CZ20003071A3 - Polymers exhibiting non-destructible memory - Google Patents

Abstract

Mixed memory-memory polymer blends having at least one memory memory; the two shapes include: a) at least one stable segment s melting point or glass transition melting point or glass transition temperature Ttrans 40 to 270 ° C, b) first adaptive segment bound to at least one stable segment, with Ttrans at least 10 ° C lower than u a stable segment, c) a second flexible segment bound at least one stable segment or a first flexible segment Ttrans at least 10 ° C than Ttrans first adaptive segment, wherein the shape memory polymer is selected from the group consisting of graft polymers, linear polymers and dendrimeric polymers, e.g., polyether esters, polyesters, polyamides, polyesteramides, polyurethanes, polysaccharides, and the molecular weight of at least one of of segments is 500 to 10000. In the method of shaping the articles, the the object forms into a given shape at a temperature above Ttrans adaptive segment and below T segment of stable segment a Cool to below Ttrans Adaptive Segment Temperature if the article is subsequently formed into a second shape, it can be return to its original shape by warming it over T, rans stable segment.

Description

Polymers with shape memory

Technical field:

The present invention relates to shape memory polymers

BACKGROUND OF THE INVENTION

This application is generally in the field of shape memory polymers and in particular shape memory polymers having improved characteristics and more than one shape in memory.

Shape memory is the ability of a material to remember the original shape even after mechanical deformation (Figure 1), which is a "one-way" effect, or cooling or heating (Figure 2), which is a "two-way" effect. This phenomenon is based on structural phase transformation.

The first known materials having these properties were shape memory metal alloys (SMA), which included TiNi (Nitinol), CuZnAl and FeNiAl. The structural phase transformation of these materials is known as martensitic transformation. These materials have been designed for a variety of purposes, including vascular stents, medical catheters, dental wires, vibration dampers, pipe connections, electrical connectors, thermostats, controls, spectacle frames, and bra reinforcements. These materials have not been used more widely so far because they are relatively expensive. Scientists are actively developing shape memory polymers (SMPs) as replacements or expanding the use of SMA partly because polymers are lighter, have a greater ability to return to their original shape, are easy to handle and more economical than SMAs. In the literature, SMPs are generally characterized as phase-separated linear block copolymers having a stable segment and a soft segment. The stable segment is typically crystalline with a defined melting point, and the adaptable segment is typically amorphous with a defined glass transition temperature. In some cases, the stable segment is amorphous and has a glass transition temperature rather than a melting point. In other cases, the adaptable segment is crystalline and has a melting point rather than a glassy one. · ···································································

- 2 transition temperature. The melting point or glass transition temperature of the adaptive segment is substantially lower than the melting point or glass transition temperature of the stable segment.

If the SMP is heated above the melting point or glass transition temperature of the stable segment, the material can be shaped. This (original) shape can be inserted into the memory of the material by cooling the SMP below the melting point or glass transition temperature of the stable segment. If the shaped SMP cools below the melting point or glass transition temperature of the adaptive segment when the shape is deformed, this (temporary) shape is fixed. They return to the original shape by heating the material above the melting point or glass transition temperature of the adaptive segment, but below the melting point or glass transition temperature of the stable segment. In another method of maintaining the transition shape, the material deforms at a temperature lower than the melting point or glass transition temperature of the adaptive segment, resulting in the stress and strain absorbed by the adaptive segments. If the material is heated above the melting point or glass transition temperature of the adaptive segment but below the melting point (or glass transition temperature) of the stable segment, the stress and strain are released and the material returns to its original shape. The return to the original state, which is caused by the temperature increase, is called influencing the thermal shape memory. Properties that describe the shape memory capability of the material are the restoration of the shape to its original state and the shape stability of the temporary shape.

In response to external changes in temperature and stress, many other physical properties of SMPs other than the ability to remember the shape vary considerably, especially at the melting point or glass transition temperature of the adaptive segment. These properties include the modulus of elasticity, hardness, elasticity, vapor penetration, damping, refractive index and dielectric constant. The modulus of elasticity (the stress ratio in the body relative to the corresponding stress) The SMP can change up to 200 times when heated above the melting point or the glass transition temperature of the adaptive segment. The hardness of the material also varies dramatically when the conformable segment is above or at the melting point or glass transition temperature. When the material is heated to a temperature above the melting point or glass transition temperature of the adaptive segment, the attenuation capability of a conventional rubber product may be up to five times higher.

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The material can quickly return to its original cast shape after many thermal cycles and can be heated above the melting point of the stable segment and reshaped and cooled to fix the new original shape.

For polymers, it is possible to influence shape memory (eg by heat shrinking foil). However, this is not a major specific feature, but is based on the polymer structure and its morphology. The effect persists for many polymers, which may vary widely in their chemical composition. However, only a few shape memory polymer systems have been described in the literature (Kim, et al., "Polyurethanes having shape memory effect", Polymer, 37, (26), 5781-93, (1996); Li, et al., " Crystallinity and morphology of segmented polyurethanes with different soft-segment lengths, J. Applied Polymer, 62, 631-38, (1996); Takahashi, et al., "Structure and properties of shape-memory polyurethane block copolymers", J. Applied Polymer Science, 60, 1061-69, (1996); Tobushi, H., et al., "Thermomechanical properties of shape memory polymers of polyurethane series and their applications", J. Physique IV (Colloque C1), 6, 377 84 (1996)).

Examples of polymers used to prepare stable and adaptable segments of SMPs include various polyethers, polyacrylates, polyamides, polysiloxanes, polyurethanes, polyetheramides, polyurethane-urea copolymers, polyether esters, and urethane-butadiene copolymers. See, for example, U.S. Patent No. 5,506,300 to Ward, et al .; U.S. Patent No. 5,145,935 to Hayashi; U.S. Patent No. 5,665,822 to Bitler, et al .; and Gorgen: "Application of Shape Memory Polyurethanes", Proceedings of the First International Conference on Shape Memory and Superelastic Technologies, SMST International Committee, pp. 115-19, (1994). Developed SMPs, mostly limited to the ability to temporarily hold only one shape in memory. The benefit would be to provide an SMP capable of creating objects capable of retaining more than one shape in memory.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide SMPs capable of:

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- 4 create objects that can retain more than one shape in memory.

It is another object of the present invention to provide SMPs with physical and chemical properties and chemical structure different from conventional SMPs.

Yet another object of the present invention is to provide a shape memory SMP that is triggered by a stimulus other than temperature.

Summary of the invention

Here is described the composition of mixtures, products made from them and methods of their preparation and use. The preferred solution has compositions of shape memory polymer blends that can retain more than one shape in memory. For example, it may be composed of a stable segment and at least two adaptable segments. Tt _ra ns of the stable segment is at least 10 ° C, preferably 20 ° C higher than Kans of one of the adaptive segments and Tt _ra ns of each subsequent adaptive segment is at least 10 ° C, more preferably 20 ° C lower than Ttrans of the previous adaptive segment. The relatively high Tt _wound multiblock copolymer with the relatively low Kans conformable segment can be blended or blended with the second relatively low Tt _wound multiblock copolymer with the same adaptive segment as the first multiblock copolymer. If the matched segments in the two multiblock copolymers are identical, the polymers are miscible when the matched segments are melted. The resulting mixture has three transition temperatures: one for the first stable segment, one for the second stable segment, and one for the adaptive segment. Thus, these materials are able to remember two shapes.

Any polymers that are crystalline or amorphous and have T _wounds in the regions defined herein can be used to form stable and conformable segments. The melting point or glass transition temperature (hereinafter referred to as T _tra ns) of the stable segment is at least 10 ° C, preferably 20 ° C higher than the T _tra ns of the adaptive segment. The stable segment _titre is preferably between -30 and 270 ° C, and more preferably between 30 and 150 ° C. The weight ratio of the stable segment to the adaptable segment is approximately in the ratio between 5: 95 and 95: 5, preferably between 20: 80 and 80: 20.

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The shape memory polymers in some cases have at least one physical cross-linking (physical interaction of a stable segment) or contain covalent cross-linking instead of a stable segment. The shape memory polymers may also penetrate inside the grid or partially penetrate inside the grid. In addition to solid state to liquid state changes (melting point or glass transition temperature), in addition, both stable and adaptable segments can pass from one solid state to another solid state and undergo ionic interactions requiring polyelectrolytic segments or supramolecular interference through highly organized hydrogen bridges.

The articles can be prepared from blends of shape memory polymers, for example, by injection molding, blowing, extrusion, and laser deposition. In the preparation of objects having the shape memory of articles can be shaped at a temperature above the T trans of the hard segment _TR and is cooled below a temperature Tt _wounds of the soft segment. If the object subsequently is formed into a second shape, it can return to its original shape by heating above T _tra ns soft segment and below the Tm of the hard segment _ra ns.

Articles with two or more shapes in memory may be prepared by forming a polymer blend with a stable segment, a first adaptive segment, and a second adaptive segment, wherein the first adaptive segment has a T _tran with at least 10 ° C below the stable segment and at least 10 ° C above the second adaptive segment. . After shaping the mixture at a temperature above T _tran of the stable segment, it may be cooled to a temperature below the temperature T _tr ans of the first adaptive segment and above the temperature of the second adaptive segment and formed into a second shape. The mixture may be formed into a third shape after it has cooled below the Tt _and ns of the second adaptive segment. To return the mixture to the second shape, the mixture may be heated over the Tt _wound from the second adaptive segment. To return to the first shape, the mixture may be heated over the T _tra ns of the first adaptive segment. The mixture can also be heated above the T _tra ns hard segment, wherein the composition loses the memory of the first and second shapes and can be reshaped using the method described above. Thermoset polymers can be prepared by preforming the macromonomers, for example by extrusion and stabilizing the original shape at a temperature above the Ttrans of the thermoset polymer, for example by a photochemically excited reaction

- 6 reactive groups of the macromonomer. However, the original shape can only be programmed once.

In a preferred solution, a shape change occurs in response to a temperature change. In another embodiment, however, the composition may change its shape in response to irradiation, change in ion concentration and / or pH, electric field, magnetic field, or ultrasound. For example, the SMP may have at least one stable segment and at least one adaptive segment, wherein at least two segments, preferably two adaptive segments, are interconnected through a functional group that is cleavable by radiation, electric field, magnetic field, or ultrasound. The temporary shape is stabilized by crosslinking the linear polymers. Cleavage of these bonds can return to their original state. The stimuli for crosslinking and cleavage of these bonds may be either the same or different.

Overview of pictures

Figure 1 is a one-way representation of shape memory affecting.

Figure 2 is a representation of a "two-way" shape memory effect.

Figure 3 shows combinations of suitable groups of thermoplastics.

Figure 4 is a preferred flow diagram of photoreactive crosslinking synthesis.

Figure 5 is an illustration of the formation of the shape memory excited by the photo path.

Figure 6 is an illustration of the shape memory temperature affecting mechanism of a multiblock copolymer.

Figure 7 is a diagram depicting the voltage versus elongation of a shape memory polymer for a multi-block copolymer.

Figure 8 is a diagram depicting the melting point of diols, dimethacrylates and poly-s-caprolactone thermosets on the molar mass M _{n of the} macromonomer.

DETAILED DESCRIPTION OF THE INVENTION

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- 7 The composition of the shape memory polymer blends, the articles made therefrom and the methods for their preparation and use are provided. The shape memory polymers may consist of at least one stable segment and at least one adaptive segment, or may consist of at least one kind of adaptive segment, characterized in that at least one kind of adaptive segment is crosslinked in the absence of a stable segment. In a preferred solution, the polymers may have two or more shape memories.

Definition of terms used

Polymer is meant a shape memory polymer if the original shape of the polymer recovers its heating above the recovery temperature (defined as the T _tra ns soft segment) even if the mechanical failure of the original molded shape of the polymer at a temperature lower than the shape recovery temperature , or if the memory shape can be restored to its original state using another stimulus.

As used herein, the term "segment" refers to a block or sequence of groups in a polymer forming part of a shape memory polymer.

As used herein, the terms hard segment and soft segment are relative terms relating to T _tra ns segments. The stable segment (s) has a higher T _tra ns than the adaptable segment (s). The ratio of the weight of the stable segment to the adaptable segment is approximately between 5: 95 and 95: 5, more preferably between 20: 80 and 80: 20.

As used herein, the term "biodegradable" refers to substances that are biodegradable and / or degradable and / or degradable by mechanical disruption by interacting with the physiological environment into components that are metabolizable or excreted within a period of minutes to three years , preferably faster than one year, while maintaining the desired structural integrity. As used herein in reference to polymers, the term " degradation " is intended to mean polymer chain cleavage such that the molecular weight reaches approximately constant levels of oligomers and the polymer particles undergo further degradation.

9

9

The term "total degradation" refers to the cleavage of the polymer to the molecular level so that complete decomposition of the mass occurs. The term "degrading" as used herein includes "total degradation" unless otherwise indicated.

Composition of blends of shape memory polymers

The shape memory polymers may be thermoplastics, thermosets, interpenetrated gratings, semi-penetrated gratings or mixed gratings. The polymers may be simple polymers or blends of polymers. The polymers may be linear, branched, thermoplastic side chain, or any kind of dendritic structural element. The stimuli causing shape changes can be temperature, ionic strength change, pH, light, electric field, magnetic field or ultrasound.

Thermoplastic shape memory materials can be shaped (e.g. molded) to a desired shape above the T _tra ns hard segment (s) and cooled to a temperature below the shape recovering temperature, where the polymer may undergo mechanical deformation and creates tension in it. The original shape of the deformed polymers can be restored by heating them to a temperature higher than the shape recovery temperature. Above this temperature, the polymer stress is released, and the polymer returns to its original shape. Shaped memory thermoset materials, on the other hand, are shaped to the desired shape before the macromonomers used to form thermoset polymers are polymerized. After the shape has been stabilized, the macromonomers are then polymerized.

The polymer blends must mainly be compressible by at least one percent or expandable by at least five percent of the original thickness at a temperature below the shape recovery temperature, with the possibility of stabilizing deformation using such stimuli as heat, light, ultrasound, magnetic field or electric field. In some cases, the materials have a recovery rate of up to 98% (compared to test samples).

When a significant stress is applied resulting in mechanical deformation at a temperature below the shape recovery temperature, the stresses in the adaptive segments are

9 or amorphous regions are maintained and the major shape change is maintained even after partial tension relief by the elasticity of the polymer. If the molecular chain configuration is broken by affecting the controlled arrangement of the molecular chains at a temperature below the glass transition temperature, a new molecular chain arrangement results from the increase in volume and the reduction of the free volume space. The original shape is restored by contracting stable segment aggregates by increasing the temperature according to the stiffness of the control chain conformations, and the polymer shape is restored to a memorized shape. In addition, when changing from solid to liquid state (melting point or glass transition temperature), stable or adaptable segments can undergo ionic interactions including polyelectrolyte segments or supramolecular effects based on highly organized hydrogen bridges. SMPs can pass from a solid state to an intermediate solid state (eg, morphological change). Solid state to solid state transitions are well known to those skilled in the art, for example, block polystyrene butadiene.

Objects formed using the shape memory of polymers can be prepared to regulate direction change during recovery. In other words, contraction and expansion can occur along one or more axes depending on how the polymer is shaped and stressed. For example, in the SMP fiber, the shape change may be limited to one dimension, for example, to the longitudinal direction of the fiber.

In another case, the thermal and electrical conductivity of the SMP materials may be varied in response to a temperature change.

The compositions may vary in moisture permeability, particularly when the polymer is formed into a thin film (i.e., less than about 10 µm). Some polymer blends have sufficient permeability in their original state, for example, for water vapor molecules that can penetrate the polymer film, while water molecules are not small enough to penetrate the polymer film. The resulting materials have low moisture permeability at temperatures below room temperature and high permeability at temperatures above room temperature.

I. Polymer segments

9

9 ···· 94 · 4

. 9 9999 9

9999 4 9 9 • 9 · 9 4 9 · 94 4444

949 949 999 9494 99 99

WITH

- 10 Polymers contain "hard" and "soft" segments. The segments are preferably oligomers. As used herein, the term "oligomer" refers to a linear chain molecule having a molecular weight of up to 15,000 Daltons. The polymer-forming segments are selected according to the desired glass transition temperature (if at least one segment is amorphous) or the melting point (s) (if at least one segment is crystalline), which in turn depends on the desired use, taking into account environment for which they are to be used. The average molecular weight of the polymer segment is preferably greater than 400 and most preferably in the range between 500 and 15000.

The transition temperature at which the polymer becomes suddenly soft and deformation can be controlled by varying the composition of the monomer and the type of monomer. This allows the shape memory to be affected at the desired temperature. The thermal properties of polymers can be determined, for example, by dynamic mechanical thermoanalysis or differential scanning calorimetry (DSC). In addition, the melting point can be determined using a standard melting point apparatus.

The polymers may be thermosetting or thermoplastic, although thermoplastic polymers are preferred for ease of casting. Nevertheless, for some applications, thermosets are preferred because they are generally softer in their original shape at temperatures higher than T _Tran than physically crosslinked polymers.

The degree of crystallinity of the polymer or polymer block (s) is preferably between 3 and 80%, more preferably between 3 and 60%. If the degree of crystallinity is greater than 80% while the adaptable segments are amorphous, the resulting polymer composition has poor shape memory characteristics.

The tensile modulus of polymers at a temperature below T _tr ans is usually between 50 MPa and 2 GPa (gigapascals), while the tensile modulus of polymers above T _tr ans is usually between 1 and 500 MPa. The ratio of the modulus above and below Ttrans is 20 or higher. The higher the ratio, the better the memory of the resulting polymer blend.

The polymer segments may be natural or synthetic, although synthetic polymers are preferred. Polymer segments may be biodegradable or non-biodegradable, although biodegradable polymers are preferred for in vivo medical use. Generally, these materials decompose by hydrolysis, exposure to water or enzymes

9999

9 9

999

9 9 ·

999 999 9

9 · 99

9 • 999

- 11 9 9 9

9 9

9 9 • 4 4 9 under physiological conditions, surface erosion, total erosion, or a combination thereof. Non-biodegradable polymers used for medical purposes should preferably not contain aromatic groups other than those found in natural amino acids.

Polymers are selected on the basis of their glass transition temperature (if at least one segment is amorphous) or the melting point (s) (if at least one segment is crystalline), which actually requires a method of application while taking into account the environment in which they will be used. The average molecular weight of the polymer block is preferably greater than 400 and most preferably in the range between 500 and 15,000.

The polymer may be in the form of a hydrogel (usually absorbing up to 90% by weight of water) and may optionally be cross-linked with multivalent ions or polymers. The ionic cross-linking between the adaptive segments can be used to maintain a structure that can be deformed upon deformation by splitting the ionic cross-linking between the adaptive segments. The polymer may also be in the form of a gel in solvents other than water or aqueous solutions. In these polymers, the temporary shape can be fixed by hydrophilic interactions between the adaptive segments.

Representative natural polymer blocks or polymers include proteins such as zein, modified zein, casein, gelatin, gluten, serumalbumin and collagen and polysaccharides such as alginate, celluloses, dextrans, pullulan and polyhyaluronic acid as well as chitin, poly-3-hydroxyalkanoates especially poly-β-hydroxybutyrate, poly-3-hydroxyoctanoate and poly-3-hydroxy fatty acids. Representatives of naturally biodegradable polymer blocks or polymers include polysaccharides such as alginate, dextran, cellulose, collagen and derivatives thereof (substitution, with added groups such as alkyl, alkylene, hydroxylated, oxidized and other modifications commonly prepared by those skilled in the art) and proteins such as albumin , zein and copolymers and mixtures thereof, alone or in combination with synthetic polymers.

Representative synthetic polymer blocks or polymers include polyphosphazenes, polyvinyl alcohols, polyamides, polyesteramides, polyamino acids, synthetic polyamino acids, polyanhydrides, polycarbonates, polyacrylates,

polyalkylenes, polyacrylamides, polyalkylene glycols, polyalkylene oxides, polyalkylene terephthalates, polyorthoesters, polyvinyl ethers, polyvinyl esters, polyvinyl halides, polyvinylpyrrolidone, polyesters, polylactides, polyglycolides, polysiloxanes, polyurethanes and copolymers thereof. Examples of suitable polyacrylates include polymethymethacrylate, polyethyl methacrylate, polybutyl methacrylate, polyisobutyl methacrylate, polyhexyl methacrylate, polyisodecyl methacrylate, polylauryl methacrylate, polyphenyl methacrylate, polymethyl acrylate, polyisopropyl acrylate, polyisobutyl acrylate, polyisobutyl acrylate, polyisobutyl acrylate, polyisobutyl acrylate, polyisobutyl acrylate, polyisobutyl acrylate.

Synthetically modified natural polymers include cellulose derivatives such as alkylcelluloses, hydroxyalkylcelluloses, cellulose ethers, cellulose esters, nitrocelluloses and chitosan. Examples of suitable cellulose derivatives are methylcellulose, ethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxybutylmethylcellulose, cellulose acetate, cellulose propionate, cellulose acetate butyrate, cellulose acetate phthalate, carboxymethyl cellulose, triacetate cellulose and triacetate cellulose. These are collectively called "celluloses".

Representative segments of synthetic degradable polymers include polyhydroxy acids such as polylactides, polyglycolides, and copolymers thereof; polyethylene terephthalate; polyanhydrides; polyhydroxybutyric acid; polyhydroxyvaleric acid; a polylactide-poly-s-caprolactone copolymer; a polyglycolide-poly-c-caprolactone copolymer; polycarbonates, polypseudoamino acids; polyamino acids, polyhydroxyalkanoates, polyanhydrides, polyorthoesters; and mixtures and copolymers thereof. Polymers containing labile bonds such as polyanhydrides and polyesters are well known for their hydrolytic reactivity. The rate of their hydrolytic degradation can be changed by simply changing the polymer backbone and the structural sequence.

Examples of non-biodegradable synthetic polymer segments include ethylene vinyl acetate, polymethacrylic acid, polyamides, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylphenol, and copolymers and mixtures thereof.

Polymers can be obtained from commercial sources such as Sigma Chemical Co., St. Louis,

MO; Polysciences, Warrenton, PA; Aldrich Chemical Co., Milwaukee, WI .; Fluka, •

- 13 Ronkonkoma, NY; and BioRad, Richmond, CA. Alternatively, polymers can be synthesized from monomers obtained from commercial sources using standard technologies.

Hydrogels

Hydrogels can be formed from polyethylene glycols, polyethylene oxide, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylates, polyethylene terephthalate, polyvinyl acetate, and copolymers and mixtures thereof. Many polymer blocks, such as acrylic acid, are elastomers only when the polymer is hydrated and hydrogels are formed. Other polymer blocks, such as methacrylic acid, are crystalline and capable of melting even when the polymers are not hydrated. Depending on the application and the conditions of use, any type of polymer block may be used.

For example, shape memory is observed for acrylic acid copolymers only in the hydrogel state, since acrylic acid units are mainly hydrated and behave as an adaptable elastomer with a very low glass transition temperature. Dry polymers are not shape memory polymers. When acrylic acid units are dry, they act like a hard plastic even above the glass transition temperature and show no sudden change in mechanical properties when heated.

In contrast, copolymers containing methyl methacrylate polymer blocks as adaptive segments exhibit shape memory properties even when dry.

Certain polymers, for example, block copolymers of polyethylene oxide and polypropylene oxide (PLURONICS ™, BASF) are soluble in water at temperatures below body temperature and become hydrogels at temperatures above body temperature. By incorporating these polymers as blocks into shape memory polymers, shape memory polymers are formed with the ability to react to temperature changes quite the opposite of conventional shape memory polymers. These materials restore their shape upon cooling below their shape recovery temperature instead of being heated above their shape recovery temperature. This effect is called the inverse effect of thermal shape memory. Blends of shape memory polymers including these polymer blocks are suitable for various biomedical •

14 applications where the polymer can be introduced as a liquid and cooled in situ to restore the intended shape. The inverse thermal effect of the shape memory can be obtained by placing two different blocks miscible at temperatures lower than T _misc but immiscible at higher temperatures in the polymer. The phase separation at higher temperatures stabilizes the temporary shape.

The conductive polymers are various polymers such as polyacetylenes and polypyrroles. These materials are particularly preferred for applications where electrical conductivity is important. Examples of applications include tissue engineering and any biomedical applications where cell growth is promoted. These materials can find particular applications in the computer field because they are capable of absorbing heat better without increasing temperature than SMA. Conductive shape memory polymers are useful in the field of tissue engineering to promote the growth of tissue, e.g., neural tissue.

II. Joining of polymer segments

Preference is given to blends of shape memory polymers in which more than one shape memory can be formed. Part of the mixture may be the hard segment and at least two soft segments, where T _tra ns of the hard segment is between 30 and 270 ° C and is at least 10 ° C, but preferably about 20 ° C higher than T _tra ns of one of the soft segments and Tt _wounds of each subsequent soft segment is at least 10 ° C, preferably about 20 ° C lower than T _tra ns preceding soft segment.

One or more segments may optionally be biodegradable or linked to another segment through a biodegradable linkage such as an ester, amide, anhydride, carbonate or orthoester linkage.

The shape memory effect is based on the morphology of the polymer. With respect to thermoplastic elastomers, the original shape of the article is fixed by physical crosslinking due to the stable segment. For thermoset polymers, the adaptive segments are covalently crosslinked instead of having stable segments. The original shape is determined by the crosslinking process.

Compared to the previous method, segmented polyurethane SMPs do not •

15 the mixture of segments described herein are linear. The segments may be partially grafted or attached to dendremeric side groups.

Thermoplastic and thermoset polymers

The polymers may be in the form of diblock, triblock, quadlock or multiblock copolymers, branched or graft polymers, thermoplastic elastomers containing dendritic structures, and mixtures thereof. Figure 3 shows some combinations of suitable groups of thermoplastic materials forming stable and conformable segments. The shape memory thermoplastic polymers may also be a blend of one or more homo or copolymers with one or more diblock, triblock, quadlock or multiblock copolymers, branched or graft polymers. These types of polymers are well known to those skilled in the art.

The polymers may also be thermoset polymers. There are four different types of thermoset polymers having shape memory capability. These include polymers with polymer lattices, semi-interpenetrated lattices, interpenetrated lattices, and mixed interpenetrated lattices.

i. Polymer lattices

The polymer lattice is prepared by covalent cross-linking of macromonomers, i.e. polymers containing polymerizable end groups such as carbon-carbon double bonds. The polymerization process can be induced by light or heat sensitive initiators or by irradiation with ultraviolet light ("UV radiation") without initiator. The shape memory polymer lattices are prepared by crosslinking one or more adaptive segments corresponding to one or more thermal transitions. For biomedical applications, cross-linking is performed using a radiation-inducing stimulus and requires no chemical initiator. Preferably, the radiation crosslinker eliminates the need for the presence of initiator molecules, which may be toxic. Figure 4 is a diagram of the reaction sequence for the synthesis of the preferred crosslinking agent with a total yield of about 65%.

- 16 ii. Interpenetrated grids

Interpenetrated gratings ("IPNs") are defined as grids in which the two components are cross-linked but not to each other. The original shape is determined by a grid with the highest crosslink density and the highest mechanical strength. The material has at least two T _tran with corresponding different adaptable segments of both grids.

iii. Mixed interpenetrated gratings

The mixed IPN has at least one lattice with a physically crosslinked polymer (thermoplastic polymer) and at least one lattice with a covalently crosslinked polymer (thermoset polymer) that cannot be separated by any physical means. The original shape is given by a covalently crosslinked grid. The temporary shape corresponds to the Tt _wounds with the flexible segments and the T _tra ns stable segment of the thermoplastic elastomer component.

The interpenetrated lattice is best prepared by polymerizing a reactive macromonomer in the presence of a thermoplastic polymer, for example, by photopolymerization of carbon-carbon double bonds. In this solution, the weight ratio of thermoset polymer to thermoplastic polymer is preferably between 5: 95 and 95: 5, more preferably between 20: 80 and 80: 20.

iv. Semi-interpenetrated grids

Semi-interpenetrated gratings ("semi-IPN") are defined as two independent components where one component is a cross-linked polymer (polymer lattice) and the other component is a non-cross-linked polymer (homopolymer or copolymer) where the components cannot be separated by physical means. Semi-IPN has at least one temperature transition corresponding to the adaptable segment (s) and homo- or copolymer components. The crosslinked polymer preferably has between about 10 and 90% by weight of the semi-interpenetrated grid component.

v. Polymer blends

Shape memory polymers may exist as physical blends of thermoplastic polymers. In one instance, the shape memory polymer blend may be prepared by the interaction or mixing of two thermoplastic polymers. Polymers

They may be semi-crystalline homopolymers, semi-crystalline copolymers, linear-chain thermoplastic elastomers, side-chain thermoplastic elastomers or any kind of dendritic structural element, and branched copolymers, and these may be mixed together in any combination.

For example, multi-block copolymers with a relatively high Ttrans stable segment and an adaptable segment with a relatively low T _tr ans can be blended or blended with a second multi-block copolymer with a stable segment of relatively low Ttrans and the same adaptive segment as the first multiblock copolymer. The conforming segments in the two multiblock copolymers are identical, so that when the conforming segments melt, the polymers are miscible with each other. In the resulting mixture, there are three transition temperatures, one in the first stable segment, another in the second stable segment, and another in the adaptive segment. Also, these materials can remember two different shapes. The mechanical properties of these polymers can be adjusted by varying the weight ratio of the two polymers.

Other types of blends of at least two multi-block copolymers may be prepared in which at least one of the segments is miscible with at least one of the segments of other multi-block copolymers. If two different segments are miscible and together build a domain, then the thermal transition of that domain depends on the mass content of the two segments. The maximum number of memory shapes is based on the number of thermal transitions of the mixture.

Shape memory compositions may have a better shape memory capability than the component of the composition itself. The shape memory compositions consist of at least one multiblock copolymer and at least one homo- or copolymer. Two- or four-block copolymers may be suitable substitutes for multi-block copolymers.

Shape memory compositions are well suited for industrial applications since a wide range of mechanical, thermal and shape memory capabilities can be obtained from only two or three base polymers by mixing them in different weight ratios. The twin screw extruder is an example of a standard process that can be used for mixing the components and mixing process.

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- 18 Polymers with functional groups that respond to non-thermal stimuli

In a preferred solution, the blend of shape memory polymers comprises at least one stable segment and at least one adaptable segment, or more adaptable segments that are covalently crosslinked, and wherein at least two of the segments are bonded through a light-cleavable functional group. , changing ion concentration, changing pH, electric field, magnetic field and / or ultrasound. In addition to changing the shape in response to changes in temperature, the composition may also change its shape in response to light, change in ion concentration, change in pH, electric field, magnetic field and / or ultrasound. The temporary shape of these polymers is fixed by covalent crosslinking.

i. Photochemical stimuli

Photoreversible reactions can be used to bind the conforming segments and keep the polymer in a temporary shape. The original shape of the material is given by the stable segment. By photochemical cleavage of these bonds, the material returns to its original shape. Because these reactions are photoreversible, bonds can form and decompose cycles. Each time ties are torn, they must always be re-formed to create a memory shape. Examples of such functional groups capable of undergoing photoreversible reactions are cinnamyl acid and cinnamylidene acid derivatives (cinnamylidene). Binding and cleavage can be induced by different UV wavelengths. In addition, cleavage can occur by thermal action.

For another solution, the polymers may contain side chains with chromophores such as azo groups that absorb light. Chromophores can also be built into the main chain. The stable and / or conformable segments may also contain double bonds that shift the isomers of the chromophores from the cis to the trans position upon light absorption. Light can also be used to segment isomerise, which dramatically affects the Ttrans segment. The original shape of such polymers is determined by the stable segment. Thereafter, the polymers may be deformed into an intermediate shape. Transitional shape made

- 19 fixes by the action of light on the polymer, causing photoisomerization. In this method, the polymer is prevented from returning to its original shape because the temperature of the thermal transition has increased. In this way, a transition from one solid phase to another can also be induced.

ii. Changes in ionic strength and / or pH

Various functional groups are known to cross-link in the presence of certain ions or in response to a change in pH. For example, it is known that calcium ions crosslink amine and alcohol groups, i.e., the amino groups on the alginate can be crosslinked by calcium ions. Also, carboxylate and amine groups are charged at certain pH values. When these groups are charged, they can cross-link with counterions. The presence of groups reacting to changes in the concentration of certain types of ions and / or changes in pH will result in reversible cross-linking between these segments in stable or adaptable segments. When the segments are crosslinked, the shape of the object can be fixed. Upon deformation of the shape, the change in ionic concentration or pH may result in cleavage of the ionic interactions that have created cross-linking between the segments and thus release the deformation chain and thereby return the object to its original shape. Since ionic bonds are formed and cleaved by this process, this can only occur once. Nevertheless, the bonds can be re-formed by changing the ion concentration or pH, so that the process can be repeated as desired.

iii. Electric and magnetic fields

Various residues, such as chromophores with a large number of delocalized electrons, increase the temperature after insertion of electric or magnetic fields as a result of the increased electron flux caused by this field. When the temperature of these materials increases, the shape memory caused by heat can occur in the same way as if the material were heated directly. Such compositions are particularly suitable for biomedical applications where direct application of heat to the implanted material could cause problems, but the inserted magnetic or electric field only has an effect on those molecules that contain a chromophore and do not heat surrounding tissue.

• * • ·

- 20 iV. Ultrasound

Various materials contain reactive groups fragmented in response to ultrasound. Examples of such groups are those which form stable radicals such as nitroso and triphenylmethane. The shape of the object is allowed to be fixed when bonding between two or more adaptive segments, for example using heat or light. Upon deformation of the shape, the effect of ultrasound can break the bonds between the adaptive segments and release the strain causing the deformation. The object then returns to its original shape. Since covalent bonds are formed and degraded in this process, only one can occur.

III. Methods of production of polymers

The polymers used to form segments in the SMP described above are both commercially available and can be synthesized by routine chemical methods. Those skilled in the art can readily prepare polymers using known chemical procedures.

IV. Methods of forming polymer blends

The compositions may be formed into a first shape under appropriate conditions, for example at a temperature above the T _tr ans of the stable segments and allowed to cool below the Ttrans of the adaptable segment (s). Standard technologies are extrusion and injection molding. The article may optionally be reformed into a second shape. Using heat or another set of conditions returns the object to its original shape.

Thermoset polymers can be prepared by extruding the prepolymerized material (macromonomers), and fixed by the original shape at a temperature above T _tra ns thermoset polymer, for example by irradiation with reactive groups on the monomer. The intermediate shape is fixed by cooling the material below T _tra ns after material deformation.

The crosslinking can also be carried out in a solution of macromonomers. Solvent

- 21 removed from the gel formed by a subsequent step.

Such mixtures formed from thermoplastic polymers may be blown, extruded into sheets or injection molded, for example, to form fibers. The compositions may also be shaped by other methods known to those skilled in the art of solid object machining, such as laser machining, micro machining, hot wire use, and CAD / CAM (computer-aided design / computer-controlled manufacturing) processes. In forming thermoset polymers, these processes are preferred.

1. Transitions between shapes

In some applications, it is advantageous to proceed in small steps from the temporary shape to another temporary shape or the original shape. Under operator control, it is possible to move back and forth between the shapes as required.

A. Wide thermal transitions

Tt is usually _wound shape memory sharp, so that the polymer returns to its original shape simply by heating the material only a few degrees Celsius. Alternatively, however, the shape memory polymers have a wide temperature transition, so that the original shape will only fully return when the polymer is heated above the upper limit of the thermal transition. Partial return occurs when heated to a temperature between the lower and upper limit of the thermal transition. In this case, the starter is the temperature and the effect is necessarily independent of the time interval of heat exposure.

B. Gradual energy transfer

To restore the memory shape, a certain amount of energy is required to convert the shape memory polymer. To achieve a thermal effect on the shape memory, the amount of energy required to completely restore the shape memory depends on the thermal capacity of the material. For very sensitive materials, therefore, the amount of energy depends on the radiation dose. When the solution which is preferred, is to have the polymer to influence the thermal shape memory sharp thermal transition, and its execution is to be based on the time to temperature of greater than Tt _wounds · Other factors affecting the transition include the mass or dimensions of the material and the temperature and heat transfer coefficient to Media ···· • 4

• · • ·

- 22 or an environment (and used to heat it) in contact with the material. For example, the higher the ambient temperature, the greater the rate at which the memory shape is restored.

C. Selective energy transfer and alternative mechanisms

In the classical way of influencing the thermal shape memory, the entire polymer must be heated (and transferred) by thermal energy from an external source to restore the original shape. In an alternative solution, the polymer is heated by an energy source other than a thermal source. By using this technique it is possible not only to heat the whole object with the shape memory, but also some parts (another way of starting and improving the regulation to restore the original shape).

i. Light energy

Polymers absorb light of different wavelengths depending on their chemical structure. Polymers typically exhibit strong radiation absorption in the infrared (IR) and near infrared (NIR) regions. The strongest and most suitable absorption regions for proper application can be found using IR or NIR spectroscopy. Shape memory polymers may also exhibit strong absorption in the ultraviolet (UV) region. Polymers can be treated with light having at least one of the specific frequencies in their spectrum to absorb light energy and heat up. The absorption characteristics of shape memory polymers can be modified by the addition of chromophores, which are fragments, functional groups, or molecules exhibiting strong absorption in specific regions of the UV / visible / IR / NIR / microwave spectrum. The chromophore may be covalently bound to the polymer, combined as a physical mixture with the polymer, or both.

In preferred biomedical cases, non-invasive regulation of the implantation of SMC articles may be used. For example, the implanted article may be treated with a specific external light source that does not simultaneously heat the tissue, serum, or other parts of the physiological environment surrounding the SMP implant. Such a light source (eg a light bulb) must emit one or more frequencies (eg near infrared, "NIR") that are not absorbed.

• · · · · · · · · · · · · · · ·

- 23 physiological environment, but is absorbed by the shape memory material. The use of NIR light is known in the diagnostic art.

In an alternative solution, interference techniques are used to control the frequency of light acting on the SMP implant. Interference provides a three-dimensional (3D) order to the area to be treated because a specific frequency absorbed by the shape memory object is created at a specific location by the interference of two or more beams intersecting at that specific location. The sources of these beams are outside the body, and the beam frequencies are generally modulated by a radio frequency selected to produce the desired frequency upon interference.

ii. Ultrasound

In an alternative embodiment, bubbles of gas or liquid containing bubbles, preferably fluorocarbons, are incorporated into the shape memory article.

Using standard ultrasonic technology, a cavitation effect can be induced in the gas / liquid mixture to heat the SMP. The technology of controlled 3-D ultrasound application is known to those skilled in biomedical diagnostics.

iii. In general

It is also possible to influence the energy transfer due to the interaction of the shape memory polymer with the electromagnetic! field. The use of magnetic fields to induce heating or localized thermal changes is well known. In yet another solution, energy transfer is generated by non-radiant effects, such as Foerster-Perrin energy transfer.

2. Two-way shape memory influencing

Shapes of shape memory polymers can be prepared to have two original (permanent) shapes, ie, two-way shape memory effects. These systems always consist of at least two components. The components are combined by layered technology (similar to bimetals) or the grids can be blended. By varying the temperature, the shape memory article changes its shape towards permanent shape 1 or permanent shape 2. Each of the permanent shapes belongs to one component of the object. The resulting shapes are always in

- 24 balance between the two shapes. The temperature dependence of the shape is due to the fact that the mechanical properties of one component (“component A”) are almost independent of temperature in the desired temperature range. The mechanical properties of the second component ('component B') are temperature dependent. In one case, component B predominates stronger at lower temperatures compared to component A, while component A predominates at higher temperatures and determines the actual shape. An object with two-way memory can be prepared by (a) restoring the original shape of component A; (b) deforming the article to its original shape of component B; and (c) fixing the original shape of component B under stress to the component.

3. Initiation of restoration of the original shape by polymer degradation

The recovery of the shape memory polymer may be initiated by a hydrolytic degradation process. In a preferred solution, this characteristic is incorporated into a system comprising a thermoplastic polymer composed of a stable segment and at least one adaptable segment or a thermoset comprising at least one adaptable segment (one-component systems). In these polymers, two adaptive segments can be bound by an immediately hydrolysable bond. The term "readily hydrolyzable bond" is used herein to refer to groups having a hydrolysis rate greater than that of other polymer functional groups. The original shape of these polymers is determined by stable segments (thermoplastic material) or by covalent crosslinking (thermoset). The temporary shape is fixed by cross-linking between the two adaptive segments after deformation of the article. When the crosslinking between the adaptive segments is hydrolyzed, the original shape is restored. Rapidly hydrolyzable functional groups include activated ester linkages such as glycolyl glycolate and anhydride linkages.

In another preferred solution, the polymer is a two-component system in which at least one component is a covalent lattice such as IPN, mixed IPN or semi-IPN. A covalent lattice is an amorphous lattice having a very low Tt _wound . The covalent lattice determines the original shape of the system and the other component deforms the system to fix the intermediate shape. The second component in the case of IPN is another grid, the homo- or copolymer in the case of semi-IPN and the thermoplastic elastomer in the case of mixed IPN. The first component (covalent lattice) hydrolyzes more slowly than the second

- 25 component, so that the polymer restores its original shape when the second component degrades.

φ · · tot tot tot tot tot tot tot tot tot tot tot tot tot tot tot tot tot tot tot <toto <<<<<<<< ·· ··

V. Applications

These materials have a huge number of applications.

1. Therapeutic, prophylactic and diagnostic applications

These materials are particularly suitable for medical and biological applications.

For example, any of a variety of therapeutic, prophylactic, and / or diagnostic agents may be incorporated into a polymer composition that can locally or systematically deliver the introduced agents after administration to the patient. Examples include synthetic inorganic or organic compounds or molecules, proteins and peptides, polysaccharides and other sugars, lipids and nucleic acid molecules having therapeutic, prophylactic or diagnostic activity. Nucleic acid molecules include genes, plasmid DNA, DNA itself, transcription inhibitors of the molecule that bind complementary DNA to inhibit transcription, ribozymes, and flanking ribozyme sequences. Agents such as vasoactive agents, neuroactive agents, hormones, growth factors, cytokinetics, anesthetics, steroids, anticoagulants, anti-inflammatory agents, immunomodulatory agents, cytotoxic agents, prophylactic agents, antibiotics, antiviral agents, inhibitors, antigens and antibodies that are introduced can have many biological effects. In some cases, the proteins may be antibodies or antigens that would otherwise be injected to achieve an appropriate response. Proteins are defined as substances containing 100 amino acid residues or more; the peptides have less than 100 amino acid residues. Unless otherwise indicated, the term protein refers to both proteins and peptides. Polysaccharides such as heparin can also be administered. Compounds with a large molecular weight range, for example between 10 and 500000 grams per mole, can be encapsulated.

Diagnostic or imaging agents that can be used include commercially available reagents used in positron emission tomography (PET), computer controlled

- 26 tomography (CAT), single photon emission computed tomography, X-ray, fluoroscopy, magnetic resonance imaging (MRI) and ultrasound contrast media.

2. Subjects and devices for biomedical applications

Mixtures of polymers can be used to prepare articles for use in biomedical applications. For example, sewing aids, materials for orthodontics, bone screws, nails, plates, sieves, orthotics, pumps, catheters, tubes, foils, stents, orthopedic clips, splints, tapes for preparing castings and skeletons for tissue engineering, contact lenses, drug delivery devices, implants and heat indicators.

Mixtures of implantable polymers are preferably prepared from biocompatible polymers and, in most applications, from biodegradable polymers. Biodegradable polymers degrade at a controlled rate depending on the composition and crosslinking of the polymer. Degradable polymer implants eliminate the need for implant repair and can be used in conjunction with the introduction of therapeutic agents. Materials can be used in many applications requiring load and controlled degradation. The polymer blends can be shaped into an implant that can be implanted into the body to perform a mechanical function. Examples of such implants include rods, pins, screws, plates and anatomical shapes. Especially preferred are compositions for preparing a suture material that is sufficiently rigid to be easy to work with, but when it reaches body temperature it softens to form a second shape that is more tolerable to the patient and still allows healing.

Another preferred application is the catheter area. Catheters generally require a high insertion rigidity, but if they are already in place, it is better if they are soft and flexible. In a preferred solution, the SMP catheter is rigid below body temperature for ease of insertion, and upon warming to body temperature it softens and reduces patient annoyance and complications.

The polymer blend may be combined with fillers, reinforcing materials, radioimaging materials, excipients, or other materials necessary for proper implantation application. Those skilled in the art will readily determine the amount of such substances to be incorporated into the composition.

- 27

The articles may incorporate various therapeutic and / or diagnostic agents as described above.

3. Non-medical applications

There are many applications other than biomedical applications for formulating shape memory polymers. These applications include: shape memory polymer foams, impact-absorbing parts such as bumpers and other body parts, food packaging, automatic chokes for internal combustion engines, polymer composites, textiles, moisture-permeable substances such as sportswear, material for diapers and shoe linings, pipe joints, mold core materials, heat-shrink tubing, rewritable compact discs (CDs) and dowel pins, temperature sensors, damping materials, pads and protective equipment, toys, pipe jointing materials for internal encapsulation, dowel pins, materials for medical aids used in plastering, etc., office and teaching materials, artificial flowers, dolls, internal lamination of dot matrix printer rollers for computers, soundproof materials, components requiring recovery after deformation u after impact absorption such as car bumpers and other components, building filler materials in divided parts of buildings, portable containers that can be collapsed when not in use and which return to their original state in use, mechanical devices such as couplings, etc., various heat shrinkable hoses, materials for human cosmetic use, polymeric memory foam, fibers, polymer composites, seals and gaskets, choke valves, sound insulation and oil filters.

The shape memory foams have a deformed shape and a seemingly cast shape. They have their deformed shape when compressed at a temperature greater than T _tra ns and maintain this compressed shape at a temperature less than Tt _ws as it is compressed, and the compressed polymer returns to its original cast shape after heating above the temperature to restore the original shape. Foams can be prepared by polymerizing materials in the presence of a blowing agent (eg, gas or low boiling solvent).

VII. Methods of use

Certain articles are intended to maintain the desired shape when ·

- 28 shall not be treated in a manner inconsistent with their normal use. For example, automobile bumpers maintain their desired shape until impact. A product having an SMP can be used in its desired shape, but can be repaired after damage (eg, deformation), for example, by heat.

Other objects are intended to be used in their first intended shape and the second shape is for the second intended use. Such examples include biomedical articles that may form a second shape upon reaching body temperature or after application of external stimuli that heat the article above body temperature.

Other objects are for the intended use, so that the shape changes in response to temperature changes by triggering some action, such as turning on a mechanical or electrical switch. For example, the circuit breaker can be used to control the temperature of the SMP environment, such as temperature sensors and automotive chokes.

The present invention will be better understood with reference to the following non-limiting examples.

Examples

Example 1: Shape memory polymers of esterurethane copolymer

A group of biocompatible and biodegradable multiblock copolymers having a shape memory with thermal effect was synthesized. These polymers were composed of a crystallizable stable segment (T _m ) and an adaptable segment having a temperature transition temperature T _tran with between room temperature and body temperature. Unlike the previous segmented polyurethanes, the stable segment was an oligoester or oligoetherester and did not contain an aromatic component.

The mechanism for programming the temporary shape and a permanent shape restoring multiblock copolymer is shown in Figure 6. The permanent shape of the materials was formed by melting the polymer and cooling above Tt _wounds (Fig. 6 - top position). Then the polymer was formed into a temporary shape (Fig. 6 - right position), which was fixed by cooling below T _tr ans (Fig. 6 - bottom position). After the pressure has been removed,

- 29 restored its original shape by reheating over T _tr ans 0 1 • 0 0

Synthesis of telechellates, oligomers with functional groups at both ends

The telechellate macrodiol was synthesized by ring-opening polymerization of cyclic monomers with di (n-butyl) tin oxide as a transesterification catalyst under a nitrogen atmosphere.

The stable segment of α, ω-dihydroxy [oligo (ethylene glycol glycolate) ethylenoligo (ethylene glycol glycolate)] (PDS1200 and PDS1300) was prepared as follows: Monomeric p-dioxan-2 he was obtained before its further use by distillation (thermal depolymerization) of the oligomers. 57 g (0.63 mol) of monomer, 0.673 g (10.9 mmol) of ethylene glycol and 0.192 g (0.773 mmol) of di (n-butyl) tin oxide were heated at 80 ° C for 24 hours. The end of the reaction (equilibrium) was in the GPC building. The product was dissolved in hot 1,2-dichloroethane and filtered through a hot Buchner funnel packed with silica gel. The product was obtained by precipitation in hexane and drying under vacuum for 6 hours.

Flexible segment

i. Crystalline

Poly-s-caprolactone with different _Mn are commercially available for example from Aldrich and Polysciences. Here was used PCL-2000.

ii. Amorphous α, c) -dihydroxy [oligo (L-lactate-co-glycolate) ethylenoligo (L-lactate-co-glycolate)] - (abbreviated: PLGA2000-15) was prepared as follows: In a 1000 ml two-necked round bottom flask was heated to melt at 40 ° C and with stirring 300 g (2.08 mol) of L, L-dilactide, 45 g (0.34 mol) of diglycolide and 4.94 g (0.80 mol) of ethylene glycol. Next, 0.614 g (2.5 mmol) of di (n-butyl) tin oxide was added. After 7 hours the reaction reached equilibrium as determined by GPC. The reaction mixture was dissolved in 1,2-dichloroethane and

9 • 9

- 30 purified on a silica gel column. The product was obtained by precipitation in hexane and dried for 6 hours in vacuo.

Properties of telechellates

As shown in Table 1 below, the molecular weight M _n and the thermal properties of the macrodiols were determined.

Table 1: Molecular weight and thermal properties of macrodiols

Designation M _n GPC [g.rnor ² ] M _n VPO [g.rnor ² ] T _m [° C] J [Jg ¹ ] Tg [° C] _ΔΟ Ρ [Jg ^1] PCL2000 1980 1690 43 73.5 <-40 PDS1300 1540 1340 97 74.5 <-20 - PDS1200 2880 1230 95 75.0 <-20 - PLGA200 0 2020 1960 - - 29.0 0.62

Synthesis of thermoplastic elastomers (multiblock copolymers)

In a 100 ml two-necked round-bottomed flask connected to a Soxhlet extractor packed with a 0.4 nm molecular sieve, two different macrodiols (one stable segment and one adaptive segment) described in Table 2 below were dissolved in 80 ml 1,2-dichloroethane. refluxed for drying by azeotropic solvent extraction. Freshly distilled trimethylhexane-1,6-diisocyanate was added via syringe and the reaction mixture was heated to 80 ° C for at least 10 days. The mixture was sampled at regular intervals to determine the molecular weight of the GPC polymer. At the end of the reaction, the product was obtained by precipitation of the polymer in hexanes and purified by repeated dissolution in 1,2-dichloroethane and precipitation in hexanes.

Multiblock copolymers were prepared from the following two types of polymers.

(i) PDC polymers contained poly-s-caprolactone. The _tr adaptable segment is the melting point.

(ii) PDL polymers comprise α, β-dihydroxy [oligo (L-lactate-co-glycolate) ethylenoligo (Llactate-co-glycolate)]. The adaptive segment T _{r and} n is the glass transition point.

- 30 »·· ·»

»··

I · · «

Table 2: Synthesis of multiblock copolymers

Polymer 1. diol m [g], n [mmol] 2. diol m [G] n [mmol] TMDI [mmol] time [d] PDC22 PDS1200 3,0245 2,653 PCL2k 6,0485 3,024 5,738 10 PDL23 PDS1200 2,2787 2,000 PLGA2k 6,1443 3,070 5,163 10 PDC27 PDS1300 2,5859 1,724 PCL2k 5.3611 2,681 4,368 14 PDC40 PDS1300 3,6502 2,433 PCL2k 3,9147 1,957 4,510 13 PDC31 PDS1300 3.2906 2,194 PCL2k 4,8619 2,431 4,500 16 PDL30 PDS1300 3,7115 2,474 PLGA2k 4,0205 2,011 4,480 16

Properties of thermoplastic elastomers

The determined physical, mechanical and degradation properties of the mixtures are shown in Tables 3 - 9 below.

Hydrolytic degradation behavior of the new materials was tested in a solution buffered to pH 7 at 37 ° C. Polymers have been shown to be completely degradable and their rate of degradation can be adjusted by the concentration of readily hydrolyzable ester bonds. The values of relative mass loss m _r = m (t ₀ ) / m (t) are in% at 37 ° C and the relative molecular mass loss M _r = M _w (t) / M _w (t ₀ ) is in% at 37 ° C.

The toxicity of two different multiblock copolymers was investigated in a chicken embryo assay. It was shown that the germs developed normally and their condition was not affected by polymer samples.

Table 3: Composition of copolyesterurethanes determined by 400 MHz ¹ H-NMR spectroscopy

Designation Stable segment Weight content [%] * Adaptable segment Weight content [%] * PDL23 PDS 23.0 PLGA 54.2 PDL30 PDS 30.0 PLGA 52.1

PDC22 PDS 22.0 PCL 64.5 PDC27 PDS 27.0 PCL 61.1 PDC31 PDS 31.1 PCL 55.4 PDC40 PDS 40.4 PCL 46.2

* The rest up to 100% is the urethane content.

Table 4: Molecular weight M _{w of} urethane copolymer films determined by multidetector GPC

Designation Polymer foil M _W (LS) M _w (Visc) dn / dc [g.mor] [g.mor ¹ ] [ml.g- ¹ ] PDL23 161,500 149,000 0,065 PDL30 79,100 83,600 0.057 PDC22 119,900 78,500 0,078 PDC27 72,700 61,100 0,080 PDC31 110,600 108,600 0,065 PDC40 93,200 86,300 0,084

Table 5: Transition temperatures T _m and T _g , melting heat AH _m and changes in heat capacity

Ac _p polymer foils from DSC measurement (values are from the second heating)

Designation Tm1 [° C] Γγπ1 [J-g ' ¹ ] ,"O 1 o AC _P [Jg ¹ ] Tm2 [° C] AHm2 [J-g- ¹ ] PDL23 - 34.5 0.38 - PDL30 - - 33.5 0.25 85.0 8.5 PDC22 35.0 26.0 - - - - PDC27 37.0 25.0 - - 75.5 3.5 PDC31 36.5 28.5 - - 76.5 5.5 PDC40 35.0 7.0 - - 77,5 ' 7.0

Table 6: Mechanical properties of polymer films at 50 ° C from strength test

Code module E [MPa] £ r [%] σ _Γ [MPa] Smax [%] Cmax [MPa] PDC27 1.5 1350 2.1 1300 2.3 PDC31 1.5 1400 4.9 1300 5.4 PDC40 4.0 1250 5.8 1300 5.9 PDL30 2,0 1400 2.1 1250 2.3

• ·

- 33 Table 7: Degradability of PDL22

Degradation time [d] M _r (viscosimetric) [%] M _r (light scattering) [%] 14 81.3 85.7 21 67.1 74.6 29 62.9 65.6 42 43.6 47.7 56 54.4 41.9

Table 7: Degradability of PDL23

Degradation time [d] M _r (viscosimetric) [%] M _r (light scattering) [%] 14 61.1 87.3 21 40.7 76.7 29 32.8 62.2 42 17.4 46.7 56 16.9 18.5

Table 9: Relative weight loss

PDC22 PDL23 Degradation time m _r m _r [%] [%] [%] 14 99.2 98.1 21 99.3 97.5 29 98.6 97.2 42 98.3 96.9 56 97.3 93.3

Shape memory properties

Figure 7 shows the results of tensile strength tests performed with multiblock copolymers as a function of the number of thermolytic cycles. The average shape stability of polymers affected by thermal cycles and the rate of strain recovery rate as a function of the number of cycles is shown in Tables 10 and 11. The polymers have high shape stability and equilibrium is reached after only two cycles.

4 4 4

- 34 4,444 • 44

Table 10: Average rate of shape stability Rf

Designation Rf [%] PDC27 97.9 PDC40 96.2 PDL30 97.7

Table 11: Dependence of the number of cycles on the voltage recovery rate R _r

PDC27 PDC40 PDL23 Number of cycles Rr [%] Rr [%] Rr [%] 2 77.3 73.7 93.8 3 93.2 96.3 98.8 4 98.5 98.7 98.9 5 98.5 98.7 98.8

Example 2: Degradable shape memory thermoset with crystallizable adaptive segment

A large number of poly-ε (caprolactone) dimethacrylates and thermosets were evaluated for mechanical properties and shape memory.

Macromonomer synthesis

Poly-s-caprolactondimethacrylates (PCLDMA) were prepared as follows: To a solution of polys- (caprolactone) diol of M _n = 2000 g.mol ^-1 (20.0 g, 10 mmol) and triethylamine (5.3 g, 38 mmol) in 200 mL dry THF was added dropwise at 0 ° C methacryloyl chloride (3.7 mL, 38 mmol). The solution was stirred for 3 days at 0 ° C and the precipitated salt was filtered off. After concentrating the mixture at room temperature under reduced pressure, 200 mL of ethyl acetate was added and the solution was again filtered and precipitated by a 10-fold excess of a mixture of hexanes, ethyl ether and methanol (18 mL).

• · • · <··· • ··

- 35: 1: 1). The colorless precipitate was collected, dissolved in 200 mL of dichloroethane, precipitated again and carefully dried at room temperature under reduced pressure.

Synthesis of thermosets

The macromonomer (or monomer mixture) was heated 10 ° C above its melting point (T _m ) and filled into a casting mold consisting of two glass plates (25 mm x 75 mm) and a 0.60 mm Teflon liner. To obtain good homogeneity, the melt was stored at _Tm for another hour. Light treatment was performed on a warmed plate at T _m for 15 min. The distance between the head of the heating lamp and the sample was 5.0 cm. After cooling to room temperature, the sample was extracted overnight and carefully washed with a 100-fold amount of dichloromethane. Finally, the sample was dried at room temperature under reduced pressure.

Properties of macromonomers and thermosets

The following Table 12 lists the poly-s- (caprolactone) dimethacrylates that have been prepared, along with the corresponding degree of acrylation (D _a ) (%). The number after PCLDMA is the molecular weight M _n of the poly-? - (caprolactone) diol used for the synthesis as determined by ¹ H-NMR and GPC, rounded to 500.

Table 12: Poly-s- (caprolactone) diol and degree of acrylation

Name Da [%] PCLDMA1500 87 PCLDMA2000 92 PCLDMA3500 96 PCLDMA4500 87 PCLDMA6500 93 PCLDMA7000 85 PCLDMA10000 86

Figure 8 shows the melting point (T _m ) of diols, dimethacrylates and thermosets of poly-ε-

- 36 caprolactone as a function of the molecular weight of M _n macromonomers. In the diagram, macrodiols are represented by macromonomers ... · and thermosets _ Δ

The strength properties of poly-s-caprolactone thermosets C1 to C7 at room temperature are given in Table 13, where E is the modulus of elasticity (Young's modulus), _s is the elongation and s is the ultimate strain, and _{m and} x is the maximum stress, emaxis the elongation at a _max , sr is the elongation at break and a _R is the breaking stress. Table 14 below gives the tensile values of the same polyε-caprolactone thermosets at 70 ° C.

Table 13: Strength properties of thermosets at room temperature

Designation E [MPa] es [%] σε [MPa] Smax [%] Omax [MPa] Sr [%] Steed [MPa] NO. 1 2.4 ± 0.6 - - 16.1 ± 2.0 0.4 ± 0.1 16.1 ± 2.3 0.38 ± 0.02 C2 35 ± 3 - - 20.6 ± 0.3 4.7 ± 0.1 20.6 ± 0.3 4.7 ± 0.1 C3 38 ± 1 48 ± 1 11.2 ± 0.1 180 ± 20 12.1 ± 1.2 190 ± 20 11.7 ± 1.6 C4 58 ± 4 54 ± 1 12.2 ± 0.1 247 ± 4 13.6 ± 1.9 248 ± 13 15.5 ± 2.7 C5 72 ± 1 56 ± 2 15.5 ± 0.2 275 ± 10 15.6 ± 1.7 276 ± 6 15.0 ± 1.0 C6 71 ± 3 43 ± 2 14.2 ± 0.1 296 ± 14 15.5 ± 0.2 305 ± 8 13.8 ± 2.7 C7 71 ± 2 42 ± 5 13.6 ± 0.2 290 ± 30 16.2 ± 0.5 290 ± 30 15.7 ± 0.9

Table 14: Strength properties of thermosets at 70 ° C

Designation E [MPa] Omax [MPa] Sr [%] NO. 1 1.84 ± 0.03 0.40 ± 0.08 24 ± 6 C2 2.20 ± 0.12 0.38 ± 0.05 18 ± 2 C3 6.01 ± 0.12 2.05 ± 0.21 43 ± 9 C4 2.30 ± 0.16 0.96 ± 0.01 61 ± 3 C5 1.25 ± 0.08 0.97 ± 0.15 114 ± 13 C6 1.91 ± 0.11 1.18 ± 0.06 105 ± 11 C7 0.70 ± 0.09 0.79 ± 0.10 210 ± 7

- 37 Shape memory

For thermosets were determined by the thermomechanical properties indicated in Table 15, values of average molecular weights (M _n) holds for the macromonomer. Lower limit temperature T _(is 0 ° C and the upper limit temperature Th was 70 ° C. The extension of the temporary shape is 50%. Rf (2) the speed voltage recovery during the second cycle, R _{f> it} T is the total rate of restoration of power after 5 cycles, Rf is the average rate of fixation.

Table 15: Thermomechanical properties of thermosets

Designation M _n [g.mol ^-1 ] Rf (2) [%] Rf.tot [%] Rf [%] C4 4500 93.3 93.0 93.9 ± 0.2 C5 6500 96.3 94.5 93.9 ± 0.2 C6 7000 93.8 92.1 92.5 ± 0.1 C7 10000 98.6 96.8 86.3 ± 0.5

? / / Ooo ~ 3opf

Claims (40)

Patent claims A blend of shape memory polymers, characterized in that it has at least two shapes in memory. 2. A composition according to claim 1 comprising: a) at least one hard segment which has a Tt _wounds between -40 and 270 ° C, (b) a first adaptive segment having a T _tra ns of at least 10 ° C lower than that of the stable segment (s) and which is bound to at least one stable segment; c) a second adaptive segment bound to at least one of the stable segments or a first adaptive segment having a T _tra ns at least 10 ° C lower than the Tt _{rans of the} first adaptive segment, 3. The composition according to claim 2, characterized in that T _tra ns hard segment is in the range between 30 and 150 ° C. The composition according to claim 3, wherein the T _tran of the stable segment is in the range between 30 and 100 ° C. 5. The composition according to claim 2, characterized in that Tt _wounds first soft segment (s) is at least 20 ° C below Tm _trans of the hard segment (s). 6. The composition of claim 2 wherein the T _trans of the second soft segment (s) is at least 20 ° C below the Tm _{of wounds} with the first soft segment (s). 7. The composition of claim 1 wherein the shape memory polymer comprises a thermoplastic polymer. The composition of claim 1 wherein the polymer comprises multiple segments and has a molecular weight M _{n of} at least one of the segments being between about 500 and 10,000. 9. The composition of claim 1 wherein the shape memory polymer is selected from the group consisting of graft polymers, linear polymers, and dendrimeric polymers. 10. The composition of claim 1 wherein the polymer comprises stable and conformable segments and the stable segment comprises cyclic fragments. - 39 11. The composition of claim 10 wherein said fragments are selected from the group consisting of crown ethers and cyclic oligopeptides. 12. The composition of claim 1 wherein the shape memory polymer is biodegradable. 13. The composition of claim 12 wherein the polymer comprises stable and adaptable segments and at least one of the stable and adaptable segments is selected from the group consisting of polyhydroxy acids, polyorthoesters, polyetheresters, polyesters, polyamides, polyesteramides, polydepsipetides, aliphatic polyurethanes, polysaccharides, polyhydroxyalkanoates and copolymers thereof. 14. The composition of claim 11 wherein the polyether ester is selected from the group consisting of oligo (p-dioxanone) and copolymers thereof. 15. The composition of claim 1, wherein the polymer comprises at least two adaptive segments, and the segments are attached via a bond that is cleavable by stimuli selected from the group consisting of ultrasound, electric field, magnetic field, and radiation. The composition of claim 1, wherein the polymer comprises at least one stable segment and two adaptive segments, and wherein the ratio between the weight of the stable segment to the first adaptive segment with the second adaptive segment is between about 5: 95 to 95: 5. 17. A composition according to claim 1 comprising a thermoset polymer having at least two covalently crosslinked crystallizable soft segments, characterized in that the first soft segment has a Tt _wounds between 250 ° C and -40 ° C; and the second adaptable segment attached to the first adaptive segment has a T _tr ans at least 10 ° C lower than the Ttrans of the first adaptive segment. The composition of claim 17, wherein the first adaptable segment has a Ttrans of between 200 ° C and 0 ° C. The composition of claim 17, wherein at least one of the stable and adaptable segments comprises a cross-linkable group and further comprises at least one of the stable and adaptable segments, which is bound by forming an interpenetrated grid or a semi-interpenetrated grid. - 40 · <♦ · • · 4 20. The composition of claim 17 wherein the stable and conformable segments form a mixed interpenetrated grid. 21. The composition of claim 17, wherein the stable and conformable segments form a shape memory semi-IPM consisting of a thermoset polymer having at least one conformable segment and a homo- or copolymer. 22. The composition of claim 21, wherein the resulting semi-IPN has a highest Ttrans in the range between 200 ° C and -40 ° C. 23. The composition of claim 21 wherein the thermoset polymer is degradable. 24. The composition of claim 21 wherein the homo- or copolymer is degradable. 25. The composition of claim 21 having a multiple shape memory wherein the number of shapes in the memory is equal to the number of polymer thermal transitions. 26. The composition of claim 1, comprising a shape memory IPN comprising interpenetrated crosslinking of thermoset polymers. 27. The composition of claim 1 comprising a shape memory mixed IPN consisting of a thermoplastic elastomer comprising at least one stable segment and at least one conformable segment and a thermoset comprising at least one conformable segment. 28. A shape memory polymer composition comprising: (a) at least one stable segment having a T _tra ns between -30 ° C and 270 ° C; (b) at least one adaptable segment having a T _tra ns of at least 10 ° C lower than that of the stable segment (s) and which is bound to at least one stable segment, wherein at least one of the stable or adaptable segments comprises a functional group that is capable of forming a crosslink which can be cleaved by stimuli selected from the group consisting of radiation, electric field, magnetic field and ultrasound. A shape memory polymer blend, characterized in that at least one of the stable or adaptable segments undergoes transitions between two solid states and / or interactions related to flfl. - 41 polyelectrolytic segments or supramolecular influences based on bonds of highly organized hydrogen bridges. 30. The composition of claim 29, wherein the polycationic metal salt binds at least two segments in which the formed bond can be cleaved by an aqueous solvent. 31. A method of shaping shape memory articles with two or more shapes in memory, comprising: (a) preparing a shape memory polymer blend consisting of: (i) at least one stable segment having a T _tr ans of between -30 ° C and 270 ° C; (ii) a first adaptable segment having a T _tra ns at least 10 ° C lower than the Ttrans of the stable segment (s) and which is bound to at least one stable segment, iii) a second adaptable segment bound to at least one stable segment and a first adaptable segment having a Tt _wound with at least 10 ° C lower than a Tt _wound from the first adaptable segment; b) heating the mixture over Tt _wounds with a stable segment; c) shaping the mixture into a desired first shape; d) cooling the mixture to a temperature below the Tt _wound from the stable segment and above the Tt _{rans of the} first adaptive segment to cure the stable segment while maintaining the first and second adaptive segments in a molten or amorphous state; e) shaping the mixtures into a desired second shape; f) shaping the mixtures into a desired third shape; and g) cooling the mixture below the T _{rans of the} second adaptive segment to fix the second shape. 32. The method of claim 31, wherein the mixture is extruded or injection molded. 33. The method of claim 32, further comprising heating the mixture over the Ttrans of the second adaptive segment to return the mixture to the second shape. 34. The method of claim 33, further comprising heating the mixtures above the Tn ns of the first adaptive segment to return the mixture to the first. - 42 ♦ 4 44 shape. 35. The method of claim 34, further comprising heating the mixture above the stable segment to lose memory of the first and second shapes. 36. A method of forming a shape memory composition comprising: (a) preparing a polymer blend containing: (i) at least one stable segment having a T _trans between -30 ° C and 270 ° C; (ii) at least one adaptable segment having a Tt _{rans of} at least 10 ° C lower than the T _tr ans of the stable segment (s) which is bound to at least one stable segment, wherein at least one of the stable or adaptable segments comprises a functional group capable of forming a crosslinking which can be cleaved using stimuli selected from the group consisting of radiation, electric field, magnetic field and ultrasound; b) heating the mixture above the T _tra ns of the stable segment; c) shaping the mixture into a desired first shape; d) cooling the mixture to a temperature below the Tt _wound from the stable segment and above the T _tra ns of the adaptive segment; e) shaping the mixture into a desired second shape; and f) fixing the second shape by binding the adaptive segments. 37. The method of claim 36, further comprising: g) forming the mixture into a third shape and cooling under a Tt _wound with an adaptive segment. 38. The method of claim 37, further comprising returning the mixture to a second shape by heating over a Tt _wound from the adaptive segment, but lower than the Tn ns of the stable segment. 39. The method of claim 38 further comprising returning the mixture to the first shape using stimuli selected from the group consisting of radiation, electric field, magnetic field, and ultrasound. A composition according to any one of claims 1, 28 or 29, comprising blends of polymers.