Compression of finite size polymer brushes

Abstract

We consider edge effects in grafted polymer layers under compression. For a semi-infinite brush, the penetration depth of edge effects $\xi \propto h_0(h_0/h{)}^{1/2}$ is larger than the natural height $h_0$ and the actual height $h$. For a brush of finite lateral size $S$ (width of a stripe or radius of a disk), the lateral extension $u_S$ of the border chains follows the scaling law $u_S=\xi \varphi (S/\xi )$. The scaling function $\varphi (x)$ is estimated within the framework of a local Flory theory for stripe-shaped grafting surfaces. For small $x$, $\varphi (x)$ decays as a power law in agreement with simple arguments. The effective line tension and the variation with compression height of the force applied on the brush are also calculated.

6 pages, 7 figures, submitted to PCCP

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