Bridging frustrated Lewis pairs as thermal triggers for the reactions of Si-H and Si-OR.

Abstract

The composition contains a mixture of silyl hydrides, silanols and / or silyl ethers, and bridging frustrated Lewis pairs.

Description

[Background technology]

[0001] FIELD OF THEINVENTION The present invention relates to the use of a bridged frustrated Lewis pair as a thermal trigger for the chemical reaction of silyl hydrides with silyl ethers and / or silanols. The bridged frustrated Lewis pair dissociates upon heating to release a Lewis acid. The Lewis acid acts as a catalyst for the chemical reaction of silyl hydrides with silyl ethers and / or silanols.

[0002] Introduction Frustrated Lewis pair ("FLP") is a term that refers to a pair of Lewis acids and Lewis bases in which the Lewis acid and Lewis base cannot complex and neutralize each other due to steric congestion. When the Lewis acid and Lewis base of an FLP are mixed, they remain independent of each other rather than mixing and neutralizing each other. In addition, FLPs have been found to indirectly bind to each other in the form of bridged frustrated Lewis pairs ("B-FLP"), in which a bridge molecule binds to both the acid and base of the FLP, forming a complex with the bridge molecule between the Lewis acid and the Lewis base. In some cases, the bridge molecule cleaves to produce a blocked Lewis acid and a blocked Lewis base, and a portion of the bridge molecule can complex with each of the Lewis acid and Lewis base, blocking further complexation or reaction. Hydrogen (H2) is an example of a bridge molecule that cleaves in this manner upon forming a B-FLP.

[0003] B-FLP has been used to activate bridge molecules for use in chemical reactions. For example, hydrogen (H2) has been used as a bridge molecule in B-FLP to activate hydrogen for use in hydrogenation reactions (see, e.g., JACS 2015, 137, 10018-10032), and carbon dioxide has been used as a bridge molecule in B-FLP to activate carbon dioxide for deoxyhydrosilylation (see, e.g., JACS 2010, 132, 10660-10661). Other molecules used as bridge molecules in B-FLP for use in activation for chemical reactions include nitrous oxide (N2O), sulfur dioxide (SO2), alkenes, and alkynes. See, for example, Angew. Chem. Int. Ed. 2009, 48, 6643-6646; Angew. Chem. Int. Ed. 2015, 54, 6400-6441 and JACS 2015, 137, 10018-10032. Summary of the Invention [Problem to be solved by the invention]

[0004] It would be surprising and useful to discover additional uses for B-FLP, especially if such uses allow for the control of chemical reactions other than those involving cross-linking molecules.

[0005] The present invention provides a surprising and unexpected use of B-FLP as a thermal trigger for the reaction of silyl hydrides (Si-H) with silanols (Si-OH) or silyl ethers (Si-OR).

[0006] Si-H and Si-OR are known to react in the presence of a strong Lewis acid catalyst to produce siloxanes and RH in a reaction known as the Piers-Rubinsztajn ("PR") reaction. Since the discovery of the PR reaction, it has been found that silanols can be used in place of silyl ethers in PR-like reactions to produce siloxanes and hydrogen gas. The use of PR and PR-like reactions (together referred to herein as "PR-type reactions") may be desirable to cure siloxanes in coatings, adhesives, elastomers, and foaming applications. However, these reactions are notoriously rapid. Thus, PR-type reaction systems are typically two-part systems in which the catalyst is kept away from the Si-H and / or Si-OH / Si-OR until a reaction is desired. It is desirable that the PR-type reaction components can be stored together in a one-part system in such a way that they provide storage stability for storage, but have a way to trigger the PR-type reaction when it is desired to cure the system. There are systems in which the Lewis acid catalyst is complexed with an ultraviolet (UV) photosensitive blocker that prevents the PR type reaction from becoming possible until irradiated with UV light. However, such systems must be stored in the dark for storage stability and must be exposed to UV light to initiate curing. The release of the Lewis acid upon exposure to UV light tends to be slow, resulting in a reaction that is slowly initiated upon exposure to UV light. The application of a UV-blocked Lewis acid requires a thin film to trigger so that the UV light can effectively penetrate into the composition and achieve high surface area exposure. Thus, UV blocking of the Lewis acid has disadvantages when a composition is desired that does not need to remain blocked from UV light exposure before initiating the Lewis acid catalyzed reaction, does not require rapid initiation of the reaction (rapid release of Lewis acid), and / or does not require the ability to rapidly trigger the reaction in the bulk composition.

[0007] The present invention is a result of the discovery that B-FLP can be used in one-component PR type reaction systems as a latent thermally triggered Lewis acid catalyst. That is, B-FLP, which contains a Lewis acid PR type reaction catalyst, can be combined with a silyl hydride and a silanol and / or a silyl ether to form a one-component reaction system that is storage stable at 23° C., but reacts rapidly when heated to release the Lewis acid from the B-FLP. When heated, the B-FLP dissociates and liberates the Lewis acid catalyst, allowing the catalyst to initiate the PR reaction. Desirably, the compositions of the present invention using B-FLP can be exposed to UV light without triggering the reaction by unblocking the Lewis acid.

[0008] B-FLP has been found to be a particularly efficient triggering agent because it is resistant to remixing once decomposed. This means that once the Lewis acid is liberated, it continues to catalyze the reaction without being inhibited by the reformation of B-FLP. This is an advantage over Lewis acids inhibited by direct complexation with a Lewis base, because the Lewis base can remain in solution and recombine with the free Lewis acid, neutralizing the Lewis acid and inhibiting its ability to catalyze the reaction. B-FLP requires the reformation of a bridge complex between the Lewis acid and the base, and this reformation is much less likely to occur randomly. This is especially true for escape-prone bridge molecules, such as those that are gaseous and either fall out of the reaction system once B-FLP is decomposed, or react with another molecule in the system and become unavailable. As a result, the use of B-FLP offers unprecedented control over irreversibly triggering the reaction without the formation of impeding catalyst inhibitors, since once heated sufficiently to dissociate B-FLP, the acid catalyst is expected to be essentially irreversibly released to catalyze a rapid PR-type reaction.

[0009] In a first aspect, the invention is a composition comprising a mixture of a silyl hydride, a silanol and / or a silyl ether, and a bridging frustrated Lewis pair.

[0010] In a second aspect, the invention is a chemical reaction process comprising the steps of: (a) providing a composition of the first aspect; and (b) heating the composition to a temperature sufficient to dissociate a Lewis acid from a bridged frustrated Lewis pair.

[0011] The present invention is useful for preparing coatings, adhesives, elastomers and foams. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Test methods refer to the most recent test method as of the priority date of this document unless a date is given with the test method number. Reference to a test method includes both a reference to the testing society and the test method number. The following test method abbreviations and identifiers apply herein: ASTM refers to ASTM International, EN refers to European Norm, DIN refers to Deutsches Institut fuer Normung, and ISO refers to the International Organization for Standardization.

[0013] Products identified by trade names refer to compositions available under those trade names from suppliers as of the priority date of this application.

[0014] "Plurality" means two or more. "And / or" means "and, or alternatively." All ranges are inclusive of endpoints unless otherwise indicated. Products identified by trade names refer to compositions available from suppliers under those trade names as of the priority date of this document, unless otherwise indicated herein.

[0015] The compositions of the present invention comprise a mixture of silanols and / or silyl ethers, silyl hydrides, and bridging frustrated Lewis pairs, and are useful as thermally triggered reactive mixtures that are storage stable at 23° C.

[0016] A "silanol" is a molecule that contains a silicon-hydroxyl ("Si-OH") bond and can contain multiple Si-OH bonds.

[0017] A "silyl ether" is a molecule that contains a silicon-oxygen-carbon ("Si-O-C") bond, and can contain multiple Si-O-C bonds.

[0018] A "silyl hydride" is a molecule that contains a silicon-hydrogen (Si-H) bond and can contain multiple Si-H bonds.

[0019] A "frustrated Lewis pair," or "FLP," is a system of Lewis acids and Lewis bases in which the Lewis acid and Lewis base are unable to complex and completely neutralize ("block") each other due to steric congestion. FLPs are known in the art and have been characterized in papers such as JACS 2015, 137, 10018-10032 and papers identified therein. Desirably, an FLP is a system of Lewis acids and Lewis bases in which the congestion makes the complex and neutralization impossible at 20 degrees Celsius (°C). Although FLPs are known in the art, whether any Lewis pair is an FLP can be determined by mixing equimolar amounts of the Lewis acid and Lewis base at 20°C in a solvent that dissolves both. A Lewis acid and Lewis base can be considered an FLP if more than 10 mole percent of the Lewis acid and Lewis base remain dissociated. The extent of dissociation is determined by any reasonable means, such as nuclear magnetic resonance spectroscopy or, preferably, ion chromatography using a conductivity or photometric detector.

[0020] Upon heating of the compositions of the present invention, B-FLP releases a Lewis acid that catalyzes the reaction of silanols and / or silyl ethers with silyl hydrides. Heating the composition to a temperature of 80° C. or more, 90° C. or more, 100° C. or more, 110° C. or more, 120° C. or more, 130° C. or more, 140° C. or more, 150° C. or more, 160° C. or more, 170° C. or more, 180° C. or more, 190° C. or more, 200° C. or more, 210° C. or more, while generally not exceeding 300° C., not exceeding 250° C., not exceeding 240° C., not exceeding 230° C., not exceeding 220° C., not exceeding 210° C., not exceeding 200° C., not exceeding 175° C., not exceeding 150° C., not exceeding 140° C., not exceeding 130° C., not exceeding 120° C., not exceeding 110° C., or even not exceeding 100° C., causes the components in the composition to react and cure in 10 minutes or less, preferably not exceeding 5 minutes, even more preferably not exceeding 1 minute, and even more preferably not exceeding 30 seconds.

[0021] The reaction of a silyl ether with a silyl hydride can be generally represented by the following reaction: Si-H+Si-OR+Lewis acid →Si-O-Si+RH+Lewis acid where R is an alkyl, substituted alkyl, aryl, or substituted aryl, provided that it has a carbon bonded to the oxygen shown. An "alkyl" is a hydrocarbon group derived from an alkane by removing a hydrogen atom. A "substituted alkyl" is an alkyl having at least one carbon or hydrogen replaced with an atom or chemical moiety other than carbon and hydrogen. An "aryl" is a group derived from an aromatic hydrocarbon by removing a hydrogen atom. A "substituted aryl" is an aryl having at least one carbon or hydrogen replaced with an atom or chemical moiety other than carbon and hydrogen.

[0022] The reaction of a silanol with a silyl hydride can be generally represented by the following reaction: Si-H + Si-OHi + Lewis acid → Si-O-Si + H2 + Lewis acid

[0023] The compositions of the present invention are storage stable. By "storage stable" is meant that the composition does not form a gel at 23° C. for 5 hours or less, preferably 10 hours or less, more preferably 15 hours or less, and even more preferably 24 hours or less.

[0024] Silanol / Silyl Ether The present invention may include silanols without any silyl ethers, silyl ethers without any silanols, or both silanols and silyl ethers. When the composition includes both silanols and silyl ethers, the silanols may be different molecules from the silyl ethers, or the silanols and silyl ethers may be the same molecule having both Si-OH and Si-OC bonds.

[0025] The silanols and silyl ethers for use in the present invention may be linear, branched, or a combination of linear and branched molecules. A branched molecule contains three or four "branches" emanating from a single "branch" or "backbone" atom. A "branch" contains two atoms bonded together. Thus, a branched molecule contains one atom (the "backbone" atom) bonded to three or four atoms (the first branch atom), each of which has an additional atom (the second branch atom) bonded to it. The branches can extend any number of atoms beyond two. Preferably, the branches in the branched molecule contain 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, or even 10 or more atoms. At the same time, while there is technically no upper limit to the length of the branches in the branch atoms, branched silanols and silyl ethers for use in the present invention can typically have up to 10,000 atoms, preferably up to 5,000, up to 1,000, up to 500 atoms, and can have up to 100, up to 50, up to 30, up to 20, and even up to 10 atoms in each branch.

[0026] The silanol of the present invention has a Si-OH bond. The silanol can have one or more Si-OH bonds. Any type of silanol is expected to be suitable. The silanol can be a hydroxylated silane or a hydroxylated siloxane. The silanol can be a siloxane with a degree of polymerization (DP) of 10 or more, preferably 20 or more, more preferably 30 or more, 40 or more, 50 or more, 75 or more, 100 or more, 250 or more, 500 or more, 1000 or more, 2,000 or more, 4,000 or more, 6,000 or more, and 8,000 or more, while typically 10,00 or less, preferably 8,000 or less, 6,000 or less, 4,000 or less, 2,000 or less, 1,000 or less, 800 or less, 600 or less, 400 or less, 200 or less, or even 100 or less. DP corresponds to the number of siloxy (Si-O-containing) groups present in a molecule and is determined by silicon-29 nuclear magnetic resonance ( 29 It can be determined by Si NMR spectroscopy.

[0027] The silyl ether of the present invention may have one or more Si-O-C bonds. In general, any silyl ether is expected to be suitable. Typically, the silyl ether has a degree of polymerization (DP) of 10 or more, preferably 20 or more, more preferably 30 or more, and may be 40 or more, 50 or more, 75 or more, 100 or more, 250 or more, 500 or more, 1000 or more, 2,000 or more, 4,000 or more, 6,000 or more, and 8,000 or more, while typically 10,00 or less, preferably 8,000 or less, 6,000 or less, 4,000 or less, 2,000 or less, 1,000 or less, 800 or less, 600 or less, 400 or less, 200 or less, or even 100 or less. DP corresponds to the number of siloxy (Si-O-containing) groups present in the molecule, as measured by silicon-29 nuclear magnetic resonance (NMR) ( 29 It can be determined by Si NMR spectroscopy.

[0028] The silanols and / or silyl ethers of the present invention may be polymeric. Desirably, the silanols and / or silyl ethers are polysiloxane molecules having one or more Si-OH and / or Si-OC bonds. The polysiloxanes may be linear and may have a structure such that M(≡SiO 1 / 2 ) type and D(=SiO 2 / 2 ) type units. Alternatively, the polysiloxane may be branched and contain only T(-SiO 3 / 2 ) and / or Q(SiO 4 / 2 ) type units. Typically, M, D, T, and Q units have a methyl group bonded to a silicon atom that does not have an oxygen bonded to it, providing a valence of four for each silicon, with each oxygen bonded to the silicon of another unit. By referring to these as M, D, T, and Q "type" units, it is meant that a group such as one selected from the group consisting of hydrogen, alkyl, substituted alkyl, aryl, and substituted aryl groups can be bonded to the silicon atom in place of one or more methyls.

[0029] Examples of suitable silanols include those available from Dow Chemical Company as XIAMETER™ PMX-0156 silanol fluid, XIAMETER™ PMX-0930 silanol fluid, and DOWSIL™ DS polymer, DOWSIL™ RSN-217 Flake resin, DOWSIL™ RSN-233 Flake resin, and those available from Gelest as α,ω-hydroxyl terminated poly(dimethylsiloxane), DMS-S12 (550 g / mol, 16-32 cSt), DMS-S14 (1270 g / mol, 35-45 cSt), and DMS-S31 (21,600 g / mol, 1000 cSt). XIAMETER is a trademark of Dow Corning Corporation. DOWSIL is a trademark of The Dow Chemical Company.

[0030] Examples of suitable silyl ethers include those listed in The Dow Chemical These include those commercially available from Company under the trade names XIAMETER™ OFS-6070 silane, XIAMETER™ OFS-6011 silane, XIAMETER™ OFS-6020 silane, XIAMETER™ OFS-6030 silane, DOWSIL™ Z-6062 silane, DOWSIL™ Z-6300 silane, DOWSIL™ Z-6341 silane, XIAMETER™ OFS-6040 silane, DOWSIL™ Z-6023 silane, DOWSIL™ Z-6015 silane, XIAMETER™ OFS-6920 silane, XIAMETER™ OFS-6690 silane, and XIAMETER™ OFS-6076 silane, DOWSIL™ 3074 intermediate, and DOWSIL™ 3037 intermediate. XIAMETER is a trademark of Dow Corning Corporation. DOWSIL is a trademark of The Dow Chemical Company.

[0031] Typically, the total concentration of silanols and silyl ethers in the composition is 70 weight percent (wt%) or more, 75 wt% or more, 80 wt% or more, 85 wt% or more, or even 90 wt% or more, while typically is 90 wt% or less, 85 wt% or less, 80 wt% or less, or even 75 wt% or less, based on the total weight of silyl hydrides, silanols, silyl ethers, and B-FLP in the composition.

[0032] Silyl hydride Silyl hydrides contain one, preferably two or more Si-H bonds. The Si-H bonds are typically part of polysilanes (molecules containing multiple Si-H bonds) or polysiloxanes. Silyl hydrides containing multiple Si-H bonds are desirable as crosslinkers in the compositions of the present invention because they can react with multiple silanol and / or silyl ether groups.

[0033] The silyl hydride may be the same as the silanol and / or silyl ether, or may be a different molecule. That is, when the composition includes a silanol, the silanol may also contain a Si-H bond and function as both the silanol and silyl hydride components of the composition. Similarly, when the composition includes a silyl ether, the silyl ether may also contain a Si-H bond and function as both the silyl ether and silyl hydride components of the composition. Alternatively, the silyl hydride component may be a different molecule from the silanol and / or silyl ether also present in the composition. The silanol and / or silyl ether may not include a Si-H bond.

[0034] The silyl hydrides of the present invention may be polymeric. The silyl hydrides may be linear, branched, or contain a combination of linear and branched silyl hydrides. The silyl hydrides may be polysilanes, polysiloxanes, or combinations of polysilanes and polysiloxanes.

[0035] Desirably, the silyl hydride is a polysiloxane molecule having one Si-H bond or two or more Si-H bonds. The polysiloxane may be linear and contain only M and D type units. Alternatively, the polysiloxane may be branched and contain T and / or Q type units.

[0036] Examples of suitable silyl hydrides include pentamethyldisiloxane, bis(trimethylsiloxy)methyl-silane, tetramethyldisiloxane, tetramethylcyclotetrasiloxane, and hydride-terminated poly(dimethylsiloxanes), such as those available from Gelest under the trade names DMS-H03, DMS-H25, DMS-H31, and DMS-H41, and α,ω-hydride-terminated polyphenylmethylsiloxane (340 g / mol, 2-5 cSt: from GelestP under the name PMS-HO3).

[0037] The concentration of silyl hydride is typically sufficient to provide a molar ratio of Si-H groups to combined silanol and silyl ether groups that is typically 0.2 or more, 0.5 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1.0 or more, 1.2 or more, 1.4 or more, 1.6 or more, 1.8 or more, 2.0 or more, 2.2 or more, or even 2.5 or more, while typically being 5.0 or less, 4.5 or less, 4.0 or less, 3.5 or less, 3.0 or less, 2.8 or less, 2.5 or less, 2.3 or less, 2.0 or less, 1.8 or less, 1.6 or less, 1.4 or less, 1.2 or less, or even 1.0 or less.

[0038] Either the silanol / silyl ether or the silyl hydride (or both) can function as a crosslinker in the reaction. A crosslinker has at least two reactive groups per molecule and reacts with two different molecules through these reactive groups to crosslink them together. Increasing the length of the linear chain between the reactive groups in the crosslinker tends to increase the flexibility of the resulting crosslinked product. In contrast, shortening the length of the linear chain between the reactive groups in the crosslinker tends to reduce the flexibility of the resulting crosslinked product. In general, to obtain a more flexible crosslinked product, a linear crosslinker is desired, and the length between the reactive sites is selected to obtain the desired flexibility. To obtain a less flexible crosslinked product, a shorter linear crosslinker or even a branched crosslinker is desired to reduce the flexibility between the crosslinked molecules.

[0039] Typically, the concentration of the silyl hydride in the composition is 5% by weight or more, 10% by weight or more, 15% by weight or more, 20% by weight or more, or even 25% by weight or more, while typically 30% by weight or less, 25% by weight or less, 20% by weight or less, 15% by weight or less, or even 5% by weight or less, based on the total weight of the silyl hydride, silanol, silyl ether, and B-FLP in the composition.

[0040] Bridged frustrated Lewis pair A bridged frustrated Lewis pair ("B-FLP") is a complex that includes an FLP, where the Lewis acid and Lewis base of the FLP are both bound to a bridge molecule to form a neutralized complex with the bridge molecule that is between the Lewis acid and the Lewis base (i.e., "bridged"). The bridge molecule can be cleaved, such as in the case of H2, such that one portion of the bridge molecule blocks the Lewis acid and another portion of the bridge molecule blocks the Lewis base. Alternatively, and preferably, the bridge molecule remains intact, and the B-FLP becomes a stable complex (at least at 23°C) with the bridge molecule simultaneously bound to the Lewis acid and Lewis base of the FLP.

[0041] The Lewis acid is selected from the group consisting of aluminum alkyls, aluminum aryls, arylboranes including triarylboranes (including substituted aryl and triarylboranes such as fluorinated arylboranes including tris(pentafluorophenyl)borane), boron halides, aluminum halides, gallium alkyls, gallium aryls, gallium halides, silylium cations, and phosphonium cations. Examples of suitable aluminum alkyls include trimethylaluminum and triethylaluminum. Examples of suitable aluminum aryls include triphenylaluminum and tris-pentafluorophenylaluminum. Examples of triarylboranes include the following formula: [ka] where R is independently selected at each occurrence from H, F, Cl, and CF3. Examples of suitable boron halides include (CH3CH2)2BCl and boron trifluoride. Examples of suitable aluminum halides include aluminum trichloride. Examples of suitable gallium alkyls include trimethylgallium. Examples of suitable gallium aryls include triphenylgallium. Examples of suitable gallium halides include trichlorogallium. Examples of suitable silylium cations include (CH3CH2)3Si + X -and Ph3Si + X - Examples of suitable phosphonium cations include FP(C6F5)3 + X - Examples include:

[0042] Lewis bases are the following bases: PR3, P(NR2)3, NR3, N(SiR3) x R 3-x , RC(NR)N, P(NR)R3, guanidine (C(=NR)(NR2)2), amidine (RC(=NR)NR2), phosphazene, and [ka] where R is independently selected at each occurrence from the group consisting of hydrogen, alkyl, substituted alkyl, aryl, and substituted aryl. Examples of suitable Lewis bases for structure PR3 include tri(t-butyl)phosphine, tri(cyclohexyl)phosphine, PhP(tBu), (cyclohexyl)P(tBu), nBuP(tBu), Me(tBu), tBuP(i-Pr), P(CH 11 )3, P(iBu)3, and P(n-Bu)3. Examples of suitable Lewis bases of the structure RC(NR)N include 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo4.4.0dec-5-ene, and 2,3,4,6,7,8,9,10-octahydropyrimidol[1,2-a]azepine (DBU). Examples of suitable guanidines include guanidine, biguanidine, and 1,1-dimethylguanidine. Examples of suitable amidines include diethylamide and diisopropylamide. Examples of suitable phosphazenes include tert-butylimino-tri(pyrrolidino)phosphorene, tert-octylimino-tris(dimethylamino)phosphorene, and 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine. Examples of suitable Lewis bases of the following structure are: [ka] Examples include 1,3-dimesityl-imidazol-4,5-dihydro-2-ylidene, 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, and 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene.

[0043] A crosslinking molecule within the broadest scope of the present invention includes any molecule that simultaneously binds and blocks the Lewis acid and Lewis base of the FLP to form a B-FLP. The interaction of the crosslinking molecule with the Lewis acid and Lewis base is such that the Lewis acid and Lewis base are blocked by the crosslinking molecule (or a portion thereof) at 23°C, but at least the Lewis acid is desirably unblocked at a temperature of 120°C or higher, preferably 110°C or higher, more preferably 100°C or higher, even more preferably 90°C or higher, 80°C or higher, or even 70°C or higher, while at the same time being desirably 300°C or lower, 240°C or lower, 220°C or lower, 200°C or lower, 180°C or lower, 160°C or lower, 150°C or lower, 125°C or lower, or even 100°C or lower. Unblocking the Lewis acid of the B-FLP can be evidenced by a composition of the present invention containing a B-FLP that cures in less than one-tenth of the time required to gel at 23°C.

[0044] Examples of suitable cross-linking molecules include carbon dioxide, hydrogen molecules (H2), nitriles, alkenes, alkynes, ketones, esters, and aldehydes. Desirably, the cross-linking molecules contain 10 or less, preferably 9 or less, carbon atoms, and may contain 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, 2 or less, and even 1 or less or 0 carbon atoms, while the cross-linking molecules may contain 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, and even 6 or more carbon atoms. As mentioned earlier in this specification, in B-FLP, some cross-linking molecules can be cleaved, with a portion of the cross-linking molecules blocking the Lewis acid and the Lewis base, and a portion of the cross-linking molecules blocking the Lewis base. It is preferred that the cross-linking molecules remain uncleaved while cross-linking the Lewis acid and the Lewis base of the FLP. In that respect, the cross-linking molecules are preferably not H2. More preferably, the cross-linking molecules do not include any molecules that cleave while cross-linking the Lewis acid and the Lewis base of the FLP.

[0045] B-FLP is desirably "stable" in the compositions of the present invention, meaning that it does not dissociate and release a Lewis acid at temperatures below 23° C. B-FLP can be stable at temperatures below 30° C., below 50° C., below 70° C., and even below 80° C. At the same time, B-FLP dissociates at temperatures above 120° C., preferably above 110° C., more preferably above 110° C., above 100° C., above 90° C., and even above 80° C. B-FLP can be stable at temperatures below ... 1 H and 31 P, 11 B and / or 27 Dissociation of B-FLP can be determined by examining for evidence of free Lewis acid by ion exchange (I) or by the addition of 1,2-dichlorophenyl ether (I) or ...

[0046] One method for preparing B-FLP is by mixing the Lewis acid and Lewis base of the FLP together with the crosslinking molecule in a solvent at 23° C. The mixing promotes the formation of the B-FLP. The B-FLP can be isolated from the solvent, typically by evaporating the solvent or by filtering if the B-FLP precipitates from the solvent. The B-FLP can be stored for long periods at or below 23° C. The B-FLP can be mixed with a silyl hydride and a silanol and / or a silyl ether to form the composition of the present invention.

[0047] In contrast to typical blocked Lewis acid systems, the Lewis acid of the B-FLP of the present invention is complexed with a Lewis base via a bridging molecule, thus resulting in bimolecular complexation. Prior art suggests directly complexing the Lewis acid with a blocking agent that is sensitive to ultraviolet (UV) light, so that upon irradiation with UV light, the blocking agent dissociates from the Lewis acid. The B-FLP of the present invention does not require a UV-sensitive blocking agent and may not include any component that liberates the Lewis acid from the B-FLP upon irradiation with UV light. The B-FLP and compositions of the present invention may not include a photoacid generator or any other component that generates a Lewis acid upon exposure to UV radiation.

[0048] The compositions of the present invention typically contain sufficient B-FLP to provide a Lewis acid concentration of 0.1 parts per million (ppm) or more, 1 ppm or more, 10 ppm or more, 50 ppm or more, 100 ppm or more, 200 ppm or more, 300 ppm or more, 400 ppm or more, 500 ppm or more, 600 ppm or more, 700 ppm or more, 800 ppm or more, 900 ppm or more, 1000 ppm or more, while typically 10,000 ppm or less, 5,000 ppm or less, 1,000 ppm or less, based on the combined weight of silyl hydride, silanol, and silyl ether in the composition.

[0049] The composition of the present invention offers the advantage of a one-component reactive system that is storage stable even when exposed to UV light.Unlike the prior art, the composition does not require UV light for reaction, and does not require the composition to be shielded from exposure to UV light to maintain storage stability.Desirably, the stability of the B-FLP of the present invention is not dependent on (i.e., independent of) exposure to UV light.

[0050] The compositions of the present invention may be free of water, or may contain water, preferably at a concentration of 1 weight percent (wt%) or less, 0.75 wt% or less, 0.5 wt% or less, 0.25 wt% or less, 0.1 wt% or less, 0.05 wt% or less, or even 0.01 wt% or less, based on the weight of the composition.

[0051] Optional Ingredients The composition of the present invention may consist of a silyl hydride, a silyl ether and / or a silanol, and a B-FLP. Alternatively, the composition of the present invention may further comprise one optional ingredient or a combination of two or more optional ingredients. The optional ingredients are desirably present in a concentration of 50% by weight or less, 40% by weight or less, 30% by weight or less, 20% by weight or less, 10% by weight or less, 5% by weight or less, or even 1% by weight or less based on the weight of the composition.

[0052] Examples of possible optional components include one or a combination of two or more components selected from the group consisting of hydrocarbyl solvents (typically at a concentration of 10% by weight or less, 5% by weight or less, or even 1% by weight or less based on the weight of the composition), pigments such as carbon black or titanium dioxide, fillers such as metal oxides including SiO2 (typically at a concentration of 50% by weight or less based on the weight of the composition), moisture scavengers, optical brighteners, stabilizers (such as antioxidants and UV stabilizers), and corrosion inhibitors. The composition of the present invention may also be free of any one of such additional components or any combination of two or more of such additional components.

[0053] In particular, the composition of the invention may contain up to 1% by weight of water, up to 0.5% by weight of water relative to the weight of the composition. Desirably, the composition is free of water.

[0054] Chemical Reaction Process The present invention includes a chemical reaction process comprising the steps of (a) providing a composition of the present invention, and (b) heating the composition to a temperature sufficient to dissociate a Lewis acid from B-FLP. Upon heating the composition of the present invention, the Lewis acid is released from B-FLP and catalyzes the reaction of the silyl hydride with the silanols and / or silyl ethers, as described above. The composition of the present invention may be provided in step (a) by mixing together B-FLP, the silyl hydride, and the silanols and / or silyl ethers.

[0055] The chemical reaction process can be carried out in the absence of water or with a concentration of water that is 1 weight percent (wt%) or less, 0.75 wt% or less, 0.5 wt% or less, 0.25 wt% or less, 0.1 wt% or less, 0.05 wt% or less, or even 0.01 wt% or less, based on the weight of the composition provided in step (a).

[0056] The composition has use, for example, as a coating that undergoes a thermally triggered curing reaction, or as a reactive composition for molding applications where the fluid is placed in a mold and heated to trigger curing to form a molded article. In such applications, the process of the present invention further comprises the step after step (a) and before step (b) where the composition is applied to a substrate or placed in a mold. EXAMPLES

[0057] Preparation of B-FLP B-FLP (1). In a glovebox, a Schlenk flask equipped with a magnetic stir bar is charged with tri(t-butyl)phosphine (200 milligrams (mg), 1.0 millimole (mmol), 1 equivalent (equiv)) and tris-pentafluorophenylborane (500 mg, 1 mmol, 1 equiv) and the components are dissolved in 10 milliliters (mL) of toluene. The Schlenk flask is sealed and removed from the glovebox. The Schlenk flask is connected to a Schlenk line. The contents of the Schlenk flask are stirred throughout the next step. The Schlenk line is purged with nitrogen and then carbon dioxide is bubbled through the line for 2 minutes. The Schlenk flask is exposed to a carbon dioxide atmosphere and then the flask cap is replaced with a septum. A needle is inserted through the septum to create an outlet for carbon dioxide gas and improve carbon dioxide circulation. After 5 minutes, a white solid precipitates from the reaction mixture. The flask is sealed and stirred at room temperature for an additional hour. Move the flask to a glove box. Add 20 mL of hexane and isolate the white solid by filtration through a glass frit. Wash the white solid with hexane three times (10 mL each time). The white solid is B-FLP(1) (540 mg, 71% yield). B-FLP(1) can be stored without decomposition even when exposed to UV light. 1 H, 31 P, and 11 The solid is characterized by B nuclear magnetic resonance spectroscopy (NMR) to confirm the absence of impurities and starting materials. The predicted reaction and structure of B-FLP (1) is as follows: [ka]

[0058] Example 1. Silyl ether reaction A composition is prepared in a glove box by mixing B-FLP (1) (2.3 mg, 0.08 wt%), hydrosilane 1 (2 g, 74 wt%), and methyltrimethoxysilane (0.7 g, 26 wt%) in a scintillation vial equipped with a polytetrafluoroethylene (PTFE) coated magnetic stir bar. Hydrosilane I has the following formula: MD 3.3 D H 5.3 M and is commercially available from The Dow Chemical Company as DOWSIL™ 6-3570 polymer (DOWSIL is a trademark of The Dow Chemical Company).

[0059] A vent needle is inserted through the septum of the vial. The composition is stirred for 48 hours at 23° C. No reaction is evident. 1 H and 31 P NMR shows no significant decomposition of B-FLP(1).

[0060] Remove the composition from the glove box and expose it to air for 30 minutes. No reaction is evident. Again, 1 H and 31 P NMR shows no significant decomposition of B-FLP(1).

[0061] The composition was heated to 90° C., gas evolution occurred in about 60 seconds, and the composition rapidly solidified into a foam that was insoluble in organic solvents and exhibited a cross-linked structure.

[0062] Example 1 illustrates the stability of B-FLP(1) and the storage stability of the composition of Example 1, as well as the ability to thermally trigger the cure of silyl hydrides and silyl ethers with B-FLP at 90°C.

[0063] Example 2. Silyl ether reaction. B-FLP(1) is left in an atmosphere at 23° C. for 24 hours. 1 H and 31 P NMR shows no significant decomposition of B-FLP(1).

[0064] A composition is prepared by mixing B-FLP(1) (12.3 mg, 0.2 wt%), hydrosilane II (5 g, 93 wt%), and trimethoxysilane (0.37 g, 7 wt%) in a scintillation vial equipped with a PTFE-coated magnetic stir bar and stirring is initiated. Hydrosilane II has the following formula: M H D 15 M H and is commercially available from The Dow Chemical Company as DOWSIL™ Q2-5057S intermediate.

[0065] No reaction occurred over 48 hours at 23° C. Upon heating to 90° C., gas evolution was evident 5 minutes thereafter, and the composition rapidly solidified to a cured polysiloxane. The foam was insoluble in organic solvents, indicating a crosslinked polymer structure.

[0066] Example 2 demonstrates the stability of B-FLP(1) and the storage stability of the composition of Example 2, as well as the ability to thermally trigger the cure of silyl hydrides and silyl ethers with B-FLP at 90°C.

[0067] Example 3. Silanol reaction. Silyl Hydride MD H 65 M is prepared in the following manner: 40 grams of DI water, 10 grams of heptane, and 0.05 grams of tosylic acid were added to a three-neck flask equipped with a mechanical stirrer. A mixture of 200 grams of methyldichlorosilane and 10 grams of trimethylchlorosilane was added dropwise to the reaction solution with stirring within 30 minutes. After stirring for 1 hour at 23°C, the reaction solution was washed three times with 50 mL of DI water each time, dried over anhydrous sodium sulfate, and filtered through a layer of activated carbon. The volatiles were removed by Rotovap to give the silyl hydride MD. H 65 I got M.

[0068] 9 grams of Silylhydride MD H 65 M and 1 gram of silanol (M OH D5MOH A composition is prepared by mixing B-FLP(1) and B-FLP(2) (available commercially as DMS-S12 from Gelest) together in a speed mixer. 0.148 grams of a 5 weight percent solution of B-FLP(1) in tetrahydrofuran is added to obtain a mixture containing 500 parts by weight of B-FLP(1) per million parts by weight of the mixture. The mixture is mixed in a speed mixer. In particular, the composition of silyl hydrides and silanols is represented by the formula: "M" corresponds to -SiO(CH3)3, "M OH " corresponds to -SiO(OH)(CH3)2, and D H is standard notation where —SiO(H)(CH)— corresponds to —SiO(H)(CH)—, the subscripts are the relative number of units per molecule, and the absence of a subscript means that the subscript is 1.

[0069] The composition has a shelf life at 23° C. of 16 hours as indicated by gel formation at 16 hours. A 125 micrometer film of the composition is stretched onto a glossy paper substrate and heated in an oven to 90° C. At 90° C. the film cures in 30 seconds to a solid film with no tacky surface.

[0070] Example 3 demonstrates the stability of B-FLP, the storage stability of compositions containing B-FLP, silyl hydrides and silanols, and the ability of B-FLP to trigger curing of the silyl hydrides and silanols upon heating to 90°C.

[0071] Comparative Example: Ex3 using BCF instead of AB-FLP(1) Ex3 is repeated, except that instead of 0.148 g of the 5 wt % solution of B-FLP(1), 500 parts by weight of tris(pentafluorophenyl)brane ("BCF") per million parts by weight of the mixture is added as the unblocked Lewis acid catalyst. The composition gels immediately (less than 1 minute) at 23° C. Comparative Example A shows that the Lewis acid in the B-FLP of Ex3 immediately triggers the reaction of the composition at 23° C. when unblocked, confirming the results from Example 3, where B-FLP stabilizes the BCF catalyst at 23° C. but releases it at 90° C., causing it to react rapidly.

Claims

1. 1. A composition comprising a mixture of silyl hydrides, silanols and / or silyl ethers, and bridging frustrated Lewis pairs, comprising: The bridged frustrated Lewis pair is (i) (a) a Lewis acid selected from the group consisting of aluminum alkyls, aluminum aryls, aryl boranes, fluorinated aryl boranes, boron halides, aluminum halides, gallium alkyls, gallium aryls, gallium halides, silylium cations, and phosphonium cations; (b) the following structures: PR 3 , P(NR 2 ) 3 , NR 3 , N(SiR 3 ) x R 3-x , RC(NR)N, P(NR)R 3 , guanidine, amidine, phosphazene, and 【Chemistry 1】 wherein R is independently at each occurrence selected from the group consisting of hydrogen, alkyl, substituted alkyl, aryl, and substituted aryl. and a Lewis base selected from the group consisting of molecules having the formula: (c) a bridging molecule that binds the Lewis acid and Lewis base, the bridging molecule being selected from the group consisting of carbon dioxide, a nitrile, an alkene, an alkyne, a ketone, an ester, and an aldehyde; or (ii) a blocked Lewis acid formed from the Lewis acid (a) and a portion produced by cleavage of hydrogen (H2), and a blocked Lewis base formed from the Lewis base (b) and another portion produced by cleavage of hydrogen (H2).

2. The composition of claim 1 , wherein the Lewis acid is a fluorinated aryl borane.

3. The Lewis base is ３ , N.R. ３ 3. The composition of claim 1 or 2, wherein the aryl group is selected from the group consisting of guanidines, amidines, and phosphazenes.

4. The composition of any one of claims 1 to 3, wherein the cross-linking molecule is selected from the group consisting of carbon dioxide, a nitrile, an alkyne, and an alkene.

5. The Lewis acid is a fluorinated arylborane and the Lewis base is PR ３ and N.R. ３ 2. The composition of claim 1, wherein R is independently selected at each occurrence from the group consisting of hydrogen, alkyl, substituted alkyl, aryl, and substituted aryl, and the bridging molecule is selected from the group consisting of carbon dioxide, alkynes, alkenes, and nitriles.

6. 6. The composition of claim 1, wherein the bridged frustrated Lewis pair does not include a photoacid generator or other component that generates a Lewis acid upon exposure to ultraviolet radiation.

7. (a) providing a composition according to any one of claims 1 to 6; (b) heating said composition to a temperature sufficient to dissociate said Lewis acid from said bridged frustrated Lewis pair.

8. 8. The process of claim 7, wherein step (a) comprises mixing together a bridged frustrated Lewis pair, a silyl hydride, and a silanol and / or a silyl ether.

9. 9. The process of claim 7 or 8, wherein after step (a) and before step (b), the composition is applied to a substrate or placed in a mold.

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