TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Claimed): The preparation of polymer comprises preparing a composition comprising (I) and diisocyanate monomer and then polymerizing the composition. Preferred Components: The diisocyanate monomer contains a compound of formula (OCN-A-NCO) (II). The diisocyanate monomer comprises aliphatic diisocyanate monomers, alicyclic diisocyanate monomers, aryl aliphatic diisocyanate monomers and/or aromatic diisocyanate monomers, preferably hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2-methylpentamethylene-1,5-diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, perhydro-2,4'-diphenylmethane-diisocyanate and perhydro-4,4'-diphenylmethane-diisocyanate, 1,4-diisocyanato-2,2,6-trimethylcyclohexane, terephthalyidene diisocyanate, 1,3-tetramethyl benzene dimethyl diisocyanate, 1,4-tetramethyl benzene dimethyl diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane (H6XDI), 2,4- and 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, phenyl diisocyanate, 2,3,5,6-tetramethyl-1,4-diisocyanato-benzene, naphthalene-1,5-diisocyanate, 3,3'-dimethyl-4,4'-biphenyl diisocyanate, lysine-diisocyanate and/or lysine ester-diisocyanate. The molar ratio of (I) and diisocyanate monomer is not less than 0.1.The initiator further comprises dihydric alcohol monomer. The total molar ratio between (I) and dihydric alcohol monomer and the molar ratio between (I) and diisocyanate monomer are not less than 1, preferably 1-5. The dihydric alcohol monomer comprises diol compounds of formula (III). The dihydric alcohol monomer comprises compounds of formula ((HO)2Q(COOH)m) (IV). The dihydric alcohol monomer is bisphenol A, tetrabromobisphenol A, bisphenol B, bisphenol E, bisphenol F, bisphenol S, 3,3'-dyhydroxy diphenyl disulfide, ethanediol, polyethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, cyclohexanediol, cyclohexanedimethanol, caprylyl glycol, neopentyl glycol, trimethyl pentanediol, phenyldicarbinol, benzenediol, cresorcin, diethylene glycol, triethylene-glycol, dipropylene glycol, tripropylene glycol, dimethylolpropionic acid, tartaric acid or compound with halogen substituent group. The initiator further comprises hardening agent containing 2,2'-(4,4'-(9H-fluorene-9,9-diyl)bis(4,1-phenylene))bis(methylene)dioxirane compound of formula (V). The optical element comprises packaging material, a transparent base plate, a lens or a functional film. The composition comprises an organic solvent, the initiator, dihydric alcohol monomer and hardening agent.A = aliphatic or aromatic group;X = halo;B = hydrocarbon of formula (-(CR2)n-), sulfur dioxide or dithio;n = 1-2;Q = 2-12C hydrocarbon group; andm = 0 or 1-4.