Notes
Influences of various parameters on the morphological properties of highly porous methacrylate polymers, prepared by the polymerisation of high internal phase emulsions, was studied. By varying the type of the initiator, the amount of surfactant, the amount of the internal phase, the monomer ratio, the mixing speed and temperature, the cavity diameter could be controlled and tailored in the range between sub-micron and up to 90%m. In addition, mechanical properties, that are very important in high porous materials, were also optimised. The most studied and used system for PolyHIPE materials is based on styrene, crosslinked with divinylbenzene and based on the fact that neat poly (methyl methacrylate) exhibits better mechanical properties han styrene, the same trend was also expected for poliHIPE materials. The combination of the use of an overhead stirrer and longer mixing time resulted in porous material with hierarchical distribution of pores, which had a flexural modulus of elasticity of 211 MPa at 75% porosity and, which is the highest flexural modulus for PolyHIPE materials of comparable porosity. Further on, porous PolyHIPE materials based on glycidyl methacrylate, crosslinked with ethylene glycol dimethacrylate, were prepared. Glycidyl methacrylate is interesting because it contains reactive epoxy groups, which are suitable for the further functionalization. By varying the type of the initiator, the amount of surfactant, the amount of the internal phase, the monomer ratio and the mixing speed and temperature, the morphology was successfully optimised and thus suitable for further functionalization. The toughness of the material, which is very important in flow-through systems, was again improved with the addition of methyl methacrylate. Hereinafter, enzyme glucose oxidase was successfully immobilised by nucleophil addition via amino groups on glycidyl methacrylate based PolyHIPE supports, which were than used for a model reaction of oxidation of glucose into gluconic acid. The activity of the prepared support with immobilisesd enzyme was determined with FIA system. As a result, a graph of the surface as a function of time was obtained in the form of linear line, which proved the effectiveness of immobilisation. In the last part, prepared PolyHIPE materials were functionalized with different thiols and used to bind for the removal of silver, lead and cadmium ions from water. The removal of heavy metal ions was also carried on real sample of contaminated water. With material, functionalized with pentaerythritol tetrakis(3-mercaptopropionate), we were able to remove 89.6% of Ag+ ions, and 48.2% of Pb2+ ions and with material, functionalized with 1,9-nonanedithiol, we were able to remove 82.3% of Ag+ ions and of 8% Pb2+ ions. At the beginning, Cd2+ ions were adsorbed on the surface of functional polyHIPE materials but with time they were washed off the material. The trend with the removal of low concentrations of metal ions from the real sample was simillar. With the material, functionalized with pentaerythritol tetrakis(3-mercaptopropionate), a large majority of the silver ions was removed and with the material, functionalized with 1,9-nonanedithiol most of the silver and cadmium ions were removed. Nevertheless, we can say that the functionalized poliHIPE supports are suitable for the selective removal of silver ions from contaminated water.