Pulsed laser degradation of polyethylene oxide and polyacrylamide in aqueous solution

The kinetics of degradation of polyethylene oxide (PEO) and polyacrylamide (PAM) was investigated using a pulsed Nd:YAG laser, operating at 266 nm wavelength with $\sim 6$ ns pulses. Gel permeation chromatograph was used to monitor the change in molecular weight with time. Continuous distribution kinetics for random chain scission was used to obtain the rate coefficient for the degradation process. The measured rate coefficients for the degradation are $1.9\times 10^4$ and $1.2\times 10^4 \hspace {5mm} s^{-1}$ for PEO and PAM, respectively. A pathway for degradation has been proposed based on the experimental observations. The signi.cance of polymer concentration and the laser light intensity along with the requirement of oxygen for degradation has been correlated to the mechanism of the degradation process. The degradation was found to decrease with increasing polymer concentration while a threshold light intensity was required to initiate the degradation process.