Toughening of silicone-based polymer material with addition of polyrotaxane

Abstract

Provided is a composition which contains a silicone-based polymer material and a plurality of polyrotaxanes, wherein: each polyrotaxane has a plurality of cyclic molecules and a chain polymer that penetrates through openings of the plurality of cyclic molecules; and a polysiloxane chain is bonded to at least some of the plurality of cyclic molecules.

Description

Strengthening of silicone-based polymer materials by adding polyrotaxane

[0001] The present invention relates to a composition containing a silicone polymer material and a plurality of polyrotaxanes, and a method for producing the same.

[0002] Silicone polymer materials, including silicone rubber, have excellent heat resistance, weather resistance, and water resistance, and are therefore used in a wide range of applications, including sealing materials for electrical and electronic materials, automobiles, and building materials, as well as heat dissipation materials and shock absorption materials. However, they have poor tear properties.

[0003] Polyrotaxanes are known to improve the mechanical properties of polymers, such as toughness and extensibility, when blended with them. Polyrotaxanes are highly compatible with polymeric materials with a certain degree of polarity, such as polyamides, polyesters, and polyacrylates, and their effects are readily apparent. However, they are less compatible with polymeric materials with low polarity, such as silicone-based polymers, fluorine-based polymers, and polyolefins. Composites of silicone-based polymers with polyrotaxanes could increase the toughness of the resulting polymer blends, but such composites have traditionally been difficult due to compatibility issues.

[0004] On the other hand, crosslinkable materials, in which certain crosslinking points are maintained through associative dynamic covalent bonds, are known as vitrimers, and various bond exchange modes of dynamic covalent bonds are currently known (Non-Patent Document 1). Examples of siloxane-containing vitrimers have been reported: an epoxy vitrimer synthesized using a polysiloxane oligomer called bis(potassium) oligoaminopropylmethylsiloxane diolate (K-PAMS) as an epoxy resin curing agent (Non-Patent Document 2); a vitrimer synthesized from 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (BAS) and bisphenol A diglycidyl ether (DGEBA) using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as an organic catalyst (Non-Patent Document 3); and a styrenic copolymer crosslinked with a bisalkoxysilane crosslinker, in which the introduction of adjacent amino moieties accelerates the silyl ether exchange rate (Non-Patent Document 4).

[0005] Jie Zheng et al., Volume 51, December 2021, Pages 586-625 DOI: 10.1016 / j.mattod.2021.07.003Xiao Wu, et al., J. Mater. Chem. A, 2018, 6, 10184 DOI: 10.1039 / c8ta02102cTapas Debsharma et al., J.Am. Chem. Soc. 2022, 144, 12280-12289 DOI: 10.1021 / jacs.2c03518J. Am. Chem. Soc. 2017. 139, 14881-14884

[0006] The problem to be solved by the present invention is to provide a composition in which a silicone-based polymer material and a plurality of polyrotaxanes are well mixed or dispersed. A further problem to be solved by the present invention is to provide a composition in which a silicone-based polymer material and a plurality of polyrotaxanes are well mixed or dispersed and which has improved mechanical strength.

[0007] The present invention encompasses the embodiments described below.

[0008] Item 1. A composition comprising: a silicone-based polymer material; and a plurality of polyrotaxanes, each of which comprises a plurality of cyclic molecules and a chain polymer passing through openings of the plurality of cyclic molecules, and a polysiloxane chain bonded to at least a portion of the plurality of cyclic molecules. Item 2. A composition comprising: a silicone-based polymer material; and a plurality of polyrotaxanes, each of which comprises a plurality of cyclic molecules and a chain polymer passing through openings of the plurality of cyclic molecules, and a polysiloxane chain bonded to at least a portion of the plurality of cyclic molecules. 1 (R 1Item 1. The composition according to Item 1, wherein a bond exchange reaction occurs upon heating between a metal silanol group or a metal silanolate group of a polysiloxane chain bonded to a cyclic molecule of the polyrotaxane (wherein the metal silanol group is Si or C) and a silanol group or a metal silanolate group of a polysiloxane chain bonded to a cyclic molecule of the polyrotaxane. Item 3. The composition according to Item 1 or 2, further comprising a bond exchange catalyst. Item 4. The composition according to Item 2, which is a transparent composition. Item 5. The composition according to Item 1 or 2, wherein the silicone-based polymer material comprises a silicone elastomer. Item 6. The composition according to Item 1 or 2, wherein the silicone-based polymer material comprises a poly(dimethylsiloxane) skeleton. Item 7. The composition according to Item 1, wherein the content of polyrotaxane in the composition is 0.1% by mass or more and 99.9% by mass or less. Item 8. Item 9. A method for producing a composition comprising a silicone-based polymer material and a plurality of polyrotaxanes, each polyrotaxane comprising a plurality of cyclic molecules and a linear polymer that penetrates the openings of the plurality of cyclic molecules, with polysiloxane chains bonded to at least a portion of the plurality of cyclic molecules, the method comprising mixing the silicone-based polymer material and the plurality of polyrotaxanes in the presence of a bond exchange catalyst. Item 10. A method for producing a composition comprising a silicone-based polymer material and a plurality of polyrotaxanes, each polyrotaxane comprising a plurality of cyclic molecules and a linear polymer that penetrates the openings of the plurality of cyclic molecules, with polysiloxane chains bonded to at least a portion of the plurality of cyclic molecules, the silicone-based polymer material comprising a silicone elastomer that is a crosslinked product of a base agent and a crosslinking agent, the method comprising mixing the base agent, the crosslinking agent, and the plurality of polyrotaxanes in the presence of a crosslinking catalyst to crosslink the base agent and the crosslinking agent. Item 11. The method according to Item 9, further comprising, before the crosslinking, reacting a plurality of cyclic molecules of each polyrotaxane with cyclic dimethylsiloxane to form a plurality of polyrotaxanes in which a polysiloxane chain is bonded to at least a portion of the plurality of cyclic molecules. Item 12. Further heating the composition in the presence of a bond exchange catalyst to form -Si-OR bonds in the silicone-based polymer material. 1 (R 1Item 10. The method according to Item 9, further comprising causing a bond exchange reaction between a metal silanolate group or a silanol group of a polysiloxane chain in the polyrotaxane (wherein the metal silanolate group is Si or C) and the silanol group or the metal silanolate group of a polysiloxane chain in the polyrotaxane.

[0009] According to the present invention, there is provided a composition in which a silicone polymer material and a plurality of polyrotaxanes are well mixed or dispersed.

[0010] Schematic diagram illustrating the bond exchange between silyl ether (-Si-O-Si-) and silanol (-Si-OH) in a composition containing a silicone-based polymer material and a polysiloxane-grafted polyrotaxane. Scheme illustrating the reaction of bonding polysiloxane to cyclodextrin. GPC measurement of PDMS-PR-1. PDMS-grafted polyrotaxane. 1 H-NMR spectra. Photographs of various crosslinked films. Stress-strain curves of various films.

[0011] As used herein, the term "polymer" refers to a compound having a repeating structure consisting of multiple basic units derived from the polymerization of monomers. The term "polymer" includes "resin."

[0012] As used herein, "resin" includes natural resins and synthetic resins, and "resin" includes elastomers and rubbers.

[0013] In this specification, the term "comprise" is a concept that encompasses "consist essentially of" and "consist only of."

[0014] In the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in an example or a value that can be unambiguously derived from an example. Furthermore, in this specification, a numerical value connected with "to" means a numerical range that includes the numbers before and after "to" as the upper and lower limits.

[0015] Hereinafter, an embodiment of the present invention will be described.

[0016] In order to hybridize silicone polymer materials with polyrotaxanes, the inventors focused on the bond exchange between silyl ethers (-Si-O-Si- or -Si-OC-) of siloxane-containing vitrimers and silanol groups (-Si-OH) or metal silanolate groups (-Si-OM, where M is a metal).

[0017] Grafting polysiloxane onto the polyrotaxane cyclic molecules allows for good mixing of the polysiloxane-grafted polyrotaxane with a silicone-based polymer material. Furthermore, promoting bond exchange between the silicone polymer material and the siloxane-grafted polyrotaxane suppresses phase separation of the siloxane-grafted polyrotaxane in the silicone polymer material matrix, enabling more uniform dispersion than with physical mixing.

[0018] According to one aspect of the present invention, there is provided a composition containing a silicone-based polymer material and a plurality of polyrotaxanes, each polyrotaxane comprising a plurality of cyclic molecules and a chain polymer that penetrates openings of the plurality of cyclic molecules, and a polysiloxane chain bonded to at least some of the plurality of cyclic molecules.

[0019] As shown schematically in Figure 1 for ease of understanding, a composition according to an embodiment of the present invention contains a silicone-based polymer material 1 and multiple polyrotaxanes 2 (only one is shown in the figure). The polyrotaxane 2 comprises multiple cyclic molecules 3 and a chain polymer 4 that passes through the openings of the multiple cyclic molecules 3, with blocking groups 5 bonded to both ends of the chain polymer 4 to prevent the cyclic molecules 3 from falling off the chain polymer 4. Furthermore, a polysiloxane chain 6 is bonded to at least some of the multiple cyclic molecules 3. The terminals 7 of the polysiloxane chain 6 are hydroxy groups or metal alkoxides.

[0020] A bond exchange reaction of the silyl ether (-Si-O-Si- or -Si-OC-) in the silicone-based polymer material 1 occurs between the -Si-OH or -Si-OM (M is a metal) at the end 7 of the polysiloxane chain 6 bonded to the cyclic molecule 3 of the polyrotaxane 2, thereby enhancing the compatibility between the silicone-based polymer material 1 and the polyrotaxane 2. M is particularly an alkali metal such as lithium, potassium, or sodium. Heating the composition further promotes the bond exchange reaction. This is thought to improve the mechanical strength (e.g., toughness) of the vitrimer compared to a composition of the silicone-based polymer material 1 and a polyrotaxane to which the polysiloxane chain 6 is not grafted.

[0021] In some embodiments, the silicone-based polymer material is a silicone resin. Silicone resin refers to a thermosetting resin whose main component is silicone, a polymer having a main skeleton formed of siloxane bonds. Silicone resins include silicone rubber, which exhibits elasticity. In some embodiments, the silicone-based polymer material is an organopolysiloxane, such as an organopolysiloxane represented by the following composition formula (Chemical Formula I):

[0022] In the formula, R 1is preferably an unsubstituted or substituted monovalent hydrocarbon group having preferably 1 to 20 carbon atoms, more preferably 1 to 6 carbon atoms, such as a linear alkyl group such as a methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, or eicosyl group; an isopropyl group, tert Examples of suitable alkyl groups include branched alkyl groups such as butyl, isobutyl, 2-methylundecyl, and 1-hexylheptyl; cyclic alkyl groups such as cyclopentyl, cyclohexyl, and cyclododecyl; alkenyl groups such as vinyl, allyl, butenyl, pentenyl, and hexenyl; aryl groups such as phenyl, tolyl, and xylyl; aralkyl groups such as benzyl, phenethyl, and 2-(2,4,6-trimethylphenyl)propyl; halogenated alkyl groups such as 3,3,3-trifluoropropyl and 3-chloropropyl; and alkyl groups substituted with a cyano group. Preferred are alkyl, alkenyl, and aryl groups, with methyl, vinyl, and phenyl being particularly preferred. The multiple substituents may be the same or different. a is a number ranging from 1.9 to 2.4, preferably from 1.95 to 2.05.

[0023] In some embodiments, the silicone polymer material preferably contains a poly(dimethylsiloxane) skeleton in view of compatibility with the polyrotaxane. The organopolysiloxane preferably has an average degree of polymerization of 100 to 3,000.

[0024] In some embodiments, the silicone-based polymer material comprises a silicone elastomer. Silicone elastomer is synonymous with "organopolysiloxane elastomer" and refers to a viscoelastic, deformable organopolysiloxane. The silicone elastomer is preferably a viscoelastic, deformable crosslinked organopolysiloxane. Silicone elastomers can be stretched and then returned to their original shape, i.e., elastically deformable.

[0025] Examples of silicone elastomers include those obtained by the condensation reaction of a methoxysilyl group (≡SiOCH3) with a hydroxysilyl group (≡SiOH), the condensation reaction of a hydrosilyl group (≡SiH) with a hydroxysilyl group (≡SiOH), the radical reaction of a mercaptopropylsilyl group (≡Si-CH3H6SH) with a vinylsilyl group (≡SiCH=CH2), and the addition reaction of a vinylsilyl group (≡SiCH=CH2) with a hydrosilyl group (≡SiH). However, from the viewpoint of reactivity, condensation or addition reactions are preferred. These reactions are preferably carried out in the presence of a crosslinking catalyst. Examples of crosslinking catalysts include platinum catalysts such as platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex.

[0026] The molecular weight of the silicone-based polymer material, silicone elastomer, or organosiloxane is not particularly limited, and may be, for example, a number-average molecular weight or weight-average molecular weight of 500 to 1,000,000. The polyrotaxane used in the present disclosure includes polysiloxane-graft polyrotaxane, which comprises a plurality of cyclic molecules and a chain polymer that penetrates the openings of the plurality of cyclic molecules, and in which a polysiloxane chain is bonded to at least a portion of the plurality of cyclic molecules.

[0027] Polyrotaxane is a compound having a structure comprising a plurality of cyclic molecules and a chain polymer that penetrates the openings of the plurality of cyclic molecules, with blocking groups attached to both ends of the chain polymer to prevent the cyclic molecules from falling off. Polyrotaxane may be produced based on known literature, or a commercially available product from a manufacturer such as ASM Inc. may be used.

[0028] Examples of linear polymers constituting polyrotaxanes include molecules capable of threading through the rings of multiple cyclic molecules. The linear polymer is preferably a polymer having repeating units of a monomer. Examples of linear polymers include polyalkylenes, polyesters, polyethers, polyamides, polyacrylics, and linear polymers having a benzene ring. Examples of preferred linear polymers include polyethylene glycol, polyethylene oxide, polypropylene glycol, polylactic acid, polycaprolactone, polyethylene, polypropylene, polyvinyl acetal, polyvinyl methyl ether, polyvinylpyrrolidone, polyacrylamide, polymethyl acrylate, polymethyl methacrylate, and polystyrene. While the linear polymer preferably does not have an ester bond, it may have an ester bond as long as the effects of the present invention are achieved. The linear polymer may have a branched chain as long as it is configured to be capable of threading through the rings of the cyclic molecules. In one preferred embodiment, the linear polymer is at least one selected from the group consisting of polyethylene glycol, polyvinyl alcohol, polyethyleneimine, and copolymers containing at least one of these. In a more preferred embodiment, the chain polymer is at least one selected from the group consisting of polyethylene glycol, polypropylene glycol, and polyethylene glycol.

[0029] The chain polymer may be a polymer whose entire structure is a repeating structure of the same monomer, or may be a block copolymer having at least two blocks, or may be a block copolymer having at least three blocks.

[0030] For example, when the chain polymer is a water-soluble chain molecule consisting of one type of polymer, it may be a polymer consisting of only polyethylene glycol, only polypropylene glycol, only polyvinyl alcohol, only polyethyleneimine, or only polyethylene glycol.When the chain polymer is a chain polymer consisting of three blocks, the central block may be polypropylene glycol and both sides may be polyethylene glycol.

[0031] The molecular weight of the linear polymer is not particularly limited, but the number average molecular weight is, for example, more preferably 3,000 to 50,000, more preferably 7,000 to 200,000, and even more preferably 10,000 to 100,000. Alternatively, the weight average molecular weight is, for example, more preferably 3,000 to 500,000, more preferably 7,000 to 200,000, and even more preferably 10,000 to 100,000. The number average molecular weight and weight average molecular weight referred to herein can be determined from polyethylene glycol equivalent values ​​measured by gel permeation chromatography (GPC).

[0032] Both ends of the chain polymer preferably have reactive groups capable of reacting with blocking groups for preventing cyclic molecules from dropping off from the chain polymer, which makes it easier for the blocking groups described below to be bonded to both ends of the chain polymer. Examples of reactive groups include amino groups, hydroxyl groups, carboxyl groups, thiol groups, disulfides, vinyl groups, acryloyl groups, methacryloyl groups, and sulfo groups. Preferred are amino groups and carboxyl groups.

[0033] The blocking group bonded to the linear polymer of polyrotaxane is not particularly limited as long as it acts to prevent detachment of the cyclic molecules from the linear polymer. For example, the blocking group may be selected from the group consisting of a dinitrophenyl group, cyclodextrin, adamantane group, trityl group, fluorescein, silsesquioxane, pyrene, substituted benzene (substituents include, but are not limited to, alkyl, alkyloxy, hydroxy, halogen, cyano, sulfonyl, carboxyl, amino, phenyl, etc.; one or more substituents may be present), optionally substituted polynuclear aromatics (substituents include, but are not limited to, the same as those described above; one or more substituents may be present), and steroids. Preferably, the blocking group is selected from the group consisting of a dinitrophenyl group, cyclodextrin, adamantane group, trityl group, fluorescein, silsesquioxane, and pyrene, with adamantane group or cyclodextrin being more preferred.

[0034] Examples of cyclic molecules constituting polyrotaxanes include various cyclodextrins (α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, and derivatives thereof, preferably derivatives that retain the carbon skeleton of cyclodextrin but in which any one or more functional groups bonded to the carbon skeleton have been substituted), crown ethers, benzocrowns, dibenzocrowns, dicyclohexanocrowns, and derivatives thereof. In terms of ease of grafting polysiloxane chains, the cyclic molecule is preferably cyclodextrin. Furthermore, cyclodextrin may be a derivative in which one or more hydroxyl groups of cyclodextrin have been substituted with other functional groups. Examples of cyclodextrin derivatives include, but are not limited to, methylated α-cyclodextrin, methylated β-cyclodextrin, methylated γ-cyclodextrin, hydroxypropylated α-cyclodextrin, hydroxypropylated β-cyclodextrin, and hydroxypropylated γ-cyclodextrin. Hydroxypropylated α-cyclodextrin, hydroxypropylated β-cyclodextrin, and hydroxypropylated γ-cyclodextrin are preferred in terms of improving the mechanical strength of the composition containing them.

[0035] In the present disclosure, a polysiloxane chain is bonded to at least some of the multiple cyclic molecules of the polyrotaxane. While the polysiloxane chain may be bonded to all of the cyclic molecules in the polyrotaxane in the composition, it is sufficient that the polysiloxane chain is bonded to at least some of the cyclic molecules in the polyrotaxane in the composition, as long as a silyl ether-silanol bond exchange reaction occurs between the silicone-based polymer material and the polysiloxane chains of the cyclic molecules of the polyrotaxane. By grafting the polysiloxane chains onto the cyclic molecules of the polyrotaxane, the compatibility between the silicone-based polymer material and the polyrotaxane is improved compared to when the polysiloxane chains are not grafted onto the cyclic molecules of the polyrotaxane.

[0036] For example, when the cyclic molecule is cyclodextrin, the cyclodextrin has a hydroxyl group in the molecule. Therefore, as shown in the synthesis scheme in Figure 2, by reacting the cyclodextrin (represented by a ring) of polyrotaxane (PR) with a cyclic siloxane in a solvent in the presence of a bond exchange catalyst, the cyclic siloxane ring opens, allowing the introduction of a polysiloxane chain (in the figure, a polydimethylsiloxane chain) into the cyclic molecule. Examples of bond exchange catalysts include, but are not limited to, basic catalysts such as 1,8-diazabicycloundecene-7 and 1,5-diazabicyclo-5. Examples of solvents include, but are not limited to, at least one organic solvent selected from the group consisting of DMSO, chloroform, DMF, DMAc, NMP, dichloromethane, THF, and toluene. Examples of cyclic siloxanes include, but are not limited to, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane. The reaction temperature between the polyrotaxane and the cyclic siloxane is preferably, but not limited to, 0 to 150°C, more preferably 40 to 100°C. The reaction time between the polyrotaxane and the cyclic siloxane is preferably, but not limited to, 30 minutes to 72 hours, more preferably 30 minutes to 1 day. The siloxane chain bonded to the cyclic molecule has a hydroxy group at its terminal.

[0037] The cyclic molecule may further have an additional functional group other than the polysiloxane chain, such as a hydroxyl group, a carboxyl group, an amino group, an epoxy group, an isocyanate group, a thiol group, an aldehyde group, an acetyl group, a propyl group, a hexanoyl group, a methyl group, an ethyl group, a propyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, a polycaprolactone-modified hydroxypropyl group, a cyclohexyl group, a butylcarbamoyl group, a hexylcarbamoyl group, a phenyl group, an alkoxysilane group, an acryloyl group, a methacryloyl group, a cinnamoyl group, a polymer (such as a polycarbonate group, a polyamide group, or a polyurethane group), or a derivative thereof.

[0038] The polyrotaxanes may be crosslinked to one another via the functional groups of the cyclic molecules. The functional groups of the polyrotaxanes may be bonded directly to one another, or may be bonded via a crosslinking agent reactive with the functional groups of the cyclic molecules. The elastomerization of the polyrotaxanes by crosslinking can further toughen the composition of this embodiment.

[0039] In this specification, the inclusion rate refers to the ratio of the amount of cyclic molecules that encapsulate a linear polymer to the maximum amount of cyclic molecules that encapsulate the linear polymer. The inclusion rate can be determined, for example, by nuclear magnetic resonance spectroscopy (NMR) or gel permeation chromatography (GPC).

[0040] The inclusion rate of the polyrotaxane is preferably 0.1 to 100%, more preferably 0.1 to 50%, even more preferably 1 to 50%, and most preferably 1 to 30%.

[0041] The amount of polyrotaxane in the composition of the present embodiment is not particularly limited, but from the viewpoint of improving the compatibility and toughness of the composition, it is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 5% by mass or more.

[0042] In order to achieve the inherent function of the polymer, the amount of polyrotaxane in the composition is preferably 50% by weight or less, more preferably 40% by weight or less, and even more preferably 30% by weight or less. In one embodiment, in order to improve the mechanical strength of the composition, the amount of polyrotaxane in the composition is 20% by weight or less.

[0043] In one embodiment, the amount of polyrotaxane in the composition is 0.1% by mass or more and 99.9% by mass or less, hi another embodiment, the amount of polyrotaxane in the composition is 1 to 40% by mass, more preferably 1 to 30% by mass, and even more preferably 1 to 20% by mass.

[0044] In terms of improving the mechanical strength of the composition, the mass ratio of the silicone polymer material (particularly the silicone elastomer) to the polyrotaxane (silicone polymer material:polyrotaxane) in the composition is preferably 99.0:0.1 to 1:1, more preferably 99:1 to 1:1, even more preferably 95:5 to 1:1, still more preferably 95:5 to 3:2, and even more preferably 95:5 to 4:1.

[0045] The total amount of the silicone-based polymer material and the polyrotaxane in the composition is not particularly limited, but from the viewpoint of improving the toughness of the composition, it is preferably 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more.

[0046] In some embodiments, the silicone-based polymer material, silicone elastomer, or organosiloxane has —Si—OR 1 (R 1 R has Si or C, and a bond exchange reaction occurs between the silanol group or metal silanolate group of the polysiloxane chain bonded to the cyclic molecule of the polyrotaxane upon heating. 1 A preferred example is trialkylsilyl, where each alkyl in the trialkyl is preferably independently an alkyl having 1 to 6 carbon atoms. The polysiloxane chain preferably has a silanol group or a metal silanolate group at its terminal. The metal silanolate group is preferably an alkali metal silanolate group. For bond exchange between silyl ether (-Si-O-Si-) and silanol group (-Si-OH), see, for example, Tapas Debsharma et al., J.Am. Chem. Soc. 2022, 144, 12280-12289 DOI: 10.1021 / jacs.2c03518.

[0047] The composition of the present invention preferably contains a bond exchange catalyst. This catalyst induces a bond exchange reaction between the silyl ether of the silicone-based polymer material and the silanol group or metal silanolate group of the polysiloxane chain grafted to the cyclic molecule of the polyrotaxane. The bond exchange catalyst is preferably a basic catalyst. Such basic catalysts are well known and include, but are not limited to, the above-mentioned 1,8-diazabicycloundecene-7 and 1,5-diazabicyclo-5. The amount of the bond exchange catalyst or basic catalyst to be added can be determined appropriately by one skilled in the art. In some embodiments, the amount of the bond exchange catalyst or basic catalyst is 0.001 to 10% by mass based on 100 parts by mass of the silicone-based polymer material.

[0048] In addition to the silicone-based polymer material and the polyrotaxane, the composition according to the embodiment of the present invention may contain other additives, such as a plasticizer, a surfactant, a lubricant, a filler, a dispersant, an antioxidant, a light stabilizer, an ultraviolet absorber, a colorant, a flame retardant, etc. These additives may be used alone or in combination of two or more.

[0049] The composition of the present embodiment, which contains the silicone-based polymer material and the polyrotaxane described above, has improved toughness compared to a composition that differs only in that no polysiloxane chain is bonded to the polyrotaxane.

[0050] In some embodiments, the stress at break of the composition, as measured in a uniaxial extension test, is increased relative to the stress at break of a control that differs from the composition only in that no polysiloxane chains are attached to the polyrotaxane.

[0051] In some embodiments, the elongation at break of the composition, as measured in a uniaxial extension test, is increased compared to the elongation at break of a control that differs from the composition only in that no polysiloxane chains are attached to the polyrotaxane.

[0052] In some embodiments, the stress at break of a composition after heating for 12 hours or more at 50°C as measured in a uniaxial extension test is at least 2 times greater than the stress at break of a control that differs only in that it is not heated. In some embodiments, the elongation at break of a composition after heating for 12 hours or more at 50°C as measured in a uniaxial extension test is at least 1.5 times greater than the elongation at break of a control that differs only in that it is not heated.

[0053] Next, a method for producing a composition containing a silicone-based polymer material according to an embodiment of the present invention and a plurality of polyrotaxanes will be described.

[0054] According to one aspect of the present invention, there is provided a method for producing a composition by simply mixing a silicone-based polymer material with a plurality of polyrotaxanes. The method includes mixing a silicone-based polymer material with a plurality of polyrotaxanes, each polyrotaxane comprising a plurality of cyclic molecules and a linear polymer that penetrates the openings of the cyclic molecules, with a polysiloxane chain bonded to at least a portion of the cyclic molecules. The silicone-based polymer material and the polyrotaxane with a polysiloxane chain bonded to at least a portion of the cyclic molecules are as described above. Mixing the silicone-based polymer material with the plurality of polyrotaxanes is preferably carried out at a temperature between 0 and 40°C, more preferably between 15 and 40°C.

[0055] The above method may further include, before mixing the silicone-based polymer material and the plurality of polyrotaxanes, reacting a plurality of cyclic molecules of each polyrotaxane with cyclic dimethylsiloxane to form a plurality of polyrotaxanes in which polysiloxane chains are bonded to at least some of the plurality of cyclic molecules.

[0056] The silicone-based polymer material and the plurality of polyrotaxanes are preferably mixed in the presence of a bond exchange catalyst. The method may further include heating the composition containing the silicone-based polymer material, the plurality of polyrotaxanes, and the bond exchange catalyst to promote bond exchange between the silicone-based polymer material, the silyl ether, and the silanol groups or metal silanolate groups of the polyrotaxanes.

[0057] Alternatively, the method may further comprise contacting a bond exchange catalyst with a composition comprising the silicone-based polymer material and the plurality of polyrotaxanes after mixing the silicone-based polymer material and the plurality of polyrotaxanes. By contacting the composition comprising the silicone-based polymer material and the plurality of polyrotaxanes with the bond exchange catalyst, the bond exchange catalyst migrates into the composition.

[0058] The method may further include, after the contacting, heating the composition comprising the silicone-based polymeric material, the plurality of polyrotaxanes, and the bond exchange catalyst to promote bond exchange between the silicone-based polymeric material, the silyl ether, and the silanol groups or metal silanolate groups of the polyrotaxane.

[0059] In the composition of the above embodiment of the present invention, heating promotes the bond exchange reaction and increases transparency. Heating the thermosetting composition increases the compatibility of the polysiloxane-graft-polyrotaxane with the silicone-based polymer material, resulting in transparency. The heating temperature is not particularly limited, but is preferably lower than the melting point of the silicone-based polymer material, and in one embodiment, is 30 to 240°C. In one embodiment, it is 30 to 200°C. In one embodiment, it is 50 to 180°C. The reaction time is preferably 30 minutes to 72 hours, more preferably 30 minutes to 1 day, but is not limited thereto.

[0060] According to another aspect of the present invention, there is provided a method for producing a composition comprising a silicone-based polymer material and a plurality of polyrotaxanes, each polyrotaxane comprising a plurality of cyclic molecules and a chain polymer passing through openings of the plurality of cyclic molecules, with polysiloxane chains bonded to at least some of the plurality of cyclic molecules, wherein the silicone-based polymer material comprises a silicone elastomer that is a crosslinked product of a base agent and a crosslinking agent. The method includes mixing the base agent, the crosslinking agent, and the plurality of polyrotaxanes in the presence of a crosslinking catalyst, and crosslinking the base agent and the crosslinking agent.

[0061] Combinations of the main component (1) and the crosslinking agent (2) include the following, where one compound can be either the main component (1) or the crosslinking agent (2), and the other compound can be the other of the main component (1) and the crosslinking agent (2): A compound having a methoxysilyl group (≡SiOCH3) and a compound having a hydroxysilyl group (≡SiOH) A compound having a hydrosilyl group (≡SiH) and a compound having a hydroxysilyl group (≡SiOH) A compound having a mercaptopropylsilyl group (≡Si-C3H6SH) and a compound having a vinylsilyl group (≡SiCH=CH2) A compound having a vinylsilyl group (≡SiCH=CH2) and a compound having a hydrosilyl group (≡SiH)

[0062] Examples of crosslinking catalysts include platinum catalysts such as platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex.

[0063] The method may further include, prior to the cross-linking, reacting a plurality of cyclic molecules of each polyrotaxane with cyclic dimethylsiloxane to form a plurality of polyrotaxanes in which polysiloxane chains are bonded to at least a portion of the plurality of cyclic molecules.

[0064] The method may further include, after the crosslinking, contacting the composition containing the silicone-based polymer material and the plurality of polyrotaxanes with a bond exchange catalyst. By allowing the bond exchange catalyst to act at a different time from the crosslinking catalyst, catalytic interference can be prevented. The method may further include, after the contacting, heating the composition containing the silicone-based polymer material and the plurality of polyrotaxanes to promote bond exchange between the silicone-based polymer material, the silyl ether, and the silanol groups or metal silanolate groups of the polyrotaxane, preferably in the presence of the bond exchange catalyst.

[0065] In the composition of the above embodiment of the present invention, heating promotes the bond exchange reaction and increases transparency. Heating the thermosetting composition increases the compatibility of the polysiloxane-graft-polyrotaxane with the silicone-based polymer material, resulting in transparency. The heating temperature is not particularly limited, but is preferably lower than the melting point of the silicone-based polymer material, and in one embodiment, is 30 to 240°C. In one embodiment, it is 30 to 200°C. In one embodiment, it is 50 to 180°C. The reaction time is preferably 30 minutes to 72 hours, more preferably 30 minutes to 1 day, but is not limited thereto.

[0066] As described above, this simple synthesis method for polysiloxane graft polyrotaxane can achieve good mixing of a silicone polymer material and a polyrotaxane. Furthermore, the formation of chemical bonds between the silicone polymer material and the polysiloxane graft polyrotaxane in the resulting composition suppresses phase separation of the polyrotaxane, enabling more uniform dispersion than physical mixing.

[0067] The obtained composition according to the embodiment of the present invention can be molded into any three-dimensional shape, such as a film, sheet, cylinder, or case, by a known molding technique such as extrusion molding, press molding, vacuum molding, injection molding, blow molding, inflation molding, or foam molding, to form a molded article.

[0068] The composition according to the embodiment of the present invention and a molded article containing the same have high toughness and can be used for various purposes such as films, sheets, and household goods. As used herein, a film refers to a thin film having a thickness of less than 250 μm. A sheet refers to a plate-like member having a thickness of 250 μm or more.

[0069] Furthermore, when the composition according to an embodiment of the present invention is a thermosetting composition containing a silicone elastomer, such a composition and a molded article containing the same have toughness, and therefore can be suitably used in devices for which it is desired that maintenance be unnecessary or can be omitted, such as automobiles, ships, spacecraft, airplanes, windmills, sporting goods, building materials, defense products, electronic products, packaging materials, etc. The thermosetting composition according to an embodiment of the present invention can also be used in composite materials that constitute such devices.

[0070] The disclosures of all patent applications and publications cited herein are hereby incorporated by reference in their entirety.

[0071] The following examples are intended for illustrative purposes only and are not intended to limit the scope of the present invention in any way. Unless otherwise specified, reagents are commercially available or are obtained or prepared according to conventional techniques or literature procedures in the art.

[0072] Example 1: Grafting of polydimethylsiloxane (PDMS) onto polyrotaxane (PR) 1.0 g of PR35 (a polyrotaxane consisting of linear PEG (weight-average molecular weight 35,000), cyclic α-cyclodextrin, and adamantaneamine capping groups, with a CD inclusion rate of 28%) and 8.4 mL of ultra-dehydrated dimethyl sulfoxide (Fujifilm Wako Pure Chemical Industries, Ltd.) were added to a nitrogen-purged two-necked flask. The mixture was heated to 50°C in an oil bath to dissolve the PR35 compound, in which some of the α-CD OH groups had been hydroxypropylated. Next, 1.0 mL of diazabicycloundecene (DBU, Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was stirred at 50°C for 30 minutes. Separately, 24.4 g of hexamethylcyclotrisiloxane (Tokyo Chemical Industry Co., Ltd.) was dissolved in 25.8 mL of ultra-dehydrated chloroform (Fujifilm Wako Pure Chemical Industries, Ltd.), and the resulting chloroform solution was added in 10 mL portions to the reaction solution over 20 minutes. After addition, the mixture was stirred at 50°C for 5 hours under a nitrogen atmosphere.

[0073] After the reaction, the chloroform was mainly removed using a rotary evaporator. After removal of the solvent, 300 mL of methanol was added, causing the solid to precipitate. The supernatant was removed by decantation, and the precipitate was recovered. The precipitate was washed with 300 mL of methanol and dried under reduced pressure at room temperature to obtain 12.0 g of a grafted product (PDMS-PR-1) in which PDMS was grafted onto translucent PR35.

[0074] The obtained PDMS-PR-1 was dissolved in chloroform and subjected to GPC measurement. The GPC chart for RI detection is shown in Figure 3. The peak was almost monomodal. The peak intensity showed a negative value because the refractive index of the chloroform solution of PDMS-PR-1 was smaller than that of chloroform (1.44). In addition, PDMS-PR-1 was dissolved in deuterated chloroform and 1 H-NMR measurements were carried out. 1The H-NMR chart is shown in Figure 4. A proton peak derived from the methyl group of PDMS was observed around 0 ppm. Some of the CDs in PR35 are modified with hydroxypropyl groups, and proton peaks derived from CDs were observed at 4.8-5.1 ppm, proton peaks derived from hydroxypropyl groups and PEG at 3.2-3.8 ppm, and proton peaks derived from the methyl group of the hydroxypropyl group at 1.0-1.2 ppm. 1 The results of H-NMR confirmed that PDMS was grafted onto PR35.

[0075] The amount of PDMS introduced is 1 The product was analyzed by H-NMR. As shown in Figure 4, when the integral value of the proton peak derived from CD between 4.8 and 5.1 ppm was set to 6.00 (considered as 1 equivalent of CD), the integral value of the proton peak derived from the methyl group of PDMS near 0 ppm was 2280. In other words, it was analyzed that 2280 ÷ 6 = 380 equivalents of dimethylsiloxane units of PDMS were introduced per equivalent of CD.

[0076] Example 2: Solvent Solubility of PDMS-PR-1, Compatibility with PDMS Base and Crosslinker. A solubility test was conducted on the PDMS-PR-1 synthesized in Example 1. A 10 mg sample was mixed with 1 mL of solvent, and the solubility of the sample after standing for 1 hour and the turbidity of the solution were used to confirm the solvent solubility. PDMS-PR-1 was highly soluble in chloroform and dichloromethane, soluble in THF and acetone but the solution became cloudy, and insoluble in dimethyl sulfoxide, dimethylformamide, methanol, and water. In contrast to the high solubility of PR35 used as the raw material, it exhibited low solubility in water, suggesting the solubility of the PDMS graft group. Compatibility tests of PDMS-PR-1 with the PDMS base resin and crosslinker were conducted using the PDMS elastomer raw materials, poly(dimethylsiloxane-co-methylhydrosiloxane) trimethylsilyl-terminated (PDMS base resin, Mw: ~13,000 g / mol, Sigma-Aldrich) and poly(dimethylsiloxane) vinyl-terminated (PDMS crosslinker, Mw: ~25,000 g / mol, Sigma-Aldrich). PDMS-PR-1 was highly compatible with the PDMS base resin, resulting in a colorless and transparent mixed solution. However, it was soluble in the PDMS crosslinker, but the solution became cloudy.

[0077] Example 3: Preparation of PDMS-PR-1-Containing PDMS Elastomer. 0.1 g of the PDMS base resin, 0.1 g of crosslinker, and 0.01 g of PDMS-PR-1 used in Example 2 were thoroughly dissolved in 2 mL of chloroform. 2 μL of platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex solution (Sigma-Aldrich) was added dropwise as a crosslinking catalyst. After rapid stirring, the solution was cast into a PFA Petri dish. The crosslinked sheet was left at room temperature for at least 12 hours and then peeled off from the Petri dish. A PDMS-PR-1-containing PDMS elastomer sheet (PDMS / PR elastomer) was prepared by drying under reduced pressure at 50°C for at least 12 hours for further crosslinking and solvent removal. A PDMS elastomer sheet (PDMS elastomer) without PDMS-PR-1 was also prepared as a comparison material using the same procedure.

[0078] Example 4: Preparation of PDMS elastomer with silyl ether bond exchange catalyst. The PDMS / PR elastomer sheet prepared in Example 3 was immersed in 10 mL of chloroform solution containing 2 μL of DBU (Tokyo Chemical Industry Co., Ltd.) as a silyl ether bond exchange catalyst and allowed to stand at room temperature for at least 5 hours to evaporate the chloroform. The PDMS-PR-1-containing PDMS elastomer sheet with DBU permeated into the interior was dried under reduced pressure at 50°C for at least 12 hours to remove residual solvent and promote the bond exchange reaction. This sample was designated BE-PDMS / PR elastomer 50. A sample was prepared using a PDMS elastomer sheet without PDMS-PR-1 using the same procedure. This sample was designated BE-PDMS / PR elastomer 50. To further activate the bond exchange reaction, the PDMS-PR-1-containing PDMS elastomer sheet was dried under reduced pressure at 50°C for at least 12 hours and then heated at 150°C for 2 hours to obtain the sample designated BE-PDMS / PR elastomer 150.

[0079] Example 5: Compatibility and Mechanical Properties of Various Elastomers Figure 5 shows photographs of the appearance of a PDMS elastomer without PR (top left), BE-PDMS elastomer 50 (top right), a PDMS / PR elastomer (bottom left), and a BE-PDMS / PR elastomer 50 (bottom right). The appearance of the PDMS elastomer without PR was unchanged with or without the bond exchange catalyst; all were colorless and transparent. On the other hand, the PDMS / PR elastomer with PR added showed clear opacity without the bond exchange catalyst, suggesting the formation of PR domains. However, the BE-PDMS / PR elastomer 50 and BE-PDMS / PR elastomer 150, which contained the bond exchange catalyst and were heated at 50°C and 150°C, showed reduced opacity and high transparency (BE-PDMS / PR elastomer 150 is not shown). This is suggested to be due to the formation of chemical bonds between the PDMS graft groups of PR and the PDMS network via silyl ether bond exchange, resulting in the chemical incorporation of PR into the network.

[0080] Similar effects were also observed in the mechanical properties of the uniaxial elongation test shown in Figure 6. Bond exchange did not significantly change the mechanical properties of the PDMS elastomer without PR. The PDMS / PR elastomer, in which PR was physically mixed, showed no change in Young's modulus, which indicates material hardness, compared to the unadded elastomer, but the elongation at break was approximately doubled. Furthermore, BE-PDMS elastomer 50 showed an elongation at break that was approximately four times higher than the unadded elastomer. It is believed that the addition of PR improves toughness due to the stress dispersion effect of PR, and that a dramatic improvement in toughness was achieved by chemically combining it with PDMS through bond exchange.

[0081] On the other hand, in the case of BE-PDMS elastomer 150, the Young's modulus was reduced to about half of that without PR, and the elongation at break was also at the same level. This suggests that there is a combination of bond exchangeability and PR morphology in the PDMS network that achieves optimal mechanical properties, and that active bond exchange at 150°C disrupts this balance.

Claims

1. A composition comprising: a silicone-based polymer material; and a plurality of polyrotaxanes, each of which comprises a plurality of cyclic molecules and a chain polymer passing through openings of the plurality of cyclic molecules, and a polysiloxane chain is bonded to at least a portion of the plurality of cyclic molecules.

2. -Si-OR in the silicone polymer material 1 (R 1 2. The composition according to claim 1, wherein a bond exchange reaction occurs by heating between the cyclic molecule of the polyrotaxane and a silanol group or a metal silanolate group of the polysiloxane chain bonded to the cyclic molecule of the polyrotaxane.

3. The composition of claim 1 or 2, further comprising a bond exchange catalyst.

4. The composition of claim 2 which is a transparent composition.

5. The composition according to claim 1 or 2, wherein the silicone-based polymeric material comprises a silicone elastomer.

6. The composition according to claim 1 or 2, wherein the silicone-based polymeric material comprises a poly(dimethylsiloxane) backbone.

7. The composition according to claim 1, wherein the content of the polyrotaxane in the composition is 0.1% by mass or more and 99.9% by mass or less.

8. A method for producing a composition comprising a silicone-based polymer material and a plurality of polyrotaxanes, each polyrotaxane comprising a plurality of cyclic molecules and a chain-like polymer penetrating openings of the plurality of cyclic molecules, and a polysiloxane chain being bonded to at least a portion of the plurality of cyclic molecules, the method comprising mixing the silicone-based polymer material and the plurality of polyrotaxanes in the presence of a bond exchange catalyst.

9. A method for producing a composition comprising a silicone-based polymer material and a plurality of polyrotaxanes, each polyrotaxane comprising a plurality of cyclic molecules and a chain polymer passing through openings of the plurality of cyclic molecules, and a polysiloxane chain being bonded to at least a portion of the plurality of cyclic molecules, wherein the silicone-based polymer material comprises a silicone elastomer which is a crosslinked product of a base agent and a crosslinking agent, the method comprising: mixing the base agent, the crosslinking agent, and the plurality of polyrotaxanes in the presence of a crosslinking catalyst to crosslink the base agent and the crosslinking agent.

10. The method of claim 9, further comprising reacting a plurality of cyclic molecules of each of the polyrotaxanes with cyclic dimethylsiloxane prior to the crosslinking to form a plurality of polyrotaxanes having polysiloxane chains bonded to at least a portion of the plurality of cyclic molecules.

11. The composition is further heated in the presence of a bond exchange catalyst to form -Si-OR bonds in the silicone-based polymeric material. 1 (R 1 The method of claim 9, further comprising: causing a bond exchange reaction between a metal silanolate group or a silanol group of a polysiloxane chain in the polyrotaxane, the metal silanolate group being a silanol group or a metal silanolate group of a polysiloxane chain in the polyrotaxane.

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