 |
Andrea's Project Page - RISE Summer 2006 |
 |
Intern: Andrea R. Bayles, Biochemistry, UC Santa Barbara
Mentor: J. Benjamin Beck
Faculty Supervisor: Craig Hawker
Department: Materials |
PREPARATION OF POLYMERIC NANOPARTICLES VIA INTRAMOLECULAR CROSSLINKING: CHAIN COLLAPSE
Polymeric nanoparticles, 5-20 nm in diameter, exhibit interesting properties
that lend them to advances in many areas of technology. Synthesizing
nanoparticles within a diameter range of 5-20 nm, however, is not trivial.
Current methods such as dendrimerization and microemulsion techniques are thus
far incapable of preparing nanoparticles in this desired size range.
I used intramolecular chain collapse to produce polymeric nanoparticals 5-20 nm
diameter by crosslinking single polymer chains upon themselves. In this method,
functional groups within linear polymer chains react under dilute conditions to
create intramolecular cross-links, forming a collapsed polymer particle.
Linear copolymers of methyl methacyrate and isocyanatoethyl methacrylate were
synthesized via RAFT-mediated free radical polymerization. Copolymer
composition was confirmed by 1H NMR, and Gel Permeation Chromatography (GPC)
provided the average molecular weight and polydispersity index of the polymer
products.
The isocyanate groups located on the individual polymer chains were reacted
with the difunctional 2-2´-(ethylenedioxy)bis-(ethylamine) species to make urea
linkages. that. This reaction, achieved by the dropwise addition of polymer
to diamine, collapses each chain into a nanoparticle. Infrared spectroscopy
(IR) confirmed the presence of ureas and absence of isocyanates in the collapsed
samples. GPC demonstrated relative decreases in hydrodynamic volume indicating
a successful collapse reaction.
Return to the RISE 2006 project list
