High Pressure Induced Coil-Globule Transitions of Smart Polymers

Autor: David B. Adolf, A. Kirpach
Rok vydání: 2006
Předmět:
Zdroj: Macromolecular Symposia. 237:7-17
ISSN: 1521-3900
1022-1360
DOI: 10.1002/masy.200650502
Popis: In current work time-resolved optical spectroscopy (TROS) has been used to study coil-globule transitions monitored by the local segmental dynamics of anthracene labeled poly (N-isopropymethacrylamide), PNIPMAM as a function of pressure (0.1 MPa-200 MPa) over a temperature range of 283 K to 333 K. The positions of temperature-induced transition were observed to be independent on molecular weight of polymer at low pressures. The positions of pressure-induced transition were observed to be dependent on molecular weight of polymer at temperatures below LCST at atmospheric pressure. Double globule-coil-globule transition was observed to occur with pressure increasing at temperatures nearly above LCST. All these results along with values of intrinsic viscosity evaluated from values of correlation times measured for globules formed at different pressure/temperature conditions suggest the different mechanisms of compactisation governed by pressure and temperature and, correspondently, the different types of final structures. At low pressures with temperature increasing the compact, well-packed globules are forming via initial interactions between neighboring parts of polymer chain and further collapse. Relatively loosened particles are forming with pressurizing at low temperatures. Interaction between remote along the chain units takes part from the first stage of globule formation. And finally, rather solvated and irregularly twisted particles are forming at high pressure and high temperatures, i.e. at conditions, when both processes are involved.
Databáze: OpenAIRE
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