N-Vinyl lactam based biomedical devices

As a new article of manufacture, a contact lens formed from a hydrophilic polymer formed by polymerizing (a) (1) one or more N-vinyl lactams and/or heterocyclic N-vinyl monomers, said N-vinyl lactams being selected from the group consisting of N-vinyl-2-pyrrolidinone, N-(1-methyl) vinyl pyrrolidinone, N-vinyl-2-piperidone and N-vinyl-2-caprolactam which may be substituted in the lactam ring by one or more lower alkyl groups, said heterocyclic N-vinyl monomers being selected from the group consisting of N-vinyl imidazole, N-vinyl succinimide, N-vinyl diglycolylimide, N-vinyl glutarimide, N-vinyl-3-morpholinone and N-vinyl-5-methyl-3-morpholinone, and (2) from zero to 50 weight percent of the total monomer present is at least one hydrophobic monomer or hydrophilic monomer other than N-vinyl lactam and/or heterocyclic N-vinyl monomer, said hydrophobic monomer(s) being selected from the group consisting of acrylates, methacrylates, itaconates, fumarates, maleates and crotonates wherein the esterified group has from 1 to 30 carbon atoms, said hydrophilic monomer(s) being selected from the group consisting of hydroxyesters, free acids, amides and amines of acrylates, methacrylates and itaconates, and (b) a resonance free di(alkene tertiary amine) cyclic compound crosslinking agent alone or in admixture with a crosslinking agent of another chemical structure in which case said cyclic compound is at least 50 mole percent of said mixture, said cyclic compound having the formula CH.sub.2 :CG(CH.sub.2).sub.x N.about.J.about.N(CH.sub.2).sub.x CH:CH.sub.2 wherein x is 0 or 1, G is hydrogen or methyl and J is the balance of structure forming cyclic dialkene urea, said agent being present in an amount from 0.01 to 10 weight percent of the total monomer of (A) (1) and (A) (2) present to form a crosslinked 3-dimensional polymeric network, said polymer having an oxygen permeability of at least 24.times.10.sup.-11 cm.sup.2 cm/(sec.cm.sup.2 mmHg) and a tear initiation strength of at least 3 g/mm of thickness.