Temporal control of the reaction was attained by turning the light source on and off in automated intervals. Liu and coworkers. further expanded on the utility of monitoring photopolymerizations in situ by determining reactivity ratios of the copolymerization of methyl methacrylate and 2-(dimethylamino)ethyl methacrylate. Conventionally, reactivity ratios are obtained by performing mathematical fits of feed ratios (f1) and polymer compositions (F1).