Cross-linked imperfect Lewis pairs as thermal triggers for Si-H and Si-O-Si reactions

Abstract

The composition contains a mixture of silyl hydride, siloxane, and bridged frustrated Lewis pairs, and can be cured by thermal induction.

Description

Technology Field

[0001] The present invention relates to the use of bridged frustrated Lewis pairs as thermal triggers for the chemical reaction between silyl hydrides and siloxanes. The bridged frustrated Lewis pairs dissociate upon heating to release Lewis acids. The Lewis acids act as catalysts for the chemical reaction between silyl hydrides and siloxanes. Background Technology

[0002] introduction

[0003] An incomplete Lewis pair ("FLP") is a term referring to a pair of Lewis acids and Lewis bases in which the Lewis acid and Lewis base are unable to complexe or neutralize each other due to steric congestion. When combined, the Lewis acid and Lewis base of the FLP remain independent of each other rather than being combined and neutralized. However, FLPs have been found to be indirectly bound to each other in the form of cross-linked incomplete Lewis pairs ("B-FLP"), where a cross-linking molecule binds to both the acid and base of the FLP to form a complex with the cross-linking molecule between the Lewis acid and the Lewis base. In some cases, the cross-linking molecule can be cleaved to produce a blocked Lewis acid and a blocked Lewis base, where a portion of the cross-linking molecule complexes with the Lewis acid and Lewis base, respectively, blocking further complexation or reaction of each. Hydrogen (H2) is an example of a cross-linking molecule that is cleaved in such a manner when forming B-FLP.

[0004] B-FLP has been used to activate crosslinking molecules for use in chemical reactions. For example, hydrogen (H2) has been used as a crosslinking 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 crosslinking molecule in B-FLP to activate carbon dioxide for deoxygenated hydrosilylation (see, e.g., [JACS 2010, 132, 10660-10661]). Other molecules used as crosslinking molecules in B-FLP to activate them for chemical reactions include nitrous oxide (N2O), sulfur dioxide (SO2), alkenes, and alkynes. For example, see [Angew. Chem. Int. Ed. 2009, 48, 6643-6646]; [Angew. Chem. See Int. Ed. 2015, 54, 6400-6441]; and literature [JACS 2015, 137, 10018-10032].

[0005] Discovering additional uses for B-FLP would be surprising and useful, especially if such uses enable control over chemical reactions other than those involving crosslinking molecules.

[0006] The present invention provides a surprising and unexpected use for B-FLP as a thermal trigger for the reaction of silyl hydride (Si-H) and siloxane linkage (Si-O-Si).

[0007] It has been found that Si-H and Si-O-Si undergo a rearrangement reaction in the presence of a strong Lewis acid, where silicon from the silyl hydride bonds to the oxygen of the siloxane linkage, while silicon from the siloxane linkage bonds to the hydrogen of the silyl hydride. Surprisingly, the silyl hydride and siloxane linkage participating in the rearrangement reaction may be on the same molecule or on different molecules. This rearrangement reaction tends to accelerate in the presence of a strong Lewis acid. Such a reaction can be useful for rapidly curing systems containing Si-H and siloxane linkages without requiring water or moisture. However, this requires a two-part system for storage in which the Lewis acid catalyst is kept separated from the combination of silyl hydride and siloxane linkages until time, such as curing, is required. It is desirable to provide a storage-stable one-part system utilizing a rearrangement reaction that can induce curing, while being storage-stable at 23°C.

[0008] The present invention is the result of the discovery that B-FLP can be used as a thermally induced potential Lewis acid catalyst in these rearrangement reaction systems. That is, B-FLP containing a Lewis acid PR reaction catalyst can be mixed with a silyl hydride and a siloxane linkage to form a reactive system that is storage-stable but can be induced to harden upon heating. Upon sufficient heating, the Lewis acid dissociates from B-FLP, and the Lewis acid acts as an acid catalyst to initiate the rearrangement reaction of the silyl hydride and the siloxane linkage.

[0009] B-FLP has been found to be a particularly efficient triggering agent because, once broken, it has no potential for recombination. This means that once the Lewis acid is released, it will continue to catalyze the reaction without inhibition by the reformation of B-FLP. This is advantageous compared to Lewis acids directly inhibited by Lewis bases, because the Lewis base remains in solution and can recombine with the liberated Lewis acid to neutralize it. B-FLP requires the reformation of the cross-linked complex between the Lewis acid and the Lewis base, which is much less likely to occur randomly. This is especially true for transient cross-linking molecules, such as those in the gaseous phase that exit the reaction system once B-FLP is broken. Consequently, the use of B-FLP provides unprecedented control, inducing the reaction irreversibly without interference from catalyst inhibitors, because the acid catalyst is irreversibly released when heated sufficiently to dissociate B-FLP, catalyzing a rapid rearrangement reaction.

[0010] In the first aspect, the present invention is a composition comprising a mixture of silyl hydride, siloxane, and cross-linked incomplete Lewis pairs.

[0011] In a second aspect, the present invention is a chemical reaction method 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 cross-linked incomplete Lewis pair.

[0012] The present invention is useful for manufacturing coatings, adhesives, and elastomers. Specific details for implementing the invention

[0013] Unless a date is indicated along with a test method number, the test method refers to the most recent test method as of the priority date of this document. References to a test method include both a reference to the testing association and the test method number. The following test method abbreviations and identifiers apply to this specification: ASTM refers to the International ASTM; EN refers to the European Norm; and DIN refers to the Deutsches Institut It refers to Normung; ISO refers to the International Organization for Standardization.

[0014] The product identified by the trademark refers to a composition available from a supplier under that trademark at the priority date of the present application.

[0015] "Multiple" means two or more. "And / or" means "and, or alternatively." All scopes include endpoints unless otherwise indicated. A product identified by a trademark refers to a composition available from a supplier under that trademark at the priority date of this application, unless otherwise stated in this specification.

[0016] The composition of the present invention comprises a mixture of siloxane, silyl hydride, and cross-linked incomplete Lewis pairs.

[0017] "Siloxane" refers to a molecule containing at least one siloxane (Si-O-Si) linkage. Preferably, the siloxane of the present invention is "polysiloxane," which refers to a molecule containing multiple Si-O-Si links. Polysiloxane typically comprises siloxane units referred to as M, D, T, or Q units. A standard M unit has the chemical formula (CH3)3SiO1 / 2. A standard D unit has the chemical formula (CH3)2SiO2 / 2. A standard T unit has the chemical formula (CH3)SiO3 / 2. A standard Q unit has the chemical formula SiO4 / 2. The M-type, D-type, and T-type units may have one or more methyl groups replaced by hydrogen or some other moiety.

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

[0019] "Alkyl" is a hydrocarbon radical derived by the removal of a hydrogen atom from an alkane. "Substituted alkyl" is an alkyl having an atom or chemical moiety other than carbon and hydrogen instead of at least one carbon or hydrogen.

[0020] "Aryl" is a radical derived by the removal of a hydrogen atom from an aromatic hydrocarbon. "Substituted aryl" is an aryl having an atom or chemical moiety other than carbon and hydrogen in place of at least one carbon or hydrogen.

[0021] An "incomplete Lewis pair" or "FLP" is a system of Lewis acids and Lewis bases in which, due to steric congestion, the Lewis acid and Lewis base are unable to complexe and completely neutralize ("block") each other. FLPs are known in the art and are characteristically defined in papers such as [JACS 2015, 137] and the papers identified therein. Preferably, an FLP is a system of Lewis acids and Lewis bases in which, due to congestion, their complexe and neutralization are not possible at 20°C. FLPs are known in the art, and it is possible to determine whether a Lewis pair is an FLP by combining equal molar amounts of Lewis acid and Lewis base at 20°C in a solvent that dissolves both the Lewis acid and the Lewis base. If more than 10 mol% of the Lewis acid and Lewis base remain dissociated, the Lewis acid and Lewis base may be considered an FLP. The degree of dissociation is determined by any suitable means, for example, nuclear magnetic resonance spectroscopy, or preferably by ion chromatography using a conductivity detector or a photometric detector.

[0022] When the composition of the present invention is heated, B-FLP releases a Lewis acid that catalyzes the reaction between a siloxane and a silyl hydride. The step of heating the composition to a temperature of 80°C or higher, 90°C or higher, 100°C or higher, 110°C or higher, 120°C or higher, 130°C or higher, 140°C or higher, 150°C or higher, 160°C or higher, 170°C or higher, 180°C or higher, 190°C or higher, 200°C or higher, 210°C or higher, and simultaneously generally to a temperature of 300°C or lower, 250°C or lower, 240°C or lower, 230°C or lower, 220°C or lower, 210°C or lower, 200°C or lower, 175°C or lower, 150°C or lower, 140°C or lower, 130°C or lower, 120°C or lower, 110°C or lower, or even 100°C or lower, reacts the components in the composition within less than half the time required for the composition to gel at 23°C, preferably less than 1 / 5 of that time, more preferably less than 1 / 10 of that time. and harden.

[0023] The Lewis acid-catalyzed reaction of siloxanes and silyl hydrides is generally a rearrangement reaction represented by the following reaction:

[0024] Si'-H + Si-O-Si + Lewis acid → Si'-O-Si + Si-H + Lewis acid

[0025] This rearrangement reaction is useful for forming new siloxane bonds and creating cross-linked polysiloxane systems. A particularly desirable feature of this reaction compared to other Lewis acid-catalyzed reactions, such as the Piers-Rubinstein (PR) reaction, is that it typically produces very few volatile byproducts, unlike the PR reaction. Volatile byproducts can generate bubbles when curing siloxane polymers using this reaction, potentially resulting in cloudy siloxane polymers. Therefore, this reaction is ideal for producing transparent cured compositions and films.

[0026] The composition of the present invention is storage stability. "Storage stability" means that the composition does not form a gel for 5 hours or less, preferably 24 hours or less, more preferably 48 hours or less, and even more preferably 1 week or less at 23°C.

[0027] Silroksan

[0028] Preferably, the siloxane component is a polysiloxane containing a plurality of siloxane linkages. The polysiloxane contains a plurality of siloxy (SiO) groups. The siloxy-containing groups are typically denoted as M, D, T, or Q groups. The polysiloxane may be linear and may contain only M (≡SiO1 / 2) type and D (=SiO2 / 2) type units. Alternatively, the polysiloxane may be branched and may contain T (-SiO3 / 2) type and / or Q (SiO4 / 2) type units. Typically, the M, D, T, and Q units have methyl groups attached to silicon atoms, where oxygen is not attached to provide a valence of 4 to each silicon atom, and each oxygen is attached to silicon of another unit. Referring to these as M, D, T, and Q "type" units means that a group selected from the group consisting of hydrogen, alkyl, substituted alkyl, aryl, and substituted aryl groups can be bonded to a silicon atom instead of one or more methyl groups. For example, MH is an M-type unit in which one methyl group is replaced by a hydrogen.

[0029] The polysiloxane may have 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 even 8,000 or more, which is typically 1,000 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 groups present in the molecule and can be determined by silicon-29 nuclear magnetic resonance (29Si NMR) spectroscopy.

[0030] The siloxane component may contain Si-H bonds, which implies that it can also function as a silyl hydride component. In practice, the siloxane component and the silyl hydride component may be the same molecule in the present invention. Alternatively, the siloxane component and the silyl hydride component may be different molecules. In practice, the siloxane molecule may not have Si-H bonds and / or the silyl hydride component may not have Si-O-Si linkages.

[0031] Examples of suitable siloxanes without Si-H bonds include XIAMETER™ PMX-200 silicon fluid available from The Dow Chemical Company.

[0032] Examples of suitable siloxanes containing Si-H bonds include poly(methylhydrosiloxane) and trimethylsilyl-terminated poly(dimethylsiloxane-co-methylhydrosiloxane), both of which are available from Sigma-Aldrich. Additional examples of suitable siloxanes containing Si-H bonds include pentamethyldisiloxane, bis(trimethylsiloxy)methylsilane, tetramethyldisiloxane, tetramethylcyclotetrasiloxane, and hydride-terminated poly(dimethylsiloxane), which are available from Gelest, for example, under the trade names DMS-H03, DMS-H25, DMS-H31, and DMS-H41.

[0033] Typically, the concentration of siloxane in the composition is 70 wt% or more, 75 wt% or more, 80 wt% or more, 85 wt% or more, or even 90 wt% or more based on the total weight of the silyl hydride, siloxane, and B-FLP in the composition, and at the same time is typically 90 wt% or less, 85 wt% or less, 80 wt% or less, or even 75 wt% or less.

[0034] silyl hydride

[0035] The silyl hydride contains one, preferably more than one, Si-H bond. The Si-H bond is typically part of a polysilane (a molecule containing multiple Si-H bonds) or a polysiloxane. A silyl hydride containing multiple Si-H bonds may be preferred as a crosslinking agent in the composition of the present invention because it can react with multiple siloxane links.

[0036] The silyl hydride of the present invention may be polymeric. The silyl hydride may be linear or branched, or may contain a combination of linear and branched silyl hydrides. The silyl hydride may be a polysilane, a polysiloxane, or a combination of a polysilane and a polysiloxane.

[0037] Preferably, the silyl hydride is a polysiloxane molecule having one or more Si-H bonds. When the silyl hydride is a polysiloxane, the Si-H bonds are on silicon atoms of M-type or D-type siloxane units. The polysiloxane may be linear and may contain only M-type and D-type units. Alternatively, the polysiloxane may be branched and may contain T-type and / or Q-type units.

[0038] Examples of suitable silyl hydrides include pentamethyldisiloxane, bis(trimethylsiloxy)methylsilane, tetramethyldisiloxane, tetramethylcyclotetrasiloxane, and hydride-terminated poly(dimethylsiloxane), which are available from Gelest under the trade names DMS-H03, DMS-H25, DMS-H31, and DMS-H41.

[0039] The concentration of the silyl hydride 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, and even 2.5 or more, and at the same time is typically 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, and is sufficient to provide a molar ratio of Si-H groups to siloxane linkages.

[0040] Either siloxane or silyl hydride (or both) can serve as a crosslinking agent in the reaction. The crosslinking agent has at least two reactive groups per molecule and reacts with two different molecules through these reactive groups to crosslink them together. Increasing the linear length between reactive groups within the crosslinking agent tends to increase the flexibility of the resulting crosslinked product. Conversely, decreasing the linear length between reactive groups within the crosslinking agent tends to decrease the flexibility of the resulting crosslinked product. Generally, to achieve a more flexible crosslinked product, a linear crosslinking agent is required, and the length between the reactive sites is selected to achieve the desired flexibility. To achieve a less flexible crosslinked product, a shorter linear crosslinking agent or even a branched crosslinking agent is preferred to reduce the flexibility between the crosslinked molecules.

[0041] A silyl hydride can be the same molecule as a siloxane—that is, a single molecule containing both a siloxane linkage and a silyl hydride functional group can serve as both a silyl hydride and a siloxane. Alternatively, a silyl hydride can be a molecule different from a siloxane. A silyl hydride may not have a siloxane linkage. A siloxane may not have a silyl hydride group.

[0042] The composition (and reaction method) of the present invention may include more than one silyl hydride, more than one siloxane, and / or more than one component acting as both a silyl hydride and a siloxane.

[0043] Typically, the concentration of silyl hydride in the composition is 5 wt% or more, 10 wt% or more, 15 wt% or more, 20 wt% or more, and even 25 wt% or more based on the total weight of silyl hydride, siloxane and B-FLP in the composition, and at the same time is typically 30 wt% or less, 25 wt% or less, 20 wt% or less, 15 wt% or less, or even 5 wt% or less.

[0044] Cross-linked incomplete Lewis pairs

[0045] A cross-linked incomplete Lewis pair ("B-FLP") is a complex containing FLP, wherein both the Lewis acid and Lewis base of FLP are bound to a cross-linking molecule to form a neutralized complex with the cross-linking molecule existing between the Lewis acid and the Lewis base (i.e., "cross-linking"). The cross-linking molecule can be cleaved, as in the case of H2, into a portion of the cross-linking molecule blocking the Lewis acid and another portion of the cross-linking molecule blocking the Lewis base. Alternatively, and preferably, the cross-linking molecule is kept intact, and B-FLP is a stable complex (at least at 23°C) with the cross-linking molecule simultaneously bound to the Lewis acid of FLP and the Lewis base of FLP.

[0046] Lewis acids are selected from the group consisting of aluminum alkyls, aluminum aryls, aryl boranes including triaryl boranes (including substituted aryl and triaryl boranes such as fluorinated aryl boranes including tris(pentafluorophenyl)boranes), boron halides, aluminum halides, gallium alkyls, gallium aryls, gallium halides, silyllium 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 triaryl boranes include those having the following chemical formulas:

[0047]

[0048] In the above formula, R is independently selected from H, F, Cl, and CF3 in each case. 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 silyllium cations include (CH3CH2)3Si+X- and Ph3Si+X-. Examples of suitable phosphonium cations include FP(C6F5)3+X-.

[0049] Lewis bases are selected from the group consisting of the following bases: PR3, P(NR2)3, NR3, N(SiR3)xR3-x, RC(NR)N, P(NR)R3, guanidine(C(=NR)(NR2)2)

[0050] , amidin (RC(=NR)NR2), phosphazene, and

[0051] ;

[0052] In the above formula, R is independently selected from the group consisting of hydrogen, alkyl, substituted alkyl, aryl, and substituted aryl in each case. Examples of suitable Lewis bases for structural formula PR3 include tri(t-butyl)phosphine, tri(cyclohexyl)phosphine, PhP(tBu)2; (cyclohexyl)P(tBu)2; nBuP(tBu)2; Me(tBu)2; tBuP(i-Pr)2; P(C6H11)3; P(iBu)3; and P(n-Bu)3. Examples of suitable Lewis bases for structural formula RC(NR)N include 1,5,7-triazabicyclo[4.4.0]des-5-ene; 7-methyl-1,5,7-triazabicyclo4.4.0des-5-ene; Includes 2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepine, (DBU). Examples of suitable guanidines include guanidine, biguanidine, and 1,1-dimethylguanidine. Examples of suitable amidines include diethylamide and di-isopropylamide. 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. Structural formula

[0053]

[0054] Examples of suitable Lewis bases include 1,3-dimethytyl-imidazole-4,5-dihydro-2-ylidene; 1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene; and 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazole-2-ylidene.

[0055] In the broadest scope of the present invention, the crosslinking molecule comprises any molecule that forms B-FLP by simultaneously binding and blocking the Lewis acid and Lewis base of FLP. The interaction between the crosslinking molecule and the Lewis acid and Lewis base is such that the Lewis acid and Lewis base are blocked by the crosslinking molecule (or part thereof) at 23°C, but the Lewis acid is not blocked at temperatures 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, and simultaneously preferably 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. The non-blocking of the Lewis acid of B-FLP can be demonstrated by the fact that the composition of the present invention containing B-FLP cures within less than half the time required for gelation at 23°C.

[0056] Examples of suitable crosslinking molecules include carbon dioxide, hydrogen molecules (H2), nitriles, alkenes, alkynes, ketones, esters, and aldehydes. Preferably, the crosslinking molecule contains 10 or fewer, preferably 9 or fewer carbon atoms, and may contain 8 or fewer, 7 or fewer, 6 or fewer, 5 or fewer, 4 or fewer, 3 or fewer, 2 or fewer, and even 1 or fewer or 0 carbon atoms; at the same time, the crosslinking molecule may contain one or more, 2 or more, 3 or more, 4 or more, 5 or more, and even 6 or more carbon atoms. As previously mentioned in this specification, some crosslinking molecules may be cleaved into a portion of the crosslinking molecule that blocks Lewis acids in B-FLP and a portion of the crosslinking molecule that blocks Lewis bases. It is preferable that the crosslinking molecule remain uncleaved while crosslinking the Lewis acids and Lewis bases of the FLP. In this regard, the crosslinking molecule is preferably not H2. More preferably, the crosslinking molecule does not contain any molecule that is cleaved while crosslinking the Lewis acid and Lewis base of the FLP.

[0057] B-FLP is preferably "stable" in the composition of the present invention, meaning that it does not dissociate to release a Lewis acid at a temperature of 23°C or lower. B-FLP may be stable at temperatures of 30°C or lower, 50°C or lower, 70°C or lower, and even 80°C or lower. At the same time, B-FLP dissociates at temperatures of 120°C or higher, preferably 110°C or higher, more preferably 110°C or higher, 100°C or higher, 90°C or higher, and even 80°C or higher. Whether B-FLP dissociates is determined by finding evidence of a liberated Lewis acid by nuclear magnetic resonance spectroscopy (where appropriate, based on 1H and 31P, 11B and / or 27Al). Alternatively, dissociation of B-FLP can be detected by a composition that cures faster than the same composition without B-FLP at a given temperature.

[0058] One method for preparing B-FLP is to combine the Lewis acid and Lewis base of FLP with a crosslinking molecule in a solvent at 23°C. The mixing promotes the formation of B-FLP. B-FLP can usually be isolated from the solvent by evaporating the solvent, or by filtration if B-FLP precipitates from the solvent. B-FLP can be stored for a long period at 23°C or below. B-FLP can be combined with silyl hydrides and siloxanes to form the composition of the present invention.

[0059] 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 through a crosslinking molecule and thus complexed with two molecules. The prior art proposed directly complexing the Lewis acid with a blocking agent sensitive to ultraviolet (UV) light, so that the blocking agent dissociates from the Lewis acid upon irradiation with UV light. The B-FLP of the present invention does not require a UV photosensitive blocking agent and may not contain such a component that causes the Lewis acid to be released from the B-FLP upon irradiation with UV light. The B-FLP and composition of the present invention may not contain a photogenerator and may not contain any other component that generates a Lewis acid upon exposure to UV radiation.

[0060] The composition of the present invention provides the advantage of a one-component reactive system, which is storage stability even when exposed to UV light. Unlike the prior art, the composition does not require UV light to react, nor does the composition need to be blocked from exposure to UV light to maintain storage stability. Preferably, the stability of the B-FLP of the present invention does not depend on exposure to UV light (i.e., is independent of such exposure).

[0061] The composition of the present invention typically contains B-FLP sufficient to provide a Lewis acid concentration of 0.1 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, or 1000 ppm or more, based on the total weight of the silyl hydride and siloxane in the composition, and at the same time typically 10,000 ppm or less, 5,000 ppm or less, or 1,000 ppm or less.

[0062] The composition of the present invention may not contain water. Alternatively, the composition of the present invention may contain water at a concentration of preferably 1 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.

[0063] Optional ingredients

[0064] The composition of the present invention may consist of a silyl hydride, a siloxane, and B-FLP. Alternatively, the composition of the present invention may further comprise one optional component or a combination of more than one of these components. The optional component is preferably present at a concentration of 50 wt% or less, 40 wt% or less, 30 wt% or less, 20 wt% or less, 10 wt% or less, 5 wt% or less, or even 1 wt% or less, based on the weight of the composition.

[0065] Examples of possible optional components include one component or a combination of more than one component 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 containing SiO2 (typically at a concentration of 50% by weight or less based on the weight of the composition), moisture removers, fluorescent whitening agents, stabilizers (e.g., antioxidants and UV stabilizers), and corrosion inhibitors. The composition of the present invention may also not contain any one of such additional components or any combination of more than one of the additional components.

[0066] In particular, the composition of the present invention may contain 1% by weight or less and 0.5% by weight or less of water based on the weight of the composition. Preferably, the composition does not contain water.

[0067] Chemical reaction method

[0068] The present invention comprises a chemical reaction method comprising: (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 of the composition of the present invention, a Lewis acid is released from B-FLP and catalyzes the reaction between the silyl hydride and the siloxane as previously described. The composition of the present invention may be provided in step (a) by mixing B-FLP, the silyl hydride, and the siloxane together. As mentioned above, the silyl hydride and the siloxane may be the same molecule.

[0069] The chemical reaction method can be carried out in the absence of water, or with a water concentration of 1 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).

[0070] The composition is applied, for example, as a coating undergoing a thermally induced curing reaction, or as a reactive composition for a molding application in which a fluid is placed in a mold and heated to induce curing to form a molded article. In such an application, the method of the present invention may further include the step of applying the composition to a substrate or placing it in a mold after step (a) and before step (b).

[0071] Examples

[0072] Manufacturing of B-FLP (1)

[0073] While working inside a glove box, tri(t-butyl)phosphine (200 mg, 1.0 mmol, 1 equivalent) and tris-pentafluorophenylborane (500 mg, 1 mmol, 1 equivalent) are placed in a Schlenk flask equipped with a magnetic stirring bar, and these components are dissolved in 10 mL of toluene. The Schlenk flask is sealed and removed from the glove box. The Schlenk flask is connected to the Schlenk line. The contents of the Schlenk flask are stirred throughout the entire following step. The Schlenk line is purged with nitrogen, and then carbon dioxide is bubbled through the line for 2 minutes. The Schlenk flask is opened to a carbon dioxide atmosphere, and then the cap on the flask is replaced with a diaphragm. A needle is inserted through the diaphragm to create an outlet for carbon dioxide gas, thereby improving the circulation of carbon dioxide. After 5 minutes, a white solid precipitates from the reaction mixture. Seal the flask and stir at room temperature for an additional 1 hour. Transfer 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 three times with hexane (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. Characterize the solid by 1H, 31P, and 11B nuclear magnetic resonance spectroscopy (NMR) to confirm the absence of impurities and starting materials. The expected reaction and structure of B-FLP(1) are as follows:

[0074]

[0075] Comparative Example (Comparative Example) A: No Lewis acid

[0076] 5.0 g of MHDH8D20MH (available from Gelest as HMS-271) is added to a dental cup with a maximum capacity of 10 g. The material is mixed in a FlackTek SpeedMixer at 3,500 revolutions per minute (3,500 rpm) for 1 minute. The resulting material is poured into an aluminum pan and heated to 100°C on a hot plate. After 2 minutes, no bubbles were clearly visible, indicating a lack of reaction. The material is allowed to be set at 23°C for 2 weeks, and curing is still not evident. Comparative Example A demonstrates the need for a curing catalyst to cure MHDH8D20MH at 23°C or 100°C.

[0077] Comparative Example B: Comparative Example A + BCF

[0078] Comparative Example A is repeated except that it contains 0.0253 g of tris(pentafluorophenyl)borane ("BCF") per million parts by weight of MHD376MH. Bubbles were clearly visible when the mixture was poured into an aluminum pan after rotation, even without heating to 100°C. The mixture was left at 23°C without heating, and it hardened into a hard material within 2 hours at 23°C. Comparative Example B shows that MHD376MH hardens rapidly in the presence of a Lewis acid catalyst even at 23°C.

[0079] Example (Ex) 1: Comparative Example A + B-FLP(1)

[0080] Comparative Example B is repeated except that 0.253 g of B-FLP (1) is used instead of 0.0253 g of BCF. After leaving the mixture at 23°C for 14 days, it still did not harden or show any signs of reaction. During the test, the composition is exposed to ambient light (including ultraviolet light). The mixture is heated to 100°C in a high-temperature place, and bubbles begin to form within 2 minutes, indicating that a reaction has occurred. After 5 minutes on a hot plate, the mixture is removed and set to 23°C. The mixture hardened within 24 hours.

[0081] EX 2: Mixed reactants

[0082] 0.243 g of B-FLP (1), 2.5 g of MHDH8D20MH (available from Gelest as HMS-271), and 2.5 g of MD80M (available from The Dow Chemical Company as Zymeter™ 100 centistokes (cSt) PMX-200 fluid) are added to a dental cup with a maximum capacity of 10 g and mixed. The ingredients are mixed in a FlakTec speed mixer at 3500 rpm for 1 minute to form a mixture. The mixture is poured into an aluminum pan and set to 23°C. After 14 days, there are no signs of reaction or curing. During the test, the composition is exposed to ambient light (including ultraviolet light). The mixture is heated in the aluminum pan to 100°C. After 2 minutes, bubbles appear clearly, indicating that a reaction has occurred. After heating for 5 minutes, the mixture and the aluminum pan are removed from the hot plate and set to 23°C. The mixture hardens within 48 hours.

[0083] Ex 3: Mixed reactants

[0084] 0.243 g of B-FLP (1), 2.5 g of MHDH8D20MH (available from Gelest as HMS-271), and 2.5 g of MD185M (available from The Dow Chemical Company as Xymeter™ 350 cSt PMX-200 fluid) were added to a dental cup with a maximum capacity of 10 g and mixed. The ingredients were mixed in a FlakTec speed mixer at 3500 rpm for 1 minute to form a mixture. The mixture was poured into an aluminum pan and set to 23°C. After 14 days, there were no signs of reaction or curing. During the test, the composition was exposed to ambient light (including ultraviolet light). The mixture was heated in the aluminum pan to 100°C. After 2 minutes, bubbles appeared clearly, indicating that a reaction had occurred. After heating for 5 minutes, the mixture and the aluminum pan were removed from the hot plate and set to 23°C. The mixture hardens within 36 hours.

[0085] Examples 1 to 3 show that B-FLP can provide a potential catalyst to a reactive system, thereby providing a storage-stable reactive system at 23°C, but once heated, the Lewis acid catalyst is released to initiate a continued reaction even if the mixture is cooled back to 23°C, which indicates that B-FLP provides a blocked catalyst that is not irreversibly blocked upon heating.

Claims

Claim 1 The mixture comprises a silyl hydride, a siloxane, and a bridged frustrated Lewis pair, wherein the bridged frustrated Lewis pair comprises: (a) a Lewis acid selected from the group consisting of aluminum alkyl, aluminum aryl, aryl borane, fluorinated aryl borane, boron halide, aluminum halide, gallium alkyl, gallium aryl, gallium halide, silyllium cation, and phosphonium cation; and (b) a Lewis base selected from the group consisting of molecules having the following structures: PR3, P(NR2)3, NR3, N(SiR3) x R 3-x , RC(NR)N, P(NR)R3, guanidine, amidine, phosphazene, and ;(wherein R is independently selected from the group consisting of hydrogen, alkyl, substituted alkyl, aryl, and substituted aryl in each case, and x is an integer from 1 to 3); and (c) a crosslinking molecule connecting the Lewis acid and the Lewis base, selected from the group consisting of carbon dioxide, nitrile, alkyne, and alkene, comprising a composition. Claim 2 ◈Claim 2 was abandoned upon payment of the registration fee.◈ The composition of Claim 1, wherein the Lewis acid is an aryl borane fluorinated. Claim 3 ◈Claim 3 was abandoned upon payment of the registration fee.◈ A composition according to Claim 1 or 2, wherein the Lewis base is selected from the group consisting of PR3, NR3, guanidine, amidine, and phosphazene. Claim 4 ◈Claim 4 was abandoned upon payment of the registration fee.◈ A composition according to Claim 1, wherein the Lewis acid is a fluorinated aryl borane, the Lewis base is selected from the group consisting of PR3 and NR3, the crosslinking molecule is selected from the group consisting of carbon dioxide, alkenes, alkynes, and nitriles; and R is independently selected from the group consisting of hydrogen, alkyl, substituted alkyl, aryl, and substituted aryl in each case. Claim 5 A composition according to claim 1 or 2, wherein the silyl hydride and the siloxane are the same molecule. Claim 6 A composition according to claim 1 or 2, wherein the cross-linked incomplete Lewis pair does not contain a photogenerator or other component that generates a Lewis acid upon exposure to ultraviolet radiation. Claim 7 A chemical reaction method comprising: (a) providing the composition of claim 1 or 2; and (b) heating the composition to a temperature sufficient to dissociate a Lewis acid from a cross-linked incomplete Lewis pair. Claim 8 ◈Claim 8 was abandoned upon payment of the registration fee.◈ The method of claim 7, wherein step (a) comprises mixing together a cross-linked incomplete Lewis pair, a silyl hydride, and a siloxane. Claim 9 A method according to claim 7, wherein, after step (a) and before step (b), the composition is applied to a substrate or placed in a mold. Claim 10 delete Claim 11 delete

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