I have done many repurposed items, old green wool army blankets, worn out quilts and other things. A lot of it depends on what you want. Flannel as a middle to give something for the stitches to bite into and hold together is a traditional usage.
I participated in some quilts for the homeless in the Seattle area. That group wanted polyester double knits for its durability and easy wash/dry. There are things to think about with the polys and especially double knits on how you work with them. You might consider an overlap seam for instance, or to serge/zigzag edges. Some are quite stiff and will never soften up! Some works and drapes much nicer than you'd think.
I did a crazy quilt project using "ugly men's ties" especially big wide textured poly ties from the 70s... for the back I used a really interesting piece of double knit. For whatever reasons, my son really loved that quilt and it was his for decades. A lot of the ties have fallen apart (is ok, they were on foundation) but the back is still lovely after all these years of heavy use. That one would have been great as a liner.
edit: I have not been good about updating my profile stuff, but I did find a picture of the back in my album here:
https://www.quiltingboard.com/member...52-622210.html
(you have to be logged in to use the link)