Chin, W. University of Washington, Dept of Bioengineering, (206) 685-3300
Verdugo, P. University of Washington, Dept of Bioengineering, (206) 685-3300

Modeling of Spontaneous Assembly of Marine Dissolved Polymers into Polymer Microgels.
The finding that marine DOM-polymers assemble forming POM-microgels has significant implications regarding the fate of DOM and their participation in the carbon cycle (Wells, Nature, 391, 531, 1998). DOM-polymer assembly resembles a second-order kinetics suggesting that more than one assembly process is responsible for the formation of marine microgels. The low concentration of DOM polymers found in seawater makes it unlikely that microgel assembly in the bulk could account for the rate of assembly we recently reported (Chin et al Nature, 391, 568, 1998). Preliminary results presented here indicate that hydrophobic-domain-containing amphiphatic DOM-polymers concentrate at the air-water interface. The polyanionic domains of these interfacial polymers are then crosslinked by Ca-ions forming nanogels that migrate from the air-water interface to the bulk. Slower modes of association by annealing in the bulk result in bigger um-size gels. A mathematical model considering two steps of assembly is presented here. It includes a linear first-order interface nanogel assembly kinetics, followed by a slower rate-limiting second-order assembly kinetics that takes place in the bulk. Predictions of this model are consistent with the observed assembly kinetics measured by dynamic laser scattering and flow cytometry and with the reports that colloidal-sized carbon (< 1 um) is the dominant form of marine organic carbon. *Supported by the Polar Program (National Science Foundation, USA)
Day: Tuesday, Feb. 2
Time: 04:45 - 05:00pm
Location: Eldorado Hotel
Code: SS34TU0445E