Synthesis and characterization of salt resistance hydrogel microspheres by inverse suspension polymerization

Abstract

A series of novel salt-resistance hydrogel microspheres P(AM-co-AMPS) are synthesized by inverse suspension copolymerization using ammonium persulfate (APS) as the initiator and N,N-methylene bisacrylamide (MBA) as the crosslinker and polyvinyl alcohol (PVA) as disperse agent. Optimization syntheses condition of hydrogel microspheres copolymer P(AM-co-AMPS) SAPs is crosslinker content 0.01%, ratio of water to oil 4%, ratio of monomer to surfactant 30%, ratio of acrylamide to 2-acrylamido-2-methylpropane sulphonic acid 80:20 and initiator APS content 1.0%. Their effects on the salt absorbency of the synthesized hydrogel microspheres are investigated. FTIR indicates the two monomeric units of the acrylamide and 2-acrylamido-2-methylpropane sulphonic acid exists in copolymer backbone. SEM indicates that the number of the micropores largely decrease with the water/oil ratio increasing from 4% to 10%. Elemental analysis indicate that the measured values of carbon, sulfur, nitrogen, hydrogen four elements is very close to theoretical value. The experimental results of salt-resistance hydrogel microspheres show the salt absorbency decrease with the increase of salt concentration. The maximum salt absorbency is 132g/g within 75min in 0.9% sodium chloride solution and the effect of calcium ion on salt absorbency is much greater than that of sodium ion.