Dynamic measurements on polymer chain dimensions below the -temperature

2014 To observe the contraction of a flexible chain, quasi-elastic light scattering and viscosity experiments were performed below the 03B8-temperature. The systems used were monodisperse polystyrene (Mw = 1.71 x 105, Mw =4.11 105, Mw = 1.26 106) dissolved in cyclohexane. It is observed that : 2014 Hydrodynamic and viscosity expansion factors, 03B1H and 03B13~, scale with the reduced variable (03B8-T T)~M. 2014 03B1H and 03B13~ have a linear behaviour in a «03B8 domain» (0~ |03B8 T / T| ~M ~ 10) which is symmetric with respect to the 03B8-temperature. 2014 There is no evidence of an asymptotic collapsed regime for (03B8-T T)~M~ 35. Dynamic measurements on polymer chain dimensions below the 03B8-temperature R. Perzynski, M. Adam and M. Delsanti (*) (**) Laboratoire Léon Brillouin, CEN Saclay, B.P. n° 2, 91190 Gif-sur-Yvette, France (**) Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA (Reçu le 26 juin 1981, accepté le 21 septembre 1981) . J. Physique 43 (1982) 129-135 JANVIER 1982, Classification Physics Abstracts 05.40 61.40K 66.90 82.90 Introduction. For a flexible polymer chain at the theta temperature, the mean interaction between monomers vanishes and the chain has a Gaussian conformation. At temperature below the Flory theta temperature [2] (near the upper critical solution temperature) the attractive interactions between monomers become important. On cooling, the chain contracts and can reach a globular state. More often the contraction below the 0-temperature is called the o coil globule transition ». A large number of theoretical and experimental works have been devoted to this subject [1-12]. The different analyses lead to similar results presented in a simple way by de Gennes [1]. Static and dynamic measurements have been performed on the « coil globule transition >> of a polystyrene chain dissolved in cyclohexane [5-10]. Unfortunately the data are sparse. For instance, D. R. Bauer et al. [6] observed a small contraction of the chain and G. Swislow [9] et al. observed a sharp coil globule transition. Whatever the sharpness of the transition, the main point of the theory is that the expansion factor must scale with the reduced variable T e M as suggestT, ed by the experiments of D. R. Bauer et al. [6]. , Here our purpose is, to : verify whether the expansion factor scales as Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphys:01982004301012900