The gamma-radiation induced reactions of aqueous polyethylene oxide solutions : with an appendix on the polymerisation of propylene oxide by organomagnesium compounds

• Main Author: Stafford, John William
• Published: University of Leicester 1968
• Subjects: 540
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.737090

The dose required to gel de-aerated aqueous polyethylene oxide, PEO, solutions was measured for different polymer concentrations and molecular weights. The observations were explained in terms of a proposed theory for the gelation process. The theory was extended to study the radiation induced molecular weight changes in the pre-gel region. Data obtained for low molecular weight polymer agreed, well with theory. Complex features were observed for higher molecular weight material. The role of water structure indetermining the solution properties of aqueous PEO was investigated through the effect of structure modifying solutes, such as alcohol, on viscometric properties. PEO in aqueous solution showed little effect on water structure, and it is proposed that the polymer is accommodated interstitially within clathrate structures which hold it in a rigid conformation. The results suggest that when sufficient alcohol is added, a rigidity - flexibility transition is induced in the macromolecule.;Many additives affect the radiation induced reactions of aqueous PEO solutions. Alcohols in high concentrations gave complex effects which were discussed in terms of polymer - water, water - additive and polymer - additive interactions. In general, for additives at much lower concentrations, the results were successfully interpreted in terms of additive - polymer interaction, additive reactivity toward water radiolysis products, and the effect of the products of such reactions on the polymer. It was found that the polymer was very reactive toward hydroxyl radicals, less reactive toward hydrogen atoms, and comparatively inactive toward the solvated electron; although solvated electron scavengers inhibit gelation. A comparison study for the radiolysis of PEO in organic solvents was found not to be easily relatable to the aqueous systems. An appendix dealing with the polymerisation of propylene oxide by organomagnesium compounds is attached. The reactions were very complex, and the project was not pursued past one year.