The Mullins-Sekerka problem via the method of potentials

It is shown that the two-dimensional Mullins-Sekerka problem is well-posed in all subcritical Sobolev spaces $H^r(\mathbb{R})$ with $r\in (3\mathrm{/}2,2)\mathrm{.}$ This is the first result where this issue is established in an unbounded geometry. The novelty of our approach is the use of potential theory to formulate the model as an evolution problem with nonlinearities expressed by singular integral operators.