What is a polyplush throw? Is it stretchy?
The most liked quilt I ever made has a cotton top, warm and natural batting, and brushed arnel for the backing. I used t-shirt knit for the binding.
Brushed arnel is a knit that feels like cotton velveteen or velvet. It's as stable as most wovens as far as the stretch factor is concerned. Bathrobes were made from it.
The only caution about using that is - Don't press it with a hot iron - it will melt.