The synthesis of a ferromagnetic polymer


The aim of this study was to prepare a ferromagnetic polymer using the design elements of molecular magnets. This involved the preparation of co-polyradicals of phenylacetylenes bearing nitronyl nitroxides and nitro/cyano groups. The magnetic properties of the materials were determined using a SQUID magnetometer. A novel rhodium catalyst, Rh(NBD)(NH3)Cl, was prepared in order to obtain good yields of polymerisation. A wide range of substituted phenylacetylenes were first homopolymerised in order to assess the efficiency of the catalyst. Yields were generally high, between 75% and 98%, and the time of polymerisation was short (one hour). SEC analysis revealed that the Mw of the polymers were in the range of 200,000 and 250,000. The discovery that phenylboronic acid acts a co-catalyst for the polymerisation served to increase the yields by 10% to 20% but the Mw of the polymers was reduced to approximately 100,000. Co-polyradicals were prepared in good to excellent yield using the new catalyst. The magnetic properties in the temperature range of 300K to 1.8K were investigated by SQUID, which revealed a spin glass system, antiferromagnets and possible dipolar magnets. Short-range ferromagnetic interactions between 300K and 100K were found in a co-polyradical containing nitronyl nitroxide and cyano substituted monomers. The magnetic properties were dependent upon both the type of monomers utilised and the ratio between them. The effects of ring substituents on the terminal alkyne have been studied by carbon-13 NMR. There was no correlation however, between the chemical shift of terminal alkyne and the polymerisability of the monomer.

Divisions: College of Engineering & Physical Sciences > School of Infrastructure and Sustainable Engineering > Chemical Engineering & Applied Chemistry
Additional Information: Department: Chemical Engineering and Applied Chemistry If you have discovered material in AURA which is unlawful e.g. breaches copyright, (either theirs or that of a third party) or any other law, including but not limited to those relating to patent, trademark, confidentiality, data protection, obscenity, defamation, libel, then please read our Takedown Policy and contact the service immediately.
Institution: Aston University
Uncontrolled Keywords: polymerisation,phenylacetylene,nitronyl nitroxide,polyradical,ferromagnetic
Last Modified: 28 Jun 2024 07:45
Date Deposited: 01 Dec 2010 14:24
Completed Date: 1999-06
Authors: Brough, Peter E.


Export / Share Citation


Additional statistics for this record