The kinetics and mechanism of the solid state polymerization of acrylamide

Abstract

AbstractCrystalline acrylamide exposed to γ‐rays polymerizes after removal from the irradiation source for periods of many months. The molecular weight of the product increases about by the same factor as the polymer yield. At 25°C., the initial propagation rate coefficient is 2.6 · 106 times lower than in water solution. The kinetics of the reaction are consistent with bimolecular radical termination and intermediate between those expected for a uniform radical distribution and the radical growth in isolated “tracks” of the γ‐rays, but electron spin resonance measuremennts indicate little dacay do the radical concentration with time. In solid solutions of acrylamide and propionamide, which is isomorphous with the monomer, the polymer chain lenght is determined by chain transfer to propionamide. The high chain transfer efficiency of propionamide in solid solution is indicative of the restraints imposed on the direction of the chain growth by lattice forces. There is no appreciable chain transfer in solid sollutionss of acrylamide containing the non‐isomorphus acetamide as the second component.