I have never had a problem mixing cotton and cotton/poly blends in the same quilt. If you are talking about the polyester double knit from back in the 60's it makes wonderful quilts for nursing homes. It can be boiled for sanitation and it never wears out. It is so heavy you do not need batting and I have only used flannel for backing. I was given a truckload of it and I cut out designs of some bright colors and appliqued them to the solid pieces, backed it, tied it and called it a quilt. The local nursing homes loved them and I was very happy to see the last of it go!