Synthesis of superabsorbent resin (SAR) was achieved by a new method, that of direct UV photopolymerization, and in particular the synthesis of a SAR of acrylic acid-potassium acrylate copolymer by UV photopolymerization was investigated. Influences of ratio (mol) of acrylate monomer to acrylic acid monomer, photoinitiators, crosslinking agents, and exposure time of IN light on the water-absorbent properties were investigated. The results showed that the water absorbency (Q) of SAR based on Irgacure 1700 or Irgacure 1800 was 545-530 mL/g, but under the same conditions Q was 450 mL/g for the SAR based on Irgacure 651. N,N'-Methylene bisacrylamide, hydroethyl acrylate, and glycerol were used as crosslinking agents, of which N,N'-methylene bisacrylamide was the most effective. It crosslinked the molecular chains through attending the copolymerization with acrylic acid (AA) and potassium acrylate. When the exposure time was 5 min, the value of Q was 1368 mL/g (the content of N,N'-methylene bisacrylamide was 100 ppm). (C) 2004 Wiley Periodicals, Inc.