Microporous polymeric foams and microtextured surfaces
First Claim
1. A foam precursor comprising:
- a highly uniform continuous matrix including an organic crystalline thermoplastic polymer and a solid crystalline additive composition dispersed uniformly in said matrix, the foam precursor produced by a process comprising the steps of;
melting the polymer with the additive composition to form an isotropic solution, said additive composition having a melting point above 25°
C. and having at least one of the following physical characteristics;
(i) a sublimation temperature between about 25°
C. and the lower of the degradation, melting or glass transition temperature of the polymer; and
(ii) extractability by solvents which are not solvents for the polymer; and
solidifying the isotropic solution such that the additive composition and the polymer separate by essentially simultaneous crystallization to produce a foam precursor containing crystals of the additive composition.
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Abstract
Highly uniform microporous foam suitable for medical applications and methods for preparing these foams. The highly uniform microporous foams are of controlled pore size that may be utilized in a variety of applications. In preparing the foams, an organic crystalline polymer is melted and combined with a selected solid crystalline fugitive compound to produce a substantially isotropic solution. The solution is cooled under controlled conditions, which foster solid-solid phase separation by the simultaneous crystallization of the fugitive compound and the polymer, to produce a foam precursor containing the solidified fugitive compound dispersed through a matrix of the organic polymer. Crystals of fugitive compound are then removed by solvent extraction and/or sublimation, or like process to produce microcellular foams having a continuous, open-cell structure.
87 Citations
23 Claims
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1. A foam precursor comprising:
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a highly uniform continuous matrix including an organic crystalline thermoplastic polymer and a solid crystalline additive composition dispersed uniformly in said matrix, the foam precursor produced by a process comprising the steps of; melting the polymer with the additive composition to form an isotropic solution, said additive composition having a melting point above 25°
C. and having at least one of the following physical characteristics;(i) a sublimation temperature between about 25°
C. and the lower of the degradation, melting or glass transition temperature of the polymer; and(ii) extractability by solvents which are not solvents for the polymer; and solidifying the isotropic solution such that the additive composition and the polymer separate by essentially simultaneous crystallization to produce a foam precursor containing crystals of the additive composition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for producing a foam precursor including a highly uniform bicontinuous matrices of an organic crystalline thermoplastic polymer and a solid crystalline additive composition, the method comprising the steps of:
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melting the polymer with the additive composition to form an isotropic solution, said additive composition having a melting point above 25°
C. and having at least one of the following physical characteristics;(i) a sublimation temperature between about 25°
C. and the lower of the degradation, melting or glass transition temperature of the polymer; and(ii) extractability by solvents which are not solvents for the polymer; solidifying the isotropic solution such that the additive composition and the polymer separate by essentially simultaneous crystallization to produce a foam precursor containing crystals of the additive composition. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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Specification