Electron Spin Polarization Transfer from Radicals of Photoinitiators to Stable Nitroxyl Polyradicals

3 Electron Spin Polarization Transfer from Radicals of Photoinitiators to Stable Nitroxyl Polyradicals 

Termination of free radical polymerization is a reaction between two macroradicals R + Rm — diamagnetic product(s) 

In particular, X can be a spin trap or dioxygen. (Peroxyl radicals are inactive in propagation of the polymerization.) 

SCHEME 12.12 Chemical structure of 2,2,6,6-tetramethyM-hydrox3fpiperidine-AI-oxyl (TEMPOL, N) and biradical (N-O-N). Both S3fmmetric (N-O-N) with isotopes and asymmetric (N-O-N) with N and N isotopes such as those presented in the scheme.  

SCHEME 12.13 Competition between chemical reaction (cross-section i rxn) and spin exchange (cross-section of a reactive polarized radical r and a nitroxyl radical 

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