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Dissertation Information for Vasily Andreyevich Migulin

NAME:
- Vasily Andreyevich Migulin

DEGREE:
- Ph.D.

DISCIPLINE:
- Chemistry

SCHOOL:
- Emory University (USA) (2000)

ADVISORS:
- Fred M. Menger

COMMITTEE MEMBERS:
- Albert Padwa
- David Goldsmith

MPACT Status: Fully Complete

Title: Synthesis and properties of multiarmed gemini surfactants

Abstract: Three families of multiarmed, multicationic gemini surfactants, having pentaerythritol, dipentaerythritol, or adamantane cores, were synthesized and examined for their colloidal properties in water. Geminis with four or six 6-carbon chains are highly water-soluble and do not self-assemble. Surface tension and conductivity measurements show that the geminis with four or six 8-carbon chains form micelles in the 3-6 mM range (critical micelle concentrations being two orders of magnitude lower than those of corresponding single-chained surfactants). According to dynamic light scattering, these micelles are small (<30 Å diameter), suggesting participation of only a few molecules per micelle; no evidence of dendritic growth below 25 mM is evident. Geminis with four or six 12-carbon chains are too water-insoluble to examine for micelle formation. Exchange of the counter-ion in the 6-carbon-chained adamantane-based geminis leads to a dramatic change of the solid-state properties. Extremely flexible fibers, up to 2 cm long, were grown with the tetratosylate gemini from acetonitrile upon acetone diffusion. Scanning electron microscopy (SEM) shows a "rhythmic" nature of 5-10% of these fibers as they display a periodic repetition of thin congruent plates. This phenomenon is explained on the basis of the Liesegang ring theory. The analogous gemini, having two dodecaborate counter-ions, forms distinct Liesegang rings on ether diffusion into acetonitrile solution. A precursor to the adamantane-based geminis, 1,3,5,7-tetrakis(bromoacetoxy)adamantane, crystallizes from ethanol upon evaporation forming long (up to 6 cm) crystalline needles of uniform width ( ca. 100 μm) with uncommonly high aspect ratios. X-ray analysis shows exquisitely positioned intra- and intermolecular CH···O=C hydrogen bonds to be responsible for the one-dimensional growth.

MPACT Scores for Vasily Andreyevich Migulin

A = 0
C = 0
A+C = 0
T = 0
G = 0
W = 0
TD = 0
TA = 0
calculated 2008-04-13 14:05:34

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