90 0 g ethyl acrylate ea 90 0 g methacrylic acid maa and 7 5 g allyl methacrylate alma in a bottle a reaction kettle was then prepared with 150 g deionized water 34 0 g of the monomer emulsion and 0 04 g ammonium persulfate in one ml deionized water the reaction kettle was heated to 80 u00b0 c while being purged with nitrogen the rest of the monomer emulsion above and 32 g of a solution containing 0 20 g ammonium persulfate aps in deionized water were fed into the reaction flask 80 u00b0 c at 4 0 g min and 0 35 g min respectively at the end of the feed the temperature of the reaction flask was cooled to 75 u00b0 c and then a solution of 0 10 g t butyl hydroxy peroxide t bhp in 1 ml of deionized water was added the reaction was cooled further to 55 u00b0 c to this was added a solution of 0 060 g sodium sulfoxylate formaldehyde ssf in 2 ml of deionized water the reaction was cooled to ambient temperature and the emulsion was filtered through 325 and 100 mesh sieves respectively to yield a polymer emulsion having an average particle size of 100 nm 265 84 g of emulsion from example 1 27 5 solids was mixed with 200 g deionized water and 10 ammonium hydroxide to produce a mixture having ph 7 to this was added dropwise 133 g of a gd iii nitrate hexahydrate.