The multi-armed PVAc was synthesized with well-defined M_n distributions and the end groups removed.

The trend of cloud point pressure in CO₂ versus M_n in multi-armed PVAc was different from that of linear PVAc.

The respective contributions of polymer–CO₂ and polymer–polymer interactions were analyzed by using MD simulations.

The radial distribution functions offered a deeper understanding on the interactions of polymer/CO₂ systems at the molecular level.