PLP Labeling in ESR spectroscopic analysis of secondary and tertiary acrylate propagating radicals

PLP labeling in ESR spectroscopic analysis of secondary and tertiary acrylate propagating radicals is demonstrated. PLP-ESR experiments have been carried out on dodecyl acrylate (DA) in dilute solution of toluene at monomer-to-polymer conversions below 30%. Radical concentrations of 10 -6 mol L-1 are produced in the sample volume of 0.2 mL by photoinitiation. The photoinitiator, α-methyl-4-(methymercapto)-α- morpholinopropiophenone (MMMP) was used as received and was added to the monomer-solvent solution under an argon atmosphere The ESR spectra of the monomer-photoinitiator-toluene solution was recorded either under laser pulsing at repetition rates of 10 or 20 Hz by a COMPex 102 Excimer Laser (Lambda Physik) or under continuous illumination by a 500 W mercury UV lamp. PLP-ESR experiments on dodecyl acrylate (DA) in dilute solution of toluene at 0°C reveal that backbiting of SPRs and propagation from MCRs are slow processes.