POLY(ETHER-CARBONATE)-BASED POLYMERS AND MEDICAL DEVICES

Abstract

A poly(ether-carbonate)-based polymer and a medical device that includes such polymer, wherein the poly(ether-carbonate)-based polymer includes urethane, urea, or urethane-urea groups, hard segments, and soft segments, wherein the soft segments include poly(ether-carbonate) residues and at least one of polyisobutylene (PIB) residues and hydrogenated polybutadiene residues, and the hard segments include diisocyanate residues and optionally chain extender residues.

Claims

1. A poly(ether-carbonate)-based polymer comprising urethane, urea, or urethane-urea groups, hard segments, and soft segments, wherein the soft segments comprise poly(ether-carbonate) residues and at least one of polyisobutylene residues and hydrogenated polybutadiene residues, and the hard segments comprise diisocyanate residues and optionally chain extender residues.

2. The poly(ether-carbonate)-based polymer of claim 1 comprising urethane groups.

3. The poly(ether-carbonate)-based polymer of claim 1 wherein the hard segments comprise chain extender residues.

4. The poly(ether-carbonate)-based polymer of claim 1 wherein the soft segments comprise poly(ether-carbonate) residues and polyisobutylene residues.

5. The poly(ether-carbonate)-based polymer of claim 1 wherein the polyisobutylene residues are derived from a polyisobutylene diol, a polyisobutylene diamine, or a combination thereof.

6. The poly(ether-carbonate)-based polymer of claim 5 wherein the polyisobutylene residues comprise aromatic-containing polyisobutylene residues.

7. The poly(ether-carbonate)-based polymer of claim 1 wherein the weight ratio of soft segments to hard segments is within a range of 90:10 to 10:90.

8. The poly(ether-carbonate)-based polymer of claim 1 wherein the weight ratio of polyisobutylene residues to poly(ether-carbonate) residues is within a range of 99:1 to 1:99.

9. The poly(ether-carbonate)-based polymer of claim 1 having a weight average molecular weight of 10,000 Daltons to 2,000,000 Daltons, as determined by gel permeation chromatography with multiangle laser light scattering detection.

10. The poly(ether-carbonate)-based polymer of claim 1 having a greater tear strength than a comparative polymer without poly(ether-carbonate) residues, wherein the comparative polymer has a shore durometer within 50% to 150% of the shore durometer of the poly(ether-carbonate)-based polymer.

11. The poly(ether-carbonate)-based polymer of claim 1 having greater overall chemical stability than a comparative polymer with poly(tetramethylene oxide) residues instead of poly(ether-carbonate) residues, wherein the comparative polymer has an amount of poly(tetramethylene oxide) residues equal to an amount of poly(ether-carbonate) residues in the poly(ether-carbonate)-based polymer, and wherein the comparative polymer has a shore durometer within 50% to 150% of the shore durometer of the poly(ether-carbonate)-based polymer.

12. A medical device comprising a polymeric region comprising the poly(ether-carbonate)-based polymer of claim 1.

13. The medical device of claim 12 comprising an implantable electrical lead, an implantable electrical pulse generator, or an implantable mechanical device.

14. The medical device of claim 13 comprising an implantable electrical lead.

15. The medical device of claim 12 wherein the polymeric region further comprises a therapeutic agent.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0031] FIG. 1 is a diagram of a lead which incorporates a polymer of the present disclosure.

[0032] FIG. 2 is a cross-sectional view of the lead body of the lead shown in FIG. 1.

[0033] FIG. 3 is a cross-section of an exemplary lead body.

[0034] FIG. 4 is a diagram of a neurological electrical lead which incorporates a polymer of the present disclosure.

[0035] FIG. 5 is a diagram of a neurological drug delivery lead which incorporates a polymer of the present disclosure.

[0036] FIG. 6 is an SEM image of PIB-PEC-PU at 400 magnification after 8 weeks of oxidation aging.

[0037] FIG. 7 is an SEM image of PIB-PTMO-PU (comparative polymer) at 400 magnification after 8 weeks of oxidation aging.

[0038] FIG. 8 is an SEM image of PIB-PU (comparative polymer) at 400 magnification after 8 weeks of oxidation aging.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0039] This disclosure provides a poly(ether-carbonate)-based polymer and a medical device that includes such polymer.

[0040] In one embodiment, a poly(ether-carbonate)-based polymer is provided that includes urethane, urea, or urethane-urea groups, hard segments, and soft segments, wherein the soft segments include poly(ether-carbonate) residues and at least one of polyisobutylene (PIB) residues and hydrogenated polybutadiene residues, and the hard segments include diisocyanate residues and optionally chain extender residues. In certain embodiments, a poly(ether-carbonate)-based (PEC-based) polymer of the present disclosure includes urethane groups, and in certain embodiments, no urea groups. Such polymers are elastomers.

[0041] The use of poly(ether-carbonate) with PIB or hydrogenated polybutadiene as soft segments results in a polymer having surprisingly better mechanical properties, particularly tear strength, compared to the similar polymers without the poly(ether-carbonate). Tear strength is very important for certain medical device applications. For example, a lead insulation tubing with low tear strength will tend to split.

[0042] In certain embodiments, a poly(ether-carbonate)-based polymer of the present disclosure has a greater tear strength than a comparative polymer without poly(ether-carbonate) residues, wherein the comparative polymer has a shore durometer within 50% to 150% of the shore durometer of the poly(ether-carbonate)-based polymer. In certain embodiments, a poly(ether-carbonate)-based polymer of the present disclosure has a tear strength at least 10%, or at least 20%, greater than a comparative polymer without poly(ether-carbonate) residues, wherein the comparative polymer has a shore durometer within 50% to 150% of the shore durometer of the poly(ether-carbonate)-based polymer.

[0043] The use of poly(ether-carbonate) with PIB or hydrogenated polybutadiene as soft segments results in a polymer having surprisingly better chemical stability compared to similar polymers without the poly(ether-carbonate).

[0044] In certain embodiments, a poly(ether-carbonate)-based polymer of the present disclosure has greater overall chemical stability than a comparative polymer with poly(tetramethylene oxide) residues instead of poly(ether-carbonate) residues, wherein the comparative polymer has an amount of poly(tetramethylene oxide) residues equal to an amount of poly(ether-carbonate) residues in the poly(ether-carbonate)-based polymer, and wherein the comparative polymer has a shore durometer within 50% to 150% of the shore durometer of the poly(ether-carbonate)-based polymer.

[0045] In certain embodiments, a poly(ether-carbonate)-based polymer of the present disclosure has a weight average molecular weight of at least 10,000 Daltons, as determined by gel permeation chromatography with multiangle laser light scattering detection. In certain embodiments, a poly(ether-carbonate)-based polymer of the present disclosure has a weight average molecular weight of up to 2,000,000 Daltons, or up to 1,000,000 Daltons, as determined by gel permeation chromatography with multiangle laser light scattering detection. In certain embodiments, a poly(ether-carbonate)-based polymer of the present disclosure has a weight average molecular weight of 10,000 Daltons to 2,000,000 Daltons, or 10,000 Daltons to 1,000,000 Daltons, as determined by gel permeation chromatography with multiangle laser light scattering detection.

[0046] A polyurethane includes linkages of the following structure:

##STR00001##

Such polymers can be made using conventional techniques. Typically, polyurethanes are made by a process in which one or more polyfunctional isocyanates (e.g., diisocyanates, including both aliphatic and aromatic diisocyanates) is reacted with one or more polyols (e.g., diols) to form a prepolymer. The resulting prepolymer can be further reacted with a chain extender, such as a diol.

[0047] A polyurea includes linkages of the following structure:

##STR00002##

Such polymers can be made using conventional techniques. Typically, polyureas are made by a process in which one or more polyfunctional isocyanates (e.g., diisocyanates, including both aliphatic and aromatic diisocyanates) is reacted with one or more polyamines (e.g., diamines) to form a prepolymer. The resulting prepolymer can be further reacted with a chain extender, such as a diol.

[0048] A polyurethane-urea includes both of the above-described linkages. Such polymers can be made using conventional techniques. Typically, polyurethane-ureas are made by a process in which one or more polyfunctional isocyanates (e.g., diisocyanates, including both aliphatic and aromatic diisocyanates) is reacted with one or more polyamines (e.g., diamines) and one or more polyols (e.g., diols) to form a prepolymer. The resulting prepolymer can be further reacted with a chain extender, such as a diol.

Soft Segments

[0049] Soft segments of the polymers of the present disclosure include poly(ether-carbonate) residues and at least one of polyisobutylene (PIB) residues and hydrogenated polybutadiene residues (i.e., polyisobutylene residues and/or hydrogenated polybutadiene residues). In certain embodiments, soft segments of the polymers of the present disclosure consist essentially of poly(ether-carbonate) residues and polyisobutylene and/or hydrogenated polybutadiene residues, wherein there may be small amounts of other soft segment residues but only minor amounts that do not change the properties of the polymer. In certain embodiments, soft segments of the polymers of the present disclosure consist of poly(ether-carbonate) residues and polyisobutylene and/or hydrogenated polybutadiene residues, wherein there no other soft segment residues. In certain embodiments, soft segments of the polymers of the present disclosure consist of poly(ether-carbonate) residues and polyisobutylene residues.

[0050] In certain embodiments, polyisobutylene and/or hydrogenated polybutadiene soft segment residues can be derived from a diol, a diamine, or a combination thereof. In certain embodiments, the polyisobutylene and/or hydrogenated polybutadiene residues are derived from one or more diols.

[0051] In certain embodiments, the polyisobutylene residues include initiator residues. The term initiator residue refers to a difunctional chemical moiety, that links two linear chains of a polymer. For example, the polyisobutylene residues can be derived from a polyisobutylene of the following formula:

##STR00003##

wherein R.sub.1 is an initiator residue; each X is independently OH, NH.sub.2, or NHR.sub.4; n=0-500; m=0-500; each of R.sub.2 and R.sub.3 is selected from a (C1-C16)alkylene, a (C3-C16)cycloalkylene, a (C2-C16)alkenylene, a (C3-C16)cycloalkenylene, a (C2-C16)alkynylene, a (C3-C16)cycloalkynylene, or a (C6-C18)arylene, wherein for each occurrence of R.sub.2 or R.sub.3 is independently optionally substituted with one or more groups selected from halo, cyano, nitro, dialkylamino, trialkylamino, (C1-C16)alkoxy, and (C1-C16 haloalkyl); and R.sub.4 is selected from a (C1-C16)alkyl, a (C3-C16)cycloalkyl, a (C2-C16)alkenyl, a (C3-C16)cycloalkenyl, a (C2-C16)alkynyl, a (C3-C16)cycloalkynyl, or a (C6-C18)aryl.

[0052] Such compounds are referred to herein as PIB or polyisobutylene, i.e., a compound formed by polymerization of isobutylene and includes an initiator residue.

[0053] In certain embodiments, the polyisobutylene residues can be derived from a polyisobutylene diol of the following formula:

##STR00004##

wherein R.sub.1 is an initiator residue, n=0-500, and m=0-500.

[0054] Such initiator residues may include aromatic residues, aliphatic residues, or combinations thereof. Examples of initiators include 5-tert-butyl-1,3-bis(1-methoxy-1-methylethyl)-benzene (or hindered dicumyl ether or HDCEF), 1,3-bis(1-chloro-1-methylethyl)-5-(1-dimethylethyl)benzene (or, alternatively, known as 1,3-bis(1-chloro-1-methylethyl)-5-tert-butylbenzene or hindered dicumyl chloride or HDCC), 2,6-dichloro-2,4,4,6-tetramethylheptane, and 2,5-dichloro-2,5-dimethylhexane.

[0055] Such initiator residues may include aromatic residues. In certain embodiments, the polyisobutylene residues include aromatic-containing polyisobutylene residues. For example, the polyisobutylene residues can be derived from a polyisobutylene diol of the following formula:

##STR00005##

wherein n=0-500 and m=0-500.

[0056] In certain embodiments, poly(ether-carbonate) soft segment residues are derived from a poly(ether-carbonate) diol, a poly(ether-carbonate) diamine, or a combination thereof. In certain embodiments, poly(ether-carbonate) soft segment residues are derived from one or more poly(ether-carbonate) diols.

[0057] In certain embodiments, the poly(ether-carbonate) residues are derived from a poly(ether-carbonate) compound of the following formula:

##STR00006##

wherein each Y is independently OH, NH.sub.2, or NHR.sub.5, t=1-9, n=0-40, and m=1-40. Each of R.sub.5 is selected from a (C1-C16)alkyl, a (C3-C16)cycloalkyl, a (C2-C16)alkenyl, a (C3-C16)cycloalkenyl, a (C2-C16)alkynyl, a (C3-C16)cycloalkynyl, or a (C6-C18)aryl.

[0058] In certain embodiments, the poly(ether-carbonate) residues are derived from a poly(ether-carbonate) diol of the following formula:

##STR00007##

wherein t=1-9, n=0-40, and m=1-40.

[0059] Thus, the soft segments of the polymers of the present disclosure include copolymers of ether and carbonate groups. This is distinct from polymers that include pure polyether soft segments pure polycarbonate soft segments separated by hard segments. While polymers of the present disclosure may include a small amount of pure polyether soft segments and pure polycarbonate soft segments, the majority (typically, greater than 50 wt-%) of the soft segments include co-polyether-polycarbonate soft segments.

[0060] In certain embodiments, the weight ratio of polyisobutylene and/or hydrogenated polybutadiene residues to poly(ether-carbonate) residues is up to 99:1, up to 95:5, or up to 90:10. In certain embodiments, the weight ratio of polyisobutylene and/or hydrogenated polybutadiene residues to poly(ether-carbonate) residues is at least 1:99, at least 50:50, or at least 80:20. In certain embodiments, the weight ratio of polyisobutylene and/or hydrogenated polybutadiene residues to poly(ether-carbonate) residues is within a range of 99:1 to 1:99, within a range of 95:5 to 50:50, or within a range of 90:10 to 80:20.

[0061] In certain embodiments, soft segments may also include additional residues selected from polybutadiene residues, hydrogenated polybutadiene residues, polycarbonate residues, polyether residues, polyester residues, polysiloxane residues, and combinations thereof, which may be provided by diols, diamines, or combinations thereof. If present, such additional soft segment residues are present in an amount of no more than 60% of final polymer by weight.

Hard Segments

[0062] A poly(ether-carbonate)-based polymer of the present disclosure includes hard segments including diisocyanate residues and optionally chain extender residues.

[0063] In certain embodiments, the diisocyanate residues are derived from 4,4-methylenediphenyl diisocyanate, 4,4-methylenebis(cyclohexyl isocyanate), toluene diisocyanate, 1,5-naphthalene diisocyanate, para-phenylene diisocyanate, 3,3-tolidene-4,4-diisocyanate, 3,3-dimethyldiphenylmethane-4,4-diisocyanate, and combinations thereof. In certain embodiments, the diisocyanate residues are derived from 4,4-methylenediphenyl diisocyanate (MDI) to contribute to a polymer having excellent hydrolysis stability.

[0064] In certain embodiments, hard segments include chain extender residues. In certain embodiments, the chain extender residues are derived from at least one chain extender selected from an aliphatic diol, an aromatic diol, an aliphatic diamine, an aromatic diamine, and a combination thereof. In certain embodiments, the chain extender includes one or more aliphatic diols. In certain embodiments, the aliphatic diol chain extender includes one or more alpha,omega-(C1-C16)alkane diols. In certain embodiments, the chain extender includes 1,2-ethane diol, 1,4-butanediol, 1,6-hexanediol, or combinations thereof.

[0065] In certain embodiments, the weight ratio of soft segments to hard segments in a poly(ether-carbonate)-based polymer of the present disclosure is up to 90:10, up to 80:20, or up to 70:30. In certain embodiments, the weight ratio of soft segments to hard segments in a poly(ether-carbonate)-based polymer of the present disclosure is at least 10:90, at least 30:70, or at least 40:60. In certain embodiments, the weight ratio of soft segments to hard segments in a poly(ether-carbonate)-based polymer of the present disclosure is within a range of 90:10 to 10:90, within a range of 80:20 to 30:70, or within a range of 70:30 to 40:60.

Medical Devices

[0066] The present disclosure also provides medical devices. Such devices include a polymeric region including the poly(ether-carbonate)-based polymer described herein. Such medical devices include, for example, an implantable electrical lead, an implantable electrical pulse generator, or an implantable mechanical device (e.g., ventricle assistance device, pump, and an artificial valve such as a prosthetic heart valve).

[0067] A prosthetic heart valve replaces the function of a native heart valve such that the prosthetic valve regulates the flow of blood through the heart. In one aspect, a prosthetic heart valve includes a base and a plurality of polymeric leaflets. Each leaflet has a root portion coupled to the base, and each leaflet has an edge portion substantially opposite the root portion and movable relative to the root portion to coat with a respective edge portion of at least one of the other leaflets of the plurality of leaflets.

[0068] Particularly suitable medical devices include medical leads. Medical leads are used to transmit electrical signals to and from medical devices such as pacemakers and neurostimulators, for example. The lead body is usually made from a piece of polymeric tubing having a round cross-section exterior and a round cross-section lumen. Typically, a coiled metallic electrical conductor having a round cross-section is placed in the lumen completely filling it. The tubing protects and insulates the conductor. The coiled conductor can usually receive a stylet to help position and place the lead during implantation. There are many examples of medical electrical leads, including, for example, those described in U.S. Pat. No. 6,785,576 (Vemess), U.S. Pat. No. 5,303,704 (Molacek et al.), U.S. Pat. No. 5,999,858 (Sommer et al.), U.S. Pat. No. 6,149,678 (DiDomenico et al.), U.S. Pat. No. 4,947,866 (Lessar et al.), U.S. Pat. No. 5,922,014 (Warman et al.), U.S. Pat. No. 5,628,778 (Kruse et al.), U.S. Pat. No. 4,497,326 (Curry), U.S. Pat. No. 5,443,492 (Stokes et al.), and U.S. Pat. No. 7,860,580 (Falk et al.).

[0069] In certain embodiments, the medical device is an implantable electrical lead. In certain embodiments, the electrical lead is a cardiac lead or a neurostimulation lead. In certain embodiments, the implantable electrical lead includes an electrical conductor and a layer including a poly(ether-carbonate)-based polymer of the present disclosure disposed on the electrical conductor. In certain embodiments, the polymeric region further includes a therapeutic agent (i.e., a drug).

[0070] As an exemplary embodiment of a medical electrical lead, FIG. 1 is a diagram of a lead assembly 10, which incorporates a polymer of the present disclosure. The lead body 26 carries four electrodes including ventricular electrodes 12 and 13 and atrial electrodes 14 and 15. Within the lead body are four conductors, one coupled to each of the electrodes and extending proximally to a corresponding electrical connector. The proximal end of the lead assembly 10 has a dual in-line connector assembly including connector pin 16, coupled to electrode 12, connector ring 18, coupled to electrode 13, connector pin 20, coupled to electrode 14 and connector ring 22, coupled to electrode 15. A stylet 24 may be 25 inserted into the lead through pin 16 to stiffen it as an aid to implantation.

[0071] Lead body 26 in FIG. 1 is preferably fabricated of silicone rubber, polyurethane or other implantable polymer. In particular, lead body 26 is preferably fabricated of a polymer of the present disclosure.

[0072] Electrodes 12, 13, 14, and 15 in FIG. 1 are preferably fabricated of platinum alloy or 30 other biocompatible metal. Connectors 16, 18, 20, and 22 are preferably fabricated of stainless steel or other biocompatible metal.

[0073] As illustrated, the lead includes electrodes which may serve as means for delivery of stimulation pulses and as means for sensing physiological electrical signals. It should also be understood that a lead according to the present disclosure may also include means for sensing other physiological parameters, such as pressure, oxygen saturation, temperature, or pH. The lead may include electrodes only, other physiologic sensors only, or a combination of both.

[0074] FIG. 2 is a cross-section through the lead body 26. In this view, it can be seen that lead body 26 is provided with four pie-shaped or generally triangular lumens. The first lumen 44 contains a first coiled conductor 43. The second lumen 46 contains a second coiled conductor 45. The third lumen 48 contains a third coiled conductor 47. The fourth lumen 50 contains a fourth coiled conductor 49. The conductors 43, 45, 47, and 49 are preferably fabricated of MP35N alloy or other biocompatible metal. In the drawing each coiled conductor is shown as a multi-filar coil; however, monofilar coils are useful as well.

[0075] One of the four conductors is coupled to pin 16 and also serves to receive a stylet. The lead body may employ the multi-lumen configuration illustrated over its entire length, with two of the lumens unused distal to electrodes 14 and 15. Alternatively, a transition to a lead body having a coaxial or side by side two-lumen configuration as typically used in bipolar pacing leads may occur at or distal to electrodes 14 and 15. As seen in cross section, the representative fourth lumen 50 has three walls each having a radius of curvature substantially greater than the radius of curvature of the conductor coil. These walls include two substantially planar walls 51 and 52 each extending along a radius of the body and an outer curved wall 53, extending along the outer circumference of the lead body. The walls are joined to one another along corners 55, 57, and 58 each of which have a radius of curvature substantially less than the radius of curvature of the conductor coils, as seen in this cross-section.

[0076] In certain embodiments, contact between a coil of a conductor and the inner surface of a lumen will be limited to those portions of the inner surfaces of the lumen which have a substantially greater radius of curvature than the conductor coil. Contact will thus be limited to discrete points of contact, rather than along substantial lengths of the individual coils, as would occur in prior leads employing circular coils and circular lumens of similar sizes. Contact will occur only along walls 51, 52 and 53, and not in corners 55, 57 and 59. Along the length of the lead, individual coils will contact various points on all three walls 51, 52, and 53.

[0077] The present medical electrical lead includes a polymeric material of the present disclosure as part or all of lead body 26, but theoretically this could apply to any insulator on the lead body.

[0078] FIG. 3 is a cross-section of another exemplary lead body showing several insulation layers: a primary insulation layer 1, which encapsulates the conductors; a secondary insulation layer 2, which contains the lumens for the conductors; and a tertiary outer insulation layer 3. The polymer of this disclosure forms part or all of any of these insulation layers.

[0079] Medical, neurological leads are used for insertion into the human body, for transmission of therapeutic agents (i.e., drugs) and/or electrical signals to body organs such as the spinal cord or brain, for acute and chronic pain relief, acute and chronic treatment of disease, and the like. The leads are used in programmable, electronic, implantable devices which deliver drugs and/or electrical stimulation in programs of therapy for the benefit of mankind.

[0080] Implantable electrical devices are capable of relieving chronic, inoperable pain by interfering with the transmission of pain signals in the spinal cord and brain. Implantable drug delivery devices are capable of delivering pain relieving drugs to the same dramatic effect. Both types of devices are also capable of new therapies for treatment of a variety of diseases. An advantage of the electrical devices is that typically no drugs are necessary. With the drug delivery devices, an advantage is that drug dosages are reduced relative to other therapies because the drugs are delivered directly to desired locations of therapy, rather than in remote locations such as the blood vessels of the extremities, and without concern for bodily elimination or chemical interaction.

[0081] With the electrical devices, electrical stimulation is typically delivered from the devices to the body through wired leads, to electrodes. The electrodes are located on and exposed to the body on the distal extremity of the leads, and the leads typically extend into and along the epidural space of the spinal cord, or into the brain at surgically drilled boreholes. The leads may also be subcutaneous where necessary. As an example, leads may extend from devices implanted above the clavicles, under the skin, to a bore hole atop the skull, and thence deep into brain tissue.

[0082] With the drug delivery devices, catheters, which for purposes of this description are also considered neurological leads, extend in similar ways. Leads in the described applications are typically smooth walled, plastic, tubular members, although variation is possible. There are many examples of medical neurological leads, including, for example, those described in U.S. Pat. No. 5,058,584 (Bourgeois), U.S. Pat. No. 5,865,843 (Baudino), U.S. Pat. Pub. No. 2008/0275429 (Sage).

[0083] Medical neurological leads include, for example, paddle leads, in-line cylindrical leads, and drug delivery catheters. These leads/catheters can be placed in numerous locations. Electrode leads are used in the epidural space, within the brain itself, in the sacral root, and within blood vessels. Cuff-type electrodes, as in U.S. Pat. No. 5,282,468 (Klepinski), can be mounted around nerve bundles or fibers. Drug delivery catheters can be placed in/adjacent the spinal column or any location within the vascular system. The polymeric material of the present disclosure may be used as all or part of the lead body, as insulation, as an inner or outer layer, etc.

[0084] Referring to FIGS. 4 and 5, an exemplary lead of the disclosure includes a distal portion 10, and associated central and proximal portions not shown. As known to persons of ordinary skill in the art, if electrical, the lead may connect to an electrical signal generating device (hereafter a signal generator), which may or may not be implantable in whole or in part into the human body. If the lead is a drug delivery lead, the lead may connect to a drug pump, which also may or may not be implantable. In either case, the lead is intended to have at least a portion engaged in the tissue of the body. Depending on the application, the lead may engage tissue in the proximal, central, or distal portions of the lead. The lead may or may not enter the epidural space which surrounds the spinal cord, or the lead may enter the brain through the skull. Generally, the lead is substantially elongated, with the dimension of its length one hundred or more times the dimension of its width.

[0085] Again, if electrical, as in FIG. 4, the lead 410 may include one or more electrodes, such as an electrode designated 412. The electrode may be annular, surrounding the lead 30 body, or in other shape or form. If a drug delivery lead, as in FIG. 5, the lead 522 may include one or more openings for transmission of drugs from the drug pump to the body, in the place of electrodes, or in addition to electrodes.

[0086] The lead 410 or 522 is desirably, generally circular in cross-section, although variations are within contemplation. Focusing on an electrical lead of FIG. 4, for illustration, an insulating, annular, external lead sheath or body 414 surrounds an electrically transmissive internal core 416, shown in phantom. The core 416 frequently takes the form of a helically wound or coiled wire, interconnected to the distal electrode(s) and the proximal signal generator. The wire has a direction of its winding, which is right hand or left hand, clockwise or counterclockwise. As desired, although not presently contemplated, the lead may also include additional intermediate or other layers, or other components.

[0087] FIG. 4. shows an electrical lead having a helical groove 418, and associated helical land 420. FIG. 5 shows a drug delivery lead or catheter having a liquid insulating, annular, external lead sheath or body 524 surrounds a liquid transmissive internal and open core or passage 526, shown in phantom.

EMBODIMENTS

[0088] Embodiment 1 is a poly(ether-carbonate)-based polymer comprising (or consisting essentially of or consisting of) urethane, urea, or urethane-urea groups, hard segments, and soft segments, wherein the soft segments comprise (or consist essentially of or consist of) poly(ether-carbonate) residues and at least one of polyisobutylene residues and hydrogenated polybutadiene residues, and the hard segments comprise (or consist essentially of or consist of) diisocyanate residues and optionally chain extender residues.

[0089] Embodiment 2 is the poly(ether-carbonate)-based polymer of embodiment 1 comprising urethane groups.

[0090] Embodiment 3 is the poly(ether-carbonate)-based polymer of embodiment 1 or 2 wherein the diisocyanate residues are derived from 4,4-methylenediphenyl diisocyanate, 4,4-methylenebis(cyclohexyl isocyanate), toluene diisocyanate, 1,5-naphthalene diisocyanate, para-phenylene diisocyanate, 3,3-tolidene-4,4-diisocyanate, 3,3-dimethyldiphenylmethane-4,4-diisocyanate, and combinations thereof.

[0091] Embodiment 4 is the poly(ether-carbonate)-based polymer of any of the previous embodiments wherein the hard segments comprise chain extender residues.

[0092] Embodiment 5 is the poly(ether-carbonate)-based polymer of embodiment 4 wherein the chain extender residues are derived from at least one chain extender selected from an aliphatic diol, an aromatic diol, an aliphatic diamine, an aromatic diamine, and a combination thereof.

[0093] Embodiment 6 is the poly(ether-carbonate)-based polymer of embodiment 5 wherein the chain extender comprises an aliphatic diol.

[0094] Embodiment 7 is the poly(ether-carbonate)-based polymer of embodiment 6 wherein the aliphatic diol chain extender comprises an alpha,omega-(C1-C16)alkane diol.

[0095] Embodiment 8 is the poly(ether-carbonate)-based polymer of embodiment 7 wherein the chain extender comprises 1,2-ethane diol, 1,4-butanediol, 1,6-hexanediol, or combinations thereof.

[0096] Embodiment 9 is the poly(ether-carbonate)-based polymer of any of the previous embodiments wherein the soft segments further comprise additional residues selected from polybutadiene residues, hydrogenated polybutadiene residues, polycarbonate residues, polyether residues, polyester residues, polysiloxane residues, and combinations thereof.

[0097] Embodiment 10 is the poly(ether-carbonate)-based polymer of any of the previous embodiments wherein the additional soft segment residues are present in an amount of no more than 60% of total polymer by weight.

[0098] Embodiment 11 is the poly(ether-carbonate)-based polymer of any of the previous embodiments wherein the soft segments comprise (or consist essentially of or consist of) poly(ether-carbonate) residues and polyisobutylene residues.

[0099] Embodiment 12 is the poly(ether-carbonate)-based polymer of embodiment 11 wherein the soft segments consist of poly(ether-carbonate) residues and polyisobutylene residues.

[0100] Embodiment 13 is the poly(ether-carbonate)-based polymer of any of the previous embodiments wherein the polyisobutylene residues and/or hydrogenated polybutadiene residues are derived from a polyisobutylene diol, hydrogenated polybutadiene diol, polyisobutylene diamine, hydrogenated polybutadiene diamine, or a combination thereof.

[0101] Embodiment 14 is the poly(ether-carbonate)-based polymer of embodiment 13 wherein the polyisobutylene residues comprise aromatic-containing polyisobutylene residues.

[0102] Embodiment 15 is the poly(ether-carbonate)-based polymer of embodiment 14 wherein the polyisobutylene residues are derived from a polyisobutylene compound of the following formula:

##STR00008##

wherein R.sub.1 is an initiator residue; each X is independently OH, NH.sub.2, or NHR.sub.4; n=0-500; m=0-500; each of R.sub.2 and R.sub.3 is selected from a (C1-C16)alkylene, a (C3-C16)cycloalkylene, a (C2-C16)alkenylene, a (C3-C16)cycloalkenylene, a (C2-C16)alkynylene, a (C3-C16)cycloalkynylene, or a (C6-C18)arylene, wherein for each occurrence R.sub.2 or R.sub.3 is independently optionally substituted with one or more groups selected from halo, cyano, nitro, dialkylamino, trialkylamino, (C1-C16)alkoxy, and (C1-C16 haloalkyl); and R.sub.4 is selected from a (C1-C16)alkyl, a (C3-C16)cycloalkyl, a (C2-C16)alkenyl, a (C3-C16)cycloalkenyl, a (C2-C16)alkynyl, a (C3-C16)cycloalkynyl, or a (C6-C18)aryl.

[0103] Embodiment 16 is the poly(ether-carbonate)-based polymer of embodiment 15 wherein the polyisobutylene residues are derived from a polyisobutylene diol of the following formula:

##STR00009##

wherein R.sub.1 is an initiator residue, n=0-500, and m=0-500.

[0104] Embodiment 17 is the poly(ether-carbonate)-based polymer of embodiment 15 or 16 wherein the initiator residues comprise aromatic residues, aliphatic residues, or combinations thereof.

[0105] Embodiment 18 is the poly(ether-carbonate)-based polymer of embodiment 17 wherein the initiator residues are derived from initiators selected from 5-tert-butyl-1,3-bis(1-methoxy-1-methylethyl)-benzene (or hindered dicumyl ether or HDCE), 1,3-bis(1-chloro-1-methylethyl)-5-(1-dimethylethyl)benzene (or, alternatively, known as 1,3-bis(1-chloro-1-methylethyl)-5-tert-butylbenzene or hindered dicumyl chloride or HDCC), 2,6-dichloro-2,4,4,6-tetramethylheptane, and 2,5-dichloro-2,5-dimethylhexane.

[0106] Embodiment 19 is the poly(ether-carbonate)-based polymer of embodiment 17 wherein the polyisobutylene residues are derived from a polyisobutylene diol of the following formula:

##STR00010##

wherein n=0-500 and m=0-500.

[0107] Embodiment 20 is the poly(ether-carbonate)-based polymer of any of the previous embodiments wherein the poly(ether-carbonate) residues are derived from a poly(ether-carbonate) diol, a poly(ether-carbonate) diamine, or a combination thereof.

[0108] Embodiment 21 is the poly(ether-carbonate)-based polymer of embodiment 16 wherein the poly(ether-carbonate) residues are derived from a poly(ether-carbonate) compound of the following formula:

##STR00011##

wherein each Y is independently OH, NH.sub.2, or NHR.sub.5, t=1-9, n=0-40, and m=1-40. Each of R.sub.5 is selected from a (C1-C16)alkyl, a (C3-C16)cycloalkyl, a (C2-C16)alkenyl, a (C3-C16)cycloalkenyl, a (C2-C16)alkynyl, a (C3-C16)cycloalkynyl, or a (C6-C18)aryl.

[0109] Embodiment 22 is the poly(ether-carbonate)-based polymer of embodiment 21 wherein the poly(ether-carbonate) residues are derived from a poly(ether-carbonate) diol of the following formula:

##STR00012##

wherein t=1-9, n=0-40, and m=1-40.

[0110] Embodiment 23 is the poly(ether-carbonate)-based polymer of any of the previous embodiments wherein the weight ratio of soft segments to hard segments is up to 90:10 (or up to 80:20, or up to 70:30).

[0111] Embodiment 24 is the poly(ether-carbonate)-based polymer of any of the previous embodiments wherein the weight ratio of soft segments to hard segments is at least 10:90 (or at least 30:70, or at least 40:60).

[0112] Embodiment 25 is the poly(ether-carbonate)-based polymer of embodiment 23 or 24 wherein the weight ratio of soft segments to hard segments is within a range of 90:10 to 10:90 (or within a range of 80:20 to 30:70, or within a range of 70:30 to 40:60).

[0113] Embodiment 26 is the poly(ether-carbonate)-based polymer of any of the previous embodiments wherein the weight ratio of polyisobutylene and/or hydrogenated polybutadiene residues to poly(ether-carbonate) residues is up to 99:1 (or up to 95:5, or up to 90:10).

[0114] Embodiment 27 is the poly(ether-carbonate)-based polymer of any of the previous embodiments wherein the weight ratio of polyisobutylene and/or hydrogenated polybutadiene residues to poly(ether-carbonate) residues is at least 1:99 (or at least 50:50, or at least 80:20).

[0115] Embodiment 28 is the poly(ether-carbonate)-based polymer of embodiment 26 or 27 wherein the weight ratio of polyisobutylene and/or hydrogenated polybutadiene residues to poly(ether-carbonate) residues is within a range of 99:1 to 1:99 (or within a range of 95:5 to 50:50, or within a range of 90:10 to 80:20).

[0116] Embodiment 29 is the poly(ether-carbonate)-based polymer of any of the previous embodiments having a weight average molecular weight of at least 10,000 Daltons, as determined by gel permeation chromatography with multiangle laser light scattering detection.

[0117] Embodiment 30 is the poly(ether-carbonate)-based polymer of any of the previous embodiments having a weight average molecular weight of up to 2,000,000 Daltons (or up to 1,000,000 Daltons), as determined by gel permeation chromatography with multiangle laser light scattering detection.

[0118] Embodiment 31 is the poly(ether-carbonate)-based polymer of embodiment 29 or 30 having a weight average molecular weight of 10,000 Daltons to 2,000,000 Daltons (or 10,000 Daltons to 1,000,000 Daltons), as determined by gel permeation chromatography with multiangle laser light scattering detection.

[0119] Embodiment 32 is the poly(ether-carbonate)-based polymer of any of the previous embodiments having a greater tear strength than a comparative polymer without poly(ether-carbonate) residues, wherein the comparative polymer has a shore durometer within 50% to 150% of the shore durometer of the poly(ether-carbonate)-based polymer.

[0120] Embodiment 33 is the poly(ether-carbonate)-based polymer of embodiment 32 having a tear strength at least 10% (or at least 20%) greater than a comparative polymer without poly(ether-carbonate) residues, wherein the comparative polymer has a shore durometer within 50% to 150% of the shore durometer of the poly(ether-carbonate)-based polymer.

[0121] Embodiment 34 is the poly(ether-carbonate)-based polymer of any of the previous embodiments having greater overall chemical stability than a comparative polymer with poly(tetramethylene oxide) residues instead of poly(ether-carbonate) residues, wherein the comparative polymer has an amount of poly(tetramethylene oxide) residues equal to an amount of poly(ether-carbonate) residues in the poly(ether-carbonate)-based polymer, and wherein the comparative polymer has a shore durometer within 50% to 150% of the shore durometer of the poly(ether-carbonate)-based polymer.

[0122] Embodiment 35 is a medical device comprising a polymeric region comprising the poly(ether-carbonate)-based polymer of any of the previous embodiments.

[0123] Embodiment 36 is the medical device of embodiment 35 comprising an implantable electrical lead, an implantable electrical pulse generator, or an implantable mechanical device.

[0124] Embodiment 37 is the medical device of embodiment 36 comprising an implantable electrical lead.

[0125] Embodiment 38 is the medical device of embodiment 37 wherein the implantable electrical lead comprises an electrical conductor and a layer comprising the poly(ether-carbonate)-based polymer disposed on the electrical conductor.

[0126] Embodiment 39 is the medical device of embodiment 37 or 38 wherein the electrical lead is a cardiac lead or a neurostimulation lead.

[0127] Embodiment 40 is the medical device of any of embodiments 35 through 39 wherein the polymeric region further comprises a therapeutic agent.

[0128] Embodiment 41 is a medical lead comprising an elongated lead body comprising a polymeric material, wherein the polymeric material comprises a poly(ether-carbonate)-based polymer of any of embodiments 1 through 34.

[0129] Embodiment 42 is the medical lead of embodiment 37 in the form of a medical electrical or neurological lead.

[0130] Embodiment 43 is a medical electrical lead comprising:

[0131] an elongated lead body having a first lumen, extending longitudinally along said lead body; and

[0132] a conductor located within and extending longitudinally along said lumen;

[0133] wherein the lead body comprises a polymeric material, wherein the polymeric material comprises a poly(ether-carbonate)-based polymer of any of embodiments 1 through 34.

[0134] Embodiment 44 is a medical, neurological lead for use in electrical signaling and/or drug delivery comprising:

[0135] an elongated body with a distal portion, a central portion and a proximal portion;

[0136] wherein the body includes delivery means extending to said distal portion; and

[0137] wherein the elongated body comprises a polymeric material, wherein the polymeric material comprises a poly(ether-carbonate)-based polymer of any of embodiments 1 through 30.

[0138] Embodiment 45 is the lead of embodiment 44 wherein the delivery means comprises electrical signal delivery means.

[0139] Embodiment 46 is the lead of embodiment 45 wherein the electrical signal delivery means is an implantable lead having at least one electrode.

[0140] Embodiment 47 is the lead of embodiment 44 wherein the delivery means comprises drug delivery means.

[0141] Embodiment 48 is the lead of embodiment 47 wherein the drug delivery means comprises a catheter.

[0142] Embodiment 49 is the lead of any of embodiments 44 through 48 wherein the polymeric material is a polymeric insulation material.

EXAMPLES

[0143] Objects and advantages of the disclosure are further illustrated by the examples provided herein. The particular materials and amounts thereof recited in these examples, as well as other conditions and details, are merely illustrative and are not intended to be limiting. The person of ordinary skill in the art, after carefully reviewing the entirety of this disclosure, will be able to use materials and conditions in addition to those specifically described in the examples.

Materials

[0144] 4,4-Methylenebis(phenyl isocyanate) (MDI, Aldrich, 98%), 1,4-butanediol (BDO, Aldrich, 99%), polycarbonate diol (PC-diol, ETERNACOLL UH200, 2000 g.Math.mol.sup.1), poly(ether-carbonate) diol (PEC-diol, ETERNACOLL UT200, 2000 g.Math.mol.sup.1), poly(tetramethylene oxide) (PTMO) diol (Aldrich, 1000 g.Math.mol.sup.1), Hydrogenate polybutadiene (HPB) diol (Cray Valley, 3000 g.Math.mol.sup.1), Stannous octoate (Aldrich, 92.5%), 1-Methyl-2-pyrrolidinone(NMP, anhydrous, Aldrich, 99.5%), toluene (anhydrous, Aldrich, 99.8%), N,N-dimethylacetamide (DMAc, anhydrous, Aldrich, 99.8%), tetrahydrofuran (THF, 99.9%), and methanol (Fisher, 99.8%) were used as received.

[0145] Polyisobutylene (PIB) diol (3000 g.Math.mol.sup.1) was made from the initiator, 1,3-di(2-methoxypropyl)-5-tert-butylbenzene (Molbase, 99%) in a reported two-step procedure (Ivan et al. J Polym Sci A Polym Chem 1990, 28, 89-104).

##STR00013##

Characterization Methods

[0146] Nuclear Magnetic Resonance (NMR) experiments were conducted on Bruker Avance III HD spectrometer (400 MHz). Samples were dissolved in either CDCl.sub.3 or THF-d.sub.8 for .sup.1H or .sup.13C NMR.

[0147] Molecular weights of polymers were determined via a size exclusion chromatography (SEC) system composed of an Agilent 1260 injection system, a Wyatt OPTILAB T-Rex refractive detector and a Wyatt DAWN Heleos II multiangle laser scattering detector. The data were processed by Astra 7. THF was the eluent, which was operated at 40 C.

[0148] Tensile testing was performed on an MTS Criterion tensile tester Model 43 according to ASTM D1708-13 method with a crosshead speed of 5 inch-min.sup.1 in an atmospheric condition at room temperature. Samples were cut using an ASTM die into dog-bone shapes from polymer films, which were compression molded at approximately 210 C. from precipitated and dried polymers. Tear strength tests was done according to ASTM D624-00(2012).

[0149] Attenuated total reflection (ATR) Fourier-transform infrared spectroscopy (FTIR) experiments were conducted at ambient conditions on a Bruker Tensor 27 with a Ge crystal using 32 scans at a resolution of 4 cm.sup.11.

[0150] Scanning electron microscopy (SEM) was conducted at room temperature using a Jeol 1T300 scanning electron microscope under high vacuum. The samples were sputter-coated with gold using a Denton Desk II sputter coater.

Example 1 (Comparative)

Preparation of Polyisobutylene-Based Polyurethane

[0151] Polyurethane (PU) having PIB as soft segment with no other soft segment residues, and MDI/BDO as hard segment was synthesized using a prepolymer method. The ratio of soft segment to hard segment was varied from 70:30 to 60:40. For example, a solution containing toluene (40 mL, anhydrous) and PIB diol (Scheme 1.1, 12.1 g, 3.8 mmol) was slowly added into a preheated flask (90 C.), which contained a stir bar and MDI (6.2 g, 24.8 mmol), under N.sub.2 atmosphere. After all PIB diols were reacted with MDI, a solution containing DMAc (40 mL, anhydrous) and BDO (1.8 g, 20.5 mmol) was then slowly added into the flask. The polymerization was then carried out at 100 C. for 20 hours. The PU products (19.8 g, yield: 98.5%) were precipitated from methanol and then dried in a vacuum oven at 50 C. Their molecular weights and tensile properties are described in Table 1.

Example 2 (Comparative)

Preparation of Polyisobutylene/Polyether-Based Polyurethane

[0152] Polyurethane (PU) having mixtures of PIB and PTMO as soft segment, and MDI/BDO as hard segment, was synthesized using a prepolymer method. The ratio of soft segment to hard segment was varied from 70:30 to 65:35. For example, a solution containing toluene (40 mL, anhydrous), PIB diol (Scheme1.1, 10.2 g, 3.2 mmol), and PTMO diol (Scheme 1.2, 2.0 g, 2.0 mmol) was slowly added into a preheated flask (90 C.), which contained a stir bar and MDI (4.2 g, 16.8 mmol), under N.sub.2 atmosphere. After all polymeric diols were reacted with MDI, a solution containing DMAc (40 mL, anhydrous) and BDO (1.0 g, 10.7 mmol) was then slowly added into the flask. The polymerization was then carried out at 100 C. for 40 hours. The PU products (16.9 g, yield: 97.1%) were precipitated from methanol and then dried in a vacuum oven at 50 C. Their molecular weights and tensile properties are described in Table 1.

Example 3 (Comparative)

Preparation of Polyisobutylene/Polycarbonate-Based Polyurethane

[0153] Polyurethane (PU) having mixtures of PIB and PC in different proportions as soft segment, and MDI/BDO as hard segment, was synthesized using a prepolymer method. The ratio of soft segment to hard segment was 70:30. For example, a solution containing toluene (40 mL, anhydrous), PIB diol (Scheme1.1, 9.7 g, 3.1 mmol), and PC diol (Scheme1.3, 1.9 g, 1.0 mmol) was slowly added into a preheated flask (90 C.), which contained a stir bar and MDI (3.9 g, 15.6 mmol), under N.sub.2 atmosphere. After all polymeric diols were reacted with MDI, a solution containing DMAc (40 mL, anhydrous) and BDO (1.0 g, 11.2 mmol) was then slowly added into the flask. The polymerization was then carried out at 100 C. for 20 hours. The PU products (16.1 g, yield: 97.2%) were precipitated from methanol and then dried in a vacuum oven at 50 C. Their molecular weights and tensile properties are described in Table 1.

Example 4

Preparation of Polyisobutylene/Poly(ether-carbonate)-Based Polyurethane

[0154] Polyurethane (PU) having mixtures of PIB and PEC in different proportions as soft segment, and MDI/BDO as hard segment, was synthesized using a prepolymer method. The ratio of soft segment to hard segment was varied from 70:30 to 65:35. For example, a solution containing toluene (40 mL, anhydrous), PIB diol (Scheme1.1, 11.57 g, 3.7 mmol), and PEC diol (Scheme1.4, 2.3 g, 1.2 mmol) was slowly added into a preheated flask (90 C.), which contained a stir bar and MDI (5.9 g, 23.4 mmol), under N.sub.2 atmosphere. After all polymeric diols were reacted with MDI, a solution containing DMAc (40 mL, anhydrous) and BDO (1.6 g, 18.1 mmol) was then slowly added into the flask. The polymerization was then carried out at 100 C. for 20 hours. The PU products (21.0 g, yield: 98.3%) were precipitated from methanol and then dried in a vacuum oven at 50 C. Their molecular weights and tensile properties are described in Table 1.

Example 5 (Comparative)

Preparation of Hydrogenated Polybutadiene/Polyether-Based Polyurethane, 85A

[0155] Polyurethane (PU) having mixtures of HPB and PTMO as soft segment, and MDI/BDO as hard segment, was synthesized using a prepolymer method. The ratio of HPB to PTMO to hard segment was 40:10:50. For example, a solution containing toluene (40 mL, anhydrous), HPB diol (8.0 g, 2.7 mmol), and PTMO diol (Scheme 1.2, 2.0 g, 2.0 mmol) was slowly added into a preheated flask (90 C.), which contained a stir bar and MDI (7.6 g, 30.4 mmol), under N.sub.2 atmosphere. A solution containing DMAc (100 mL, anhydrous), Stannous octoate (0.012 g, 0.03 mmol) and BDO (1.0 g, 10.7 mmol) was then slowly added into the flask. The polymerization was then carried out at 100 C. for 20 hours. The PU products were precipitated from water and then dried in a vacuum oven at 50 C. Their molecular weights and tensile properties are described in Table 1.

Example 6

Preparation of Hydrogenated Polybutadiene/Poly(ether-carbonate)-Based Polyurethane, 85A

[0156] Polyurethane (PU) having mixtures of HPB and PEC as soft segment, and MDI/BDO as hard segment, was synthesized using a prepolymer method. The ratio of HPB to PTMO to hard segment was 40:10:50. For example, a solution containing toluene (40 mL, anhydrous), HPB diol (8.0 g, 2.7 mmol), and PEC diol (Scheme1.4, 2.0 g, 1.0 mmol) was slowly added into a preheated flask (90 C.), which contained a stir bar and MDI (7.6 g, 30.4 mmol), under N.sub.2 atmosphere. A solution containing DMAc (100 mL, anhydrous), Stannous octoate (0.012 g, 0.03 mmol) and BDO (2.4 g, 26.4 mmol) was then slowly added into the flask. The polymerization was then carried out at 100 C. for 20 hours. The PU products were precipitated from water and then dried in a vacuum oven at 50 C. Their molecular weights and tensile properties are described in Table 1.

Example 7 (Comparative)

Preparation of Hydrogenated Polybutadiene/Polyether-Based Polyurethane, 50D

[0157] Polyurethane (PU) having mixtures of HPB and PTMO as soft segment, and MDI/BDO as hard segment, was synthesized using a prepolymer method. The ratio of HPB to PTMO to hard segment was 30:20:50. For example, a solution containing toluene (50 mL, anhydrous), HPB diol (6.0 g, 2.0 mmol), and PTMO diol (Scheme 1.2, 4.0 g, 4.0 mmol) was slowly added into a preheated flask (90 C.), which contained a stir bar and MDI (7.8 g, 31.0 mmol), under N.sub.2 atmosphere. A solution containing NMP (50 mL, anhydrous), Stannous octoate (0.013 g, 0.03 mmol) and BDO (2.2 g, 24.7 mmol) was then slowly added into the flask. The polymerization was then carried out at 100 C. for 20 hours. The PU products were precipitated from water and then dried in a vacuum oven at 50 C. Their molecular weights and tensile properties are described in Table 1.

Example 8

Preparation of Hydrogenated Polybutadiene/Poly(ether-carbonate)-Based Polyurethane, 50D

[0158] Polyurethane (PU) having mixtures of HPB and PEC as soft segment, and MDI/BDO as hard segment, was synthesized using a prepolymer method. The ratio of HPB to PTMO to hard segment was 30:20:50. For example, a solution containing toluene (50 mL, anhydrous), HPB diol (6.0 g, 2.0 mmol), and PEC diol (Scheme1.4, 4.0 g, 2.0 mmol) was slowly added into a preheated flask (90 C.), which contained a stir bar and MDI (7.7 g, 30.6 mmol), under N.sub.2 atmosphere. A solution containing NMP (50 mL, anhydrous), Stannous octoate (0.012 g, 0.03 mmol) and BDO (2.4 g, 26.3 mmol) was then slowly added into the flask. The polymerization was then carried out at 100 C. for 20 hours. The PU products were precipitated from water and then dried in a vacuum oven at 50 C. Their molecular weights and tensile properties are described in Table 1.

TABLE-US-00001 TABLE 1 PIB-PU's Formulations, Molecular Weights, and Mechanical Properties Ultimate Strain M.sub.n M.sub.w Tensile at Tear g .Math. g .Math. Strength Break Strength Polymer mol.sup.1 mol.sup.1 MPa % lbf .Math. inch.sup.1 PIB-PC-PU 57k 115k 18 336 396 (comparative) PIB-PTMO-PU 85k 161k 20 420 265 (comparative) PIB-PU 54k 111k 21 416 420 (comparative) PIB-PEC-PU 71k 131k 20 385 505 HPB-PTMO-PU, 110k 140k 34 335 461 85A(comparative) HPB-PEC-PU, 85A 80k 95k 37 289 516 HPB-PTMO-PU, 151k 260k 29 275 782 50D (comparative) HPB-PEC-PU, 50D 155k 260k 38 327 828

Example 9

Accelerated Aging Studies

[0159] The chemical stability of the polymers of Examples 1-4 in hydrolytic, acidic, basic, and oxidative conditions was tested using an arrangement of accelerated aging conditions.

[0160] Hydrolytic Stability: To test the hydrolytic stability, compression-molded polyisobutylene polyurethane (PIB-PEC-PU, PIB-PTMO-PU, PIB-PU) was aged at 85 C. in phosphate-buffered saline (137 mM NaCl, 2.7 mM KCl, 10 mM Na.sub.2HPO.sub.4, 1.8 mM KH.sub.2PO.sub.4). After 8 weeks and 16 weeks, gel permeation chromatography was used to characterize molecular weight changes of the 85 C. polymer. The molecular weight changes are shown in Table 2.

[0161] Acidic Stability: To test the acidic stability, compression-molded polyisobutylene polyurethane (PIB-PEC-PU, PIB-PTMO-PU, PIB-PU) was treated using a 1M HCl solution at 37 C. for 8 and 16 weeks. Gel permeation chromatography was used to characterize molecular weight changes. The molecular weight changes are shown in Table 2.

[0162] Basic Stability: To test the basic stability, compression-molded polyisobutylene polyurethane (PIB-PEC-PU, PIB-PTMO-PU, PIB-PU) was treated using a 1M NaOH solution at 37 C. for 8 and 16 weeks. Gel permeation chromatography was used to characterize molecular weight changes. The molecular weight changes are shown in Table 2.

[0163] Oxidative Stability: To test the oxidative stability, compression-molded polyisobutylene polyurethane (PIB-PEC-PU, PIB-PTMO-PU, PIB-PU) was treated using a solution containing 20% w/w H.sub.2O.sub.2/0.1M CoCl.sub.2 in water at 37 C. at 8- and 16-week time points, the polymer was analyzed via gel permeation chromatography, Fourier-transform infrared spectroscopy, and scanning electron microscopy. The molecular weight changes are shown in Table 2.

TABLE-US-00002 TABLE 2 Remaining Percentage of Weight Average Molecular Weight (Mw) of Polymers Upon 8- and 16-Week Exposure to the Above Solutions Aging 20% w/w Time 85 C. H.sub.2O.sub.2/0.1M Polymer (weeks) PBS 1M HCl 1M NaOH CoCl.sub.2 PIB-PEC-PU 8 67.9 97.9 93.7 78.0 PIB-PTMO-PU 8 67.5 97.3 102.1 48.4 PIB-PU 8 86.6 89.4 95.9 86.9 PIB-PEC-PU 16 58.9 106.3 92.1 85.1 PIB-PTMO-PU 16 59.9 97.4 102.5 50.4 PIB-PU 16 91.3 104.2 108.7 72.4

[0164] Changes in surface chemistry upon oxidation testing were analyzed via ATR-FTIR. No obvious changes through 8 weeks oxidation were observed.

[0165] Scanning electron microscopy was used to inspect the surface for cracking potentially brought about by exposure to 20% H.sub.2O.sub.2/0.1M CoCl.sub.2 solution for 8 weeks, as seen in the FIGS. 6-8. These images show no cracks developed on the surface of PIB-PEC PU, PIB-PTMO-PU, or PIB-PU.

[0166] The complete disclosures of the patents, patent documents, and publications cited herein are incorporated by reference in their entirety as if each were individually incorporated. Various modifications and alterations to this invention will become apparent to those of ordinary skill in the art without departing from the scope and spirit of this invention. It should be understood that this invention is not intended to be unduly limited by the illustrative embodiments and examples set forth herein and that such examples and embodiments are presented by way of example only with the scope of the invention intended to be limited only by the claims set forth herein as follows.