The present invention relates to compositions comprising poly-HEMA having a peak molecular weight between about 25,000 and about 100,000 , preferably between 25,000 and 80,000 and a polydispersity of less than about 2 to less than about 3.8 respectively and covalently bonded thereon, at least one cross-linkable functional group. The present invention further relates to low polydispersity poly-HEMA suitable for making the crosslinkable prepolymers, processes for functionalizing and purifying said poly-HEMA to form said crosslinkable prepolymers, viscous solutions made from said crosslinkable prepolymers, hydrogels made from said viscous solutions and articles made from said crosslinkable polymers, hydrogels and viscous solutions.