Reprocessable polymer composition with dynamic crosslinks

Abstract

To provide a new class of polymer elastomers using silicon-oxygen backbones that can be reprocessable thermally at temperatures beyond a required scope of applications, while maintaining advantages of commercial silicones such as high tensile strength, thermal stability, and food contact safety.SOLUTION: A polymer composition having covalent bonding networks alterable by thermally activated bond exchanges creating dynamic crosslinks comprises: a silicon-oxygen backbone chain elastomer for creating a polymer network; a non-agglomerating filler dispersed within and bonded to the polymer network; a catalyst for facilitating a condensation reaction; a silane-based crosslinker including methoxy or ethoxy groups; at least one dynamic bond activator promoting Si-O bond exchange between adjacent silicon-oxygen backbone chain elastomers of the polymer network such that dynamic crosslinks formed between the adjacent silicon-oxygen backbone chain elastomers create a three-dimensional crosslinked polymer network.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] CROSS REFERENCE TO RELATED APPLICATIONS:

[0002] This application claims priority to U.S. Provisional Application No. 63 / 514,804, filed July 21, 2023, the disclosure of which is incorporated by reference in its entirety herein.

[0003] Technical fields:

[0004] The present invention relates to polymer compositions having a covalent network that is alterable through thermally-activated bond exchanges that form dynamic crosslinks, which can be reformed by reheating and are therefore reprocessable. [Background technology]

[0005] Background technology:

[0006] Silicone accounts for a large portion of the polymer market. The annual production in China is about 370,000 tons, and the global market is expected to reach US$2.01 billion in 2025, growing at a compound annual growth rate (CAGR) of 6.1% from 2019 to 2025. Silicone rubber is widely used in consumer goods and food contact products due to its superior tensile strength, thermal stability, and food contact safety compared to elastomers such as thermoplastic polyurethane (TPU).

[0007] Due to the huge production volume, a large amount of silicone scrap and waste is generated from the manufacturing stage or from the end users. Commercial silicones cannot be reprocessed due to their thermosetting nature, which negatively impacts both production costs and the environment. Currently, the scrap rate due to demolding during manufacturing reaches up to 5%, leading to a loss of 4-11 million RMB per year. The current recycling cost of silicone is 4-7 RMB per kg, so the development of reprocessable silicone-like materials would provide a solution to save production costs and also provide a sustainable solution as it saves recycling equipment and resources.

[0008] Conventional methods for reprocessing silicone scrap and waste include either physical or chemical decomposition or a combination of both. These include: 1) Mechanically crushing fillers as reinforcement for composite materials; 2) Downcycling of polydimethylsiloxane (PDMS) into industrial lubricants by depolymerization developed by Dow Corning ( WO2014130948A1 ); 3) A hydrothermal method to reform silicone rubber with significantly poor mechanical properties.

[0009] These low value-added processes add extra cost and time to production, are not sustainable and do not leverage the strengths of silicone rubber for higher value-added applications.

[0010] Commercially available "thermoplastic silicone elastomers" include the thermoplastic silicone vulcanizate TPSiV sold by DuPont. This product is formed by dispersing crosslinked silicone rubber (a vulcanized silicone module containing PDMS) in a thermoplastic continuous phase of thermoplastic polyurethane (TPU) using a platinum hydrosilylation catalyst. The composite is said to be reprocessable by melting and remolding. In most cases, the silicone content is less than 50% w / w, and anhydrous conditions are required in the manufacturing process to obtain high quality TPSiV with high tensile strength. Furthermore, TPSiV cannot be used in food contact applications due to the possible presence of amines or amides in the TPU composite.

[0011] There is a need for a new class of polymeric elastomers using a silicon oxygen backbone that can be thermally reprocessed at temperatures beyond the application requirements while retaining the advantages of commercial silicones such as high tensile strength, thermal stability, and food contact safety for high value applications. The present invention addresses this need. Summary of the Invention

[0012] Summary of the invention:

[0013] The present invention provides new polymer systems based on silicon-oxygen backbone elastomers that facilitate changes in the material's topology through thermally activated bond exchange reactions. At their reprocessable temperatures, the polymer systems of the present invention flow as viscoelastic liquids, while at low temperatures the bond exchange reactions are immensely slow, so that the polymer systems of the present invention behave as thermoset elastomers.

[0014] In order to achieve similar material properties as commercial silicone rubber, i.e. high tensile strength, thermal stability, and food contact safety, the present invention includes: 1) the selection of different chain lengths and branching of PDMS polymers for the polymer network of the present invention allows tuning to high tensile strength; 2) the development and selection of new crosslinkers for PDMS-based polymer networks allows the selection of optimal reprocessing temperatures; 3) the high silicon-oxygen polymer content and avoidance of the use of TPU in formulation ensures food contact compatibility.

[0015] The present invention provides polysiloxane-based polymers with reversible crosslinking using at least one dynamic bond activator that promotes Si-O bonds between adjacent silicon-oxygen backbone elastomers within the polymer network. These polymers are designed to be capable of a reversible crosslinking and decrosslinking process and can be reprocessed.

[0016] In one aspect, the present invention provides a polymer composition having a covalent network that changes by thermally activated bond exchange to form dynamic crosslinks. The polymer composition is formed from a silicon-oxygen backbone elastomer that forms a polymer network. A non-agglomerating filler is dispersed and bonded within the polymer network. A catalyst promotes the condensation reaction. A crosslinker is used for crosslinking and may be one or more silanes containing one or more methoxy or ethoxy groups.

[0017] The at least one dynamic bond activator promotes Si-O bond exchange between adjacent silicon-oxygen backbone elastomers of the polymer network such that the dynamic crosslinks formed between adjacent silicon-oxygen backbone elastomers form a three-dimensional crosslinked polymer network.

[0018] In bulk form, the polymer composition has the properties of a thermoset polymer at ambient conditions and is reformable as a viscoelastic liquid at temperatures above about 170° C. In some embodiments, the tensile strength retains at least 60% of the ambient tensile strength and at least 70% of the ambient elongation at break.

[0019] In one aspect, the silicon-oxygen backbone elastomer is selected from one or more of trimethylsilyl-terminated polydimethylsiloxane and silanol-terminated polydimethylsiloxane.

[0020] In one aspect, the silicon-oxygen backbone elastomer has a molecular weight of 5,970 to 139,000 g / mol, a viscosity of 100 to 150,000 cSt, and is present in the composition in an amount of 49.6 to 65.6 wt %.

[0021] In one aspect, the filler comprises fumed silica, calcium carbonate, or zinc oxide in an amount of 24.9 to 36.9 weight percent.

[0022] In one aspect, the at least one dynamic bond activator is an ionic salt selected from an ammonium salt or a phosphonium salt, and the content thereof is 0.09 to 2.5 wt %.

[0023] In one aspect, the dynamic bond activator is tetrabutylphosphonium hydroxide.

[0024] In one aspect, the at least one catalyst comprises dibutyltin dilaurate or dibutyltin dioctoate in an amount of 0.12 to 2.3 weight percent.

[0025] In one aspect, the crosslinking agent is a silane having an ethoxy group or a silane having a methoxy group, and the amount thereof is 2.7 to 25.0 wt %.

[0026] In one aspect, the crosslinker is selected from one or more of 1,2-bis(triethoxysilyl)ethane, poly(dimethoxysiloxane), poly(diethoxysiloxane), and tetraethylsilicate.

[0027] The present invention further provides a method for making a polymer composition. A first silicon-oxygen backbone elastomer is combined with a filler and a crosslinker to form a first mixture. A second silicon-oxygen backbone elastomer is combined with a filler and a catalyst to form a second mixture. The first mixture and the second mixture are combined to form a third mixture, wherein the first mixture and the second mixture are combined in a weight ratio of 1.1:1 to 8.3:1. The third mixture is combined with at least one dynamic bond activator to form a fourth mixture, which is cured to form a polymer composition. An optional heating step can remove the solvent in vacuum at a temperature of 50 to 80°C. [Brief description of the drawings]

[0028] Brief description of the drawings:

[0029] FIG. 1 shows a schematic of the mechanism of reprocessability of polymers.

[0030] FIG. 2 illustrates the reactions involved in forming the polymer composition of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Invention details:

[0032] Silicon-oxygen backbone elastomers, such as polysiloxanes, contain repeating units of siloxane (-Si-O-) bonds. These polymers have excellent thermal stability, chemical resistance, and flexibility, which allows them to be used in a variety of applications. The incorporation of Si-O bonds between adjacent backbones can improve a variety of mechanical properties without sacrificing the ability of the polymer to be reshaped or reprocessed.

[0033] The reprocessability of these polymers is particularly useful for reducing waste and promoting sustainability: by breaking and reforming the crosslinks, the materials can be processed, shaped and reshaped repeatedly without significant degradation of their properties. This reprocessability opens up the possibility of efficiently reusing the materials and reduces the need to manufacture new polymers.

[0034] The polymeric composition is formed from silicon-oxygen backbone elastomers that form a polymer network. In one aspect, the silicon-oxygen backbone elastomers have a molecular weight of 5,970 to 139,000 g / mol, a viscosity of 100 to 150,000 cSt, and are present in the composition in an amount of 49.6 to 65.6 wt. %. In particular, they may be one or more of trimethylsilyl terminated polydimethylsiloxane (PDMS) and silanol terminated polydimethylsiloxane (PDMS).

[0035] The non-agglomerating filler is dispersed and bound within the polymer network, hi one aspect, the filler comprises fumed silica, calcium carbonate, or zinc oxide in an amount of 24.9 to 36.9 weight percent.

[0036] The catalyst promotes the condensation reaction and includes dibutyltin dilaurate or dibutyltin dioctoate, etc., in an amount of 0.12-2.3 wt %. The crosslinker is used for crosslinking and may be one or more silanes containing one or more methoxy or ethoxy groups. In one aspect, the crosslinker is a silane having an ethoxy group or a silane having a methoxy group, in an amount of 2.7-25.0 wt %. Examples of suitable crosslinkers include one or more of 1,2-bis(triethoxysilyl)ethane, poly(dimethoxysiloxane), poly(diethoxysiloxane), and tetraethylsilicate.

[0037] The present invention uses dynamic activators to promote Si-O bonds between adjacent silicon-oxygen backbone elastomers of a polymer network. These bonds can be in the form of silyl ether groups that can be tailored to achieve specific properties or optimize reprocessing. The ability to reversibly break and reform crosslinks between adjacent Si-O backbone elastomers creates a polymer system that flows as a viscoelastic liquid at high temperatures, but at low temperatures the bond exchange reaction is so slow that the polymer system behaves as a thermoset elastomer. This phenomenon is illustrated in Figure 1. The result is a reprocessable polysiloxane-based polymer with reversible crosslinks that allows the polymers to be processed and reshaped without significant loss of their inherent properties. As a result of the dynamic crosslinks formed between adjacent Si-O backbone elastomers, a three-dimensional crosslinked polymer network is formed with increased strength and elasticity while still being modifiable under external stimuli such as heat.

[0038] As used herein, the expression "dynamic bond activator" refers to any material that, when incorporated into a polymer network, can promote reversible connections or crosslinks between polymer chains that can be broken and reformed in response to changes in temperature, pH, or the presence of certain chemicals. Dynamic bonds enable polymers to exhibit self-healing properties, adaptability, and enhanced mechanical performance.

[0039] Dynamic bond types include reversible covalent bonds as well as non-covalent interactions such as hydrogen bonding, ionic interactions, and metal-ligand coordination.

[0040] Dynamic bond activators not only enable polymers to adapt to environmental changes and mechanical stresses, but may also help polymers to self-repair after damage, i.e., after an activation event, the polymer regains its structural integrity and mechanical properties, often with minimal external intervention.

[0041] In the present invention, dynamic bond activators can promote Si-O bonds between adjacent silicon-oxygen backbone elastomers of the polymer network. These bonds can be in the form of silyl ether groups that can be tailored to achieve specific properties or optimize the reprocessing of the polymer. The ability to reversibly break and reform crosslinks between adjacent Si-O backbone elastomers creates a polymer system that flows as a viscoelastic liquid at high temperatures, but at low temperatures the bond exchange reaction is so slow that the polymer system behaves as a thermoset elastomer. This phenomenon is illustrated in Figure 1. The result is a reprocessable polysiloxane-based polymer with reversible crosslinks that can be processed and reshaped without significant loss of their inherent properties.

[0042] In one aspect, at least one dynamic bond activator may be an ionic salt. Examples of such ionic salts include ammonium salts or phosphonium salts. Amounts on the order of about 0.09-2.5 wt% may be used. A specific example of a dynamic bond activator is tetrabutylphosphonium hydroxide. When tetrabutylphosphonium hydroxide is used as the dynamic bond activator, the formed Si-O bonds exchanged between adjacent silicon-oxygen backbone chain elastomers are silyl ethers. Another specific example of a dynamic bond activator is potassium trimethylsilanolate. Silyl ether exchange between different siloxane chains results in the formation of reversible crosslinks between different backbone polymer chains, forming a three-dimensional network. The resulting network structure provides mechanical strength and stability to the material.

[0043] Figure 2 shows the reactions involved in the formation of the polymer composition. Polysiloxanes containing crosslinkers and fillers undergo a condensation reaction in the presence of a catalyst. A dynamic bond activator (in this case tetrabutylphosphonium hydroxide) causes silyl ether exchange between different siloxane chains. Figure 2 shows the formation and decomposition of bonds that form a three-dimensional network.

[0044] In bulk form, the polymer composition has the properties of a thermoset polymer at ambient conditions and is reformable as a viscoelastic liquid at temperatures above about 170°C while retaining a tensile strength of at least 60% of its ambient tensile strength and at least 70% of its ambient elongation at break.

[0045] The present invention further provides a method for making a polymer composition. A first silicon-oxygen backbone elastomer is combined with a filler and a crosslinker to form a first mixture. A second silicon-oxygen backbone elastomer is combined with a filler and a catalyst to form a second mixture. The first mixture and the second mixture are combined to form a third mixture, where the first mixture and the second mixture are combined in a weight ratio of 1.1:1 to 8.3:1. The third mixture is combined with at least one dynamic bond activator to form a fourth mixture, which is cured to form the polymer composition. An optional heating step can remove the solvent in vacuum at a temperature of 50 to 80°C. EXAMPLES

[0046] Working Example:

[0047] Various compositions, including a comparative composition, were prepared and tested. The components and their characteristics are shown below, followed by the method for producing the compositions. Finally, the experimental outline, the components and characteristics of the prepared compositions are shown in Tables 1 to 6.

[0048] Silanol-terminated PDMS

[0049] Polydimethylsiloxane (PDMS) with terminal silanol (SiOH) groups was used to form a Si-O backbone elastomer component to form a polymer network by condensation of the terminal silanol groups. [Table 1]

[0050] Filler

[0051] Fillers increase the mechanical strength of polymer compositions, such as tensile strength, elongation at break, and tear strength. Fillers include fumed silica and zinc oxide. In contrast to the untreated silica in the examples, hexamethyldisilazane-treated silica is used as a filler to replace OH groups on the silica surface to increase hydrophobicity and promote good settling resistance of the filler without undesirable viscosity increase of silicone formulation during manufacturing process.

[0052] Crosslinking Agent

[0053] The crosslinker serves to form a polymer network with the silanol-terminated PDMS. A silane with ethoxy or methoxy groups is selected to condense with the silanol-terminated PDMS. The ethoxy or methoxy groups are removed as ethanol or methanol during the condensation reaction in the presence of the silanol-terminated PDMS. In the examples, poly(diethoxysiloxane) (containing 40-42% SiO2; abbreviated as PSI-021) and / or 1,2-bis(triethoxysilyl)ethane are used.

[0054] Trimethylsilyl-terminated PDMS

[0055] Polydimethylsiloxane (PDMS) with terminal trimethylsilyl groups is an additive for viscosity control; these trimethylsilyl-terminated PDMS chains permeate the condensed and crosslinked PDMS network, providing flexibility to the resulting material.

[0056] [Table 2]

[0057] catalyst

[0058] Dibutyltin dilaurate was used in the condensation system containing silanol-terminated PDMS and its crosslinker.

[0059] Dynamic binding activator

[0060] To allow for reprocessing, ionic salts such as ammonium or phosphonium salts were chosen. In these examples, tetrabutylphosphonium hydroxide (40%) was used.

[0061] Manufacturing procedure

[0062] A planetary centrifugal mixer is typically used to mix the example compositions. The crosslinker was added to the silanol-terminated PDMS and mixed at 2000 rpm for 20 seconds, followed by the addition of hexamethyldisilazane-treated fumed silica at 2000 rpm for 2 minutes to form a first mixture.

[0063] Dibutyltin dilaurate was added to the trimethylsilyl terminated PDMS and mixed at 2000 rpm for 20 seconds, followed by hexamethyldisilazane treated fumed silica mixed at 2000 rpm for 2 minutes to form a second mixture.

[0064] The second mixture was added to the first mixture in the weight ratios shown in Tables 3-6 (5 min; 2000 rpm) to form a third mixture.

[0065] The dynamic bond activator was added to the third mixture and mixed (5 min; 2000 rpm) to form a fourth mixture.

[0066] The fourth mixture was poured into a mold and placed in a temperature and humidity controlled chamber (25° C.; 95% RH).

[0067] The resulting cured polymer was placed in a vacuum oven at 60° C. for 4 hours as an optional post-cure step.

[0068] mechanical properties

[0069] The samples were cut to standard specimen size (dumbbell shape) according to ASTM international standards.

[0070] Reprocessability

[0071] The samples were reprocessed under molding conditions for 6 hours at 170° C. The reprocessed silicone was cut into standard specimen sizes for mechanical property measurements.

[0072] Tables 3, 4, 5, and 6 show various compositions formed by the examples and their measured mechanical properties.

[0073] It is well known that the mechanical properties of silicone rubber depend on the viscosity and the overall solids content in the composition. The viscosity and the overall solids content can be optimized by adjusting the ratio of the amounts of the components of the first and second mixtures. In Examples 1-4, various compositions are formed with tensile strengths ranging from 1.17 to 5 MPa, as shown in Table 3. These compositions have Shore A hardnesses ranging from 20 to 50 units. Comparing Examples 1-4 with Example 5, an increase in the amount of hexamethyldisilazane-treated fumed silica in the composition increases the overall solids content of the composition and increases the tensile strength from 4.21 MPa to 5 MPa to 6.03 MPa.

[0074] A high molecular weight silanol-terminated PDMS, such as DMS-S51 in Table 4, is expected to have more polymer chain entanglements, while a low molecular weight silanol-terminated PDMS, such as DMS-S33, is expected to have a higher crosslink density and higher density. Compositions containing DMS-S51 are expected to have a high elongation at break in the form of a soft rubber, according to common knowledge in the field. However, this is not the case when comparing Example 1 in Table 3 with Example 6 in Table 4 (elongation at break is 1178% for Example 1, compared to 570% for Example 6). Referring to Examples 7, 8, 9, and 10 in Table 5, which used a low molecular weight silanol-terminated PDMS (DMS-S33), the elongation at break can be adjusted by adding an appropriate amount of trimethylsilyl-terminated PDMS and crosslinking agent, poly(diethoxysiloxane) (containing 40-42% SiO2; abbreviated as PSI-021) and 1,2-bis(triethoxysilyl)ethane. The trimethylsilyl terminated PDMS chains permeate the condensed and cross-linked PDMS network, providing flexibility to the resulting material. Comparing Examples 7 and 8 in Table 5 and Examples 13 and 14 in Table 6, the use of 1,2-bis(triethoxysilyl)ethane as a cross-linker resulted in a decrease in elongation at break from 357% to 69.1%. Comparing Examples 7 and 10, the use of lower molecular weight (DMS-T21) trimethylsilyl terminated PDMS than the higher molecular weight (DMS-T31) in Table 2 reduced the elongation at break from 357% to 170%.

[0075] With reference to Comparative Examples 16 and 17, the first mixture and the second mixture are combined in a weight ratio of 24:1, but these compositions lack the property of remolding as a viscoelastic liquid at temperatures above about 170°C.

[0076] Example 5 in Table 3, Example 6 in Table 4, Examples 8 and 9 in Table 5, and Examples 14 and 15 in Table 6 have the properties of a thermoset polymer at ambient conditions and can be remolded as a viscoelastic liquid at temperatures above about 170° C. while retaining a tensile strength of up to 60% of the ambient tensile strength and up to 70% of the ambient elongation at break. [Table 3] [Table 4] [Table 5] [Table 6] [Industrial Applicability]

[0077] Industrial Applicability:

[0078] By using a dynamic bond activator that promotes Si-O exchange between adjacent silicon-oxygen backbone chains, the polymer of the present invention can be reformed and reshaped when exposed to heat. However, the polymer exhibits properties typical of thermoset materials at ambient conditions. It has a stable crosslinked structure and maintains its shape and mechanical properties. In one aspect, when heated to temperatures above about 170°C, the dynamic bond activator promotes the exchange of Si-O bonds. This process causes the polymer to behave like a viscoelastic liquid, allowing it to be reformed and reprocessed. Importantly, this reforming process does not significantly degrade the properties of the material. Instead, at least some polymer compositions maintain at least 60% tensile strength and 70% elongation at break after reforming compared to their ambient properties. This retention of mechanical properties maintains the functionality and reliability of the material after heat treatment. As a result, the polymer can be used in a variety of applications where recyclability and reprocessability are required. These applications include reusable molds and seals, including creating molds and seals that may need to be periodically reformed. The material is safe for food contact and can be used in silicone food storage containers. The polymer also has potential for use in self-healing materials and flexible electronics. Medical devices can also be manufactured from the polymer, as it is biocompatible and can be sterilized and remolded.

[0079] The foregoing description of the present invention has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations will be apparent to those skilled in the art.

[0080] The embodiments have been chosen and described in order to best explain the principles of the invention and its practical application, so that others skilled in the art can understand the invention in its various embodiments and with various modifications suited to the particular uses contemplated.

[0081] As used herein, and unless otherwise defined, the terms "substantially," "substantial," "approximately," and "about" are used to describe and explain small variations. When used in connection with an event or circumstance, these terms can include not only the exact occurrence of the event or circumstance, but also the approximate occurrence of the event or circumstance. For example, when used in conjunction with a numerical value, these terms can include a variation range of ±10% or less of the numerical value, such as ±5% or less, ±4% or less, ±3% or less, ±2% or less, ±1% or less, ±0.5% or less, ±0.1% or less, ±0.05% or less, etc.

[0082] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. In describing some embodiments, an element provided on (e.g., in physical contact with) or above another element can include the case where the former element is directly on the latter element, as well as the case where one or more intervening elements are located between the former element and the latter element.

[0083] Although the present disclosure has been described and illustrated with reference to specific embodiments thereof, these descriptions and illustrations are not limiting. Those skilled in the art should understand that various modifications can be made and equivalents can be substituted without departing from the true spirit and scope of the present disclosure as defined by the appended claims. The drawings are not necessarily drawn to scale. Due to manufacturing processes and tolerances, there may be distinctions between artistic renditions in the present disclosure and actual devices. There may be other embodiments of the present disclosure that are not specifically illustrated. The specification and drawings should be regarded as illustrative rather than restrictive. Changes can be made to adapt a particular situation, material, composition of matter, method, or process to the objective, spirit, and scope of the present disclosure. All such modifications are intended to be within the scope of the appended claims. Although the methods disclosed herein have been described with reference to certain operations performed in a particular order, it will be understood that these operations may be combined, sub-divided, or reordered to form equivalent methods without departing from the teachings of the present disclosure. Thus, unless specifically indicated herein, the order and grouping of operations are not limiting.

Claims

1. 1. A polymeric composition having a covalent network that changes by thermally activated bond exchange to form dynamic crosslinks, comprising: a silicon-oxygen backbone elastomer to form a polymer network; a non-agglomerated filler dispersed and bonded within said polymer network; a catalyst that promotes the condensation reaction; a crosslinker selected from one or more silanes containing one or more methoxy or ethoxy groups; at least one dynamic bond activator that promotes Si-O bond exchange between adjacent silicon-oxygen backbone elastomers of the polymer network such that the dynamic crosslinks formed between adjacent silicon-oxygen backbone elastomers form a three-dimensional crosslinked polymer network; Including, A polymer composition, in bulk form, that has the properties of a thermoset polymer at ambient conditions and is reformable as a viscoelastic liquid at temperatures above about 170°C.

2. 2. The polymer composition of claim 1, wherein the silicon-oxygen backbone elastomer is selected from one or more of trimethylsilyl-terminated polydimethylsiloxane and silanol-terminated polydimethylsiloxane.

3. 3. The polymer composition of claim 2, wherein the silicon-oxygen backbone elastomer has a molecular weight of 5,970 to 139,000 g / mol, a viscosity of 100 to 150,000 cSt, and is present in the composition in an amount of 49.6 to 65.6 wt %.

4. 3. The polymer composition of claim 2, wherein the filler comprises hexamethyldisilazane treated silica in an amount of 24.9 to 36.9 weight percent.

5. 2. The polymer composition of claim 1, wherein said at least one dynamic bond activator is an ionic salt selected from ammonium salts or phosphonium salts, and the content thereof is 0.09-2.5 wt.%.

6. 6. The polymer composition of claim 5, wherein said at least one dynamic binding activator is tetrabutylphosphonium hydroxide.

7. 2. The polymer composition of claim 1, wherein the at least one catalyst comprises dibutyltin dilaurate or dibutyltin dioctoate in an amount of 0.12 to 2.3 weight percent.

8. 2. The polymer composition of claim 1, wherein the crosslinking agent comprises a silane having an ethoxy group and a silane having a methoxy group in an amount of 2.7 to 25.0 wt %.

9. 9. The polymer composition of claim 8, wherein the crosslinker is selected from one or more of 1,2-bis(triethoxysilyl)ethane, poly(dimethoxysiloxane), poly(diethoxysiloxane), and tetraethylsilicate.

10. 10. The polymer composition of claim 1, wherein the reshaped polymer composition retains a tensile strength of at least 60% of its tensile strength at ambient conditions and a tensile strength of at least 70% of its elongation at break at ambient conditions.

11. A method for producing the polymer composition of claim 1, comprising the steps of: combining a first silicon-oxygen backbone elastomer with a filler and a crosslinker to form a first mixture; combining a second silicon-oxygen backbone elastomer with a filler and a catalyst to form a second mixture; combining the first mixture and the second mixture to form a third mixture, wherein the first mixture and the second mixture are combined in a weight ratio of from 1.1:1 to 8.3:1; combining the third mixture with at least one dynamic binding active agent to form a fourth mixture; curing the fourth mixture to form a polymeric composition; A manufacturing method comprising:

12. The method of claim 11, further comprising heating the polymer composition in a vacuum at a temperature of 50 to 80°C.

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