Lamellar block copolymers: Diffusion and reduction of entanglement effects
Max Planck Institut für Polymerforschung - Postfach 3148,
55021 Mainz, Germany
2 Corporate Research Science Laboratories, Exxon Research and Engineering Company, Annandale, New Jersey 08801, USA
Accepted: 20 March 1998
Motion of symmetric diblock copolymer chains in the macroscopically oriented lamellar phase is studied by molecular-dynamics simulation. For diblocks of length N=40 ( and , where Ne is the entanglement length of the homopolymer melt, the diffusion constant parallel to the interface is nearly independent of χ, while the perpendicular component is strongly suppressed as χ, the Flory-Huggins parameter, is increased in agreement with theoretical predictions based on the Rouse model. For even longer chains (N up to 400) a strong reduction of entanglement effects is observed. We argue that due to the reduced chain overlap in the lamellar phase in this intermediate regime the chain motion is similar to an ellipsoidal molecule in a smectic phase.
PACS: 36.20.-r – Macromolecules and polymer molecules / 61.25.Hq – Macromolecular and polymer solutions; polymer melts; swelling / 83.80.Es – Polymer blends
© EDP Sciences, 1998