Research on Chemical Intermediates

, Volume 28, Issue 2–3, pp 159–174 | Cite as

Conformational disorder in the propagating radical of dimethacrylate polymers

  • Anna M. Ferretti
  • Giorgio Costante
  • Alessandro Ponti
Article

Abstract

Photopolymerization of methacrylic monomers yields samples with trapped radicals that are easily detected by electron paramagnetic resonance (EPR) spectroscopy. Despite its simplicity, there is no general agreement about the interpretation of this spectrum, in particular, about the role of methylene β protons. An extensive ENDOR study of the propagating radical in photopolymerized dimethacrylates has been carried out in order to obtain detailed information about methylene hyperfine couplings and, thus, about radical conformation. It is shown that literature models are not able to reproduce the ENDOR results and that only accurate fitting of ENDOR spectra obtained by saturating the EPR spectrum at different positions gives reliable information about radical conformation, thanks to the exploitation of conformational selectivity. It turns out that most radicals are in the minimum energy conformation, but any possible conformation is assumed by non negligible fractions of radical.

EPR ENDOR METHACRYLATE POLYMERS CONFORMATION 

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Copyright information

© VSP 2002 2002

Authors and Affiliations

  • Anna M. Ferretti
  • Giorgio Costante
  • Alessandro Ponti

There are no affiliations available

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