Implant comprising silicone foam

Abstract

The present invention relates to novel implants, in particular breast implants, which have biodurability, biocompatibility, provide soft tissue sensation, and have reduced density. The present invention relates to an implant comprising a shell and a filler encapsulated by the shell wherein the filler comprises a silicone foam obtained from a foamable crosslinkable silicone composition, the invention relates to a composition comprising an organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule, an organosilicon-containing compound having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule, a hydrosilylation catalyst, at least one porogen as water, hydrogel or aqueous silicone emulsion, and at least one surfactant, at least one chemical blowing agent; and a linear polydimethylsiloxane.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 63 / 393,084, filed on July 28, 2022, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present invention relates to the technical field of implants. More particularly, the present invention relates to new implants, especially breast implants, comprising silicone foam, which provide a soft tissue feel and have a reduced density. Background Art

[0004] Today, reconstructive and cosmetic surgery has become a common practice, as almost any part of the body can be augmented to create balance and harmony. Implants are used in reconstructive and cosmetic surgery. The use of implants is expected to increase significantly due to an aging population, increased life expectancy and lifestyle, and improved implant technology. The term "implant" in this patent document refers to a medical device that is manufactured to replace a missing biological structure, support a damaged biological structure, or enhance an existing biological structure.

[0005] The implant needs to be able to assume a specific three-dimensional shape and maintain that shape for a certain period of time, depending on the nature of the implant. The implant also needs to be biodurable so that it is not damaged by interaction with the human body; and it needs to be biocompatible. The biocompatibility of a medium-term or long-term implantable medical device refers to its ability to perform its intended function without producing any adverse local or systemic effects.

[0006] Breast implants are performed in the largest number of cases of all types of cosmetic and reconstructive implants. Reconstructive breast surgery is performed to rebuild a woman's breasts affected by a mastectomy, while cosmetic breast surgery is performed to change the appearance of a woman's breasts, such as by adding implants to increase breast size, correct asymmetry, change shape, and repair deformities.

[0007] Additionally, implants are now increasingly used for other facial implants such as eyebrows, nose, cheeks, chin and lips, as well as various body implants such as tracheal stents, implantable fat augmentations or replacements such as gluteus maximus or cheek implants; or firmer tissue such as calves, biceps, triceps or abdominal muscles.

[0008] Most implants are composed of silicone-based materials, which have long been recognized as one of the most biocompatible synthetic materials available, if not the most biocompatible synthetic material available.

[0009] As a desired improvement in implant technology, there remains a need for a biocompatible, lightweight material. For example, lightweighting of breast implants is of interest to any company that manufactures said implants. Lightweighting not only improves patient fit, improves ergonomics, and reduces fatigue-related issues or injuries, but also reduces the amount of material required to produce the device. This also applies to tissue expansion products, such as those used during mastectomy procedures for patients waiting for an implant.

[0010] Patent application US 2019 / 0314144 A1 discloses a method for manufacturing a breast implant, comprising producing an elastic filling material comprising a foam by mixing a carbonate with a hydrolyzed silicone. According to the article, the carbon dioxide bubbles are produced by the reaction of a bicarbonate (such as sodium bicarbonate) with hydrochloric acid (HCl), which is a byproduct of the hydrolysis of silicone monomers. The foaming agent here releases the bubbles by acidification. In the case of the intended use as an implant, managing the acidity of the final silicone foam may be a potential risk.

[0011] In international patent application WO 2020 / 072374, a kit for preparing a customizable silicone gel or foam that simulates flesh is disclosed. The kit according to this document can be a customized solution to improve the sensory feel of implant materials to match the feel of their natural flesh. The kit comprises at least 3 parts, wherein the first part comprises an alkenyl-containing organopolysiloxane and a hydrosilylation catalyst, the second part comprises an alkenyl-containing organopolysiloxane and an organic silicon-containing compound containing hydrogen atoms, and the third part comprises a linear polydimethylsiloxane. According to one embodiment, the third part may also include a foaming agent, which can produce gas by chemical decomposition or evaporation. According to another embodiment, the foaming agent can be provided to the formulation through the fourth part of the kit. The foaming agent that releases gas at an elevated temperature can be a bicarbonate, particularly ammonium bicarbonate (NH4) HCO3, sodium bicarbonate NaHCO3, calcium bicarbonate Ca(HCO3)2 or other alkali metal bicarbonates. These foaming agents release CO2 to produce hollow bubbles.

[0012] Currently, there remains a need for a material for producing implants that is biodurable, biocompatible, provides soft tissue feel, and has reduced density. Summary of the invention SUMMARY OF THE INVENTION

[0014] All these objects and others are achieved by the present invention, which relates to an implant comprising a shell and a filling enclosed by the shell, wherein the filling comprises a silicone foam obtained from a foamable, cross-linkable silicone composition comprising:

[0015] - at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule;

[0016] - at least one organosilicon compound B having at least two, preferably at least three, silicon-bonded hydrogen atoms per molecule;

[0017] - at least one hydrosilylation catalyst C;

[0018] - at least one porogen D which is water, a hydrogel or an aqueous silicone emulsion;

[0019] - at least one chemical blowing agent E; and

[0020] - at least one linear polydimethylsiloxane F having a dynamic viscosity at 25° C. of 50 to 100 000 mPa.s.

[0021] The silicone foam defined above can be described as a "double-expanded" silicone foam:

[0022] - On the one hand, a porogen D, which is water, a hydrogel or an aqueous silicone emulsion, generates hydrogen bubbles while being incorporated into a polyaddition-crosslinkable silicone composition comprising an organopolysiloxane A having silicon-bonded alkenyl groups, an organosilicon-containing compound B containing silicon-bonded hydrogen atoms, and a hydrosilylation catalyst C, and

[0023] - Chemical blowing agents E, on the other hand, release gas, typically carbon dioxide, by decomposition.

[0024] The inventors have found that the resulting double-blown silicone foam exhibits a low density and a foam cell structure that is significantly more uniform and stable than using only one blowing agent or the other, while also maintaining a flesh-like feel. It is very suitable for use as a filler in implants, preferably breast implants.

[0025] Detailed description of the invention

[0026] All viscosities considered in this description correspond to dynamic viscosity quantities, measured in a manner known per se at 25° C. at a shear rate gradient low enough to make the viscosity measured with a Brookfield-type machine independent of the rate gradient.

[0027] Unless specifically stated otherwise, the contents expressed in % or ppm are by weight.

[0028] The foamable and crosslinkable silicone composition according to the present invention comprises at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule. Preferably, the organopolysiloxane A has at least two silicon-bonded C2-C6 alkenyl groups per molecule. It may be composed of the following units: at least two siloxy units of the following formula: Y a R 1 b SiO (4-a-b) / 2

[0029] in:

[0030] - Y represents a C2-C6 alkenyl group, preferably a vinyl group,

[0031] -R 1 is a monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably selected from an alkyl group having 1 to 8 carbon atoms such as methyl, ethyl or propyl, a cycloalkyl group having 3 to 8 carbon atoms and an aryl group having 6 to 12 carbon atoms,

[0032] - a=1 or 2, b=0, 1 or 2 and the sum of a+b=2 or 3,

[0033] and optionally, units of the formula: R 1 c SiO (4-c) / 2

[0034] Where R 1 has the same meaning as above and c=0, 1, 2 or 3.

[0035] Preferably, the dynamic viscosity of organopolysiloxane A at 25° C. may be 100 to 120,000 mPa.s, preferably 100 to 80,000 mPa.s, more preferably 1,000 to 50,000 mPa.s, even more preferably 5,000 to 20,000 mPa.s. The organopolysiloxane A may preferably be referred to as organopolysiloxane oil.

[0036] The organopolysiloxane A may be a linear organopolysiloxane, a cyclic organopolysiloxane or a branched organopolysiloxane (resin). The foamable and crosslinkable silicone composition according to the invention may contain a mixture of different organopolysiloxanes A.

[0037] According to one embodiment, the organopolysiloxane A may be a linear organopolysiloxane. The linear organopolysiloxane exhibits a structure consisting essentially of D or D Vi Siloxy unit and terminal M or M Vi The linear structure formed by the siloxy unit, where D, D Vi , M and M Vi The definition is as follows: D:R1 2SiO 2 / 2 Siloxy unit, D Vi :Selected from Y2SiO 2 / 2 or YR 1 SiO 2 / 2 Siloxyl unit of siloxyl unit, M:R 1 3SiO 1 / 2 Siloxy unit, M Vi :Selected from YR 1 2SiO 1 / 2 and Y2R 1 SiO 1 / 2 Siloxy units; symbols Y and R 1 As described above.

[0038] As the end "M or M Vi As examples of " " units, there may be mentioned trimethylsiloxy, dimethylphenylsiloxy, dimethylvinylsiloxy or dimethylhexenylsiloxy.

[0039] As "D or D Vi As examples of " " units, there may be mentioned dimethylsiloxy, methylphenylsiloxy, methylvinylsiloxy, methylbutenylsiloxy, methylhexenylsiloxy, methyldecenylsiloxy or methyldecadienylsiloxy.

[0040] Examples of linear or cyclic organopolysiloxanes which may be the organopolysiloxane A according to the invention are:

[0041] - poly(dimethylsiloxane) containing dimethylvinylsilyl end groups;

[0042] - poly(dimethylsiloxane-co-methylphenylsiloxane) containing dimethylvinylsilyl end groups;

[0043] - poly(dimethylsiloxane-co-methylvinylsiloxane) containing dimethylvinylsilyl end groups;

[0044] - poly(dimethylsiloxane-co-methylvinylsiloxane) containing trimethylsilyl termini; and

[0045] - Cyclic poly(methylvinylsiloxane).

[0046] Preferably, the organopolysiloxane A has a weight content of alkenyl units of 0.001% to 30%, preferably 0.01% to 10%, preferably 0.02% to 5%.

[0047] According to a preferred embodiment, the organopolysiloxane A comprises terminal dimethylvinylsilyl units, and even more preferably, the organopolysiloxane A is a poly(dimethylsiloxane) comprising terminal dimethylvinylsilyl groups. The number of dimethylsiloxane units may be 5-1000, preferably 100-600.

[0048] According to another embodiment, the organopolysiloxane A may be a 2-6 Branched organopolysiloxane (i.e. resin) of alkenyl units. It is preferably selected from the organosilicon resin of the following formula:

[0049] -M Vi Q, in which the alkenyl group bonded to the silicon atom is carried by the M group,

[0050] -MM Vi Q, in which the alkenyl group bonded to the silicon atom is carried by a portion of the M unit,

[0051] -MD Vi Q, in which the alkenyl group bonded to the silicon atom is carried by the D group,

[0052] -MDD Vi Q, wherein the alkenyl group bonded to the silicon atom is carried by a portion of the D group,

[0053] -MM Vi TQ, in which the alkenyl group bonded to the silicon atom is carried by a portion of the M unit,

[0054] -MM Vi DD Vi Q, in which the hydrogen atoms bonded to the silicon atoms are carried by a portion of the M and D units,

[0055] - and mixtures thereof,

[0056] Among them, M Vi , D and D Vi As defined above, T: Formula R 1 SiO 3 / 2 Siloxy units, and Q: formula SiO 4 / 2 The siloxy units, where R 1 Has the same meaning as above.

[0057] According to a preferred embodiment, the foamable crosslinkable silicone composition according to the present invention comprises a mixture of at least one linear organopolysiloxane as defined above and at least one branched organopolysiloxane (i.e., resin) as defined above. For example, the foamable crosslinkable silicone composition according to the present invention may comprise a mixture of a linear poly(dimethylsiloxane) containing dimethylvinylsilyl end groups and a branched organopolysiloxane of formula M Vi Q.MMVi Q.MD Vi Q. MDD Vi Q.MM Vi TQ or MM Vi DD Vi Q, preferably M Vi Q.MM Vi Q.MD Vi Q or MDD Vi A mixture of silicone resins of Q. The amount of linear poly(dimethylsiloxane) in the foamable and crosslinkable silicone composition according to the present invention may be 0.8%-94% by weight, preferably 2.5%-45% by weight, and more preferably 3.5%-25% by weight of the total composition. The amount of silicone resin in the foamable and crosslinkable silicone composition according to the present invention may be 0%-10% by weight, preferably 0.01%-5% by weight, and more preferably 0.05%-2% by weight of the total composition.

[0058] The foamable and crosslinkable silicone composition according to the present invention further comprises at least one organic silicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule. The organic silicon-containing compound B is preferably an organohydrogenpolysiloxane compound containing at least two and preferably at least three hydrosilyl functional groups (or Si-H units) per molecule.

[0059] The organic silicon-containing compound B may advantageously be an organopolysiloxane comprising at least two, preferably at least three, siloxy units of the formula: d R 2 e SiO (4-d-e) / 2 ,

[0060] in:

[0061] - Same or different R 2 represents a monovalent group having 1 to 12 carbon atoms,

[0062] - d = 1 or 2, e = 0, 1 or 2 and d + e = 1, 2 or 3;

[0063] and optionally, other units of the formula: R 2 f SiO (4-f) / 2 ,

[0064] Where R 2 has the same meaning as above, and f=0, 1, 2 or 3.

[0065] It should be understood that in the above formula, if there are multiple R 2 groups, they may be the same or different from each other. 2R may represent a monovalent group selected from an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms and an aryl group having 6 to 12 carbon atoms which is optionally substituted by at least one halogen atom such as chlorine or fluorine. 2 can be advantageously selected from methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl, and most preferably, R 2 It's methyl.

[0066] The sign d is preferably equal to 1.

[0067] The organic silicon-containing compound B may have a linear, branched or cyclic structure. The degree of polymerization is preferably greater than or equal to 2. Typically, it is less than 5,000.

[0068] When it comes to linear polymers, they are essentially selected from the group consisting of polymers having the formula D:R 2 2SiO 2 / 2 or D':R 2 HSiO 2 / 2 The siloxy units of the units and the units selected from the group consisting of the units of the formula M:R 2 3SiO 1 / 2 or M':R 2 2HSiO 1 / 2 The terminal siloxy unit of the unit is formed, wherein R 2 Has the same meaning as above.

[0069] Preferably, the viscosity of the organic silicon-containing compound B is from 1 mPa.s to 5,000 mPa.s, more preferably from 1 mPa.s to 2,000 mPa.s, and still more preferably from 5 mPa.s to 1,000 mPa.s.

[0070] Examples of organohydrogenpolysiloxanes that may be the organosilicon-containing compound B according to the invention comprising at least two silicon-bonded hydrogen atoms are:

[0071] - poly(dimethylsiloxane) containing hydrodimethylsilyl termini;

[0072] - poly(dimethylsiloxane-co-methylhydrogensiloxane) containing trimethylsilyl termini;

[0073] - poly(dimethylsiloxane-co-methylhydrogensiloxane) containing hydrodimethylsilyl termini;

[0074] - poly(methylhydrogenosiloxane) containing trimethylsilyl termini; and

[0075] - Cyclic poly(methylhydrogensiloxane).

[0076] When the organic silicon-containing compound B has a branched structure, it is preferably selected from the organic silicone resins of the following formula:

[0077] - M'Q, in which the hydrogen atom bonded to the silicon atom is carried by the M group,

[0078] - MM'Q, in which the hydrogen atoms bonded to the silicon atoms are carried by a part of the M unit,

[0079] - MD'Q, in which the hydrogen atom bonded to the silicon atom is carried by the D group,

[0080] - MDD'Q, in which the hydrogen atom bonded to the silicon atom is carried by a part of the D group,

[0081] - MM'TQ, in which the hydrogen atoms bonded to the silicon atoms are carried by a part of the M unit,

[0082] - MM'DD'Q, in which the hydrogen atoms bonded to the silicon atoms are carried by a part of the M and D units,

[0083] - and mixtures thereof,

[0084] wherein M, M', D and D' are as defined above, T: Formula R 2 SiO 3 / 2 Siloxy units and Q: formula SiO 4 / 2 The siloxy units, where R 2 Has the same meaning as above.

[0085] Preferably, the weight content of hydrosilyl Si—H functional groups in the organic silicon-containing compound B is 0.2% to 91%, more preferably 3% to 80%, and more preferably 15% to 70%.

[0086] Advantageously, the molar ratio of hydrosilyl SiH functional groups of the organic silicon-containing compound B to olefin functional groups of the compound A is from 1 to 50, preferably from 2 to 30, more preferably from 3 to 20.

[0087] According to a preferred embodiment, the foamable crosslinkable silicone composition according to the invention comprises a mixture of at least one organic silicon-containing compound B1 having at least three silicon-bonded hydrogen atoms per molecule and at least one organic silicon-containing compound B2 having two silicon-bonded hydrogen atoms per molecule. The organic silicon-containing compound B2 preferably contains terminal dimethylhydrogensilyl units, and even more preferably, the organic silicon-containing compound B2 is a poly(dimethylsiloxane) containing terminal dimethylhydrogensilyl groups. The number of dimethylsiloxane units in the organic silicon-containing compound B2 may be from 1 to 200, preferably from 1 to 150, more preferably from 3 to 120. Such an organic silicon-containing compound B2 may be described as a "chain extender" due to its presumed effect of increasing the mesh size of the network when it is crosslinked. In addition, such an organic silicon-containing compound B1 having three or more silicon-bonded hydrogen atoms per molecule may be described as a "crosslinker". Preferably, the organic silicon-containing compound B1 is a poly(dimethylsiloxane-co-methylhydrogensiloxane) containing trimethylsilyl terminal groups and / or hydrodimethylsilyl terminal groups.

[0088] The hydrosilylation catalyst C may be chosen in particular from compounds of platinum and rhodium, but may also be chosen from silicon compounds, such as those described in patent applications WO2015 / 004396 and WO2015 / 004397; germanium compounds, such as those described in patent application WO2016 / 075414; or complexes of nickel, cobalt or iron, such as those described in patent applications WO2016 / 071651, WO2016 / 071652 and WO2016 / 071654. Catalyst C is preferably a compound derived from at least one metal belonging to the platinum group. These catalysts are well known. Use may in particular be made of complexes of platinum with organic products as described in US Pat. Nos. 3,159,601, 3,159,602 and 3,220,972 and EP 0057459, EP 0188978 and EP 0190530, or of complexes of platinum with vinylated organosiloxanes as described in US Pat. Nos. 3,419,593, 3,715,334, 3,377,432 and 3,814,730.

[0089] Preferably, catalyst C is a compound derived from platinum. Preferably, catalyst C is a Karstedt platinum catalyst.

[0090] The foamable and cross-linkable silicone composition according to the present invention comprises water, hydrogel or aqueous silicone emulsion as porogen D. Water can be directly added to the foamable and cross-linkable silicone composition. Advantageously, water can be introduced in the form of an aqueous silicone emulsion, such as an oil-in-water silicone direct emulsion or an oil-in-water silicone inverse emulsion, which comprises a silicone oil continuous phase, an aqueous phase and a stabilizer.

[0091] According to one embodiment, water is introduced via an emulsion of silicone oil in water having a water content of about 60% by weight. When water is introduced into the foamable crosslinkable silicone composition via an emulsion, the dispersion of water in the foamable crosslinkable silicone composition and its storage stability are improved.

[0092] According to one embodiment, an emulsifier may be added with water or with an aqueous silicone emulsion. The emulsifier may be selected by a person skilled in the art from typical emulsifiers. It may be an anionic, cationic, amphoteric or nonionic emulsifier. Of these, nonionic surfactants are most preferred because they may have the least effect on the hydrosilylation reaction. The emulsifier may be added in an amount such that the weight ratio of emulsifier to water may be from 1:5 to 5:1, preferably from 2:1 to 1:2.

[0093] A portion of the hydrosilyl functional groups of the organic silicon-containing compound B will react with the water provided by the porogen D and form gaseous hydrogen, making good foaming of the composition possible.

[0094] The foamable and cross-linkable silicone composition according to the present invention comprises at least one chemical blowing agent E. Preferably, the chemical blowing agent E is at least one bicarbonate salt (also commonly referred to as "bicarbonate salt"). More preferably, the chemical blowing agent E is selected from ammonium bicarbonate (NH4)HCO3, sodium bicarbonate NaHCO3, calcium bicarbonate Ca(HCO3)2 and mixtures thereof. Even more preferably, the chemical blowing agent E is ammonium bicarbonate.

[0095] The chemical blowing agent E may have a median particle size (D50) of ≤50 μm, even more preferably ≤10 μm. According to a preferred embodiment, the particles of the chemical blowing agent E may be ground and sieved before use.

[0096] For ease of application and production, the chemical blowing agent E may be pre-dispersed in the organopolysiloxane A, for example at a level of 30% to 60% by weight, and eventually incorporated with any additives that may help stabilize the resulting composition for shelf life.

[0097] The foamable and crosslinkable silicone composition according to the present invention comprises at least one linear polydimethylsiloxane F having a dynamic viscosity at 25° C. of 50 to 100,000 mPa.s, preferably 50 to 70,000 mPa.s, more preferably 100 to 20,000 mPa.s, more preferably 200 to 5,000 mPa.s, even more preferably 1,000 to 2,000 mPa.s.

[0098] According to a first embodiment of the invention, the linear polydimethylsiloxane F has the following formula: (CH3)3SiO(SiO(CH3)2) n Si(CH3)3 (I)

[0099] wherein n is an integer of 50-900, preferably 50-700.

[0100] According to a second embodiment of the present invention, the linear polydimethylsiloxane F has the following formula: (CH3)3SiO(SiO(CH3)2) n Si(CH3)2(Y) (II)

[0101] Where Y is C 2-6 The alkenyl group is preferably vinyl, and n is an integer from 50 to 900, preferably from 50 to 700. The compound has exactly one silicon-bonded alkenyl group per molecule.

[0102] Preferably, the linear polydimethylsiloxane F according to the invention is a mixture of linear polydimethylsiloxanes (I) and (II). The weight ratio of (I): (II) may be from 100:0 to 0:100, or from 90:10 to 10:90, or from 80:20 to 20:80, or from 70:30 to 30:70. The foamable and crosslinkable silicone composition according to the invention may be free of or substantially free of linear polydimethylsiloxane (II). The linear polydimethylsiloxane F according to the invention is one or more linear polydimethylsiloxanes (I) as defined above.

[0103] The foamable, cross-linkable silicone composition according to the invention may optionally contain additives. Examples of suitable additives include: elastic additives, reinforcing fillers, thermally or electrically conductive fillers, nanoparticles, silicone resins, pigments, antimicrobial agents, UV stabilizers, dyes, pigments, fragrances, flavoring agents, essential oils, flame retardant additives, thermal stabilizers, rheology modifiers, viscosity modifiers, thickeners, adhesion promoters, biocides, preservatives, enzymes, peptides, surfactants, active diluents, active pharmaceutical ingredients, excipients or cosmetic ingredients. The content of additives is generally less than 5% by weight, preferably less than 2.5% by weight, more preferably less than 1% by weight, relative to the total weight of the foamable, cross-linkable silicone composition. Suitable additive(s) may be selected by a person skilled in the art according to the intended application and the general knowledge in the art.

[0104] According to one embodiment, the foamable crosslinkable silicone composition according to the present invention may optionally contain at least one filler, preferably a reinforcing filler, which generally improves the mechanical strength of the cured silicone elastomer article. The filler may be precipitated silica, fumed (or pyrolyzed) deposited silica, colloidal silica and mixtures thereof. The specific surface area of ​​these active reinforcing fillers should be at least 10 m2 / g, and preferably 50m 2 / g to 400m 2 In a preferred embodiment, the silica reinforcing filler has a specific surface area of ​​at least 10 m2 as determined by the BET method. 2 / g and preferably 50m 2 / g to 400m 2 / g of fumed silica. The fumed silica can be used as it is in an untreated form, but is preferably subjected to a hydrophobic surface treatment. The amount of silica reinforcing filler in the foamable and crosslinkable silicone composition according to the present invention can be 0%-10% by weight, preferably 0.01%-5% by weight, and more preferably 0.05%-2% by weight of the total composition.

[0105] According to one embodiment, the foamable and cross-linkable silicone composition according to the invention comprises (by weight, relative to the total weight of the composition):

[0106] - a partial mixture of 1.99% to 98.99% of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule, at least one organosilicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule, at least one hydrosilylation catalyst C and at least one porogen D, the porogen D being water, a hydrogel or an aqueous silicone emulsion;

[0107] - 0.01% to 2% of at least one chemical blowing agent E; and

[0108] - 1% to 98% of at least one linear polydimethylsiloxane F having a dynamic viscosity at 25°C of 50 to 100000 mPa.s.

[0109] According to another embodiment, the foamable and cross-linkable silicone composition according to the invention comprises (by weight, relative to the total weight of the composition):

[0110] - 4.95% to 49.95% of a partial mixture of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule, at least one organosilicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule, at least one hydrosilylation catalyst C and at least one porogen D, the porogen D being water, a hydrogel or an aqueous silicone emulsion;

[0111] - 0.05% to 1.5% of at least one chemical blowing agent E; and

[0112] - 50% to 95% of at least one linear polydimethylsiloxane F having a dynamic viscosity at 25°C of 50 to 100000 mPa.s.

[0113] According to another embodiment, the foamable and cross-linkable silicone composition according to the invention comprises (by weight, relative to the total weight of the composition):

[0114] - 6.9% to 24.9% of a partial mixture of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule, at least one organosilicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule, at least one hydrosilylation catalyst C and at least one porogen D, the porogen D being water, a hydrogel or an aqueous silicone emulsion;

[0115] - 0.1% to 1.0% of at least one chemical blowing agent E; and

[0116] - 75% to 93% of at least one linear polydimethylsiloxane F having a dynamic viscosity at 25°C of 50 to 100000 mPa.s.

[0117] Within the above-mentioned embodiment, a partial mixture of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule, at least one organosilicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule, at least one hydrosilylation catalyst C, and at least one porogen D which is water, a hydrogel, or an aqueous silicone emulsion may have the following composition (by weight relative to the total weight of the partial mixture):

[0118] - 40% to 95% of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule;

[0119] - 1% to 20% of at least one organic silicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule;

[0120] - 2 to 400 ppm of at least one platinum hydrosilylation catalyst C, calculated on the weight of platinum metal;

[0121] - 0.3% to 2.5% of at least one porogen D, wherein the porogen D is water, hydrogel or aqueous silicone emulsion.

[0122] More preferably, the partial mixture may have the following composition (by weight, relative to the total weight of the partial mixture):

[0123] - 50% to 90% of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule;

[0124] - 3% to 15% of at least one organic silicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule;

[0125] - 5 ppm to 200 ppm of at least one platinum hydrosilylation catalyst C, calculated on the weight of platinum metal;

[0126] - 0.5% to 1.5% of at least one porogen D, wherein the porogen D is water, hydrogel or aqueous silicone emulsion.

[0127] Another object of the present invention relates to a method for preparing the above-mentioned implant. The implant comprises a shell and a filler enclosed by the shell. According to one embodiment, the filler enclosed by the shell consists of or essentially consists of an organosilicon foam according to the present invention. According to other embodiments, in addition to the foam, the filler may also comprise other elements, including a flexible body, such as an air-containing or gas-containing body. According to one embodiment, the filler enclosed by the shell comprises hollow microspheres. As examples of suitable hollow microspheres, hollow glass microspheres or hollow ceramic microspheres can be cited.

[0128] Hollow glass microspheres are sometimes called "hollow glass beads" or "hollow glass bubbles". They are small hollow spheres of hardened silica (glass) whose size and density can vary depending on the grade. They have a shell that is thick enough to maintain structural rigidity. Due to their hollow nature, they are very lightweight and the density varies with size and wall thickness. In bulk, they appear as a white powder. The main differences between the grades are their size, strength and density, where the strength of the microspheres is expressed as their average isostatic crushing strength.

[0129] According to one embodiment, the hollow glass beads are hollow borosilicate glass microspheres.

[0130] According to one embodiment, the hollow glass microspheres have a true density of 0.10 g / cm 3 (g / cm3) to 0.75g / cm 3 .

[0131] The term "true density" is the quotient obtained by dividing the mass of the hollow glass microsphere sample by the true volume of that mass of glass bubbles (measured by a gas densimeter). The "true volume" is the aggregated total volume of the glass bubbles, not the bulk volume.

[0132] According to a preferred embodiment, the hollow glass microspheres are selected from:

[0133] 1. 3M™ Glass Bubbles Floated Series (A16 / 500, G18, A20 / 1000, H20 / 1000, D32 / 4500 and H50 / 10,000EPX glass bubble products) and 3M™ Glass Bubbles K, S, iM and XLD Series (such as, but not limited to, K1, K11, K15, S15, S22, K20, K20HS, K25, S32, S32LD, S35, XLD3000, S28HS, S35, K37, S38, S38HS, S38XHS, S32HS, K46, K42HS, S42XHS, S60, S60HS, iM16K, iM30K glass bubble products) are sold by 3M Company. The glass bubbles exhibit various crushing strengths ranging from 1.72 MPa (250 psi) to 186.15 MPa (27,000 psi), at which ten percent of the volume of the first plurality of glass bubbles is broken. Other glass bubbles sold by 3M may also be used, such as 3M™ Glass Bubbles-HGS Series and 3M™ Glass Bubbles with Surface Treatment.

[0134] 2. Hollow glass microspheres sold under the trade name SPHERICEL® (such as the following products: 110P8, 60P18, 34P30 and 25P45) or under the trade name Q-Cel® Lightweight (such as the following products: 6014, 6019, 7019, 6019S, 5020, 5020FPS, 7023, 7028, 2058, 6036, 7037, 7040S, 6042S, 6048 and 5070S), sold by Potters Industries Inc.

[0135] Suitable hollow glass microspheres are unsurface treated or surface treated. Surface treated hollow glass microspheres may typically be hydrophobic. The surface treatment agent may be, for example, a silane coupling agent, such as aminopropyl triethoxysilane, γ-glycidoxypropyl trimethoxysilane, γ-(methacryloyloxy)propyl trimethoxysilane (also known as silane coupling agent KH-570) and sodium methyl silicate.

[0136] Hollow ceramic microspheres, also known as cenospheres, are lightweight, inert hollow spheres filled with inert air or gas, typically produced as a byproduct of coal combustion in thermal power plants. They are made primarily of silica and alumina. The color of cenospheres varies from gray to almost white, and their density is about 0.4 g / cm 3 -0.8g / cm 3. It flows like a liquid and has a powdery appearance. Suitable hollow microspheres are unsurface treated or surface treated with a silane-based coupling agent, such as one or more of the following: 3-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminopropylmethyldimethoxysilane or 3-aminopropylmethyldiethoxysilane.

[0137] Commercially available examples of hollow ceramic microspheres are produced by 3M TM Commercially available Z-Light™ Spheres Microspheres (such as the following products: 3M TM Z-Light™ Spheres G-3125, G-3150 and G-3500).

[0138] According to a first embodiment, the present invention is directed to a method for preparing an implant comprising a shell and a filling enclosed by the shell, comprising the following steps:

[0139] 1a) combining the components of the foamable, cross-linkable silicone composition according to the invention and as defined above to provide a filler precursor for a silicone foam,

[0140] 1b) filling the silicone foam filler precursor into the shell, and

[0141] 1c) foaming and cross-linking the silicone foam filler precursor to provide the implant.

[0142] A suitable shell can be selected by a person skilled in the art according to the common knowledge in the art. The shell can be, for example, a silicone elastomer, preferably a vulcanized silicone rubber, which can be single-layer or multi-layer, smooth or textured, barrier-coated, or covered with polyurethane foam. Conventional breast implant shells are multi-layer or laminated. Specifically, such shells include an outer "anti-cracking" layer and an inner "barrier" layer, which is sandwiched between the outer layers and effectively blocks silicone seepage. For example, it can include a low-diffusion silicone elastomer shell made using an outer layer of a dimethyl-diphenyl silicone elastomer having a mole percentage of diphenyl polymer of 5% and a barrier layer of a dimethyl-diphenyl silicone elastomer having a mole percentage of diphenyl polymer of 15%. Another suitable example of a flexible shell that can be used according to the present invention is a flexible shell that comprises a substantially uniform layer that surrounds and directly contacts the silicone gel of the core, made of a silicone elastomer that comprises a polydimethylsiloxane backbone having diphenyl side groups, for example, the molar percentage of the diphenylsiloxane units is about 15%.

[0143] Flexible implant shells can be manufactured by traditional dip molding or spraying processes. Dip molding processes generally involve dipping a mandrel of suitable shape into a silicone elastomer dispersion, while spraying processes involve spraying the silicone elastomer dispersion onto a mandrel of suitable shape. The shell is then peeled off the mandrel and the shell holes produced by the molding process are repaired. The hollow interior of the shell can then be filled with a filling precursor of the present invention through the holes in the patch. The holes in the patch are then sealed with a silicone adhesive, and the prosthesis is heat cured. Another method of forming an implant shell is rotational molding, such as the system and method described in U.S. Patent No. 6,602,452. Alternatively, the shell can be manufactured by injection molding.

[0144] According to another embodiment, the present invention is directed to a method for preparing an implant comprising a shell and a filling enclosed by the shell, comprising the following steps:

[0145] 2a) combining the components of the foamable, cross-linkable silicone composition according to the invention and as defined above to provide a filler precursor for a silicone foam,

[0146] 2b) foaming and crosslinking the filler precursor of the silicone foam, and

[0147] 2c) Creating a shell around the silicone foam to provide an implant.

[0148] According to said embodiment, step 2b) can preferably be carried out in a mold so that the silicone foam can have a specific desired geometry.

[0149] The housing can be obtained in step 2c) according to the method known to a person skilled in the art as described above, but using the silicone foam obtained in step 2b) instead of the mandrel of suitable shape. For example, step 2c) can preferably be carried out by dipping the silicone foam obtained in step 2b) into the silicone elastomer dispersion. Alternatively, step 2c) can preferably be carried out by spraying the silicone elastomer dispersion onto the silicone foam obtained in step 2b).

[0150] Step 1c) and step 2b) of the method according to the present invention (i.e. foaming and crosslinking of the filler precursor into silicone foam) can be carried out by heating at a temperature range of 50°C-200°C, preferably 100°C-170°C. The temperature of step c) can be adjusted according to the degradation temperature of the chemical blowing agent E. For example, for ammonium bicarbonate, the degradation temperature is about 60°C. The temperature of step 1c) and step 2b) can preferably be set to above 60°C so that both foaming and crosslinking can be carried out substantially simultaneously. Alternatively, step 1c) and step 2b) can be started at room temperature, and the temperature can be increased thereafter in order to control the foaming by the chemical blowing agent E and the crosslinking, respectively.

[0151] Another object of the present invention is to provide a new method for additive manufacturing of 3D shaped articles made of said silicone foam. Such a method also enables the manufacture of complex shaped objects made of such biocompatible materials.

[0152] An object of the present invention relates to a method for additively manufacturing a 3D-shaped article made of silicone foam, in particular for use in medical devices, comprising the following steps:

[0153] 3a) printing a portion of the foamable, cross-linkable silicone composition as defined above using a 3D printer to form a deposit in a support material SM, the support material SM being a gel or microgel suitable for 3D-gel printing of silicone foams, the deposit being achieved by means of a device having at least one delivery unit positionable in the x-, y- and z-directions,

[0154] 3b) partially or completely foaming and crosslinking the printed foamable and cross-linkable silicone composition to obtain a silicone foam deposit within the support material SM,

[0155] 3c) Optionally, repeating steps a) and b) a number of times until the desired 3D-shape is obtained,

[0156] 3d) removing the support material SM mechanically or via dissolution in a solvent, and

[0157] 3e) Recycling of 3D-shaped articles made from silicone foam.

[0158] According to a specific embodiment, step 3b) can be carried out by heating in a temperature range of 50°C-200°C, preferably 100°C-170°C. The temperature of step 3b) can be adjusted according to the degradation temperature of the chemical blowing agent E. For example, for ammonium bicarbonate, the degradation temperature is about 60°C. The temperature of step 3b) can preferably be set to above 60°C so that both foaming and crosslinking can be carried out substantially simultaneously. Alternatively, step 3b) can be started at room temperature, and the temperature can be increased thereafter in order to control the foaming by the chemical blowing agent E and the crosslinking, respectively. This specific embodiment can advantageously provide a silicone foam having anisotropic properties.

[0159] Printing is preferably performed layer by layer using a 3D printer which may be selected from an extrusion 3D printer or a material jetting 3D printer. 3D printing is often associated with a number of related technologies for making physical objects from computer-generated (such as computer-aided design (CAD)) data sources. A "3D printer" is defined as a machine for 3D printing, and "3D printing" is defined as the production of an object by depositing material using a print head, nozzle or another printer technology".

[0160] In a preferred embodiment, the method for manufacturing an article made of silicone foam according to the present invention uses an extrusion 3D printer. The foamable cross-linkable silicone composition is extruded through a nozzle. The nozzle can be heated to help distribute the addition cross-linkable silicone composition. The foamable cross-linkable silicone composition to be distributed through the nozzle can be supplied by a cartridge-like system. A coaxial cartridge system with a static mixer and only one nozzle can also be used. The pressure will be adapted to the fluid to be distributed, the relevant nozzle average diameter and the printing speed. Due to the high shear rate that occurs during the nozzle extrusion process, the viscosity of the foamable cross-linkable silicone composition is greatly reduced, thereby allowing the printing of fine layers. The cartridge pressure can vary from 1 bar (i.e. atmospheric pressure) to 28 bar, preferably from 1 bar to 10 bar, and most preferably from 2 bar to 8 bar. An adapted device using an aluminum cartridge will be used to resist this pressure. Before moving in the z-axis (vertical) plane once a layer is completed, the nozzle and / or the building platform moves in the xy (horizontal plane) to complete the cross section of the object. The nozzle has a high xyz-movement accuracy of about 10 pm. After printing each layer on the x-, y-working plane, the nozzle is displaced in the z-direction only far enough to apply the next layer in the x-, y-working position. In this way, the 3D article is built one layer at a time from bottom to top. The average diameter of the nozzle is related to the thickness of the layer. In one embodiment, the diameter of the layer is 50 pm-2000 pm, preferably 100 pm-800 pm, most preferably 100 pm-500 pm. Advantageously, the printing speed is 1 mm / s to 50 mm / s, preferably 5 mm / s to 30 mm / s, to obtain the best compromise between good accuracy and manufacturing speed.

[0161] The support material SM is a gel or microgel suitable for 3D-gel printing of silicone foam. The gel or microgel provides constant support for the liquid material during 3D-printing. This allows more complex objects to be printed without the need for additional supports, and at a faster speed. The support material SM can be selected by a person skilled in the art from disclosed materials, such as those disclosed in the following documents: International Patent Applications WO 2019 / 215190 A1 and WO 2020 / 127882 A1, or US Patent Applications US 2015 / 0028523 A1, US 2018 / 0036953 A1, and US 2018 / 0057682 A1. Further details can also be found in the scientific publication by Arthur Colly, Christophe Marquette and Edwin-Joffrey Courtial: “Poloxamer / Poly(ethylene glycol) Self-Healing Hydrogel for High-Precision Freeform Reversible Embedding of Suspended Hydrogel” (Langmuir 2021, 37, 14, 4154-4162).

[0162] According to one embodiment of the claimed method, the support material SM can be provided as a matrix, for example in a container, and placed at a desired temperature. According to another embodiment, the support material SM can be delivered at specific locations simultaneously with the foamable, cross-linkable silicone composition or at staggered intervals by means of a device having at least one delivery unit positionable in the x-, y- and z-directions.

[0163] The 3D-shaped article made of silicone foam recovered from step 3e) can advantageously be used as a medical device. Within the framework of the present invention, the 3D-shaped article made of silicone foam can be used as an implant, preferably as a breast implant.

[0164] According to a specific embodiment, the present invention aims at a method for preparing an implant comprising a shell and a filling enclosed by the shell, the method comprising the following steps: providing a 3D-shaped article made of silicone foam according to the above-mentioned method, and generating a shell around the silicone foam to provide an implant.

[0165] Alternatively, the silicone foam and the shell according to the present invention may be 3D printed simultaneously by using a specially designed 3D printer equipped with a dual nozzle system capable of 3D printing the shell and the filler simultaneously.

[0166] After the implant according to the present invention is completed, the steps required to manufacture the finished product can be similar to those known in the art. For example, the filled implant is packaged and the packaged implant is sterilized.

[0167] The implant according to the invention may be a breast implant, a facial implant such as eyebrows, nose, cheeks, chin and lips, or another body implant such as a tracheal stent, an implantable fat augmentation or replacement such as a gluteus maximus, breast or cheek implant; or a firmer tissue such as a calf, bicep, tricep or abdominal muscle. Preferably, the implant according to the invention is a breast implant. DETAILED DESCRIPTION

[0168] Various embodiments of the present invention may be better understood by reference to the following examples, which are provided by way of illustration.The present invention is not limited to the examples given herein.

[0169] Example

[0170] raw material:

[0171] Organopolysiloxane A1 = a mixture of several polydimethylsiloxane oils having dimethylvinylsilyl terminal units, with viscosities varying from about 4,000 mPa to about 100,000 mPa.s at 25°C, and an average viscosity of about 10,000 mPa.s at 25°C.

[0172] Organopolysiloxane A2 = MD Vi Q branched organopolysiloxane, in which the vinyl group bonded to the silicon atom is carried by the D group

[0173] Organopolysiloxane B1 = poly(methylhydrogen)siloxane with trimethylsilyl terminal units, viscosity at 25°C about 20 mPa.s

[0174] Organopolysiloxane B2 = polydimethylsiloxane with dimethylhydrogensilyl terminal units, viscosity at 25°C about 7 mPa.s

[0175] Catalyst C = 10% by weight of platinum metal, known as Karstedt catalyst

[0176] Emulsion D = Silicone emulsion containing approximately 59.5% by weight water

[0177] Foaming agent E1 = ammonium bicarbonate

[0178] Foaming agent E2 = finely ground ammonium bicarbonate (NH4HCO3 content = 50% by weight) mixed with silica and polydimethylsiloxane oil

[0179] Polydimethylsiloxane F1 = PDMS, viscosity at 25°C is about 1000 mPa.s

[0180] Polydimethylsiloxane F2 = PDMS, viscosity at 25°C is about 5000 mPa.s

[0181] Polydimethylsiloxane F3 = a mixture of several polydimethylsiloxane oils (PDMS and polydimethylsiloxane with one dimethylvinylsilyl end unit and one trimethylsilyl end unit) with an average viscosity of about 300 mPa.s at 25°C

[0182] Polydimethylsiloxane F4 = a mixture of several polydimethylsiloxane oils (PDMS and polydimethylsiloxane with one dimethylvinylsilyl end unit and one trimethylsilyl end unit) with an average viscosity of about 1000 mPa.s at 25°C

[0183] Polydimethylsiloxane F5 = a mixture of several polydimethylsiloxane oils (PDMS and polydimethylsiloxane with one dimethylvinylsilyl end unit and one trimethylsilyl end unit) with an average viscosity of about 2000 mPa.s at 25°C

[0184] Polydimethylsiloxane F6 = a mixture of several polydimethylsiloxane oils (PDMS and polydimethylsiloxane with one dimethylvinylsilyl end unit and one trimethylsilyl end unit) with an average viscosity of about 20,000 mPa.s at 25°C

[0185] Comparative Example 1:

[0186] The foamable cross-linkable silicone composition was prepared by mixing the components mentioned in Table 1 below:

[0187] Table 1

[0188] The obtained hydrogen-blown silicone foam showed high stiffness and did not feel sufficiently similar to human tissue.

[0189] Comparative Example 2:

[0190] The silicone foam disclosed in Table 14 of the prior art document WO2020 / 072374 was reproduced. The raw materials (linear PDMS, polydimethylsiloxane with dimethylvinylsilyl terminal units, platinum catalyst, crosslinker and ammonium bicarbonate) were mixed and the temperature was kept at 150°C for 30 minutes to allow crosslinking and foaming to occur. The silicone foam was only chemically foamed.

[0191] The feel of this material was greatly improved compared to Comparative Example 1, but it was found to have a very irregular cell structure which caused manufacturing concerns as the device was to have a uniform fleshy feel.

[0192] Embodiment 1-6:

[0193] A foamable and cross-linkable silicone composition was prepared by mixing the components mentioned in the following Table 2. After mixing, the temperature was maintained at 150° C. for 60 minutes.

[0194] Table 2

[0195] The organic silicone foam obtained according to the present invention is a foam simultaneously hydrogen-foamed and chemically-foamed, which exhibits low density, low weight, good cell structure and has a natural tissue-like feel.

[0196] Embodiment 7-9:

[0197] A foamable and cross-linkable silicone composition was prepared by mixing the components mentioned in the following Table 3. After mixing, the temperature was maintained at 150° C. for 60 minutes.

[0198] Table 3

[0199] Embodiment 10-15:

[0200] General composition of hydrogen-blown silicone foam "H2B foam":

[0201] - 67.10% by weight of a mixture of several polydimethylsiloxane oils having dimethylvinylsilyl terminal units, with an average viscosity of about 1,000 mPa.s at 25°C;

[0202] - 11.2% by weight of treated fumed silica;

[0203] - 0.64% by weight of water;

[0204] - 0.64% by weight of emulsifier;

[0205] - 0.03% by weight of Karstedt's catalyst (containing 10% by weight of platinum metal);

[0206] - 20.00% by weight of a poly(methylhydrogen)siloxane having trimethylsilyl terminal units and having an average viscosity of about 20 mPa.s at 25° C.;

[0207] - 0.39% by weight of ethynylcyclohexanol.

[0208] A foamable and cross-linkable silicone composition was prepared by mixing the components mentioned in the following Table 4. After mixing, the temperature was maintained at 150° C. for 60 minutes.

[0209] Table 4

[0210] PVP10 = Polyvinylpyrrolidone; average molecular weight 10,000

[0211] PVP40 = Polyvinylpyrrolidone; average molecular weight 40,000

[0212] Embodiment 16:

[0213] Example 10 was reproduced except that the composition of the hydrogen-blown silicone foam "H2B Foam" contained 14.6% by weight of treated fumed silica (instead of 11.2% by weight) and 63.7% by weight of the same mixture of polydimethylsiloxane oils (instead of 67.1% by weight).

[0214] The silicone foams obtained using the compositions of Examples 7-16 exhibit low density, low weight, and good cell structure.

Claims

1. An implant comprising a shell and a filler enclosed by the shell, wherein the filler comprises a silicone foam obtained from a foamable and cross-linkable silicone composition, the foamable and cross-linkable silicone composition comprising: - at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule; - at least one organic silicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule; - at least one hydrosilylation catalyst C; - at least one porogen D which is water, a hydrogel or an aqueous silicone emulsion; - at least one chemical blowing agent E; and - at least one linear polydimethylsiloxane F having a dynamic viscosity at 25° C. of 50 to 100 000 mPa.s.

2. The implant according to claim 1, wherein the organopolysiloxane A is a linear organopolysiloxane; preferably, the organopolysiloxane A comprises a terminal dimethylvinylsilyl unit, and more preferably, the organopolysiloxane A is a poly(dimethylsiloxane) comprising a terminal dimethylvinylsilyl group.

3. The implant according to claim 1, wherein the organopolysiloxane A is a 2-6 Branched organopolysiloxane of alkenyl units; preferably selected from the following silicone resins: -M Vi Q, in which the alkenyl group bonded to the silicon atom is carried by the M group, -MM Vi Q, in which the alkenyl group bonded to the silicon atom is carried by a portion of the M unit, -MD Vi Q, in which the alkenyl group bonded to the silicon atom is carried by the D group, -MDD Vi Q, wherein the alkenyl group bonded to the silicon atom is carried by a portion of the D group, -MM Vi TQ, in which the alkenyl group bonded to the silicon atom is carried by a portion of the M unit, -MM Vi DD Vi Q, in which the hydrogen atoms bonded to the silicon atoms are carried by a portion of the M and D units, - and mixtures thereof, Where M: R 1 3SiO 1 / 2 Siloxy unit, M Vi :Selected from YR 1 2SiO 1 / 2 and Y2R 1 SiO 1 / 2 Siloxy units, D:R 1 2SiO 2 / 2 Siloxy unit, D Vi :Selected from Y2SiO 2 / 2 or YR 1 SiO 2 / 2 Siloxy units of siloxy units, T: formula R 1 SiO 3 / 2 Siloxy units, and Q: formula SiO 4 / 2 The symbol Y is C 2-6 alkenyl, preferably vinyl; and the symbol R 1 It is a monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably selected from an alkyl group having 1 to 8 carbon atoms such as methyl, ethyl or propyl, a cycloalkyl group having 3 to 8 carbon atoms and an aryl group having 6 to 12 carbon atoms.

4. The implant according to claim 1, wherein the foamable, cross-linkable silicone composition comprises a mixture of at least one linear organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule and at least one branched organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule.

5. The implant according to any one of claims 1 to 4, wherein the foamable, cross-linkable silicone composition comprises a mixture of at least one organic silicon-containing compound B1 having at least three silicon-bonded hydrogen atoms per molecule and at least one organic silicon-containing compound B2 having two silicon-bonded hydrogen atoms per molecule.

6. The implant according to any one of claims 1 to 5, wherein the porogen D is an aqueous silicone emulsion.

7. The implant according to any one of claims 1 to 5, wherein the porogen D is a mixture of water and at least one emulsifier.

8. The implant according to any one of claims 1 to 7, wherein the chemical foaming agent E is at least one bicarbonate, preferably selected from ammonium bicarbonate (NH4)HCO3, sodium bicarbonate NaHCO3, calcium bicarbonate Ca(HCO3)2 and mixtures thereof; and more preferably, the chemical foaming agent E is ammonium bicarbonate.

9. The implant according to any one of claims 1 to 8, wherein the linear polydimethylsiloxane F is a mixture of linear polydimethylsiloxane (I) and (II) in a weight ratio of (I): (II) of 100:0 to 0:100, Wherein the linear polydimethylsiloxane (I) has the following formula: (CH3)3SiO(SiO(CH3)2) n Si(CH3)3 (I) wherein n is an integer of 50-900, preferably 50-700, and Wherein the linear polydimethylsiloxane (II) has the following formula: <h2 style=";text-align:left;direction:ltr">(CH3)3SiO(SiO(CH3)2)<h2 style=";text-align:left;direction:ltr"> n <h2 style=";text-align:left;direction:ltr"> Si(CH3)2(Y)(II) Where Y is C 2-6 The alkenyl group is preferably a vinyl group, and n is an integer of 50-900, preferably 50-700.

10. The implant according to any one of claims 1 to 9, wherein the foamable and cross-linkable silicone composition according to the invention comprises (by weight, relative to the total weight of the composition): - a partial mixture of 1.99% to 98.99% of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule, at least one organosilicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule, at least one hydrosilylation catalyst C and at least one porogen D, the porogen D being water, a hydrogel or an aqueous silicone emulsion; - 0.01% to 2% of at least one chemical blowing agent E; and - 1% to 98% of at least one linear polydimethylsiloxane F having a dynamic viscosity at 25°C of 50 to 100000 mPa.s.

11. The implant according to claim 10, wherein the partial mixture of the at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule, the at least one organosilicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule, the at least one hydrosilylation catalyst C and the at least one porogen D has the following composition (by weight relative to the total weight of the partial mixture), wherein the porogen D is water, a hydrogel or an aqueous silicone emulsion: - 40% to 95% of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule; - 1% to 20% of at least one organic silicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule; - 2 to 400 ppm of at least one platinum hydrosilylation catalyst C, calculated on the weight of platinum metal; - 0.3% to 2.5% of at least one porogen D, wherein the porogen D is water, hydrogel or aqueous silicone emulsion.

12. The implant according to any one of claims 1-11, wherein the filler enclosed by the shell comprises the silicone foam, and further comprises hollow microspheres, preferably hollow glass microspheres.

13. The implant of any one of claims 1-12, wherein the implant is a breast implant, a facial implant such as eyebrows, nose, cheeks, chin and lips, or another body implant such as a tracheal stent, an implantable fat augmentation or replacement such as a gluteus maximus or cheek implant; or a firmer tissue such as a calf, bicep, tricep or abdominal muscle; and preferably, the implant is a breast implant.

14. A method for preparing an implant comprising a shell and a filler enclosed by the shell, comprising the steps of: 1a) combining the components of a foamable, cross-linkable silicone composition as defined in any one of claims 1 to 13 to provide a filler precursor for a silicone foam, 1b) filling the silicone foam filler precursor into the shell, and 1c) foaming and cross-linking the silicone foam filler precursor to provide the implant.

15. A method for preparing an implant comprising a shell and a filler enclosed by the shell, comprising the steps of: 2a) combining the components of a foamable, cross-linkable silicone composition as defined in any one of claims 1 to 13 to provide a filler precursor for a silicone foam, 2b) foaming and crosslinking the filler precursor of the silicone foam, and 2c) Creating a shell around the silicone foam to provide an implant.

16. A method for additively manufacturing a 3D-shaped article made of silicone foam, in particular for use in medical devices, comprising the following steps: 3a) printing a portion of the foamable, cross-linkable silicone composition as defined in any one of claims 1 to 13 using a 3D printer to form a deposit in a support material SM, the support material SM being a gel or microgel suitable for 3D-gel printing of silicone foams, the deposit being achieved by means of a device having at least one delivery unit positionable in the x-, y- and z-directions, 3b) partially or completely foaming and crosslinking the printed foamable and cross-linkable silicone composition to obtain a silicone foam deposit within the support material SM, 3c) Optionally, repeating steps a) and b) a number of times until the desired 3D-shape is obtained, 3d) removing the support material SM mechanically or via dissolution in a solvent, and 3e) Recycling of 3D-shaped articles made from silicone foam.

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