# Polymères neutres solubles dans l'eau : Origine et signatures de la dépendance en concentration du paramètre de Flory chi

Abstract : The origin and signatures of the concentration dependent Flory $\chi _(eff)$-parameter for neutral water-soluble polymers are studied. The three versions of two-state model proposed previously to explain the phase behavior of Poly(ethylene oxide) in water lead to $\chi _(eff)(\phi )$. This dependence can serve as a useful diagnostic of the performance of models: it allows to distinguish between different models and test involving parameters. The emergence of $\chi _(eff)(\phi )$ from alternative single-state models is also discussed. The macroscopic signatures of $\chi _(eff)(\phi )$ are illustrated on the example of swelling of isolated coils and planar brushes. The $\phi$ dependence of $\chi _(eff)$ in systems with uniform concentration gives rise to two main consequences: a shift in the crossover between Gaussian and self-avoidance regimes, and a possibility of a first-order collapse transition for isolated flexible coils. $\chi _(eff)(\phi )$ can lead to a vertical phase separation in polymer brushes involving coexistence of two phases of finite concentration. This approach is applied to the interpretation of indirect evidence that Poly(N-isopropylacrylamide) brushes exhibit this effect.
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https://tel.archives-ouvertes.fr/tel-00003935
Submitted on : Tuesday, December 9, 2003 - 2:27:34 PM
Last modification on : Wednesday, November 4, 2020 - 1:59:39 PM
Long-term archiving on: : Friday, April 2, 2010 - 7:51:40 PM

### Identifiers

• HAL Id : tel-00003935, version 1

### Citation

Vladimir Baulin. Polymères neutres solubles dans l'eau : Origine et signatures de la dépendance en concentration du paramètre de Flory chi. Biological Physics [physics.bio-ph]. Université Joseph-Fourier - Grenoble I, 2003. English. ⟨tel-00003935⟩

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