The polyacrylic acid (PAA) hydrogels were prepared by solution polymerization with acrylic acid (AA) as mono-mer,polyethylene glycol (PEG) as pore forming agent,N,N-methylenebis acrylamide (BIS) as cross-linking agent,and ammonium persulfate (APS) as initiator,then they were freeze-dried. The chemical composition,thermal stability,microstructure,and the swelling behavior in water and different pH buffer solutions of the PAA hydrogels with different PEG in feed ratios were studied. Furthermore, the water-retaining property of the hydrogels for soil was tested. The results show that the introduction of PEG don't affect the chemical composition and thermal stability of PAA hydrogels; whereas,the diameter and pore density of these two pores, macropores of 0.7-2μm and ultra-large pores of 60-200μm exist in the PAA hydrogels,increase with the addition of PEG; the water swelling abilities and pH sensitivity of PAA hydrogels improved with the addition of PEG. The addition of a definite amount of hydrogels in soil can enhance its water retention.%以丙烯酸(AA)为单体、聚乙二醇(PEG)为致孔剂、N,N-亚甲基双丙烯酰胺(BIS)为交联剂、过硫酸铵(APS)为引发剂,通过自由基溶液聚合及冷冻干燥法制备聚丙烯酸(PAA)水凝胶,研究PEG的加入量对PAA水凝胶的化学组成、热稳定性、微观结构及在水和不同pH缓冲液中的溶胀行为的影响,同时测试了水凝胶对土壤的保水性能.结果表明,PEG的加入并不影响PAA水凝胶的化学组成和热稳定性;PAA水凝胶中存在0.7～2μm大孔和60～200μm超大孔,孔径和孔隙率随着PEG加入量的增加而增大;PAA水凝胶的吸水溶胀性和pH敏感性皆随着PEG加入量的增加而增大;适量水凝胶的使用可增强土壤的保水性.
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