A class of polymers constructed with the monomer ethylene, H₂C=CH₂, with hydrogen replaced by various chemical groups. Among the many vinyl-based polymers and copolymers are acrylates, methacrylates, acrylamides, acrylate-acrylamide (PHPA), vinyl acetate and the various oligomers of ethylene, polyalphaolefins, linear alphaolefins and isomerized olefins. The prefix "vinyl" is more correctly "ethenyl" and sometimes "vinylene. " "Polyvinyl" is synonymous with vinyl polymers, but not specific to an exact polymer. For example, polyvinyl acetate, polyvinyl alcohol, polyvinyl sulfide are commonly used polymers based on ethylene monomers.