the orientation vector ${\bf u}$ as the vector which connects the first monomer to the last monomer in each segment. For flexible chain it simply represents the bond between successive monomers. We started with a large spherical container with radius larger than the average radius of gyration of each polymer chain, $R=49\sigma$ Fig. \[fig:seg\_poly\](b), which was followed by contraction to $30\sigma$, $20\sigma$, and $14\sigma$ radii, Fig. \[fig:seg\_poly\](c). Therefore, the volume fractions for different confinement radii are $\varphi=4 N_{m} \sigma^{3}/ D^{3}= 0.0058, 0.025, 0.085, 0.25$, respectively.

In the simulations of each radii of confinement we performed equilibration, production run plus sampling, then shrinking the volume in a very slow process which lets the system relax the tensions and prevents the chains to strongly entangled to each other and becomes trapped into one of the local energy minima of the system. In overall we performed 24 separate simulations.

We equilibrate the system for $2\times 10^{6}\,\tau$ time steps and the production run was $3.7\times 10^{9}\,\tau$ time steps (the whole production run). We sampled the configurations each $200\,\tau$ time steps. Shrinking the volume happens during a very slow process, $1.5\times 10^{6}\,\tau$ steps. In case of strong confinement, $R=14\sigma$, we run extended simulations for additional 