Curtains probably will never be as good as an actual wall at blocking sound, especially bass. Curtains are more for appearance than sound properties. They may help stop reflections of high and midrange frequency sound within the room.
So if your room is truly dedicated to home theater you should consider building walls and doors to separate the home theater from the rest of the house. Not only that, but the construction of a dedicated home theater room is quite different from an ordinary room. Multiple layers on the walls and ceilings are typcially used to minimize sound transmission to other parts of the house, and to minimize sound reflections within the room.
So if your room is truly dedicated to home theater you should consider building walls and doors to separate the home theater from the rest of the house. Not only that, but the construction of a dedicated home theater room is quite different from an ordinary room. Multiple layers on the walls and ceilings are typcially used to minimize sound transmission to other parts of the house, and to minimize sound reflections within the room.