Chemically blown silicone foam-gel

Abstract

Chemically blown silicone foam-gels are described which can be cured from a two-component formulation and used in various applications such as implantable medical devices (e.g., breast implants).

Description

Attorney Docket No.37996.0005P1 CHEMICALLY BLOWN SILICONE FOAM-GEL CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 652,312, filed May 28, 2024, the entirety of which is incorporated into this application by reference. BACKGROUND

[0002] Silicones are used in a wide range of applications due to their varied and desirable properties. Silicones can be prepared from formulations including organopolysiloxanes having suitable reactive groups such as alkenyl groups, optional catalysts, and other components. A common application of silicones is for use in implantable medical devices. Trends in certain implantable device markets include efforts to reduce the density of materials, including silicone components. Many efforts (for example, microballoons) have been pursued to prepare low density implants with the goal of improving both functionality of the materials and ability to process them. The art, however, still recognizes a significant need to address these goals. SUMMARY

[0003] This disclosure relates to an uncured two-component silicone foam-gel formulations which when combined and cured provide for improved density and other properties, methods of making silicone foam-gels from the formulations, as well as silicone foam gels and implantable medical devices which are prepared from the formulations.

[0004] In one embodiment, the uncured, two-component silicone foam-gel formulation comprises: a) a Part A comprising: i) 100 parts of a Part A polymer, wherein the Part A polymer is an organopolysiloxane having at least one alkenyl functionality; ii) 0-60 parts of a resin base, wherein the resin base comprises an organopolysiloxane having at least one alkenyl functionality and a viscosity of 1,000-20,000 cP, and one or more oligosiloxanes; iii) 0-100 parts of a first silica base, wherein the first silica base comprises fumed silica and an organopolysiloxane having at least one alkenyl functionality andAttorney Docket No.37996.0005P1 a viscosity of 2,000-100,000 cP; wherein at least one of the resin base or first silica base is present in Part A; iv) 5-50 (e.g., 10-30) parts of a blowing agent having at least one hydroxyl functionality; and v) an addition catalyst; b) a Part B comprising: i) 1-20 parts of a Part B polymer, wherein the Part B polymer is an organopolysiloxane having at least one alkenyl functionality ii) 0-20 parts of a second silica base, wherein the second silica base comprises fumed silica and an organopolysiloxane having at least one alkenyl functionality and a viscosity of 2,000-100,000 cp; iii) 100 parts of a chain extender, wherein the chain extender is an organopolysiloxane having at least one Si–H functionality; and iv) 0.05-20 parts of a crosslinker comprising methyl-hydrogen polysiloxane; wherein the formulation is in the form of a kit in which Part A and Part B are not mixed.

[0005] Also described are implantable medical devices comprising a silicone foam-gel cured from the described the uncured, two-component silicone foam-gel formulations. Also described are methods for preparing a silicone foam-gel from the uncured, two-component formulations, as well as silicone foam-gels prepared by the described methods. DETAILED DESCRIPTION

[0006] As briefly summarized above, this disclosure is related to a chemically blown foam with the physical properties of a gel (i.e., a “foam-gel”), which can be cured for example from a formulation that includes an optional addition catalyst, vinyl- and hydride- containing organopolysiloxanes, optional resin base or silica base reinforcing components, and a hydroxyl-containing blowing agent. The purpose of this disclosure is to provide a new type of foam-gel material that is a gel-like chemically-blown foam which in some embodiments does not require an added low-density filler or related material, and which can be used for implantable medical devices such as breast implants and the like. In some embodiments, the chemically-blown foam-gel has adjustable properties including softness, bubble (“cell”) size, and work time. In some embodiments, the foam-gel is not a syntactic foam (i.e., it does not require added low-density filler), and all of the cells throughout it areAttorney Docket No.37996.0005P1 formed in situ by the production of hydrogen gas from the reaction between a crosslinker (e.g., a crosslinker comprising methyl-hydrogen polysiloxane) and hydroxyl group. The material can be a room-temperature curing material with optimal specific gravity and density properties suitable for a variety of applications including implantable medical devices. I. Foam-Gel Formulations

[0007] The foam-gel formulations are in the form of a kit that includes two parts, Part A and Part B, which are uncured and not mixed until use. Both Parts are described with reference to a principal component which is denominated as present in “100 parts,” or in some instances above 100 parts, meaning that additional components in the relevant part are present in a parts-per hundred amount (or parts-per the largest amount) relative to the principal component (in terms of mass-equivalents). For example, in Part A, the blowing agent can be included as 5-50 (e.g., 10-30) parts in some embodiments, which means 5-50 (e.g., 10-30) parts per 100 parts of the Part A polymer described below.

[0008] In some embodiments, Part A of the uncured, two-component silicone foam-gel formulation comprises: i) 100 parts of a Part A polymer, wherein the Part A polymer is an organopolysiloxane having at least one alkenyl functionality; ii) 0-60 parts of a resin base, wherein the resin base comprises an organopolysiloxane having at least one alkenyl functionality and a viscosity of 1,000-20,000 cP, and one or more oligosiloxanes; iii) 0-100 parts of a first silica base, wherein the first silica base comprises fumed silica and an organopolysiloxane having at least one alkenyl functionality and a viscosity of 2,000-100,000 cP; wherein at least one of the resin base or first silica base is present in Part A; iv) 5-50 (e.g., 10-30) parts of a blowing agent having at least one hydroxyl functionality; and v) an addition catalyst; while Part B comprises: i) 1-20 parts of a Part B polymer, wherein the Part B polymer is an organopolysiloxane having at least one alkenyl functionality; ii) 0-20 parts (e.g., 0 parts, 0-10 parts, 1-10 parts, 10-20 parts, or 15-20 parts) of a second silica base, wherein the second silica base comprises fumed silica andAttorney Docket No.37996.0005P1 an organopolysiloxane having at least one alkenyl functionality and a viscosity of 2,000-100,000 cp; iii) 100 parts of a chain extender, wherein the chain extender is an organopolysiloxane having at least one Si–H functionality; and iv) 0.05-20 parts of a crosslinker comprising methyl-hydrogen polysiloxane.

[0009] In any embodiments described in this application, it is understood that the “first” and “second” silica bases can be the same or different. The fumed silica of the first and second silica bases can be the same or different, and the organopolysiloxane having at least one alkenyl functionality can also be the same or different. In one embodiment, the first and second silica bases are the same, i.e., they include the same fumed silica and the same organopolysiloxane and are otherwise the same in terms of chemical composition. A. Alkenyl-Functionalized Organopolysiloxanes

[0010] The foam-gel formulations can include an organopolysiloxane having at least one alkenyl functionality (1) as the Part polymer, (2) as part of the resin base, (3) as part of the optional silica base, and (4) as the Part B polymer. Each of these organopolysiloxanes can be the same as or different from another alkyenyl-functionalized organopolysiloxane in the foam-gel formulation, e.g., the alkenyl-functionalized organopolysiloxanes can each have the same or different chemical structures, or the same or different properties such as viscosity or molecular weight.

[0011] The alkenyl-functionalized organopolysiloxane will generally include siloxane units having hydrocarbon groups according to the formula, —SiOR2—, where each R can be the same or different and can be substituted or unsubstituted. Such R groups can in some aspects have from 1 to 10 carbons, for example, 1-8 carbons, 1-6 carbons, 1-4 carbons, or 1-2 carbons.

[0012] Examples of the substituted or unsubstituted hydrocarbon groups bonded to silicon atoms represented by R include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl groups; aryl groups such as phenyl, tolyl, xylyl and naphthyl; aralkyl groups such as benzyl, phenylethyl and phenylpropyl; alkenyl groups such as vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, cyclohexenyl and octenyl; groups obtained by substituting some or all of the hydrogen atoms in the above-described groups with halogen atoms such as fluorine, bromine and chlorine, cyano groups and the like, such as chloromethyl groups, chloropropyl groups, bromoethyl groups, trifluoropropyl groups, and cyanoethyl groups. In one aspect,Attorney Docket No.37996.0005P1 90% or more of the R groups in each alkenyl-functionalized organopolysiloxane in the foam- gel formulation is methyl.

[0013] In one embodiment, Part A of the uncured, two-component silicone foam-gel formulation comprises: i) 100 parts of a Part A polymer, wherein the Part A polymer is a polydimethylsiloxane (PDMS) having at least one alkenyl functionality; ii) 0-60 parts (e.g., 0 parts, 1-60 parts, 20-60 parts, 25-30 parts, or 50-55 parts) of a resin base, wherein the resin base comprises a polydimethylsiloxane (PDMS) having at least one alkenyl functionality and a viscosity of 1,000- 20,000 cP, and one or more oligosiloxanes; iii) 0-100 parts (e.g., 0 parts, 1-100 parts, 0-60 parts, 1-60 parts, 20-60 parts, 30- 60 parts, 50-100 parts, 20-30 parts, or 50-55 parts) of a first silica base, wherein the first silica base comprises fumed silica and a polydimethylsiloxane (PDMS) having at least one alkenyl functionality and a viscosity of 2,000-100,000 cP; wherein at least one of the resin base or first silica base is present in Part A; iv) 5-50 parts (e.g., 10-30, 15- 30 parts, 20-30 parts, 15-25 parts, 20-25 parts, or 24 parts) of a blowing agent having at least one hydroxyl functionality; and v) an addition catalyst (e.g., 0.01-5 parts, 0.05-5 parts, 0.05 to 1 parts, 0.1 to 1 parts, 0.1 to 0.75 parts); while Part B comprises: i) 1-20 parts (e.g., 10-20 parts, or 15-20 parts) of a Part B polymer, wherein the Part B polymer is a polydimethylsiloxane (PDMS) having at least one alkenyl functionality ii) 0-20 parts (e.g., 0 parts, 1-20 parts, 0-10 parts, 1-10 parts, 10-20 parts, or 15- 20 parts) of a second silica base, wherein the second silica base comprises fumed silica and an organopolysiloxane having at least one alkenyl functionality and a viscosity of 2,000-100,000 cp; iii) 100 parts of a chain extender, wherein the chain extender is an organopolysiloxane having at least one Si–H functionality; and iv) 0.05-20 parts (e.g., 0.1-15 parts, 0.2-15 parts, 0.2-10 parts, 0.2-5 parts, 0.2-3 parts, or 0.2-1 parts) of a crosslinker comprising methyl-hydrogen polysiloxane.

[0014] In a further embodiment, Part A of the uncured, two-component silicone foam-gelAttorney Docket No.37996.0005P1 formulation comprises: i) 100 parts of a Part A polymer, wherein the Part A polymer is a vinyl-endblocked polydimethylsiloxane (PDMS); ii) 0-60 parts (e.g., 0 parts, 1-60 parts, 20-60 parts, 25-30 parts, or 50-55 parts) ofa resin base, wherein the resin base comprises a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 1,000-20,000 cP, and one or more oligosiloxanes; iii) 0-100 parts (e.g., 0 parts, 1-100 parts, 0-60 parts, 1-60 parts, 20-60 parts, 30-60 parts, 50-100 parts, 20-30 parts, or 50-55 parts) of a first silica base, wherein the first silica base comprises fumed silica and a vinyl-endblocked polydimethylsiloxane (PDMS) and a viscosity of 2,000-100,000 cP; wherein at least one of the resin base or first silica base is present in Part A; iv) 5-50 parts (e.g., 10-30, 15-30 parts, 20-30 parts, 15-25 parts, 20-25 parts, or 24parts) of a blowing agent having at least one hydroxyl functionality; and v) an addition catalyst (e.g., 0.01-5 parts, 0.05-5 parts, 0.05 to 1 parts, 0.1 to 1parts, 0.1 to 0.75 parts); while Part B comprises: i) 1-20 parts (e.g., 10-20 parts, or 15-20 parts) of a Part B polymer, wherein thePart B polymer is a vinyl-endblocked polydimethylsiloxane (PDMS); ii) 0-20 parts (e.g., 0 parts, 1-20 parts, 0-10 parts, 1-10 parts, 10-20 parts, or 15-20 parts) of a second silica base, wherein the second silica base comprises fumed silica and a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 2,000-100,000 cP; iii) 100 parts of a chain extender, wherein the chain extender is anorganopolysiloxane having at least one Si–H functionality; and iv) 0.05-20 parts (e.g., 0.1-15 parts, 0.2-15 parts, 0.2-10 parts, 0.2-5 parts, 0.2-3parts, or 0.2-1 parts) parts of a crosslinker comprising methyl-hydrogen polysiloxane; wherein each instance of the vinyl-endblocked polydimethylsiloxane (PDMS) has the following formula:,Attorney Docket No.37996.0005P1 wherein n is independently in each instance is an integer corresponding to a PDMS molecular weight ranging from 1,000-300,000 g / mol.

[0015] Viscosities of the alkenyl-functionalized organopolysiloxanes can vary, and can be the same or different when used in multiple components of Part A or Part B. In one embodiment, Part A of the uncured, two-component silicone foam-gel formulation comprises: i) 100 parts of a Part A polymer, wherein the Part A polymer is a polydimethylsiloxane (PDMS) having at least one alkenyl functionality and having a viscosity of 5,000-200,000 cP (e.g., 20,000-200,000 cP, 50,000- 150,000 cP, or 80,000-120,000 cP); ii) 0-60 parts (e.g., 0 parts, 1-60 parts, 20-60 parts, 25-30 parts, or 50-55 parts) of a resin base, wherein the resin base comprises a polydimethylsiloxane (PDMS) having at least one alkenyl functionality and a viscosity of 1,000- 20,000 cP (e.g., 1,000-15,000 cP, or 1,000-12,000 cP), and one or more oligosiloxanes; iii) 0-100 parts (e.g., 0 parts, 1-100 parts, 0-60 parts, 1-60 parts, 20-60 parts, 30- 60 parts, 50-100 parts, 20-30 parts, or 50-55 parts) of a first silica base, wherein the first silica base comprises fumed silica and a polydimethylsiloxane (PDMS) having at least one alkenyl functionality and a viscosity of 2,000-100,000 cP (e.g., 2,000-50,000 cP, 2,000-30,000 cP, 2,000- 20,000 cP, 2,000-15,000 cP, 2,000-10,000 cP, or 2,000-5,000 cP); wherein at least one of the resin base or first silica base is present in Part A; iv) 5-50 parts (e.g., 10-30, 15- 30 parts, 20-30 parts, 15-25 parts, 20-25 parts, or 24 parts) of a blowing agent having at least one hydroxyl functionality; and v) an addition catalyst (e.g., 0.01-5 parts, 0.05-5 parts, 0.05 to 1 parts, 0.1 to 1 parts, 0.1 to 0.75 parts); while Part B comprises: i) 1-20 parts (e.g., 10-20 parts, or 15-20 parts) of a Part B polymer, wherein the Part B polymer is a polydimethylsiloxane (PDMS) having at least one alkenyl functionality and having a viscosity of 5,000-200,000 cP (e.g., 20,000-200,000 cP, 50,000-150,000 cP, or 80,000-120,000 cP), which can be the same as or different from the viscosity of the Part A polymer (in one aspect the viscosity of the Part A polymer and Part B polymers are about the same).Attorney Docket No.37996.0005P1 ii) 0-20 parts (e.g., 0 parts, 1-20 parts, 0-10 parts, 1-10 parts, 10-20 parts, or 15- 20 parts) of a second silica base, wherein the second silica base comprises fumed silica and a polydimethylsiloxane (PDMS) having at least one alkenyl functionality and a viscosity of 2,000-100,000 cP (e.g., 2,000-50,000 cP, 2,000-30,000 cP, 2,000-20,000 cP, 2,000-15,000 cP, 2,000-10,000 cP, or 2,000-5,000 cP); iii) 100 parts of a chain extender, wherein the chain extender is an organopolysiloxane having at least one Si–H functionality; and iv) 0.05-20 parts (e.g., 0.1-15 parts, 0.2-15 parts, 0.2-10 parts, 0.2-5 parts, 0.2-3 parts, or 0.2-1 parts) of a crosslinker comprising methyl-hydrogen polysiloxane.

[0016] In a further embodiment, Part A of the uncured, two-component silicone foam-gel formulation comprises: i) 100 parts of a Part A polymer, wherein the Part A polymer is a vinyl- endblocked polydimethylsiloxane (PDMS) and having a viscosity of 5,000- 200,000 cP (e.g., 20,000-200,000 cP, 50,000-150,000 cP, or 80,000-120,000 cP); ii) 0-60 parts (e.g., 0 parts, 1-60 parts, 20-60 parts, 25-30 parts, or 50-55 parts) of a resin base, wherein the resin base comprises a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 1,000-20,000 cP (e.g., 1,000-15,000 cP, or 1,000-12,000 cP), and one or more oligosiloxanes; iii) 0-100 parts (e.g., 0 parts, 1-100 parts, 0-60 parts, 1-60 parts, 20-60 parts, 30- 60 parts, 50-100 parts, 20-30 parts, or 50-55 parts) of a first silica base, wherein the first silica base comprises fumed silica and a vinyl-endblocked polydimethylsiloxane (PDMS) and a viscosity of 2,000-100,000 cP (e.g., 2,000-50,000 cP, 2,000-30,000 cP, 2,000-20,000 cP, 2,000-15,000 cP, 2,000- 10,000 cP, or 2,000-5,000 cP); wherein at least one of the resin base or first silica base is present in Part A; iv) 5-50 parts (e.g., 10-30, 15- 30 parts, 20-30 parts, 15-25 parts, 20-25 parts, or 24 parts) of a blowing agent having at least one hydroxyl functionality; and v) an addition catalyst (e.g., 0.01-5 parts, 0.05-5 parts, 0.05 to 1 parts, 0.1 to 1 parts, 0.1 to 0.75 parts); while Part B comprises:Attorney Docket No.37996.0005P1 i) 1-20 parts (e.g., 10-20 parts, or 15-20 parts) of a Part B polymer, wherein thePart B polymer is a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 5,000-200,000 cP (e.g., 20,000-200,000 cP, 50,000-150,000 cP, or 80,000-120,000 cP), which can be the same as or different from the viscosity of the Part A polymer (in one aspect the viscosity of the Part A polymer and Part B polymers are about the same); ii) 0-20 parts (e.g., 0 parts, 1-20 parts, 0-10 parts, 1-10 parts, 10-20 parts, or 15-20 parts) of a second silica base, wherein the silica base comprises fumed silica and a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 2,000-100,000 cP (e.g., 2,000-50,000 cP, 2,000-30,000 cP, 2,000- 20,000 cP, 2,000-15,000 cP, 2,000-10,000 cP, or 2,000-5,000 cP); iii) 100 parts of a chain extender, wherein the chain extender is anorganopolysiloxane having at least one Si–H functionality; and iv) 0.05-20 parts (e.g., 0.1-15 parts, 0.2-15 parts, 0.2-10 parts, 0.2-5 parts, 0.2-3parts, or 0.2-1 parts) of a crosslinker comprising methyl-hydrogen polysiloxane; wherein each instance of the vinyl-endblocked polydimethylsiloxane (PDMS) has the following formula:, wherein n is independently in each instance is an integer corresponding to a PDMS molecular weight ranging from 1,000-300,000 g / mol.

[0017] In one embodiment, in the described uncured, two-component silicone foam-gelformulations Part A comprises: ii) 1-60 parts, 20-60 parts, 25-30 parts, or 50-55 parts of a resin base, wherein the resin base comprises a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 1,000-20,000 cP (e.g., 1,000-15,000 cP, or 1,000-12,000 cP), and one or more oligosiloxanes; iii) 0-100 parts (e.g., 0 parts, 1-100 parts, 0-60 parts, 1-60 parts, 20-60 parts, 30-60 parts, 50-100 parts, 20-30 parts, or 50-55 parts) of a first silica base, wherein the first silica base comprises fumed silica and a vinyl-endblocked polydimethylsiloxane (PDMS) and a viscosity of 2,000-100,000 cP (e.g., 2,000-50,000 cP, 2,000-30,000 cP, 2,000-20,000 cP, 2,000-15,000 cP, 2,000-10,000 cP, or 2,000-5,000 cP). In another embodiment, in the described uncured, two-component silicone foam-gel formulations Part A comprises: ii) 0-60 parts, 1-60 parts, 20-60 parts, 25-30 parts, or 50-55Attorney Docket No.37996.0005P1 parts of a resin base, wherein the resin base comprises a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 1,000-20,000 cP (e.g., 1,000-15,000 cP, or 1,000-12,000 cP), and one or more oligosiloxanes; iii) 1-100 parts, 1-60 parts, 20-60 parts, 30-60 parts, 50-100 parts, 20-30 parts, or 50-55 parts) of a first silica base, wherein the first silica base comprises fumed silica and a vinyl-endblocked polydimethylsiloxane (PDMS) and a viscosity of 2,000-100,000 cP (e.g., 2,000-50,000 cP, 2,000-30,000 cP, 2,000-20,000 cP, 2,000-15,000 cP, 2,000-10,000 cP, or 2,000-5,000 cP). In yet another embodiment, in the described uncured, two-component silicone foam-gel formulations Part A comprises: ii) 1-60 parts, 20-60 parts, 25-30 parts, or 50-55 parts of a resin base, wherein the resin base comprises a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 1,000- 20,000 cP (e.g., 1,000-15,000 cP, or 1,000-12,000 cP), and one or more oligosiloxanes; iii) 1- 100 parts, 1-60 parts, 20-60 parts, 30-60 parts, 50-100 parts, 20-30 parts, or 50-55 parts) of a first silica base, wherein the first silica base comprises fumed silica and a vinyl-endblocked polydimethylsiloxane (PDMS) and a viscosity of 2,000-100,000 cP (e.g., 2,000-50,000 cP, 2,000-30,000 cP, 2,000-20,000 cP, 2,000-15,000 cP, 2,000-10,000 cP, or 2,000-5,000 cP).

[0018] In one embodiment, in the described uncured, two-component silicone foam-gel formulations Part A comprises: ii) 1-60 parts, 20-60 parts, 25-30 parts, or 50-55 parts of a resin base, wherein the resin base comprises a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 1,000-20,000 cP (e.g., 1,000-15,000 cP, or 1,000-12,000 cP), and one or more oligosiloxanes; iii) 0-100 parts (e.g., 0 parts, 1-100 parts, 0-60 parts, 1-60 parts, 20-60 parts, 30-60 parts, 50-100 parts, 20-30 parts, or 50-55 parts) of a first silica base, wherein the first silica base comprises fumed silica and a vinyl-endblocked polydimethylsiloxane (PDMS) and a viscosity of 2,000-100,000 cP (e.g., 2,000-50,000 cP, 2,000-30,000 cP, 2,000-20,000 cP, 2,000-15,000 cP, 2,000-10,000 cP, or 2,000-5,000 cP), while Part B comprises: ii) 1-20 parts, 1-10 parts, 10-20 parts, or 15-20 parts) of a second silica base, wherein the silica base comprises fumed silica and a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 2,000-100,000 cP (e.g., 2,000-50,000 cP, 2,000-30,000 cP, 2,000-20,000 cP, 2,000-15,000 cP, 2,000-10,000 cP, or 2,000-5,000 cP). In another embodiment, in the described uncured, two-component silicone foam-gel formulations Part A comprises: ii) 0-60 parts, 1-60 parts, 20-60 parts, 25-30 parts, or 50-55 parts of a resin base, wherein the resin base comprises a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 1,000-20,000 cP (e.g., 1,000-15,000 cP, or 1,000-12,000 cP), and one or more oligosiloxanes; iii) 1-100 parts, 1-60 parts, 20-60 parts, 30-60 parts, 50-100 parts, 20-30 parts, or 50-55 parts) of a first silica base, wherein the firstAttorney Docket No.37996.0005P1 silica base comprises fumed silica and a vinyl-endblocked polydimethylsiloxane (PDMS) and a viscosity of 2,000-100,000 cP (e.g., 2,000-50,000 cP, 2,000-30,000 cP, 2,000-20,000 cP, 2,000-15,000 cP, 2,000-10,000 cP, or 2,000-5,000 cP), while Part B comprises: ii) 1-20 parts, 1-10 parts, 10-20 parts, or 15-20 parts) of a second silica base, wherein the silica base comprises fumed silica and a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 2,000-100,000 cP (e.g., 2,000-50,000 cP, 2,000-30,000 cP, 2,000-20,000 cP, 2,000-15,000 cP, 2,000-10,000 cP, or 2,000-5,000 cP). In yet another embodiment, in the described uncured, two-component silicone foam-gel formulations Part A comprises: ii) 1-60 parts, 20-60 parts, 25-30 parts, or 50-55 parts of a resin base, wherein the resin base comprises a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 1,000- 20,000 cP (e.g., 1,000-15,000 cP, or 1,000-12,000 cP), and one or more oligosiloxanes; iii) 1- 100 parts, 1-60 parts, 20-60 parts, 30-60 parts, 50-100 parts, 20-30 parts, or 50-55 parts) of a first silica base, wherein the first silica base comprises fumed silica and a vinyl-endblocked polydimethylsiloxane (PDMS) and a viscosity of 2,000-100,000 cP (e.g., 2,000-50,000 cP, 2,000-30,000 cP, 2,000-20,000 cP, 2,000-15,000 cP, 2,000-10,000 cP, or 2,000-5,000 cP), while Part B comprises: ii) 1-20 parts, 1-10 parts, 10-20 parts, or 15-20 parts) of a second silica base, wherein the silica base comprises fumed silica and a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 2,000-100,000 cP (e.g., 2,000-50,000 cP, 2,000-30,000 cP, 2,000-20,000 cP, 2,000-15,000 cP, 2,000-10,000 cP, or 2,000-5,000 cP). B. Other Siloxanes

[0019] In addition to the alkenyl-functionalized organopolysiloxane, the foam-gel comprises a number of other siloxanes in certain embodiments, including for example (1) one or more oligosiloxanes in the resin base, (2) a blowing agent, discussed in more detail below, that can in some aspects be an Si-OH functionalized organopolysiloxane, (3) a chain extender which is an organopolysiloxane having at least one Si–H functionality (e.g., a terminal Si–H functionality), and (4) a crosslinker which comprises methyl-hydrogen polysiloxane. In some embodiments, the catalyst can also be present in a solution or suspension of an organopolysiloxane.

[0020] The one or more oligosiloxanes of the resin base are generally branched, cage-like oligosiloxanes with the general formula, RnSiXmOy, where R is a non-reactive or a reactive group, typically an alkyl group, a phenyl group, an alkenyl group, a hydride group or a combination thereof, and X is OH, Cl, or O-alkyl. Oligosiloxanes in this class can be further condenses to give highly crosslinked polysiloxane networks. The oligomeric network of theseAttorney Docket No.37996.0005P1 siloxanes can in some aspects correspond to the structure:, where R is typically methyl, hydroxyl, or hydrogen. The four siloxane monomeric units in this structure can be described as: “M,” corresponding to Me3SiO, “D,” corresponding to Me2SiO2, “T”, corresponding to MeSiO3, and “Q,” which corresponds to SiO4. In general, the oligosiloxane of the resin base can be one or more of a DT resin, an MQ resin, an MDT resin, an MTQ resin, or a QDT resin. Any of the above-described formulations with respect to the various alkenyl-functionalized organopolysiloxanes can have a resin base that includes any of these oligosiloxanes or suitable combinations of oligosiloxanes.

[0021] In one embodiment, the resin base comprises a organopolysiloxane having at leastone alkenyl functionality and having a viscosity of 1,000-20,000 cP (e.g., 1,000-15,000 cP, or 1,000-12,000 cP), and one or more oligosiloxanes, which can be a DT oligosiloxane, an MQ oligosiloxane, an MDT oligosiloxane, an MTQ oligosiloxane, a QDT oligosiloxane, or any combination thereof. In a further embodiment, the resin base comprises a polydimethylsiloxane (PDMS) having at least one alkenyl functionality and a viscosity of 1,000-20,000 cP (e.g., 1,000-15,000 cP, or 1,000-12,000 cP), and one or more oligosiloxanes, which can be a DT oligosiloxane, an MQ oligosiloxane, an MDT oligosiloxane, an MTQ oligosiloxane, a QDT oligosiloxane, or any combination thereof. In a further embodiment, the resin base comprises a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 1,000-20,000 cP (e.g., 1,000-15,000 cP, or 1,000-12,000 cP), and one or more oligosiloxanes, which can be a DT oligosiloxane, an MQ oligosiloxane, an MDT oligosiloxane, an MTQ oligosiloxane, a QDT oligosiloxane, or any combination thereof, wherein the vinyl- endblocked polydimethylsiloxane (PDMS) has the structure shown above.

[0022] The chain extender can be an organopolysiloxane having at least one Si–Hfunctionality, typically a terminal Si–H functionality. This organopolysiloxane will generally include siloxane units having hydrocarbon groups according to the formula, —SiOR2—, where each R can be the same or different and can be substituted or unsubstituted, in addition to at least one Si-H functionality, which is typically a terminal Si-H functionality. Such R groups can in some aspects have from 1 to 10 carbons, for example, 1-8 carbons, 1-6 carbons,Attorney Docket No.37996.0005P1 1-4 carbons, or 1-2 carbons.

[0023] Examples of the substituted or unsubstituted hydrocarbon groups bonded tosilicon atoms represented by R include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl groups; aryl groups such as phenyl, tolyl, xylyl and naphthyl; aralkyl groups such as benzyl, phenylethyl and phenylpropyl; alkenyl groups such as vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, cyclohexenyl and octenyl; groups obtained by substituting some or all of the hydrogen atoms in the above-described groups with halogen atoms such as fluorine, bromine and chlorine, cyano groups and the like, such as chloromethyl groups, chloropropyl groups, bromoethyl groups, trifluoropropyl groups, and cyanoethyl groups. In one aspect, 90% or more of the R groups in each alkenyl-functionalized organopolysiloxane in the foam- gel formulation is methyl.

[0024] In one embodiment, the chain extender is a polydimethylsiloxane (PDMS) havingat least one Si-H functionality, and for example exhibiting a viscosity of 3-1,000 cP (e.g., 3- 100 cP, 100-500 cP, 500-1,000 cP, 3-50 cP, 3-40 cP, 3-30 cP, or 3-25 cP). In a further embodiment, the chain extender is a hydride-endblocked polydimethylsiloxane (PDMS), for example exhibiting a viscosity of 3-50 cP (e.g., 3-40 cP, 3-30 cP, or 3-25 cP). The hydride- endblocked polydimethylsiloxane (PDMS) can have the formula:, where n is an integer of at least 1.

[0025] The crosslinker, which comprises methyl-hydrogen polysiloxane, has a similarstructure:where n is an integer of at least 1, and where m is an integer that is 0 or at least 1. In some embodiments, the crosslinker has 100% methyl-hydrogen groups, in which case m will be 0. In other embodiments, the crosslinker will have some % of dimethyl groups, in which case m will be an integer of at least 1. The cross-linker can also have a viscosity generally ranging from 4-600 cSt (e.g., 4-500, 4-200, 3-80 cSt, 3-70 cSt, 3-60 cSt, 5-60 cSt, or 10-50 cSt). C. Blowing Agents

[0026] Part A of the foam-gel formulation also includes 5-50 parts (e.g., 10-30, 15-30Attorney Docket No.37996.0005P1 parts, 20-30 parts, 15-25 parts, 20-25 parts, or 24 parts) of a blowing agent having at least one hydroxyl functionality. In one embodiment, the blowing agent is a C2-C8 alcohol or diol, or an organopolysiloxane having at least one Si–OH functionality. Examples include propanediol, butanediol, pentanediol, or an organopolysiloxane having at least one Si–OH functionality. One non-limiting example is 1,5-pentanediol. The organopolysiloxane when used as a blowing agent can be any of those described above, for example, a polydimethylsiloxane (PDMS). In one embodiment, the blowing agent comprises a polydimethylsiloxane which is terminated with Si-OH groups (e.g., a PDMS having 4% terminal Si-OH groups).

[0027] One advantage of the described foam-gel formulations is that their densities are affected by the chemically blown nature of the formulation upon curing. Consequently, in some embodiments, the formulations can be free of any low-density fillers which have been used in the art, among other gas-forming substances. These include without limitation “gas- containing bodies,” also known as tubes or tube-like structures made of silicone or other material, as described in U.S. Patent No. 10,524,897. Low-density fillers also include hollow microspheres including those mixed with various gels as described in U.S. Patent No. 10,052,191. Other examples include hollow tubes made of ceramic or glass as described in U.S. Patent No. 10,213,293. Similarly, the formulation can be free of other substances which foam to form gas, such as carbonate and hydrolyzed silicone as described in U.S. Patent No. 10,893,935. D. Addition Catalysts

[0028] In one embodiment, the formulation comprises an addition catalyst in Part A. Examples include Platinum group catalysts, such as platinum divinyl disiloxane complexes. In a specific embodiment, Part A comprises Karstedt’s catalyst, which can for example be in a solution or suspension of an organopolysiloxane such as PDMS as a suitable amount, e.g., 1-5% by weight of the solution of suspension. The solution or suspension in some embodiments can have a viscosity of 200-1,000 cP, e.g., about 500 cP. E. Additional Optional Components

[0029] Formulations can also include in some embodiments 0.01-0.5 parts of an hydrosilylation inhibitor. Non-limiting examples include methyl vinyl cyclic inhibitors. Additional embodiments include a pigment in Part A, Part B, or in both parts.Attorney Docket No.37996.0005P1 F. Exemplary Foam-Gel Formulation Embodiments

[0030] Non-limiting exemplary embodiments of the foam-gel formulations are described in the following table, which contemplates any combination of the described components. In addition, with respect to the following exemplary formulations and those described above, any of the formulations or either or both Parts can “consist essentially of” the recited components, which means that the formulation or Part(s) cannot include additional unrecited components that materially affect the basic and novel characteristics of the formulation, which in some instances means that no material can be included if it significantly raises a resultant foam-gel’s specific gravity or density, e.g., if an unrecited material raises the foam- gel’s density to above 0.8 g / mL, the “consisting essentially of” phrase contemplates for that unrecited material to be excluded. Similarly, any of the formulations or either or both Parts described in this application may alternatively “consist of” the recited components, meaning no other elements are permitted in the formulation or Part(s).Attorney Docket No.37996.0005P1Attorney Docket No.37996.0005P1Attorney Docket No.37996.0005P1

[0031] In a further embodiment, Part A of the foam-gel formulation comprises: i) 100 parts of a Part A polymer, wherein the Part A polymer is a vinyl- endblocked polydimethylsiloxane (PDMS) and having a viscosity of 5,000- 200,000 cP (e.g., 20,000-200,000 cP, 50,000-150,000 cP, 80,000-120,000 cP, or about 100,000 cP); ii) 0-60 parts (e.g., 0 parts, 1-60 parts, 20-60 parts, 25-30 parts, or 50-55 parts) of a resin base, wherein the resin base comprises a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 1,000-20,000 cP (e.g., 1,000-15,000 cP, or 1,000-12,000 cP), and one or more oligosiloxanes which include MQ oligosiloxanes; iii) 0-100 parts (e.g., 0 parts, 1-100 parts, 0-60 parts, 1-60 parts, 20-60 parts, 30- 60 parts, 50-100 parts, 20-30 parts, or 50-55 parts) of a first silica base, wherein the first silica base comprises fumed silica and a vinyl-endblocked polydimethylsiloxane (PDMS) and a viscosity of 2,000-100,000 cP (e.g., 2,000-50,000 cP, 2,000-30,000 cP, 2,000-20,000 cP, 2,000-15,000 cP, 2,000- 10,000 cP, or 2,000-5,000 cP); wherein at least one of the resin base or first silica base is present in Part A; and wherein in other embodiments neither of the resin base or first silica base is present in Part A; and iv) 5-50 parts (e.g., 10-30, 15- 30 parts, 20-30 parts, 15-25 parts, 20-25 parts, or 24 parts) of a blowing agent having at least one hydroxyl functionality, wherein the blowing agent is 1,5-pentanediol or polydimethylsiloxane (PDMS) having at least some Si-OH terminated endgroups; v) 0.01 to 5 parts (e.g., 0.01-5 parts, 0.05-5 parts, 0.05 to 1 parts, 0.1 to 1 parts, 0.1 to 0.75 parts) of an addition catalyst, such as a Platinum catalyst; and vi) 0.01 to 5 parts (e.g., 0.01-0.5 parts, 0.03-0.2 parts, or 0.05-0.1 parts) of a hydrosilylation inhibitor, such as a methyl vinyl cyclic inhibitor; while Part B comprises: i) 1-20 parts (e.g., 10-20 parts, or 15-20 parts) of a Part B polymer, wherein the Part B polymer is a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 5,000-200,000 cP (e.g., 20,000-200,000 cP, 50,000-150,000 cP, 80,000-120,000 cP, or about 100,000 cP), which can be the same as or different from the viscosity of the Part A polymer (in one aspect the viscosity of the Part A polymer and Part B polymers are about the same, and in one aspect the Part A polymer and the Part B polymer are the same polymers);Attorney Docket No.37996.0005P1 ii) 0-20 parts (e.g., 0 parts, 1-20 parts, 0-10 parts, 1-10 parts, 10-20 parts, or 15-20 parts) of a second silica base, wherein the second silica base comprises fumed silica and a vinyl-endblocked polydimethylsiloxane (PDMS) having a viscosity of 2,000-100,000 cP (e.g., 2,000-50,000 cP, 2,000-30,000 cP, 2,000- 20,000 cP, 2,000-15,000 cP, 2,000-10,000 cP, or 2,000-5,000 cP); iii) 100 parts of a chain extender, wherein the chain extender is anorganopolysiloxane having at least one Si–H functionality, such as a hydride- endblocked polydimethylsiloxane (PDMS) (e.g., having a viscosity of 3-50 cP,, or 5-20 cP); and iv) 0.05-20 parts (e.g., 0.1-15 parts, 0.2-15 parts, 0.2-10 parts, 0.2-5 parts, 0.2-3parts, or 0.2-1 parts) of a crosslinker comprising methyl-hydrogen polysiloxane; wherein each instance of the vinyl-endblocked polydimethylsiloxane (PDMS) has the following formula:, wherein n is independently in each instance is an integer greater than 1, e.g., in some instances an integer corresponding to a PDMS molecular weight ranging from 1,000-300,000 g / mol. II. Methods and Silicone Foam-Gels

[0032] Embodiments of the disclosure also related to methods of preparing silicone foam-gels from the above-described formulations, as well as the resulting silicone foam-gels. In one embodiment, the method for preparing the silicone foam-gel comprises mixing Part A and Part B of any of the above-described formulations to form a silicone mixture, and allowing the mixture to cure. In some aspects, gas is not bubbled into Part A, Part B, or the silicone mixture.

[0033] The two Parts can be mixed at suitable ratios, in some aspects at a 1:1 ratio.Curing of the resulting mixture can be accomplished at a suitable temperature, for example at room temperature.

[0034] The resultant silicone foam-gels encompassed by the disclosure exhibit lowdensity relative to those commonly used in the art. Some embodiments of the silicone foam- gel prepared have a density of 0.4-0.9 g / mL.Attorney Docket No.37996.0005P1 III. Implantable Medical Devices

[0035] Additional embodiments of this disclosure related to implantable medical devices comprising a silicone foam-gel cured from the foam-gel formulations described above. The foam-gel cured from the formulations can be a component part of a medical device that functions as a tissue expander, a gastric restriction or gastric balloon, an artificial urethral sphincter, a drug delivery reservoir or dispensing device, or a prosthetic device such as a breast implant, a testicular prosthesis, a penile prosthesis, a calf prosthesis, a buttocks prosthesis, a vitreous body prosthesis in the eye, or an inflatable facial prosthesis.

[0036] The foam-gel cured from the formulations can also be used as a component of an implantable mechanical device such as a valve, finger joint or toe joint. The foam-gel can also be a coating or part thereof for a medical device such as a stent, housing for electronic device such as a pacemaker, or a mechanical device such as a pressure transducer or strain gauge or on a catheter, or as a drain or pump tubing.

[0037] As a prosthetic device, the foam-gel cured from the formulations can be included as a shell or a component of a shell of the device. Such devices typically also include a filler, such as a silicone gel, a water containing medium such as an aqueous solution, e.g., saline, a composite, a gas such as air. The shell typically envelopes the filler and can further include components to seal the filler in the shell such as patches, valves or sealants to establish a continuous barrier to contain the filler material. In one embodiment, a medical device comprises an outer shell including the foam-gel cured from the formulations, e.g., a prosthetic such as a breast implant. The medical device, e.g., prosthetic such as a breast implant, can further include a filler material, e.g., a silicone gel or a water containing medium such as saline. EXAMPLES

[0038] The following examples further illustrate this disclosure. The scope of the disclosure and claims is not limited by the scope of the following examples. I. Procedures Table 1. Materials Used in Part A FormulationsAttorney Docket No.37996.0005P1Table 2. Materials Used in Part B FormulationsA. Preparation of Parts A and B

[0039] To prepare Part A, all materials were added to a SpeedMixer cup and mixed for 60 seconds at 2,000 RPM. To prepare Part B, all materials were added to a SpeedMixer cup, hand-mixed for 60 seconds, then SpeedMixed for 60 seconds at 2,000 rpm, then hand-mixed and SpeedMixed for another 60 seconds each. B. General Preparation and Testing of Foam-Gels

[0040] To prepare the foam-gel, Part B and Part A were combined in a 1:1 mass ratio (Part B added first) in a SpeedMix cup (FlackTek). For samples under 100 g, the Part B and Part A were combined and then immediately mixed in a DAC 150.1 FV-K or DAC 330-100 SE SpeedMixer (FlackTek) at 2,000 rpm for 30 seconds. The lid of the cup was loosened to allow gas release, and the cup was left to cure at room temperature for at least 20 minutes. For larger samples (> 100 g), the same mix ratio was used, but the material was mixed in a DAC 1200-500 SpeedMixer (FlackTek) at 1600 rpm for 30 seconds. If the material was transferred to a container after SpeedMixing, it was poured immediately (within 30 seconds) after mixing due to its fast cure time.

[0041] Penetration data were collected using a TA.XTplus Texture Analyser (Stable Micro Systems) equipped with a 1” diameter acrylic cylinder, exerting 75.0 g of force on the sample for 15.00 seconds with a trigger force of 0.5 g. The maximum depth of the probe into the sample was recorded to the nearest 0.1 mm. Foam density was measured by water displacement.Attorney Docket No.37996.0005P1 C. Part A and B Formulations i. Part A Formulations Table 3. Foam-Gel Part A formulations (A1-A4) with 1,5-pentanediolTable 4. Foam-gel Part A formulations (A5-A7) with silanol and varying resin / silica ratioAttorney Docket No.37996.0005P1 Table 5. Foam-gel Part A formulations (A8-A9) with silanol and varied Pt and polymerii. Part B Formulations Table 6. Foam-gel Part B formulations (B1-B4)Results A. Properties of Foam-Gels with Select Part A Formulations

[0042] The foam-gel was made with Part A2 (Table 3) and A7 (Table 4) using all Part B’s from Table 6. All samples with A2 turned a pale yellow within one hour of curing, with bubble size decreasing with increasing crosslinker amounts. Table 7 shows a trend of density decreasing with increasing concentration of crosslinker. The foam-gels from Parts A2 and A7Attorney Docket No.37996.0005P1 all fall within or near the density range of 0.60-0.75 g / mL with Parts B2-4. Materials made with B1 either did not cure (A2+B1) or cured with relatively large / heterogeneous bubbles (A7+B1). Table 8 shows the penetration values of all foam-gels made with A2 and A7. Increasing crosslinker concentration results in a decreased penetration value and therefore a firmer gel. For breast implants, the desired range is ~7-20 mm. For Part A2, B3 yielded the most desirable results, while Part B2 gave the most desired results for Part A7. In the following sections, the Part A’s containing 1,5-pentanediol are primarily combined with B3, and the silanol-containing Part A's are with B2. Table 7. Density of foam-gels using A2 and A7 with B1-B4. All results given in g / mL. A2+B1 did not cure in the allotted time, and density could not be measured (no change from intermediate materials)Table 8. Penetration values of foam-gels using A2 and A7 with B1-B4. All results given in mm. A2+B1 did not cure in the allotted time, so penetration data could not be measured.B. Foam-Gel with 1,5-pentanediol as Blowing Agent in Part A

[0043] Using 5-20 cP chain extender in Part B in combination with high-hydride crosslinker resulted in a soft, gel-like material. When Part B1 (Table 6) was mixed with Part A’s A1-A4 containing 1,5-pentanediol from Table 3, the ratio of resin base to silica baseAttorney Docket No.37996.0005P1 showed to be useful for achieving a foam-gel as opposed to just a gel. Lower resin base results in a faster reaction rate and smaller bubbles, which when replaced with silica base forms a soft, durable foam-gel. Table 9 shows the density of this material ranging from 0.4- 0.7 g / mL. Sample A1+B3 in Table 9 cured in ~30 minutes and was soft and gel-like, but contained few-to-no bubbles. Sample A2+B3 cured faster than A (10-15 minutes), and formed many small bubbles, although is noticeably firmer than sample A1+B3. Sample A3+B3 cured even faster than A2+B3 (<5 min), and was a firmer gel than samples A1+B3 and A2+B3 and with smaller bubbles. Sample A4+B3 contains no resin or silica, in order to see the effect that removing reinforcement has on the foam-gel properties. The resulting material has the same density and comparable look / feel to Sample A3+B3. Table 9. Density of foam-gels prepared with 1,5-pentanediol (Table 3) using B3 from Table 6C. Foam-Gel with Silanol as Blowing Agent in Part A

[0044] 1,5-pentanediol is not fully miscible with silicone in some aspects and causes Part A to be opaque white by forming an emulsion of pentanediol in silicone. Silanols are miscible with the other polymers and dissolve fully in the Part A, making it transparent. The resulting foam-gels made with silanols (Part A: Samples A5-A9) cure faster and are stiffer than those made with 1,5-pentanediol, which was balanced by lowering the amount of Pt in Part A from 0.75 PPH (Table 3) to 0.10 PPH (Table 4, Table 5). Additionally, the amount of crosslinker in Part B can be lowered from 0.71 PPH used with 1,5-pentanediol-containing formulations (B3), to 0.50 PPH (B2). When Parts A5-A7 were combined with B2, A5 did not cure after several days, and A6 cured into a soft gel but did not contain any bubbles. Table 10 shows the density of these foam-gels, showing a similar trend of reaction rate and cell size caused by replacing the resin base with silica base as described in the previous section. Table 10. Density of foam-gels prepared with silanol (Table 4) using B2 from Table 6. A5+B2 and A6+B2 both are marked with “N / A” due to lack of curing and / or foaming, and density could not be measuredAttorney Docket No.37996.0005P1

[0045] When foam-gels are made with neither resin nor silica base in Part A (Table 5, A8), the resulting foam-gel still resembles silica (Table 10, A7+B2). Sample A8+B2 in Table 11 resembles Sample A4+B3 from Table 9, further indicating that removing reinforcement has minimal apparent effect on the foam-gel properties. When the silanol-containing foam- gel is made with the higher amount of catalyst (A9), the resulting material has a higher density (A9+B2, Table 11) than its lower-Pt counterpart A6+B2 (Table 10). Table 11. Density of foam-gels prepared with silanol (Table 5) using B2 from Table 6.

[0046] Foam-gel materials were developed for medical implants with tunable properties such as cure rate, bubble size, and softness. For breast implant applications, the use of silanol in Part A with chain extender in Part B yields a foam-gel with a density of 0.4-0.8 g / mL, and a penetration value of 3.4 mm. The density and penetration values can be adjusted by changing the amount of crosslinker in the system; both density and penetration have an inverse correlation to the crosslinker concentration. The addition of chain extenders to Part B is useful for the foam to take on gel-like properties. The rate of the foaming reaction shows an inverse correlation to the amount of resin base in the formulation. Varying the amount of resin base and silica base also affects the curing properties such as bubble size and homogeneity. For example, lowering resin amount and / or increasing silica amount will increase the speed of the reaction, providing smaller, more homogeneous bubbles.

[0047] Features and advantages of this disclosure are apparent from the detailed specification, and the claims cover all such features and advantages. Numerous variations will occur to those skilled in the art, and any variations equivalent to those described in this disclosure fall within the scope of this disclosure. Those skilled in the art will appreciate that the conception upon which this disclosure is based may be used as a basis for designing other compositions and methods for carrying out the several purposes of this disclosure. As a result, the claims should not be considered as limited by the description or examples.

Claims

Attorney Docket No.37996.0005P1 CLAIMS What is claimed is:

1. An uncured, two-component silicone foam-gel formulation comprising: a) a Part A comprising: i) 100 parts of a Part A polymer, wherein the Part A polymer is an organopolysiloxane having at least one alkenyl functionality; ii) 0-60 parts of a resin base, wherein the resin base comprises an organopolysiloxane having at least one alkenyl functionality and a viscosity of 1,000-20,000 cP, and one or more oligosiloxanes; iii) 0-100 parts of a first silica base, wherein the first silica base comprises fumed silica and an organopolysiloxane having at least one alkenyl functionality and a viscosity of 2,000-100,000 cP; wherein at least one of the resin base or first silica base is present in Part A; iv) 5-50 parts of a blowing agent having at least one hydroxyl functionality; and v) an addition catalyst; b) a Part B comprising: i) 1-20 parts of a Part B polymer, wherein the Part B polymer is an organopolysiloxane having at least one alkenyl functionality ii) 0-20 parts of a second silica base, wherein the second silica base comprises fumed silica and an organopolysiloxane having at least one alkenyl functionality and a viscosity of 2,000-100,000 cp; iii) 100 parts of a chain extender, wherein the chain extender is an organopolysiloxane having at least one Si–H functionality; and iv) 0.05-20 parts of a crosslinker comprising methyl-hydrogen polysiloxane; wherein the formulation is in the form of a kit in which Part A and Part B are not mixed.

2. The formulation of claim 1, wherein the Part A polymer has a viscosity of 5,000- 200,000 cP.

3. The formulation of claims 1 or 2, wherein Part A comprises 20-60 parts of the resin base.Attorney Docket No.37996.0005P1 4. The formulation of any of the preceding claims, wherein Part A comprises 20-60 parts of the first silica base.

5. The formulation of any of the preceding claims, which is free of any low-density filler.

6. The formulation of any of the preceding claims, wherein the addition catalyst is a Platinum group catalyst.

7. The formulation of claim 6, wherein the Platinum group catalyst is a platinum divinyl disiloxane complex.

8. The formulation of any of the preceding claims, wherein the blowing agent is a C2-C8 alcohol or diol, or an organopolysiloxane having at least one Si–OH functionality.

9. The method of claim 8, wherein the blowing agent is propanediol, butanediol, pentanediol, or an organopolysiloxane having at least one Si–OH functionality.

10. The formulation of any of the preceding claims, further comprising 0.01-0.5 parts of an hydrosilylation inhibitor.

11. The formulation of claim 10, wherein the inhibitor is a methyl vinyl cyclic inhibitor.

12. The formulation of claim 10, further comprising a pigment in Part A, Part B, or both.

13. The formulation of any of the preceding claims, wherein Part B comprises 10-20 parts of the Part B polymer.

14. An implantable medical device comprising a silicone foam-gel cured from the formulation of any of the preceding claims.

15. The device of claim 14, which is a breast implant.

16. A method for preparing a silicone foam-gel, comprising mixing Part A and Part B of the formulation of any of the preceding claims to form a silicone mixture, and allowing the mixture to cure.

17. The method of claim 16, wherein gas is not bubbled into Part A, Part B, or the silicone mixture.Attorney Docket No.37996.0005P1 18. The method of claims 16 or 17, wherein Part A and Part B are mixed at a 1:1 ratio.

19. The method of claims 16-18, wherein the mixture is allowed to cure at room temperature.

20. A silicone foam-gel prepared by the method of claims 16-19, which has a density of 0.4-0.9 g / mL.

21. A silicone foam-gel prepared by hydrosilylation of a two-component silicone formulation, the silicone foam-gel having a density of 0.4-0.9 g / mL.

22. An implantable medical device comprising the silicone foam-gel of claims 20 or 21.

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