hcl and water the product was recrystallized with 95 ethanol a the procedure of example 3 was repeated utilizing 2 acetylphenothiazine to prepare u03b3 10 2 acetylphenothiazinyl u03b2 hydroxypropyl methacrylate mhapt b the procedure of example 3 was repeated utilizing 2 chloro 8 benzoylphenothiazine to prepare u03b3 10 2 chloro 8 benzoylphenothiazinyl u03b2 hydroxypropyl methacrylate mhbcpt i 10 u03b2 hydroxyethyl 2 acetylphenothiazine a mixture of 2 0 g of 2 acetylphenothiazine and 1 5 g of ethylene carbonate was heated at 200 u00b0 c for 4 hrs upon cooling of the above reaction mixture the solidified mixture was dissolved in ethanol a brown product was obtained by recrystallization with ethanol water ii u03b2 10 2 acetylphenothiazinyl ethyl methacrylate a 2 0 g of u03b2 n hydroxyethyl 2 acetylphenothiazine was dissolved in 100 ml of methyl methacrylate and the transesterification was performed for 24 hrs by using 0 1 g of p toluenesulfonic acid as catalyst and 0 02 g of hydroquinone as inhibitor after removal of methyl methacrylate the residue was washed thoroughly with sodium carbonate solution and water a light brown product was obtained by recrystallization with ethanol water this example illustrates the use of the uv absorbing monomers of this invention to form transparent flexible hydrogel compositions possessing useful uv absorbing properties with relatively low concentrations of covalently bound uv absorbers a hydrogel was prepared using matp in the following monomer initiator composition the transmission spectrum in the uv and visible range was recorded the wavelength at 5 transmission was 432 nm for a 1 mm thick hydrogel sample fig3 ______________________________________hema 20 2 hydroxyethyl methacrylate nvp 60 n vinylpyrrolidone mma 20 methylmethacrylate.