Super-alcogels Based on 2-Acrylamido-2-methylpropane Sulphonic Acid and Poly(ethylene glycol) Macromer

Polymeric organogels, macromolecular networks with ability to imbibe polar or non-polar organic solvents, have recently been attracted by both academy and industry. These materials (called also polymer organogelator) can convert an organic liquid to a solid gel. Alcohol specific super-swelling organogels (i.e., superalcogels) can be used for various applications such as fuel gels or pharmaceutical formulations. In this paper, super-alcogels were synthesized using a macromonomer (macromer), polyethylene glycol methylether methacrylate (PEGMA), and an ionic monomer, 2-acrylamido-2-methylpropane sulphonic acid (AMPS), through solution polymerization using a persulphate initiator and a macromeric cross-linker (polyethylene glycol diacrylate). The copolymers exhibited very high absorbency of various monohydric and polyhydric alcohols including methanol, ethanol, n-propanol, isopropanol, ethylene glycol, propylene glycol, 1,3-propane diol and glycerol. For example, a typical sample imbibed ethanol and methanol as high as 33 and 36 g/g, respectively. It was found that several parameters had influence on swelling of anorganogel such as: dielectric constant of the solvent, the alcohol OH/C (as a simplemeasure of the hydrophyl/organophyl ratio) and the isomeric position of hydroxyl groupin the alcohol chemical structure. The dissociating ability of the ionic groups (i.e., SO3Hgroups) was recognized to be mainly affected by dielectric constant of the solvent.Higher AMPS content in the alcogel structure improved alcohol absorbency becauseof increased sulphonic acid mobile ions in the gel phase. Thermal and mechanicalproperties of these copolymers were also studied. Glass transition temperature of thecopolymer was decreased with increase of the macromer and the samples with highmacromeric content showed elastomeric behaviour at room temperature in dry state.Thermal stability was improved with lowering of AMPS content due to susceptibility ofsulphonic acid group at lower temperatures.