Composites and Laminates

Abstract

1. A composite material (10) comprising an expanded polytetrafluoroethylene layer (12), a densified expanded polytetrafluoroethylene layer (16a) bonded to the expanded polytetrafluoroethylene layer, a porous expanded polytetrafluoroethylene layer (16b) bonded to the densified expanded polytetrafluoroethylene layer, an adhesive (16c), and a densified expanded polyethylene layer (14), wherein the adhesive bonds the expanded polyethylene layer to the porous expanded polytetrafluoroethylene layer.

Description

[Technical Field]

[0001] This application claims the benefit of Provisional Application No. 63 / 433,143, filed December 16, 2022, which is incorporated herein by reference in its entirety for all purposes.

[0002] The present disclosure relates generally to apparatus, systems and methods for providing composite materials operable to be wear resistant, and more particularly to apparatus, systems and methods including wear resistant materials usable in implantable medical devices. [Background technology]

[0003] The materials used in manufacturing are important in providing certain properties necessary for a product to function for its intended purpose. Materials can be selected for a variety of properties, including, for example, durability. Material selection is important in a variety of industries, including, but not limited to, the medical device industry, and more specifically, implantable devices.

[0004] Implantable devices often require long-term or permanent placement within a patient. Often, implantable devices are placed in areas that are subject to motion, and certain motions, including repetitive motions, can increase the likelihood of wear and / or failure. Failure of an implantable device due to material failure can have many adverse consequences, so it is important to have materials that can maintain their structural integrity over long periods of time.

[0005] Many materials are used in a variety of industries, and properties that are desirable in one industry may also be important in another. Summary of the Invention

[0006] Provided herein are composite materials that have high friction and wear resistance during use. These composite materials achieve this resistance by combining the desirable properties of different materials into a single composite (e.g., laminate) and by firmly bonding the different materials together to provide overall wear resistance.

[0007] According to one example ("Example 1"), a composite material is provided, comprising: an expanded polytetrafluoroethylene layer; a densified expanded polytetrafluoroethylene layer bonded to the expanded polytetrafluoroethylene layer; a porous expanded polytetrafluoroethylene layer bonded to the densified expanded polytetrafluoroethylene layer; an adhesive; and a densified expanded polyethylene layer, wherein the adhesive bonds the expanded polyethylene layer to the porous expanded polytetrafluoroethylene layer.

[0008] According to another example ("Example 2"), in addition to Example 1, the adhesive is low density polyethylene.

[0009] According to another example ("Example 3"), in addition to Example 1, the composite material further includes a thin layer of low density polyethylene bonded to the oriented polyethylene layer.

[0010] According to another example ("Example 4"), in addition to Example 3, the thin layers of low density polyethylene and the adhesive sandwich the oriented polyethylene layer.

[0011] According to another example ("Example 5"), further to Example 1, the densified oriented polyethylene layer has a thickness of about 2 micrometers to about 5 micrometers.

[0012] According to another example ("Example 6"), in addition to Example 1, the adhesive is at least partially absorbed into the porous expanded polytetrafluoroethylene layer.

[0013] According to another example ("Example 7"), in addition to Example 6, the adhesive is processed at a temperature ranging from about 130°C to about 145°C to bond the densified expanded polyethylene layer and the porous expanded polytetrafluoroethylene layer.

[0014] According to another example ("Example 8"), further to Example 1, the densified expanded polytetrafluoroethylene layer has a thickness of about 2 micrometers to about 10 micrometers.

[0015] According to another example ("Example 9"), in addition to Example 1, the porous expanded polytetrafluoroethylene layer has a thickness of about 10 micrometers to about 50 micrometers.

[0016] According to another example ("Example 10"), further to Example 1, the adhesive forms a layer having a thickness of about 1 micrometer to about 200 micrometers.

[0017] According to another example ("Example 11"), an implantable device includes a tubular member formed from a composite material, the tubular member including a first polymer layer including a blood-contacting surface, a densified second polymer layer bonded to the first polymer layer, a porous expanded third polymer layer bonded to the densified second polymer layer, an adhesive, and a densified expanded polyethylene layer, the adhesive bonding the densified expanded polyethylene layer to the porous expanded third polymer layer.

[0018] According to another example ("Example 12"), in addition to Example 11, the first polymer layer is an expanded polytetrafluoroethylene layer.

[0019] According to another example ("Example 13"), in addition to Example 11, the densified second polymer layer is a densified polytetrafluoroethylene layer.

[0020] According to another example ("Example 14"), in addition to Example 11, the porous expanded third polymer layer is a porous expanded polytetrafluoroethylene layer.

[0021] According to another example ("Example 15"), in addition to Example 11, the adhesive is low density polyethylene.

[0022] According to another example ("Example 16"), in addition to Example 15, the low density polyethylene is imbibed into the porous stretched third polymer layer.

[0023] According to another example ("Example 17"), in addition to example 11, the tubular member is a graft.

[0024] According to another example ("Example 18"), in addition to example 17, the implantable device further comprises a stent coupled to the tubular member.

[0025] According to another example ("Example 19"), an implantable medical device comprises a first polytetrafluoroethylene layer and a second polyethylene layer bonded to the first polytetrafluoroethylene layer, the second polyethylene layer operable to be positioned against a structure that is non-stationary relative to the second polyethylene layer.

[0026] According to another example ("Example 20"), in addition to Example 19, the first polytetrafluoroethylene layer and the second polyethylene layer are included in any one of a graft, a tag, a cartilage substitute, an implantable medical device, and a removable medical device.

[0027] The foregoing examples are exemplary only and should not be construed as limiting or narrowing the scope of the inventive concepts otherwise provided by this disclosure. While multiple embodiments are disclosed, still other embodiments will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative examples. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. [Brief explanation of the drawings]

[0028] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification, illustrating embodiments and, together with the description, serve to explain the principles of the present disclosure.

[0029] [Figure 1] FIG. 1 is a cross-sectional view of a composite material including various layers of polytetrafluoroethylene and polyethylene, according to an embodiment.

[0030] [Figure 2] FIG. 2 is a cross-sectional view of another composite material including various layers of polytetrafluoroethylene, including an outer layer of low density polyethylene, according to an embodiment.

[0031] [Figure 3] 3A-3E are images of wear of various composite materials, according to various embodiments.

[0032] [Figure 4] FIG. 4 is a diagram of an implantable medical device implementing a composite material, according to an embodiment.

[0033] [Figure 5] FIG. 5 is a diagram of an implantable medical device with composite tags in locations where friction is likely, according to an embodiment.

[0034] [Figure 6] FIG. 6 is an implantable medical device formed from a composite of expanded polytetrafluoroethylene and expanded polyethylene, according to an embodiment.

[0035] [Figure 7] FIG. 7 illustrates an implantable medical device with a graft attachment tape formed from a composite material, according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0036] Definitions and Terminology The present disclosure should not be construed in a limiting sense. For example, the terms used in this application should be interpreted broadly in accordance with the meaning that one of ordinary skill in the art would assign to such terms.

[0037] With respect to terms related to imprecision, the terms "about" and "approximately" may be used interchangeably to refer to measurements that include and are reasonably close to the stated measurement. A measurement that is reasonably close to the stated measurement deviates from the stated measurement by a reasonably small amount, to the extent that it would be understood and readily grasped by one of ordinary skill in the relevant art. Such deviations may result from, for example, measurement error, differences in the calibration of measuring and / or manufacturing equipment, human error in reading and / or setting measurements, fine-tuning made to optimize performance and / or structural parameters to account for variations in measurements associated with other components, specific implementation scenarios, imprecise adjustment and / or manipulation of the object by a person or machine, and / or the like. If it is determined that the value of such a reasonably small difference would not be readily grasped by a person of ordinary skill in the relevant art, the terms "about" and "approximately" shall be understood to mean plus or minus 10% of the stated value.

[0038] As used herein, "couple" means to join, connect, attach, adhere, affix, or join, whether directly or indirectly, permanently or temporarily.

[0039] The term "composite material," as used herein, refers to a material comprising two or more material components that have one or more different material properties from each other. In some instances, a composite material includes at least a first material component in the form of a membrane and a second material component in the form of a polymer bonded to the membrane (e.g., by a coating and / or imbibition process). The term "laminate," as used herein, refers to multiple layers of membranes, composites, or other materials, such as, but not limited to, polymers, including, but not limited to, elastomers, elastomeric or non-elastomeric materials, and combinations thereof.

[0040] The term "film," as used herein, refers generically to one or more of a membrane, a composite, or a laminate.

[0041] The term "biocompatible material," as used herein, refers generally to any material that has biocompatible properties, including, but not limited to, synthetic materials such as biocompatible polymers, or biological materials such as, but not limited to, bovine pericardium. The biocompatible material can include a first film and a second film, as described in various embodiments herein.

[0042] The term "polyethylene" (PE), as used herein, includes all types of polyethylene, including, but not limited to, expanded polyethylene (ePE).

[0043] The term "polytetrafluoroethylene" (PTFE), as used herein, includes all types of polytetrafluoroethylene, including, but not limited to, expanded polytetrafluoroethylene (ePTFE).

[0044] The term "graft attach tape" as used herein includes any type of tape used to attach graft material or implemented onto a stent graft.

[0045] Description of Various Embodiments Those skilled in the art will readily appreciate that the various aspects of the present disclosure may be implemented by any number of methods and apparatus configured to perform the intended functions. It should also be noted that the accompanying drawings referred to herein are not necessarily drawn to scale and may be exaggerated to illustrate various aspects of the present disclosure, and in that regard the drawings should not be construed as limiting.

[0046] The composite material shown in FIG. 1 is provided as an example of various features of a composite material, and while combinations of the illustrated features are clearly within the scope of the present invention, this example and its illustration are not intended to suggest that the inventive concepts provided herein are limited from fewer features, additional features, or alternative features to one or more of the features shown in FIG. 1. For example, in various embodiments, a layer of the composite material shown in FIG. 1 can include a layer described with reference to FIG. 2. It should be understood that the reverse is also true. One or more components shown in FIG. 1 can be used in addition to or as a substitute for the components shown in FIG. 2. The composite materials of FIGS. 1 and 2 can be implemented in various devices and components, such as those shown in FIGS. 4-6. While the devices shown in FIGS. 4-6 can implement the composite materials described herein, it is understood that the composite materials can be implemented in the context of a variety of devices, systems, and methods.

[0047] FIG. 1 illustrates an exemplary composite material 10 incorporating various polymer layers to provide a durable, wear-resistant material that can be implemented in a variety of contexts, including, but not limited to, implantable medical devices. The various polymer layers are combined to impart specific properties that enhance the material's resistance to degradation due to repeated motion, which can lead to wear. Each layer can be implemented to provide a different function, such as durability in a specific direction (e.g., X, Y, and Z directions, or compression, tension, etc.). Providing a wear-resistant material that can withstand repeated motion and limit degradation or damage can extend the life of the implantable device, leading to fewer procedures, a reduced risk of device failure, and increased confidence in the device's effectiveness.

[0048] Composite material 10 includes multiple layers. For example, composite material 10 includes a base layer 12, an outer layer 14, and at least one intermediate layer 16. Base layer 12 and outer layer 14 can include materials with properties suitable for human implantation, such as materials that are biostable and suitable for contact with or direct exposure to living tissue. In some embodiments, base layer 12 can include a material suitable for contact with blood (e.g., polytetrafluoroethylene or polyethylene). The various layers can be bonded to one another in various ways, including, but not limited to, bonding, adhesion, absorption, etc. For example, composite material 10 can include a first polymer layer (e.g., base layer 12), a densified second polymer layer (e.g., first intermediate layer 16a) bonded to the first polymer layer, a porous expanded third polymer layer (e.g., second intermediate layer 16b) bonded to the densified second layer, an adhesive (e.g., third intermediate layer 16c), and a densified expanded polymer layer (e.g., outer layer 14, where the outer layer is formed from a different polymer than base layer 12).

[0049] In a more specific example, the base layer 12 is formed from polytetrafluoroethylene (PTFE) and the outer layer 14 is formed from polyethylene (PE). The PTFE base layer 12 provides Z-axis strength, while the PE outer layer 14 provides XY-axis strength, enhancing resistance to material particulation during friction (which not only thins the material where contact occurs, but can also release loose material into the body). The PTFE base layer 12 is operable to impart Z-axis strength (e.g., through compression) to the PE outer layer 14 (which may have relatively low Z-axis strength), while the PE outer layer 14 limits damage due to friction or abrasion.

[0050] The performance of the composite properties of the PTFE base layer 12 and the PE outer layer 14 is enhanced by the strong bond between the PTFE base layer 12 and the PE outer layer 14. Intermediate layers 16 may be implemented to provide a strong bond to reduce the likelihood of delamination of the composite 10, particularly materials that may include different material properties, such as hydrophobicity. By providing a strong bond between the layers, each layer contributes an individual benefit to the combined substrate as a whole. Intermediate layers may also impart other properties to the substrate, including, but not limited to, Z-axis strength. Any number of intermediate layers may be implemented to achieve a strong bond as well as provide other properties, including increased strength and durability.

[0051] With further reference to the example including the PTFE base layer 12 and the PE outer layer 14, the intermediate layer 16 can include a layer formed from a material that is the same as or similar to one or both of the PTFE base layer 12 and the PE outer layer 14. In other embodiments, the intermediate layer 16 can include a layer formed from a material that is different from the PTFE base layer 12 and the PE outer layer 14, where the different material can bond strongly to one or both of the PTFE base layer 12 and the PE outer layer 14.

[0052] In one example, Figure 1 shows a composite material 10 with a PTFE base layer 12, a PE outer layer 14, and an intermediate layer 16 of both PTFE and PE. For example, the PTFE base layer 12 is formed from expanded PTFE (ePTFE), the PE outer layer 14 is formed from expanded polyethylene (ePE), and the intermediate layer 16 includes a densified ePTFE intermediate layer 16a, an ePTFE intermediate layer 16b, and a low-density PE (LDPE) intermediate layer 16c (implemented as an adhesive). In this example, the ePTFE base layer 12 may serve as the blood-contacting surface because the properties of ePTFE are stable to blood contact. The densified ePTFE intermediate layer 16a bonded to the ePTFE base layer 12 may provide Z-axis strength to the composite material 10. The ePTFE intermediate layer 16b is bonded to the densified ePTFE intermediate layer 16a, which comprises a porous open network. The LDPE intermediate layer 16c is bonded to the ePTFE intermediate layer 16b, and the PE outer layer 14 is bonded to the LDPE intermediate layer 16c. The LDPE intermediate layer 16c acts as an adhesive between the PE outer layer 14 and the ePTFE intermediate layer 16b. For example, the LDPE intermediate layer 16c can be absorbed into the ePTFE intermediate layer 16b. The open, porous nature of the ePTFE intermediate layer 16b allows the LDPE intermediate layer 16c to at least partially penetrate or be absorbed into the pores of the ePTFE intermediate layer 16b, which can be achieved by low-temperature processing (e.g., about 130°C). In some embodiments, the PE outer layer 14 can be a densified ePE material with abrasion resistance. The PE outer layer 14 can be applied to the LDPE intermediate layer 16c by low-temperature processing (e.g., about 130°C). It is understood that various types of films can be used for the base layer, intermediate layer, and outer layer. For example, the layers can be reversed, such that PE is implemented on the base layer 12 and ePTFE is implemented on the outer layer 14. It is understood that the layers discussed herein can include one or more layers (e.g., a layer can include multiple films of the same or similar material bonded together to form individual layers).

[0053] 1, the densified ePTFE intermediate layer 16a can include a densified ePTFE film operable to provide hoop strength and creep strength to the composite 10. For an example of a densified ePTFE film, see U.S. Patent No. 7,521,010 to Kennedy and Hollenbaugh Jr. The densified ePTFE intermediate layer 16a can be from about 1 micrometer to about 200 micrometers in thickness. In some embodiments, intermediate layer 16a is about 1 micrometer to about 2 micrometers, about 2 micrometers to about 3 micrometers, about 3 micrometers to about 4 micrometers, about 4 micrometers to about 5 micrometers, about 5 micrometers to about 6 micrometers, about 6 micrometers to about 7 micrometers, about 7 micrometers to about 8 micrometers, about 8 micrometers to about 9 micrometers, about 9 micrometers to about 10 micrometers, about 10 micrometers to about 15 micrometers, about 15 micrometers to about 20 micrometers, about 20 micrometers to about 25 micrometers, about 25 micrometers to about 30 micrometers, about 30 micrometers to about 35 micrometers, about 35 micrometers to about 40 micrometers, about 40 micrometers to about 45 micrometers, about 45 micrometers to about 50 micrometers, about 50 micrometers to about 100 micrometers, about 100 micrometers to about 150 micrometers, or about 100 micrometers to about 200 micrometers. In one example, the densified ePTFE intermediate layer 16a is formed from densified ePTFE with fluorinated ethylene propylene (FEP) as an adhesive operable to maintain a strong bond or adhesion.

[0054] The ePTFE intermediate layer 16b can be formed from an open, porous ePTFE material. The ePTFE intermediate layer 16b provides an adhesive surface for absorbing other layers (e.g., the LDPE intermediate layer 16c). The ePTFE intermediate layer 16b can also provide burst strength, suture retention strength, longitudinal strength, and creep resistance to the overall structure (e.g., the composite material 10). The ePTFE intermediate layer 16b can be from about 1 micrometer to about 200 micrometers thick. In some embodiments, the ePTFE intermediate layer 16b is about 1 micrometer to about 2 micrometers, about 2 micrometers to about 3 micrometers, about 3 micrometers to about 4 micrometers, about 4 micrometers to about 5 micrometers, about 5 micrometers to about 6 micrometers, about 6 micrometers to about 7 micrometers, about 7 micrometers to about 8 micrometers, about 8 micrometers to about 9 micrometers, about 9 micrometers to about 10 micrometers, about 10 micrometers to about 15 micrometers, about 15 micrometers to about 20 micrometers, about 20 micrometers to about 25 micrometers, about 25 micrometers to about 30 micrometers, about 30 micrometers to about 35 micrometers, about 35 micrometers to about 40 micrometers, about 40 micrometers to about 45 micrometers, about 45 micrometers to about 50 micrometers, about 50 micrometers to about 100 micrometers, about 100 micrometers to about 150 micrometers, or about 100 micrometers to about 200 micrometers. In some embodiments of the ePTFE intermediate layer 16b, FEP can be included as an adhesive within the individual films that make up the ePTFE intermediate layer 16b.

[0055] The LDPE interlayer 16c acts as an adhesive to bond the various layers together, hi some embodiments, the LDPE interlayer 16c forms a layer having a thickness of from 1 micrometer to about 200 micrometers. In some embodiments, the thickness of LDPE intermediate layer 16c is about 1 micrometer to about 2 micrometers, about 2 micrometers to about 3 micrometers, about 3 micrometers to about 4 micrometers, about 4 micrometers to about 5 micrometers, about 5 micrometers to about 6 micrometers, about 6 micrometers to about 7 micrometers, about 7 micrometers to about 8 micrometers, about 8 micrometers to about 9 micrometers, about 9 micrometers to about 10 micrometers, about 10 micrometers to about 15 micrometers, about 15 micrometers to about 20 micrometers, about 20 micrometers to about 25 micrometers, about 25 micrometers to about 30 micrometers, about 30 micrometers to about 35 micrometers, about 35 micrometers to about 40 micrometers, about 40 micrometers to about 45 micrometers, about 45 micrometers to about 50 micrometers, about 50 micrometers to about 100 micrometers, about 100 micrometers to about 150 micrometers, or about 100 micrometers to about 200 micrometers. The LDPE intermediate layer 16c can act as a backer for the other layers, providing some stiffness and improving the abrasion and puncture / tear resistance of the composite 10. While the example shown with respect to FIG. 1 is formed from LDPE, it is understood that the intermediate layer 16c can be formed from a variety of other materials that function as adhesives. For example, the intermediate layer 16c can include fluoropolymers, polyurethane copolymers, silicone wet layup, polyurethane, etc. Such adhesives can be selected to melt at low temperatures, allowing them to be applied without impairing the properties of the other layers through heat treatment.

[0056] In some embodiments, the materials discussed herein may be selected based on molecular weight. It is understood that molecular weight can be a strong indicator of strength and density, and plays a role in toughness or compressibility. It is also understood that the material to be implemented may be selected taking into consideration any pre-treatments that may be performed, including heat treatments prior to incorporation into a composite, as well as how it will be affected (e.g., via heat treatments) during construction of the composite. It is also understood that the temperature at which the material is implemented may affect the properties of the composite (e.g., level of creep resistance at room temperature vs. body temperature).

[0057] 2 is an example of a composite material 10 similar to the composite material discussed with respect to FIG. 1, but further including an LDPE layer 18 bonded to the PE outer layer 14 such that the PE outer layer 14 is sandwiched between two LDPE layers. It is understood that various layers can be arranged as the base layer 12 and the outer layer 14 depending on the particular properties desired for the surface. Various characteristics that can be selected include porosity, texture, biocompatibility, coatability, handleability, coefficient of friction, etc. In some embodiments, the PE outer layer 14 (e.g., densified ePE) has a thickness of 2 micrometers to about 10 micrometers.

[0058] The various layers can have similar thicknesses, different thicknesses, or a combination of similar and different thicknesses. For example, in some embodiments, the ePTFE layer can be an ultra-thin-wall ePTFE layer. In some embodiments, the PTFE base layer 12 (e.g., densified ePTFE) has a thickness of 10 micrometers to about 50 micrometers. The PTFE base layer 12 can be provided in various configurations, including, but not limited to, a tube shape or a sheet. When formed into a tubular shape, the PTFE base layer 12 can provide a seamless tube. The PTFE base layer 12 can provide longitudinal strength to the composite material 10. The PTFE base layer 12 provides a porous luminal surface for tissue ingrowth and thrombosis resistance (e.g., via patency).

[0059] In some embodiments, the PE outer layer 14 can be either a gel or pasted ePE film. As previously described, the PE outer layer 14 can be coated on one or both sides with LDPE to improve adhesion to other layers and increase the strength of the composite material 10. For example, when the outer surface of the PE outer layer 14 is coated with LDPE, the LDPE can operate to provide abrasion resistance by helping to reduce surface tears and / or disruptions (e.g., keeping the surface intact).

[0060] In some embodiments, the PE layer can be bonded to the PTFE layer by imbibing LDPE onto at least one surface of each layer. Once the PE and PTFE layers have LDPE-imbibed surfaces, the imbibed surfaces of the PE and PTFE can be bonded together (e.g., by heat treatment at approximately 130°C). The adhesion between the LDPE-imbibed surfaces of the PE and PTFE layers can provide a peel strength of approximately 4 Newtons, indicating strong adhesion between the two layers. The stronger the adhesion between the layers, the more the individual properties of the various layers are incorporated into the composite 10. For example, achieving strong adhesion between PTFE and PE incorporates the Z-axis strength of the PTFE layer into the composite, as well as the resistance of the PE layer to pilling (e.g., thinning of the material due to extrusion). When the bond between the PE and PTFE layers is compromised or incomplete (e.g., in a composite with low peel strength), the Z-axis strength of the composite 10 can be reduced, potentially resulting in stretching and / or tearing or ripping of the material in the composite 10.

[0061] Figures 3A-3E show the abrasion resistance test results for various composites. The abrasion resistance test involved applying a force of 2 Newtons at 5 Hz for 300 seconds, with a stop test at 1500 cycles. Figure 3A shows an ePE membrane (Composite 10A) with a dense porous structure (e.g., pore size greater than 5 micrometers). The ePE membrane was not treated with LDPE. As shown, the ePE membrane exhibited pilling and tearing in the upper layer, failing by 1500 cycles. Figure 3B shows an ePE membrane (Composite 10b) with an LDPE layer. The ePE membrane has a dense porous structure (e.g., approximately 3 micrometers). The inclusion of LDPE in the ePE membrane reduced pilling, eliminated tearing, and maintained a relatively smooth surface after the test cycles. Figure 3C shows a densified ePE membrane (Composite 10c) with an LDPE layer. The densified ePE membrane (ADD measurement) exhibited no pilling, tearing, or tearing. The densified ePE membrane showed some signs of material elongation in the Z-axis direction. Figure 3D shows composite 10d, which includes two densified ePE membranes with an LDPE layer. Composite 10d was subjected to an abrasion test and showed no buildup, tearing, or splitting. Composite 10d showed some signs of material elongation in the Z-axis direction, but the stretching was less than that of the composite in Figure 3C. Figure 3E shows composite 10e, which includes a densified ePE membrane and an ePE layer (with a dense porous structure) with an LDPE layer. Composite 10e was subjected to an abrasion test and showed no buildup, tearing, or splitting. Composite 10e showed minimal material elongation in the Z-axis direction, with the ePE layer intact.

[0062] The various layers of the composite materials described herein can be processed individually or in combination. A variety of processes can be implemented, including, but not limited to, those described in Sbriglia Patent No. 9,926,416, issued March 27, 2018, Sbriglia U.S. Patent No. 10,577,468, issued March 3, 2020, Bell PCT Publication No. WO2020 / 028328, filed July 30, 2019, and Bell PCT Publication No. WO2020 / 028331, filed July 30, 2019. [Example]

[0063] The composite material 10 discussed herein can be implemented in a variety of devices and in a variety of contexts. The following are examples in which the composite material 10 can be implemented. The following examples should not be construed as limiting the invention.

[0064] Example 1 The composite material 10 can be implemented into an implantable stent graft 100. Referring to FIG. 4, the stent graft 100 includes a graft member 102 and a stent member 104 coupled thereto. The graft member 102 is formed from the composite material 10. The composite material 10 is formed as a tubular member, with the graft member 102 including a PTFE base layer 12 as a blood-contacting surface and a PE outer layer 14 coupled to the stent member 104 (see FIGS. 1 and 2). The PE outer layer 14 is operable to withstand abrasion due to movement of the stent member 104 during implantation and use. This is appropriate in many situations, including when the stent graft 100 is implanted in a curved vessel (e.g., in or near the aortic arch), a vessel subject to high pressure, or repetitive movement (e.g., the aorta). Implementing the above-described composite material 10 reduces the likelihood of abrasion of the graft member 102 of the stent graft 100 due to repetitive movement.

[0065] The biocompatible materials for the graft components discussed herein can be used in addition to, in combination with, or as layers of the composite material 10 discussed herein. In certain examples, the graft can include a fluoropolymer. In some examples, the graft can be formed from, but is not limited to, polyester, silicone, urethane, polyethylene terephthalate, or other biocompatible polymers, or combinations thereof. In some examples, bioresorbable or bioabsorbable materials can be used, such as bioresorbable or bioabsorbable polymers. In some examples, the graft can include Dacron, polyolefin, carboxymethyl cellulose fabric, polyurethane, or other woven, nonwoven, or film elastomers.

[0066] Additionally, while nitinol (NiTi) can be used as the frame or stent (and any frame discussed herein) material, other materials, including but not limited to, stainless steel, L605 steel, polymers, MP35N steel, polymeric materials, Pyhnox, Elgiloy, or other suitable biocompatible materials and combinations thereof, can be used as the frame material. The superelastic properties and flexibility of NiTi can improve the conformability of the stent. Furthermore, NiTi can be shape-set to a desired shape, i.e., when the frame is unconstrained, such as when it is deployed from a delivery system, the frame will self-expand to a desired shape.

[0067] Example 2 The composite material can be implemented as a patch or tag 200 on the implantable medical device in locations where the surface of the implantable medical device may be worn away by repeated motion. As shown in FIG. 5 , a stent graft 300 is provided with tags 200 at locations where frictional wear is likely. For example, the stent graft includes a stent member 302 and a graft member 304 coupled together. The stent member 302 includes a plurality of apexes 306. The tags 200 are positioned between the apexes 306 of the stent member 302 and the graft member 304 (e.g., the abluminal surface of the graft member 304). The tags 200 can be coupled to the graft member 304 in a variety of ways. For example, the tags 200 can be adhered via an adhesive or applied via a heat treatment (e.g., a heat gun). In other embodiments, the tags can be formed from PE or IPA and applied (e.g., absorbed) as a slurry over the mask. It will be appreciated that the tags 200 may be applied to the stent graft 300 at a variety of locations where wear or friction may occur.

[0068] Example 3 Referring to Figure 6, an artificial cartilage 400 is shown. The artificial cartilage 400 is formed from a composite material 10. The composite material includes a PE outer layer 14 and a PTFE base layer 12. The PTFE base layer 12 may include a hydrogel 402, which helps provide cushioning to the composite material 10. The PE outer layer 14 provides high friction or wear resistance, as previously described. The artificial cartilage 400 can be implemented in a variety of locations, including, but not limited to, for use as an artificial meniscus replacement.

[0069] Example 4 7, a graft attachment tape 500 is provided using the composite material 10 discussed herein. For example, the graft attachment tape 500 can be implemented in a stent graft, where the stent structure 510 includes a first apex 512 and a second apex 514. The graft attachment tape 500 can be implemented to attach the first apex 512 to a graft material 520. In some embodiments, the graft attachment tape 500 has a width such that the graft attachment tape is positioned between the second apex 514 and the graft material 520, thereby providing an abrasion-resistant barrier between the second apex 514 and the graft material 520. For example, the graft attachment tape 500 can be implemented in an ultra-thin-walled device, which can provide increased abrasion resistance in locations that may experience increased wear during use. For clarity, FIG. 7 shows only one row of vertices 512, 514 with graft attachment tape 500, but it will be understood that the graft attachment tape 500 can be positioned over or between the vertices 512, 514 of the device.

[0070] The present invention has been described above both generally and with reference to specific embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments without departing from the scope of the present disclosure. Therefore, it is intended that the embodiments cover the modifications and variations of the present invention provided they come within the scope of the appended claims and their equivalents.

Claims

1. an expanded polytetrafluoroethylene layer; a densified expanded polytetrafluoroethylene layer bonded to the expanded polytetrafluoroethylene layer; a porous expanded polytetrafluoroethylene layer bonded to the densified expanded polytetrafluoroethylene layer; Adhesive and a densified oriented polyethylene layer; comprising The composite material, wherein the adhesive bonds the expanded polyethylene layer to the porous expanded polytetrafluoroethylene layer.

2. The composite material of claim 1 , wherein the adhesive is low density polyethylene.

3. The composite material of claim 1 further comprising a thin layer of low density polyethylene bonded to said oriented polyethylene layer.

4. 4. The composite material of claim 3, wherein said thin layer of low density polyethylene and said adhesive sandwich said layer of oriented polyethylene.

5. The composite material of claim 1 , wherein the densified oriented polyethylene layer has a thickness of about 2 micrometers to about 5 micrometers.

6. The composite material of claim 1 , wherein the adhesive is at least partially absorbed into the porous expanded polytetrafluoroethylene layer.

7. 7. The composite material of claim 6, wherein the adhesive is processed at a temperature ranging from about 130°C to about 145°C to bond the densified expanded polyethylene layer and the porous expanded polytetrafluoroethylene layer.

8. The composite material of claim 1 , wherein the densified expanded polytetrafluoroethylene layer has a thickness of about 2 micrometers to about 10 micrometers.

9. The composite material of claim 1 , wherein the porous expanded polytetrafluoroethylene layer has a thickness of about 10 micrometers to about 50 micrometers.

10. The composite material of claim 1 , wherein the adhesive forms a layer having a thickness of about 1 micrometer to about 200 micrometers.

11. 1. An implantable device comprising a tubular member formed from a composite material, said tubular member comprising: a first polymer layer comprising a blood contact surface; a densified second polymer layer bonded to the first polymer layer; a porous expanded third polymer layer bonded to the densified second polymer layer; Adhesive and a densified oriented polyethylene layer; wherein the adhesive bonds the densified expanded polyethylene layer to the porous expanded third polymer layer.

12. The implantable device of claim 11 , wherein the first polymer layer is an expanded polytetrafluoroethylene layer.

13. The implantable device of claim 11 , wherein said densified second polymer layer is a densified polytetrafluoroethylene layer.

14. The implantable device of claim 11 , wherein said porous expanded third polymer layer is a porous expanded polytetrafluoroethylene layer.

15. The implantable device of claim 11 , wherein the adhesive is low density polyethylene.

16. 16. The implantable device of claim 15, wherein said low density polyethylene is imbibed into said porous expanded third polymer layer.

17. The implantable device of claim 11 , wherein the tubular member is a graft.

18. 18. The implantable device of claim 17, further comprising a stent coupled to the tubular member.

19. a first polytetrafluoroethylene layer; a second polyethylene layer bonded to the first polytetrafluoroethylene layer; comprising The implantable medical device, wherein the second polyethylene layer is operable to be placed against a structure that is non-stationary relative to the second polyethylene layer.

20. 20. The implantable medical device of claim 19, wherein the first polytetrafluoroethylene layer and the second polyethylene layer are comprised in one of a graft, a tag, a cartilage substitute, an implantable medical device, and a removable medical device.

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