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Why polymer chains in a melt are not random walks
- Source :
- EPL-Europhysics Letters, EPL-Europhysics Letters, European Physical Society/EDP Sciences/Società Italiana di Fisica/IOP Publishing, 2007, 77 (5), pp.56003
- Publication Year :
- 2007
- Publisher :
- IOP Publishing, 2007.
-
Abstract
- A cornerstone of modern polymer physics is the `Flory ideality hypothesis' which states that a chain in a polymer melt adopts `ideal' random-walk-like conformations. Here we revisit theoretically and numerically this pivotal assumption and demonstrate that there are noticeable deviations from ideality. The deviations come from the interplay of chain connectivity and the incompressibility of the melt, leading to an effective repulsion between chain segments of all sizes $s$. The amplitude of this repulsion increases with decreasing $s$ where chain segments become more and more swollen. We illustrate this swelling by an analysis of the form factor $F(q)$, i.e. the scattered intensity at wavevector $q$ resulting from intramolecular interferences of a chain. A `Kratky plot' of $q^2F(q)$ {\em vs.} $q$ does not exhibit the plateau for intermediate wavevectors characteristic of ideal chains. One rather finds a conspicuous depression of the plateau, $\delta(F^{-1}(q)) = |q|^3/32\rho$, which increases with $q$ and only depends on the monomer density $\rho$.<br />Comment: 4 pages, 4 figures, EPL, accepted January 2007
- Subjects :
- Physics
Condensed matter physics
FOS: Physical sciences
General Physics and Astronomy
02 engineering and technology
Condensed Matter - Soft Condensed Matter
021001 nanoscience & nanotechnology
Plateau (mathematics)
Random walk
01 natural sciences
Amplitude
Chain (algebraic topology)
0103 physical sciences
Soft Condensed Matter (cond-mat.soft)
Polymer physics
Wave vector
Ideal (ring theory)
010306 general physics
0210 nano-technology
[PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft]
Intensity (heat transfer)
Subjects
Details
- ISSN :
- 12864854 and 02955075
- Volume :
- 77
- Database :
- OpenAIRE
- Journal :
- Europhysics Letters (EPL)
- Accession number :
- edsair.doi.dedup.....8146514d07a87d6213b54359e875a7fd