High refractive index ophthalmic device materials prepared using a post-polymerization cross-linking method

A two-stage method for preparing an acrylic, high refractive index ophthalmic device material, wherein the ophthalmic device material comprises

• (i) at least one aryl acrylic hydrophobic monomer of the formula 2
• wherein:
• X is H or CH3;
• m is0-10;
• Y is nothing, O, S, or NR wherein R is H, CH3, CnH2n+1 (n=1-10) iso OC3H7, C6H5, or CH2C6H5;
• Ar is any aromatic ring which can be unsubstituted or substituted with CH3, C2H5, n-C3H7, iso-C3H7, OCH3, C6H11, Cl, Br, C6H5, or CH2C6H5;
• (ii) a first stage polymerization initiator selected from the group consisting of photoinitiators and thermal free radical initiators having a 10 hr t½ of about 55° C. or less;
• and
• (iii) a second stage cross-linking agent where the second stage cross-linking agent is a thermal free radical initiator having a 10 hr t1/2 of about 50° C. or greater if the first stage polymerization initiator is a photoinitiator and the second stage cross-linking agent is a thermal free radical initiator having a 10 hr t½ of about 65° C. or greater if the first stage polymerization initiator is a thermal free radical initiator having a 10 hr t1/2 of about 55° C. or less, wherein the first stage of the method comprises polymerizing the ophthalmic device material by activating the first stage polymerization initiator without activating the second stage cross-linking agent;
• and the second stage of the method comprises cross-linking the ophthalmic device material by activating the second stage cross-linking agent.