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Method for the preparation of new segmented polyurethanes with high tear and tensile strengths and method for making porous scaffolds

a polyurethane and scaffold technology, applied in the field of biomedical materials, can solve the problems of unfavorable biomedical applications, unfavorable biomedical applications, and difficult processing of polyurethane ureas, and achieve the effects of less degradation of polyurethanes, and more difficult production of polyurethanes

Inactive Publication Date: 2007-02-15
HEIJKANTS RALF GUILLAUME JEAN CATHARINA +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

"The present invention provides a method for making polyurethane using a macrodiol, diisocyanate, and chain extender without the need for a catalyst. The method involves reacting the macrodiol or chain extender with an excess of diisocyanate to form a macrodiisocyanate or reaction product, and then removing any unreacted diisocyanate. The macrodiisocyanate or reaction product is then reacted with the chain extender or macrodiol to form the polyurethane. This method can be used to make a porous scaffold by cooling down a solution of the polymer and adding a particulate material that is insoluble in the solvent. The invention also includes body implants made from the polyurethane or porous scaffold."

Problems solved by technology

The use of aromatic polyurethanes for biomedical applications, especially for applications where degradation of the polymer is required, is undesired.
That is the reason why polyurethane ureas are more difficult to process compared to polyurethanes.
In addition, polyurethane ureas are more difficult to produce compared to polyurethanes.
Due to the high reactivity between diisocyanates and diamines, large amounts of solvents are needed.
However, the polymer processing proved to be difficult.
However, the synthesis of these longer chain extenders complicates the production method.
In order to produce porous scaffolds with a reasonable thickness (>1 mm), the method has to be repeated several times, which is a disadvantage.
This results in high porosity materials with no strength and compression modulus.
In addition, it has found to be difficult to leach out all the particulate.
The remaining salts in the scaffold can cause cell damage.
A disadvantage of freeze-drying polymer solutions is that it requires solubility of the polymer in solvent that can be freeze-dried.
For polymers that are not soluble in the solvents which are applicable for freeze-drying, this technique cannot be used.
A great disadvantage of this method is that the structure is formed during washing and, therefore, the porous structure is not easy to control.

Method used

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  • Method for the preparation of new segmented polyurethanes with high tear and tensile strengths and method for making porous scaffolds
  • Method for the preparation of new segmented polyurethanes with high tear and tensile strengths and method for making porous scaffolds
  • Method for the preparation of new segmented polyurethanes with high tear and tensile strengths and method for making porous scaffolds

Examples

Experimental program
Comparison scheme
Effect test

example 1

Synthesis Polyurethane

[0143] All steps were performed under Argon atmosphere. 11.23 g (0.1246 mol) 1,4-butanediol (Aldrich, destilled from 3 Angstrom molsieves) was added to 185.86 g (1.628 mol) ε-caprolactone (Union Carbide, distilled from CaH2 under reduced pressure). This mixture was polymerized to a macrodiol 150° C. for 8 days. 50 ml (0.3229 mol) 1,4-butane diisocyanate (Bayer, distilled under reduced pressure) was added to 56.10 g (0.03546 mol) of the obtained macrodiol. The 1,4-butane diisocyanate and the poly(ε-caprolactone) prepolymer were reacted at 80° C. for 3.5 hours to obtain a macrodiisocyanate. The surplus diisocyanate, was distilled off. 60.69 g (0.0326 mol) of the obtained macrodiisocyanate was chain extended with 2.91 g (0.0323 mol) 1,4-butanediol at 80° C. until the intrinsic viscosity was at least 0.8 dl / g.

example 2

Mechanical Properties

[0144] In table 1 tear and tensile strengths of polyurethanes made according to example 1 poly(ε-caprolactone) segments of different length are compared to polyurethanes made according to prior art method where the poly(ε-caprolactone) diol segment was made using 0.08 wt. % stannous octoate as a catalyst (wt catalyst / wt polymer). Spaans used 0.1 wt. % catalyst for the preparation of the macrodiol, which is equal to 0.08 wt. % catalyst to the polymer for a macrodiol length of 2000 g / mol) (Spaans et. al. Polymer Bulletin, 41, 131-138, 1998, C. J. Spaans, Biomedical Polyurethanes Based On: 1,4-Butanediisocyanate: An Exploratory Study. 2000 PhD Thesis ISBN 90-367-1232-7, chapter 2).

[0145] Polymer films were by made according to the procedure described by Spaans (Polymer Bulletin, 4.1., 131-138, 1998) by dissolving the polymer in 1,4-dioxane at 100° C. at a concentration of 6% (w / w). The solvent was removed at 70° C. Last traces of solvent were removed under reduce...

example 3

Tear Strength as Function of Intrinsic Viscosity

[0150] The tear strength, determined according the procedure described in example 2, of polyurethanes made according to example 1 as a function of intrinsic viscosity was determined. The results are shown in table 2.

TABLE 2IntrinsicTear strengthPolyurethaneviscosity (dl / g)(kJ / m2)PU1000a0.395PU1000a0.76211PU1000a0.84213PU1000a1.18211

apolymer made according to the invention. No catalyst was used for the synthesis of the macrodiol. The macrodiisocyanate chain extended with 1,4-butanediol

[0151] It is shown that the tear strength increases with intrinsic viscosity in the range of 0.39 to 0.76 dl / g. Above 0.76 g / mol, the tear strength is constant.

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Abstract

The invention presents a new method to prepare biomedical polyurethanes with high tensile and tear strengths. Such polyurethanes are especially interesting for making foams thereof, e.g. as meniscus implants. A new method, applicable to the biomedical polyurethanes, has been found to make such foams, that can be used as scaffolds. This method is based on salt leaching and phase separation.

Description

FIELD OF THE INVENTION [0001] This invention relates to the preparation of biomedical materials based on segmented polyester urethanes. The invention also relates to the preparation of foams of these materials. This invention is also related to materials obtainable according to these methods and the use of these materials, e.g. as biomedical materials. BACKGROUND OF THE INVENTION [0002] Segmented polyurethane elastomers, which are block copolymers consisting of alternating hard (glassy or semi crystalline) and soft (elastomeric) chain segments, have unique physical and mechanical properties and are known to be biocompatible and blood compatible, due to their hard-segment-soft-segment microphase structure (M. D. Lelah and S L Cooper. Polyurethanes in medicine, CRC Press, Boca Raton, Fla., 1986). For these reasons they are used for a number of biomedical applications. [0003] It is known that aromatic polyurethanes possess better mechanical properties than aliphatic polyurethanes. For ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C08G18/00A61L27/18A61L27/56C08G18/10C08G18/24C08G18/42C08G18/44C08G18/73C08G18/80
CPCA61L27/18A61L27/56C08G18/10C08G18/246C08G18/4277C08G18/73C08L75/04C08G18/3206
Inventor HEIJKANTS, RALF GUILLAUME JEAN CATHARINAPENNINGS, ALBERT JOHANDE GROOT, JACQUELINE HERMINAVAN CALCK, RALPH VINCENT
Owner HEIJKANTS RALF GUILLAUME JEAN CATHARINA
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