|M.Sc Student||Sergienko Anatoli|
|Subject||Novel Polymeric Foams - Synthesis, Properties and|
|Department||Department of Materials Science and Engineering||Supervisor||PROF. Michael Silverstein|
Homogeneous, highly porous, low density, open cell polymer foams were prepared by polymerizing the continuous phase of HIPEs (high internal phase emulsions) containing monomers such as styrene (S), divinylbenzene (DVB), 2-ethylhexyl methacrylate (EHMA), 2-ethylhexyl acrylate (EHA) and perfluorooctylethyl methacrylate. The structure, thermal properties and mechanical properties of the foams were characterized and their interactions with water and haloorganics were evaluated. The cell diameters of the polyHIPEs ranged from 1.5 to 15 mm, the intercellular pore diameters from 0.3 to 1.5 mm, the densities from 0.05 to 0.15 g/cm3 and the surface areas from 7.0 to 132.0 m2/g. The glass transition temperatures (Tg) and compressive moduli of the polyHIPE were similar to those expected from literature. Copolymer foams with low S contents were more elastomeric (Tgs below 25°C) whereas foams with high S contents were rather brittle (Tgs above 25°C). Increasing the crosslinking comonomer (DVB) content caused an increase in Tg and in brittleness. Two methods were used in an attempt to increase the surface areas of the polyHIPE: (a) soxhlet extraction with water and methanol; (b) the addition of up to 50% of a solvating porogen, toluene, in the organic phase. The removal of a halo-organics from water using polyHIPE sorbents was studied by performing kinetic (rate) and equilibrium experiments. Important process design parameters were calculated from both the sorption isotherms and from the batch experiment kinetics: the feasibility of sorbing a specific sorbate, the sorbent capacity, and the quantity of sorbent required to achieve a given degree of sorbate removal. The rate and isotherm studies showed that there were only small differences in the amounts of bromoform sorbed by the P(S/DVB), P(EHMA/DVB) and P(EHA/DVB) polyHIPE, none of which underwent Soxhlet extraction. P(S/DVB) polyHIPE that underwent Soxhlet extraction exhibited significant increases in surface area, from 7.9 to 28.9 m2/g, and in the amount of bromoform absorbed, from 19 to 32 mg/g. When toluene is used as a solvating porogen the cell wall is rough and contains pores ranging from 5 to 100 nm in diameter. Extraction increased the surface area by about 20 fold and the sorption capacity by about 200 fold. This research has shown that polyHIPE exhibit great potential as sorbents for the removal of haloorganic contaminants from water.