Polymerisation Method

Ref: 10626
A radical polymerisation reaction which can be initiated by an oxide compound in the absence of additional catalysts and initiators.

Key advantages
  • Does not use halogenated or other organic catalysts
  • Uses oxide catalysts which are generally non-toxic, inexpensive & easily handled

Background

Polymerisation is an essential part of many industrial processes, such as the production of plastics, paints and coatings as well as various electronic and biomedical devices.

Polymers can be produced using several different synthetic pathways, such as Atom Transfer Radical Polymerisation (ATRP) and free radical polymerisation. ATRP is one of the most common types of radical polymerisation and can be used to prepare homopolymers, random, gradient, block, graft and dendritic polymers with well defined structures.

In order to initiate an ATRP reaction, it is necessary to generate a radical, typically via a reversible redox process catalysed by a transition metal complex.

The transition metal complex is typically grafted to a heterogeneous support material such as silica. In these processes, the transition metal complex undergoes a one electron oxidation and simultaneous extraction of a halogen atom from a halogenated initiator, usually an organic halide.

The removal of the halogen generates an active species that can undergo addition to a monomer, thus initiating polymerisation.
ATRP processes require a sophisticated and often expensive catalyst and require both the catalyst and a halogenated initiator.

Due to the nature of many of these catalysts, the reactions must be conducted in the absence of oxygen to prevent catalyst poisoning. These catalysts are also often expensive and, although heterogeneous in nature, are susceptible to leaching, which prevents them from being recycled and raises serious environmental issues.

Free radical polymerisation is also used to form polymers. In this process, radicals are generated as a result of thedecomposition of an unstable initiator, such as an azo compound or a peroxide-based compound.

As the initiator breaks down it produces "free" radicals that attack the given monomer, thereby initiating polymerisation. Throughout the reaction, "free" radicals are transferred from the initiator and along the growing polymer chain as new monomers are incorporated.

The initiators used in many current free radical polymerisation processes are highly reactive and extremely unstable and require that great care be taken in storing them.

The invention

A radical polymerisation reaction can be initiated by an oxide compound in the absence of additional catalysts and initiators.

The present invention relates generally to a method of forming a polymer, wherein the polymer is formed by a radical polymerisation reaction initiated by a solid oxide compound.

The method comprises the steps of:

(a) providing a reaction mixture that comprises: one or more monomers dissolved in a solvent; and - a solid oxide compound; and

(b) exposing the reaction mixture to conditions whereby a radical polymerisation reaction is initiated by the oxide compound. The metal oxides used are specially treated to render them catalytically active.

Applications

Polymerisation of acrylates, alkenes, dienes and alkynes; Low cost polymerisation catalysts.

Principal inventors

  • Professor Thomas Maschmeyer
  • Dr Antony Ward
  • Associate Professor Antony Masters
  • Rebecca Lesic

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