Polyacrylamides have been synthesised by a solution polymerisation
process using water as the solvent. The radical polymerisation performed
under a nitrogen blanket was initiated by the thermal decomposition of
potassium persulphate. The influence of monomer and initiator concentrations,
temperature and reaction time on the polymerisation conversion of
monomer into polymer and on polymer molecular weight has been investigated.
Average molecular weights of the polymers were determined by solution
viscometry and membrane osmometry. A procedure for obtaining reproducible
viscosity data.has been developed using the Ubbelohde capillary type
viscometer. Because of a degassing problem with water as a solvent and
membrane breakdown with formamide as a solvent, it was found that reliable
osmotic pressure results were only obtained with difficulty for polymers
dissolved in formamide/water (1:3) mixtures.
Polyacrylamide samples have been separated by analytical gel permeation
chromatography with silica packings. Various modified silicas and several
eluents were investigated with the aim of reducing the adsorption of polyacrylamide
onto the chromatographic packing. Studies were performed with
physically coated phases such as polyethylene oxides, Aerosol OT, with
chemically bonded phases such as hexamethyldisilazane and n-propylamine,
and with eluents such as distilled water, formamide/water (1:5), 1% 880
and ammonia/formamide. Experimental results have shown that satisfactory
separations of polyacrylamide dependent solely on a permeation mechanism
were only obtained with a porous silica having a covalently bonded aminopropyl
phase at the pore surfaces and with a mixed eluent of formamide/
water (1:5). This GPC system was calibrated with polyacrylamide fractions
prepared by fractional precipitation. Molecular weight distributions were
determined from the chromatogram for a fraction and a whole polymer. The
distribution for the unfractionated polyacrylamide was in reasonable agreement
with distributions predicted from the mechanism of polymerisation.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.