Entangled linear polymers with sticky groups

Associating polymers consist of polymer chains that carry functional groups. These functional groups are capable of forming transient interactions/bonds, which provide a convenient control of the physical properties of this class of polymeric systems. For example, depending on the temperature or/and the concentration of functional groups, the rheological behaviour of associative polymers ranges from rubber-like to liquid-like [1-3]. Here, we focus on melts of entangled, linear associative polymers. The polymer under investigation is hydrolysed poly-(n butyl acrylate) bearing functional groups along its backbone. The content of functional groups in the samples varies from 5% to 40%. The dynamics of these systems has been experimentally studied by dielectric spectroscopy and small amplitude oscillatory shear. These measurements imply that the material undergoes micro-phase separation; that is, the functional groups of the chains mainly associate in strong aggregates, which have much longer lifetime than the reptation time of ordinary, i.e. non-associative, chains of the same molecular weight as the associative ones. As a result, at the lowest experimentally available frequencies, the storage modulus does not exhibit the usual liquid-like behaviour but instead shows a plateau. By incorporating the ideas of micro-phase separation and tension equilibration [4] in the so-called time marching algorithm (TMA) [5],a tube based model that successfully predicts the linear viscoelasticity of ordinary polymer melts, we demonstrate that the aforementioned rheological data can be successfully described. References [1] A.N. Semenov and M. Rubinstein. Macromolecules. 35, (2002) 4821. [2] E. van Ruymbeke, et al. Macromolecules. 43, (2010) 4401. [3] J. Brassine, et al. Macromolecules. 46, (2013) 9134. [4] H. Watanabe, Y. Matsumiya, and E. van Ruymbeke. Macromolecules. 46, (2013) 9296. [5] E. van Ruymbeke, R. Keunings, and C. Baily. J. Non-Newtonian Fluid Mech. 128 (2005) 7.