DEFORMATIONS OF ONE TETHERED CHAIN IN STRONG FLOWS

1) We describe first the non-uniform stretching of one long flexible tethered chain (N monomers) immersed in a good solvent moving at velocity V. In strong flows the extension L is predicted to increase quadratically with velocity (L approximately N3V2). The chain can be pictured as a sequence of blobs of size y decreasing as x-1 (x being the distance measured from the chain end). 2) We extend this analysis to the stretching of a few grafted chains (<<mushroom>> regime) when a shear flow (rate s) of the solvent is imposed near the wall. Here the elongation L approximately N3/2 s1/2 and the blob size decreases as y approximately x -1/2 . 3) Finally we discuss a chain confined in a slit. We find L approximately N4/3V1/3 and blobs sizes y approximately x-3/4. In all these cases, the deformation is progressive and we expect no sharp coil stretch transitions.