic structural materials, the processes and interactions that underlie hydration and crystallization in these complex multicomponent systems and the roles of the organic molecules are poorly understood, especially at a molecular level.

Certain organic molecules dramatically slow or entirely suppress hydration and crystallization at silicate, aluminate, or carbonate surfaces, notably at approximately monolayer coverages of the inorganic particles that typically correspond to exceedingly low (as low as 0.1% by weight of solids) bulk quantities of organic molecules. Here, such effects are shown to occur as a result of the competitive adsorption of the organic molecules, including saccharides and phosphonic acids, in place of water at the particle surfaces. A combination of electron microscopy, X-ray diffraction, nuclear magnetic resonance (NMR) spectroscopy, including state-of-the-art dynamic-nuclear-polarization (DNP)-enhanced NMR techniques, are used to characterize the structures, compositions and interactions of the organic and inorganic species across complementary length scales (mm to nm).

The molecular-level measurements establish the physicochemically distinct organic-inorganic surface interactions that account for the adsorption efficacies and correspondingly different hydration effects of organic molecules, which are shown to strongly depend on their distinct molecular architectures and stereochemistries. Furthermore, the results demonstrate the dramatic influences that even subtly different organic architectures and associated surface interactions have on the hydration and crystallization processes at inorganic oxide surfaces, notably for industrially relevant dilute quantities of the organic molecules. Although the silicate, aluminate and carbonate systems are structurally and compositionally different, in each system approximately monolayer coverages of the inorganic particles by certain organic molecules are shown to slow or suppress hydration and crystallization processes.

The methods, analyses, and resulting new insights are expected to be broadly relevant for understanding the molecular origins of organic-mediated surface phenomena in diverse heterogeneous inorganic oxides and can assist in the rational selection and use of organic molecules to influence such processes.

Physical Description:
1 online resource (346 pages)
UCSB electronic theses and dissertations
Catalog System Number:
Inc.icon only.dark In Copyright
Copyright Holder:
Rahul Sangodkar
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