Tube models are not compatible with the slip-link model for entangled star polymers*

The dynamics of entangled linear and star polymers have been described reasonably successfully by both the slip-link model and various tube models.
Theory suggests that constraint dynamics plays a much larger role for star polymers than for linears, and has been essential in describing data even qualitatively.
Experimentally, the role of constraint dynamics can be examined by blending star and linear chains.
However, recent work has shown that the tube models are incapable of explaining these blends, whereas the slip-link model agrees well without any parameter adjustment.

These observations raise the question of whether slip-link models are capable of repairing the discrepancy of tube models with data.
We have attempted to coarse grain the slip-link model to a tube level of description of stars.
We find that the two models predict very different molecular weight dependence on the relaxation time of star arms without constraint dynamics.
Moreover, we find that the tube level of description is incapable of capturing the physics in the slip-link model.
We conclude that the two theories are incompatible, and at least one of them should be eliminated by comparison with data.