University of Liverpool

Pierre Chambon

Steve Rannard

Andrew Owen

Savannah Cassin

Steven Paul Rannard

Marco Giardiello

James Hobson

Jane Ford

Neill Liptrott

Hannah Rogers

Neil Kitteringham

A method of preparing a branched polymer comprises the free radical polymerisation of a multivinyl monomer in the presence of a chain transfer agent, using a source of radicals, wherein the extent of propagation is controlled relative to the extent of chain transfer to prevent gelation of the polymer. The average length of each vinyl polymer chain within the product is short.

Branched polymers

Responsive or degradable branched polymers may be prepared by the free radical polymerisation of a multivinyl monomer in the presence of a chain transfer agent, using a source of radicals, wherein the extent of propagation is controlled relative to the extent of chain transfer to prevent gelation of the polymer. The multivinyl monomer may comprise a cleavable group, for example an ester, or a multiplicity of such groups, between two vinyl groups. Said monomer may be a macromonomer containing multiple cleavage sites.

Particles comprising a branched polymer and either a block copolymer or a linear dendritic hybrid represent a category of useful materials. They may be used in for example drug delivery applications. They may be prepared by a method comprising the steps of: dissolving the branched polymer and block copolymer or linear dendritic hybrid, and optionally other component(s), in a solvent to form a solution; adding said solution to a different liquid; and removing said solvent to form a dispersion of co-precipitated particles.

Particles containing branched polymers

An oil-in-water emulsion comprises an emulsifier which is a non-gelled branched polymer (e.g. a branched vinyl polymer), wherein the ends of at least some of the chains of said polymer terminate in an alkyl chain of 5 carbon atoms or more, and wherein the oil-in-water emulsion takes the form of particles having a z-average diameter of no greater than about 1000 nm. This is useful in, for example, facilitating the carrying of hydrophobic materials within aqueous systems, to enhance oral drug delivery. The oil-in-water emulsion may be prepared by mixing an oil phase with an aqueous phase in the presence of an emulsifier, wherein said emulsifier is a non-gelled branched polymer, wherein the ends of at least some of the chains of said polymer terminate in an alkyl chain of 5 carbon atoms or more, and wherein the oil-in-water emulsion takes the form of particles having a z-average diameter of no greater than about 1000 nm. The oil phase may comprise a further solvent which is miscible with the oil, said solvent being allowed to evaporate to produce the final emulsion.

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Liverpool, United Kingdom

Pierre Chambon