Dynamic measurements on polymer chain dimensions below the θ-temperature

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Abstract
To observe the contraction of a flexible chain, quasi-elastic light scattering and viscosity experiments were performed below the θ-temperature. The systems used were monodisperse polystyrene (Mw = 1.71 x 10 5, Mw =4.11 × 105, Mw = 1.26 ×106) dissolved in cyclohexane. It is observed that : — Hydrodynamic and viscosity expansion factors, αH and α3 η, scale with the reduced variable (θ-T T)√M. — αH and α3η have a linear behaviour in a «θ domain» (0≤ |θ - T / T| √M ≤ 10) which is symmetric with respect to the θ-temperature. — There is no evidence of an asymptotic collapsed regime for (θ-T T)√M≤ 35