Solution (source code)

= Solution

For the planar good-solvent coil, $R\sim\ell N^{3/4}$. The <two-dimensional polymer overlap fraction> is therefore
$$
\phi^*\sim\frac{N\ell^2}{\ell^2N^{3/2}}=N^{-1/2},\qquad
\boxed{\phi^*\sim10^{-2}=1\%.}
$$
This is a scaling estimate; the monomer geometry and choice of coil radius set order-one numerical factors.