Radiation effects on poly (glycidyl methacrylate-co-ethyl methacrylate) copolymers and electron paramagnetic resonance characterization of vanadium hexacarbonyl using the technique of partial orientation

Part I

The effects of gamma radiation on a series of characterized copolymers, synthesisized from different molar ratios of glycidyl methacrylate (GMA) and ethyl methacrylate (EMA), have been studied using a variety of techniques.

Polymers were characterized using IR, NMR, GPC, and viscosity measurements. Radiation G values for crosslinking and scission were calculated using the analysis developed by Charlesby and Pinner in order to compare the effects of radiation on the epoxide and methacrylate functionalities. The analysis of radiation G values suggests that at glycidyl methacrylate concentrations below 10%, crosslinking does not predominate. However, at higher GMA concentrations, G values for crosslinking increase, and at GMA concentration over 60%, G values approach 10, a value only reached by chain reactions.

Spectroscopic evidence is presented for the participation of the glycidyl group in radiation-induced reactions. FTIR studies on irradiated thin films of COP show decreases in the epoxide functional group regions, ca. 908 and 1250 cm^-1. EPR results suggest that a paramagnetic species, possibly due to the epoxide group, is produced by irradiating the polymer.

Part II

The EPR spectral parameters of V(CO)₆, a stable paramagnetic species have been resolved using the experimental technique of "Partial Orientation." Slow-cooling an EPR sample of V(CO)₆ in cyclohexane produces crystallites containing the solute. When these crystallites are of sufficient size, resolution of the broadened EPR spectrum into the individual g tensors is observed. This induced resolution allows the precise assignment of the hyperfine coupling constants and g tensor values .