Abstract
Force-distance profiles were strikingly sensitive to small differences in temperature and solvent composition. Surfaces forces were measured at 18 and 28°C between mica surfaces bearing polystyrene (Mw = 490,000 g·mol-1) adsorbed from dilute cyclopentane solution (θ temperature Tθ = 19.5°C). Forces at long range were monotonically repulsive at 28°C and mildly attractive at 18°C provided that a cyclopentane containing 5% linear pentanes were used. This contrasts with experiments in 99% pure cyclopentane, in which the range of detectable forces was (2-3)RG (unperturbed radius of gyration) at 18°C and (5-6)RG at 28°C, and the forces at long range were strongly attractive at 18°C and weakly attractive even at 28°C. A change of sign of the long-range interactions between adsorbed homopolymers, over a small range of temperature, does not appear to have been reported previously.
Original language | English (US) |
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Pages (from-to) | 270-272 |
Number of pages | 3 |
Journal | Langmuir |
Volume | 5 |
Issue number | 1 |
DOIs | |
State | Published - Jan 1 1989 |
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics
- Surfaces and Interfaces
- Spectroscopy
- Electrochemistry