We recently discovered that atactic poly(methyl methacrylate) (PMMA) could complex with U and significantly increase its Tg, and PMMA could also complex with dimethylurea, which decreased its Tg . In addition, when atactic poly (vinyl acetate) (PVAc) was complexed with U, it acted as a plasticizer and lowered the Tg of PVAc . Since PMMA, PVAc, and PVC are all amorphous polymers, we decided to conduct experiments to investigate whether U or any of its derivatives and related compounds could complex with PVC and lower its Tg.