Abstract
We have studied the strain response of heneicosanoic acid monolayers to an applied sinusoidal shear stress. We have measured the complex shear modulus (G = G′ + iG″) as a function of strain amplitude and frequency, monolayer pressure, and temperature. We find that G′ and G″ are independent of the strain only at very small strain amplitudes; beyond an 'elastic limit', both G′ and G″ decrease with increasing strain amplitude. G′ and G″ are discontinuous at the L2-L2′ and L2′-S phase transitions. In the low-pressure L2 phase, G′ and G″ first increase with increasing pressure and then anomalously decrease. Compared to existing X-ray data, we find an unexpected correlation: over a range of temperatures, the pressure at which G″ is a maximum is also the one at which the monolayer lattice is hexagonal (undistorted).
Original language | English (US) |
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Pages (from-to) | 5137-5140 |
Number of pages | 4 |
Journal | Langmuir |
Volume | 13 |
Issue number | 19 |
DOIs | |
State | Published - Sep 17 1997 |
ASJC Scopus subject areas
- General Materials Science
- Condensed Matter Physics
- Surfaces and Interfaces
- Spectroscopy
- Electrochemistry