GEL FORMATION OF POLYELECTROLYTE AQUEOUS SOLUTIONS BY THERMALLY INDUCED CHANGES IN IONIZATION STATE
First Claim
1. A thermally sensitive polyelectrolyte composition comprising:
- a) a solution of a polyelectrolyte; and
b) a weak electrolyte,said weak electrolyte being dissolved in the solution of polyelectrolyte and causing said polyelectrolyte to precipitate and form a gel upon heating, when said polyelectrolyte and said weak electrolyte reach a specific charge state.
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Accused Products
Abstract
There is disclosed aqueous solutions of polyelectrolytes that can be neutralized by increasing temperature, under suitable polyelectrolyte charge state conditions, in order to obtain a homogeneous gel. This can be achieved by adding an appropriate weak electrolyte to the polyelectrolyte so that an increase of temperature will lead to a spatially homogeneous neutralization of the polyelectrolyte via proton transfer between the polyelectrolyte and the weak electrolyte. The ability of such a system to be thermally sensitive and to gel upon heating relies on the temperature dependence of the ionization equilibrium for the two components. This thermally induced neutralization reduces electrostatic repulsion between polyelectrolyte molecules allowing the manifestation of attractive polyelectrolyte-polyelectrolyte hydrophobic interactions and hydrogen bonding that result in gel formation. These new kinds of thermo sensitive gels can be used for biomedical applications.
63 Citations
25 Claims
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1. A thermally sensitive polyelectrolyte composition comprising:
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a) a solution of a polyelectrolyte; and b) a weak electrolyte, said weak electrolyte being dissolved in the solution of polyelectrolyte and causing said polyelectrolyte to precipitate and form a gel upon heating, when said polyelectrolyte and said weak electrolyte reach a specific charge state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 25)
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19. A method for preparing a thermally sensitive polyelectrolyte composition comprising:
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a) a solution of a polyelectrolyte; and b) a weak electrolyte, said method comprising the step of dissolving at a temperature below the gelling temperature of the composition a weak electrolyte in the solution of polyelectrolyte without causing gelation of the composition to occur, said composition turn into a gel upon heating when said polyelectrolyte and said weak electrolyte reach a specific charge state. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification