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US 2006/0069203 A1Published application
Block copolymers
AssigneeBiocompatibles UK Limited
InventorsAndrew Lewis, Steven Armes, Yinghua Ma
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AssigneeBiocompatibles UK Limited
InventorsAndrew Lewis, Steven Armes, Yinghua Ma
Estimating the term…
Block copolymers comprise a core block formed of hydrophilic monomers and have pendant zwitterionic groups, and at least two terminal blocks, comprising stimulus-responsive groups. The core block has a degree of polymerisation of at least 100, whilst the terminal blocks have an average degree of polymerisation of at least 20. A solution of polymer in a liquid may be caused to change its characteristics, for instance rheology, upon being subjected to a stimulus such as a change in temperature or pH. Examples comprise core blocks formed of 2-methacryloyloxyethyl-2′-trimethylammonium ethylphosphate inner salt (MPC) and terminal blocks formed of 2-(diisopropylamino)ethyl methacrylate. Upon changing the pH from around 2 to around 8, an aqueous solution of the block copolymer gels, the solution becoming mobile again upon lowering the pH. The effect is due to deprotonation of a quaternary ammonium pendant ion to form a non-ionised group and subsequent protonation to form an ionised group. This changes the hydrophilicity of the terminal blocks and allowing formation of a network of micellar structures when the pendant groups are not ionised and relatively hydrophobic and associated in micelles.
A composition comprising a solvent and a block copolymer, in which the block copolymer comprises a hydrophilic core block and at least two terminal blocks, each terminal block being stimulus-responsive in which the blocks are each formed at least in part by the polymerisation of ethylenically unsaturated monomers, wherein the average degree of each terminal block is at least 20 characterised in that the core block comprises zwitterionic pendant groups, and has a degree of polymerisation of at least 100.
A method in which a composition comprising a solvent and a block copolymer in which the block copolymer comprises a hydrophilic core block and at least two terminal blocks, each terminal block being stimulus-responsive in which the blocks are each formed at least in part by the polymerisation of ethylenically unsaturated monomers, wherein the average degree of each terminal block is at least 20 characterised in that the core block comprises zwitterionic pendant groups, and has a degree of polymerisation of at least 100 is subjected to a stimulus to which the stimulus-responsive blocks respond, whereby the terminal blocks respond to the stimulus to change the mechanical characteristics of the composition.
A polymerisation process in which core block ethylenically unsaturated monomers comprising a zwitterionic monomer are polymerised to form a core block having average degree of polymerisation of at least 100 initiation sites are formed at at least two locations on the core block and terminal block ethylenically unsaturated monomers are polymerised from the initiation sites on the core block to form at least two terminal blocks having an average degree of polymerisation of at least 20, wherein the terminal block ethylenically unsaturated monomers comprise monomers having stimulus responsive pendant groups.
Dependencies are inferred from the claim text.