SYNTHESIS OF POLYACRYLAMIDE HYDROGELS WITH PORPHYRIN FRAGMENTS IN THE SIDE CHAIN IN THE PRESENCE OF IMIDAZOLIUM IONIC LIQUIDS

The acrylamide hydrogels containing the porphyrin fragments have been obtained by radical polymerization in a solution. The synthesis has been carried out in the presence of imidazolium ionic liquids with length of the alkyl substituent in the imidazolium ring from C4 to C8. The influence of the used ionic liquids on the structure and some properties of the resulting porphyrincontaining acrylamide hydrogels has been established. The addition of an ionic liquid with a different length of the alkyl substituent into the reaction system can influence the structural changes that occur with the porphyrin comonomer during copolymerization with acrylamide. The formation of bacteriochlorin-like structures is inhibited in the presence of an ionic liquid in the reaction medium. This effect is most noticeable when using an imidazolium ionic liquid with a C8 alkyl substituent length. Hydrogels synthesized in the presence of ionic liquids have lower specific surface area compared to ones obtained without the use of ionic liquids. The lowest specific surface area values were shown by hydrogels synthesized using 1-octyl-3-methylimidazolium bromide. It was also found that the introduction of ionic liquid into the reaction mixture can contribute to both increase and decrease in the numerical values of the sorption characteristics of the resulting hydrogels, depending on the length of the alkyl substituent in the imidazolium ring and a porphyrin : acrylamide ratio. Hydrogels synthesized using 1-hexyl-3-methylimidazolium bromide and 1octyl-3-methylimidazolium bromide at an initial porphyrin : acrylamide ratio of 1:20 have the highest degree of swelling. Varying the ratio of the initial monomers and the structure of the imidazolium ionic liquid during the copolymerization process allows to control the physicochemical characteristics of the resulting porphyrin-containing hydrogels, which can be useful for solving various applied problems.