The soft-mode instability of a membrane induced by strong polymer adsorption

Abstract

The interaction between a flexible polymer and a fluctuating membrane is a fundamental problem in soft-matter physics with relevance to biological phenomena occurring in cells. We find that polymer fluctuations in a strongly adsorbed state can renormalize the bending rigidity of a planar membrane to a negative value. It gives rise to a novel phenomenon that the membrane with a small surface tension can be unstable to spontaneous formation of a soft mode, i.e., a large-amplitude undulation with the wavelength comparable to the interaction range which can be long.