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Date of Award

2-2010

Document Type

Campus Access

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Chemistry

First Advisor

Sankaran Thayumanavan

Second Advisor

Dhandapani Venkataraman

Third Advisor

Robert M. Weis

Subject Categories

Polymer Chemistry

Abstract

The process of molecular self-assembly has attracted tremendous attention due to its novel structural organizations and applications. The self-organization of amphiphilic molecules provides unique opportunities for designing novel materials for advanced nanotechnology. The development of molecular self-assembly involves the precise tailoring of chemical structures and the effective use of non-covalent forces. We are interested in the molecular design and synthesis of amphiphilic macromolecules that exhibit various self-assembled nanostructures. We modify the amphiphilic building blocks during their synthesis, investigate the structure-property relations of these amphiphilic molecules and explore their applications. Amphiphilic dendrimers are obtained when these building blocks are grown in a perfectly branched fashion, whereas amphiphlic homopolymers are produced from the linearly grown building blocks.

We show that facially amphiphilic dendrimers exhibit significant difference in surface wettability due to subtle changes in structure. These amphiphilic dendrimers respond to the surface polarity and modify the polar surfaces from hydrophilic to hydrophobic. The monodendrons are capable of providing hydrophobic surfaces, while the didendrons provide superhydrophobic surfaces. This provides an example of how a molecular level change could result in dramatic changes in surface property.

Amphiphilic homopolymer films have been immobilized onto substrates and shown to reduce protein adsorption, despite the high affinity of the hydrophobic or hydrophilic groups by themselves toward proteins. This protein-resistant property seems to arise from the unique molecular-scale alternation of incompatible functionalities. The combination of incompatible functionalities with a predefined alternating pattern within a monomer could provide a potential design for nonfouling materials.

We also designed and synthesized proton conducting systems that derived from facially amphiphilic polymers. We show that our novel molecular design leads to organized supramolecular assemblies that dramatically enhance the anhydrous conductivity. We describe the design, synthesis, and characterization of these materials, which suggest that nanoscopic organization of proton conducting functionalities should be a key consideration in obtaining efficient anhydrous proton transport.

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