Title

Magnetic resonance imaging of spiral patterns in crosslinked polymer gels produced via frontal polymerization

Document Type

Article

Publication Date

4-1-2001

Department

Chemistry and Biochemistry

Abstract

Frontal polymerization is a process in which a localized reaction zone propagates through a monomer reactant mixture, leaving a polymer product in its wake, and is the result of the coupling of the thermal transport and Arrhenius dependence of the exothermic polymerization. Under most conditions, a planar front is stable. However, for multifunctional acrylates at room temperature, fronts may propagate in a helical fashion along the axis of the reactor. This front propagation is typical of what is called a spin mode, in which the subsequent polymer sample has alternating spiral patterns of low and high monomer conversion evident on the sample surface. For the first time, we demonstrate that magnetic resonance imaging on a submillimeter scale can be used to show that the spiral patterns are not restricted to the sample surface but are distributed throughout the volume. Samples were soaked in water, and the transverse proton relaxation times were imaged. The results suggest proton mobility is smaller in the high-conversion region in which the hot spot propagated than in the low-conversion region. (C) 2001 John Wiley & Sons, Inc.

Publication Title

JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY

Volume

39

Issue

7

First Page

1075

Last Page

1080