Linear viscoelastic behavior of densely grafted poly(chloroethyl vinyl ether)-g-polystyrene combs in the melt

We have measured the linear viscoelastic behavior in the melt of two densely grafted poly(chloroethyl vinyl ether)-g-polystyrene comb polymers. Both samples have a backbone of approximately 800 ethyl vinyl ether monomers and the fractions of grafted backbone monomers are 98% and 10%, respectively. The viscoelastic behavior shows remarkable features. The comb polymer with the highest grafting density shows a power law behavior over five orders of magnitude in frequency. The power law can be understood through a "Rouse-like" motion of the entire chains with an apparent friction coefficient coming from the fast Rouse dynamics of the short grafts. Alternatively, the same behavior can be described as the signature of a "fluctuating", physical gel. The less densely grafted comb polymer has a more complex behavior. (C) 2003 The Society of Rheology.