Sugar alcohols: A novel platform for functional molecular gels
Item
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Title
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Sugar alcohols: A novel platform for functional molecular gels
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Identifier
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d_2009_2013:387d9012977b:11253
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identifier
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11558
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Creator
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Jadhav, Swapnil Rohidas,
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Contributor
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George John
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Date
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2012
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Language
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English
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Publisher
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City University of New York.
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Subject
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Nanotechnology | Materials science | Physical chemistry | Biobased Amphiphiles | Enzyme Catalysis | Green Chemistry | Molecular Gels | Oil Solidifiers | Self-Assembly
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Abstract
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The rise in interest in molecular gels is evident from the ample variety of molecular gelators (MGrs) being developed for diverse applications, ranging from medicinal to electronic devices. MGrs, typically amphiphiles, exhibit high biocompatibility and biodegradability, accounting for their emergence as potential successors to polymeric gelators. However, most of these gelators have been discovered serendipitously. Therefore there is a strong impetus to probe: (i) the process of gelation; and (ii) structural requirements for a molecule to be a successful gelator. Such systematic investigation rationalizes the relationship between the gelator structure and properties of gels. In this research work, this challenge is addressed for a new class of gelators: sugar alcohol-fatty acid conjugates.;The natural abundance and vast structural diversity of sugar alcohols and fatty acids make them ideal candidates for use in the synthesis of new MGrs. Mannitol, sorbitol and xylitol were chosen as representative entities to study the effect of subtle structural variation in sugar alcohols on the gelation mechanism. Lipase-mediated regioselective transesterification was employed to quantitatively conjugate sugar alcohols with fatty acids. The hydrophobicity of the amphiphiles was fine tuned by varying fatty acid chain length from C4 to C14. The gelation tendency (or self-assembly) of sugar alcohol-based amphiphiles was investigated in water and organic liquids. Several techniques such as XRD, microscopy (optical, SEM and TEM) and spectroscopy (FT-IR) were used to characterize the gels and to decipher the self-assembly mechanism responsible for gelation. The characterization techniques collectively helped in elucidating the relationship between the gelation efficiency and amphiphilic structure (stereochemistry of sugars or chain length of fatty acid).;These non-toxic and readily biodegradable amphiphiles exhibited unprecedented gelation in crude oil fractions, edible oil and liquid pheromones. Their utility was successfully demonstrated by developing: (i) oil spill recovery materials (Chapter 3); (ii) controlled release devices for pheromones and biopesticides (Chapter 4); and (iii) healthy vegetable oil structuring agents (Chapter 5). This entire study successfully demonstrates the prudent utilization of biobased resources and biocatalysis for developing multifunctional amphiphiles. Such value-added chemicals developed through the biorefinery concept may have an impact on industrial applications and new products.
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Type
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dissertation
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Source
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2009_2013.csv
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degree
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Ph.D.
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Program
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Chemistry
