Catalytic method of dehydropolymerizing amine boranes to polyaminoboranes

Abstract

The invention provides a method of catalytically dehydropolymerising an amine borane to produce a polyaminoborane, the method comprising the steps of: a. Providing a reaction vessel; and b. Adding a catalyst and an amine borane to the reaction vessel to initiate catalytic dehydropolymerisation of the amine borane, wherein the reaction vessel is maintained at a temperature of between 15 °C and -15 °C throughout the entire dehydropolymerisation.

Description

[0001] CATALYTIC METHOD OF DEHYDROPOLYMERIZING AMINE BORANES TO POLYAMINOBORANES

[0002] Technical Field of the Invention

[0003] The present invention relates to methods of catalytically dehydropolymerising an amine borane to produce a polyaminoborane.

[0004] Background to the Invention

[0005] Polyaminoboranes are polymers with alternating B-N main-chain backbones and having the general formula (H2BNR1R2)n. Whilst the simplest polyaminoborane, (H2BNH2)n, has been known for many years from the thermolysis of H3B NH3, poly aminoboranes are significantly less well-developed than their organic analogues, polyolefins.

[0006] Polyaminoboranes have applications in a range of fields such as hydrogen storage, polymer electronics, hypergolic fuels, and as precursors for advanced ceramic materials.

[0007] Despite the promising applications of polyaminoboranes, controlling their molecular weight during synthesis has proven to be a challenging task. The molecular weight of poly aminoboranes, particularly the number average molecular weight (Mn), is a critical parameter as it directly affects the polymer’ s physical and chemical properties. Previous methods for synthesising polyaminoboranes, whilst they may have been able to produce some high molecular weight poly aminoboranes, typically provide poor control over molecular weight, especially Mnand the poly dispersity index (PDI). This lack of control can lead to variations in polymer performance, limiting the applicability of polyaminoboranes in more precise or sensitive applications where specific molecular weight ranges are required for optimal performance. There is therefore a need for new and improved methods of synthesising polyaminoboranes that offer improved control over the molecular weight (both high and low molecular weights), especially the Mnof the polyaminoborane products, as well as improved control over their PDI, thus allowing for more predictable and reproducible polymer characteristics.

[0008] It is therefore an aim of embodiments of the invention to provide methods which ameliorate or solve one or more problems of the prior art.

[0009] It is also an aim of embodiments of the invention to overcome or mitigate at least one problem of the prior art, whether expressly disclosed herein or not.

[0010] Summary of the Invention

[0011] According to a first aspect of the invention, there is provided a method of catalytically dehydropolymerising an amine borane to produce a polyaminoborane, the method comprising the steps of:

[0012] (a) Providing a reaction vessel; and

[0013] (b) Adding a catalyst and an amine borane to the reaction vessel to initiate catalytic dehydropolymerisation of the amine borane, wherein the reaction vessel is maintained at a temperature of between 15 °C and -15 °C throughout the entire dehydropolymerisation.

[0014] Dehydropolymerisation of an amine borane refers to a process whereby the amine borane polymerises to form a polyaminoborane with the release of hydrogen (typically as hydrogen gas) as a side product. By “throughout the entire dehydropolymerisation”, it is meant from the start to the end of the dehydropolymerisation reaction. The start of the dehydropolymerisation reaction may be when the amine borane and catalyst are added to the reaction vessel or when hydrogen gas is first produced by the reaction. The end of the dehydropolymerisation may be when hydrogen gas production ceases.

[0015] Such a method in which a reaction vessel is provided at the start and throughout the dehydropolymerisation reaction at a temperature as described above surprisingly allows for high molecular weight polyaminoboranes to be produced, and allows for such polyaminoboranes to be produced with excellent control over the molecular weight, especially the Mn, and the PDI.

[0016] In some embodiments, reaction vessel may be provided in step (a) at a temperature of between 15 °C and -15 °C and maintained at said temperature throughout the entire dehydropolymerisation.

[0017] The reaction vessel may be maintained throughout the entire dehydropolymerisation at a temperature of no greater than 12 °C, or no greater than 10, 8, 6, 4, 2, or no greater than 0 °C.

[0018] The reaction vessel may be maintained throughout the entire dehydropolymerisation at a temperature of at least -14 °C, or at least -12, -10, or at least -8 °C.

[0019] In some embodiments, the reaction vessel is maintained throughout the entire dehydropolymerisation at a temperature of between 10 °C and -15 °C, or between 5 °C and -15 °C.

[0020] In preferred embodiments, the reaction vessel is maintained throughout the entire dehydropolymerisation at a temperature of between 0 °C and -15 °C. In some embodiments, reaction vessel may be provided in step (a) at a temperature stated above and maintained at said temperature throughout the entire dehydropolymerisation.

[0021] Maintaining the reaction vessel at such a temperature range throughout the entire dehydropolymerisation has been found to allow for preparation of polyaminoboranes of particularly high molecular weights, and with excellent control over Mnand PDI.

[0022] According to a second aspect of the invention, there is provided a method of catalytically dehydropolymerising an amine borane to produce a polyaminoborane, the method comprising the steps of:

[0023] (a) Providing a reaction vessel; and

[0024] (b) Adding a catalyst and an amine borane to the reaction vessel to initiate catalytic dehydropolymerisation of the amine borane, wherein the reaction vessel is maintained at a temperature of between 30 °C and 55 °C throughout the entire dehydropolymerisation.

[0025] By “throughout the entire dehydropolymerisation”, it is meant from the start to the end of the dehydropolymerisation reaction. The start of the dehydropolymerisation reaction may be when the amine borane and catalyst are added to the reaction vessel or when hydrogen gas is first produced by the reaction. The end of the dehydropolymerisation may be when hydrogen gas production ceases.

[0026] Such a method in which a reaction vessel is provided at the start and throughout the dehydropolymerisation reaction at a temperature as described above surprisingly allows for low molecular weight polyaminoboranes to be produced, and allows for such polyaminoboranes to be produced with excellent control over the molecular weight, especially the Mn, and the PDI.

[0027] In some embodiments, reaction vessel may be provided in step (a) at a temperature stated above and maintained at said temperature throughout the entire dehydropolymerisation.

[0028] The reaction vessel may be maintained throughout the entire dehydropolymerisation at a temperature of at least 32 °C, or at least 34, 36, 38, or at least 40 °C, or at least 45, or at least 50 °C.

[0029] In some embodiments, reaction vessel may be provided in step (a) at a temperature stated above and maintained at said temperature throughout the entire dehydropolymerisation.

[0030] The following statements apply to the first and second aspects of the invention.

[0031] In some embodiments, step (b) comprises the step of adding at least a portion of the amine borane to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min.

[0032] According to a third aspect of the invention, there is provided a method of catalytically dehydropolymerising an amine borane to produce a polyaminoborane, the method comprising the steps of:

[0033] (a) Providing a reaction vessel; and

[0034] (b) Adding a catalyst and an amine borane to the reaction vessel to initiate catalytic dehydropolymerisation of the amine borane, wherein at least a portion of the amine borane is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min.

[0035] Surprisingly, the present inventors have found that if at least a portion of the amine borane is added to the reaction vessel at a slow addition rate as per the above, this allows for controlled achievement of high molecular weight poly aminoboranes. Further, Mnin particular can be closely controlled by this method and PDI advantageously remains essentially unchanged.

[0036] In some embodiments, the reaction vessel is maintained throughout the entire dehydropolymerisation at a temperature of at least -15 °C, or at least -10, -5, 0, 5, 10, 15, 20, 25, 30, 35, or at least 40, or at least 45, 50, 55, or at least 60 °C.

[0037] In some embodiments, the reaction vessel is maintained throughout the entire dehydropolymerisation at a temperature of no greater than 70 °C, or no greater than 65, 60, 55, 50, or no greater than 45 °C.

[0038] In some embodiments, the reaction vessel is maintained throughout the entire dehydropolymerisation at a temperature of between 65 °C and -15 °C, or between 60 and -10 °C, or between 55 and -5 °C.

[0039] In some embodiments, reaction vessel may be provided in step (a) at a temperature stated above and maintained at said temperature throughout the entire dehydropolymerisation.

[0040] According to a fourth aspect of the invention, there is provided a method of catalytically dehydropolymerising an amine borane to produce a polyaminoborane, the method comprising the steps of:

[0041] (a) Providing a reaction vessel; and

[0042] (b) Adding a catalyst and an amine borane to the reaction vessel to initiate catalytic dehydropolymerisation of the amine borane, wherein the reaction vessel is maintained at a temperature of between 15 °C and -15 °C throughout the entire dehydropolymerisation, and wherein at least a portion of the amine borane is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min.

[0043] By “throughout the entire dehydropolymerisation”, it is meant from the start to the end of the dehydropolymerisation reaction. The start of the dehydropolymerisation reaction may be when the amine borane and catalyst are added to the reaction vessel or when hydrogen gas is first produced by the reaction. The end of the dehydropolymerisation may be when hydrogen gas production ceases.

[0044] In some embodiments, reaction vessel may be provided in step (a) at a temperature stated above and maintained at said temperature throughout the entire dehydropolymerisation.

[0045] The following statements apply to the third and fourth aspects of the invention.

[0046] In some preferred embodiments, the reaction vessel is maintained at a temperature of between 15 °C and -15 °C throughout the entire dehydopolymerisation.

[0047] The reaction vessel may be maintained throughout the entire dehydropolymerisation at a temperature of no greater than 12 °C, or no greater than 10, 8, 6, 4, 2, or no greater than 0 °C.

[0048] The reaction vessel may be maintained throughout the entire dehydropolymerisation at a temperature of at least -14 °C, or at least -12, -10, or at least -8 °C.

[0049] In some embodiments, the reaction vessel is maintained throughout the entire dehydropolymerisation at a temperature of between 10 °C and -15 °C, or between 5 °C and -15 °C. In preferred embodiments, the reaction vessel is maintained at a temperature of between

[0050] 0 °C and -15 °C throughout the entire dehydropolymerisation.

[0051] In some embodiments, reaction vessel may be provided in step (a) at a temperature stated above and maintained at said temperature throughout the entire dehydropolymerisation.

[0052] In some embodiments, the reaction vessel is maintained throughout the entire dehydropolymerisation at a temperature of between 10 °C and -15 °C; and the at least a portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min is added at an addition rate of between 0.10-4.50 mmol / min, or between 0.10-4.00 mmol / min, or between 0.10-3.50 mmol / min, or preferably between 0.10-3.00 mmol / min, more preferably between 0.20-2.50 mmol / min.

[0053] In some embodiments, the reaction vessel is maintained throughout the entire dehydropolymerisation at a temperature of between 5 °C and -15 °C; and the at least a portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min is added at an addition rate of between 0.10-4.50 mmol / min, or between 0.10-4.00 mmol / min, or between 0.10-3.50 mmol / min, or preferably between 0.10-3.00 mmol / min, more preferably between 0.20-2.50 mmol / min.

[0054] In some embodiments, the reaction vessel is maintained throughout the entire dehydropolymerisation at a temperature of between 0 °C and -15 °C; and the at least a portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min is added at an addition rate of between 0.10-4.50 mmol / min, or between 0.10-4.00 mmol / min, or between 0.10-3.50 mmol / min, or preferably between 0.10-3.00 mmol / min, more preferably between 0.20-2.50 mmol / min. According to a fifth aspect of the invention, there is provided a method of catalytically dehydropolymerising an amine borane to produce a polyaminoborane, the method comprising the steps of:

[0055] (a) Providing a reaction vessel; and

[0056] (b) Adding a catalyst and an amine borane to the reaction vessel to initiate catalytic dehydropolymerisation of the amine borane, wherein the reaction vessel is maintained at a temperature of between 30 °C and 55 °C throughout the entire dehydropolymerisation, and wherein at least a portion of the amine borane is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min.

[0057] By “throughout the entire dehydropolymerisation”, it is meant from the start to the end of the dehydropolymerisation reaction. The start of the dehydropolymerisation reaction may be when the amine borane and catalyst are added to the reaction vessel or when hydrogen gas is first produced by the reaction. The end of the dehydropolymerisation may be when hydrogen gas production ceases.

[0058] In some embodiments, reaction vessel may be provided in step (a) at a temperature stated above and maintained at said temperature throughout the entire dehydropolymerisation.

[0059] The following statements apply to the third and fifth aspects of the invention.

[0060] In some embodiments, the reaction vessel is maintained at a temperature of between 30 °C and 55 °C throughout the entire dehydropolymerisation.

[0061] The reaction vessel may be maintained throughout the entire dehydropolymerisation at a temperature of at least 32 °C, or at least 34, 36, 38, or at least 40 °C, or at least 45, or at least 50 °C. In some embodiments, reaction vessel may be provided in step (a) at a temperature stated above and maintained at said temperature throughout the entire dehydropolymerisation.

[0062] In some embodiments, the reaction vessel is maintained throughout the entire dehydropolymerisation at a temperature of at least 32 °C; and the at least a portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min is added at an addition rate of between 0.10-4.50 mmol / min, or between 0.10- 4.00 mmol / min, or between 0.10-3.50 mmol / min, or preferably between 0.10-3.00 mmol / min, more preferably between 0.20-2.50 mmol / min.

[0063] In some embodiments, the reaction vessel is maintained throughout the entire dehydropolymerisation at a temperature of at least 36 °C; and the at least a portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min is added at an addition rate of between 0.10-4.50 mmol / min, or between 0.10- 4.00 mmol / min, or between 0.10-3.50 mmol / min, or preferably between 0.10-3.00 mmol / min, more preferably between 0.20-2.50 mmol / min.

[0064] In some embodiments, the reaction vessel is maintained throughout the entire dehydropolymerisation at a temperature of at least 40 °C; and the at least a portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min is added at an addition rate of between 0.10-4.50 mmol / min, or between 0.10- 4.00 mmol / min, or between 0.10-3.50 mmol / min, or preferably between 0.10-3.00 mmol / min, more preferably between 0.20-2.50 mmol / min.

[0065] In some embodiments, the reaction vessel is maintained throughout the entire dehydropolymerisation at a temperature of at least 45 °C; and the at least a portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min is added at an addition rate of between 0.10-4.50 mmol / min, or between 0.10- 4.00 mmol / min, or between 0.10-3.50 mmol / min, or preferably between 0.10-3.00 mmol / min, more preferably between 0.20-2.50 mmol / min.

[0066] In some embodiments, the reaction vessel is maintained throughout the entire dehydropolymerisation at a temperature of at least 50 °C; and the at least a portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min is added at an addition rate of between 0.10-4.50 mmol / min, or between 0.10- 4.00 mmol / min, or between 0.10-3.50 mmol / min, or preferably between 0.10-3.00 mmol / min, more preferably between 0.20-2.50 mmol / min.

[0067] The following statements apply to third, fourth and fifth aspects of the invention, and also apply to the first and second aspects of the invention when at least a portion of the amine borane is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min.

[0068] In some embodiments, the portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min is added at an addition rate of at least 0.1 mmol / min, or at least 0.12, 0.14, 0.16, 0.18, 0.20, 0.22, or at least 0.24 mmol / min.

[0069] In some embodiments, the portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min is added at an addition rate of no greater than 2.90 mmol / min, or no greater than 2.80 mmol / min, or no greater than 2.70, 2.60, 2.50, 2.40, 2.30, or no greater than 2.20 mmol / min.

[0070] In some embodiments, the at least a portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min is added at an addition rate of between 0.10-4.50 mmol / min, or between 0.10-4.00 mmol / min, or between 0.10- 3.50 mmol / min, or preferably between 0.10-3.00 mmol / min, more preferably between

[0071] 0.20-2.50 mmol / min.

[0072] In some embodiments, step (b) comprises adding all of the amine borane to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at an addition rate specified in statements of invention above.

[0073] In other embodiments, step (b) comprises first adding the catalyst and a first portion of the amine borane to the reaction vessel, and then adding the remainder of the amine borane to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at an addition rate specified in statements of invention above.

[0074] In some embodiments, at least 70 mol% of the amine borane is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at an addition rate specified in statements of invention above, after adding the catalyst and the first portion of the amine borane, or at least 75, 80, or preferably at least 85 mol%, or at least 86, 87, 88, 89, or at least 90 mol% of the amine borane is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min or at an addition rate specified in statements of invention above, after adding the catalyst and the first portion of the amine borane.

[0075] In some embodiments, no greater than 98 mol%, or no greater than 97, 96, or preferably no greater than 95, or no greater than 94, 93, 92, 91, or no greater than 90 mol% of the amine borane is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at an addition rate specified in statements of invention above, after adding the catalyst and the first portion of the amine borane.

[0076] In some embodiments, between 85-100 mol%, or between 90-95 mol% of the amine borane is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at an addition rate specified in statements of invention above, after adding the catalyst and the first portion of the amine borane.

[0077] In some embodiments, the portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at an addition rate specified in statements of invention above, is added to the reaction vessel over a total time period of between 60-500 mins.

[0078] The portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at an addition rate specified in statements of invention above, may be added to the reaction vessel over a total time period of at least 60 mins, or at least 65, 70, 75, 80, or at least 85 mins.

[0079] The portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at an addition rate specified in statements of invention above, may be added to the reaction vessel over a total time period of no greater than 500 mins, or no greater than 490, 480, 470, or no greater 460 mins.

[0080] The portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at an addition rate specified in statements of invention above, may be added to the reaction vessel over a total time period of between 70-490 mins, or between 75-480, or between 75-470, or between 80-460 mins.

[0081] In other embodiments, the portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at an addition rate specified in statements of invention above, may be added to the reaction vessel over a total time period of between 60-120 mins, or between 70-110, or between 80-100 mins. In some embodiments, the portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at an addition rate specified in statements of invention above, is added continuously, preferably throughout the entire duration of the dehydropolymerisation reaction.

[0082] In some embodiments, the portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at an addition rate specified in statements of invention above, is added dropwise, preferably throughout the entire duration of the dehydropolymerisation reaction.

[0083] In some embodiments, the portion of the amine borane that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at an addition rate specified in statements of invention above, is added continuously throughout one part of the dehydropolymerisation reaction and added dropwise throughout another part of the dehydropolymerisation reaction.

[0084] The following statements apply to the first, second, third, fourth and fifth aspects of the invention.

[0085] In some embodiments, at least a portion of the amine borane that is added to the reaction vessel is added at an addition rate of at least 0.03 mL / min, or at least 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or at least 0.10 mL / min. In some embodiments, said portion of the amine borane may be the portion of the amine that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at a mmol / min addition rate specified in statements of invention above.

[0086] In some embodiments, at least a portion of the amine borane that is added to the reaction vessel is added at an addition rate of no greater than 1.00 mL / min, or no greater than 0.90 mL / min, or no greater than 0.80, 0.70, 0.60, 0.50, or no greater than 0.40 mL / min. In some embodiments, said portion of the amine borane may be the portion of the amine that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at a mmol / min addition rate specified in statements of invention above.

[0087] At least a portion of the amine borane that is added to the reaction vessel may be added at an addition rate of between 0.03-1.00 mL / min, or between 0.04-0.90, 0.05-0.80, 0.06- 0.70, 0.07-0.60, 0.08-0.50, 0.09-0.40, or between 0.10-0.35 mL / min. In some embodiments, said portion of the amine borane may be the portion of the amine that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at a mmol / min addition rate specified in statements of invention above.

[0088] In some embodiments, the temperature of the reaction vessel does not change by greater than 5 °C throughout the entire dehydropolymerisation, or by no greater than 4, 3, 2, or by no greater than 1 °C throughout the entire dehydropolymerisation.

[0089] In some embodiments, the temperature of the reaction vessel is kept constant throughout the entire dehydropolymerisation.

[0090] At least a portion of the amine borane may be added to the reaction vessel using a method that is independently selected from the group consisting of: addition via a dropping funnel, addition via a syringe pump, addition via a cannula, addition via a peristaltic pump, and addition via an automated dosing system. In some preferred embodiments, at least a portion of the amine borane is added to the reaction vessel using a syringe pump. In some embodiments, said portion of the amine borane may be the portion of the amine that is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min, or at an addition rate specified in statements of invention above. In some embodiments, at least a portion of the amine borane is added drop wise to the reaction vessel. In some embodiments, at least a portion of the amine borane is added continuously to the reaction vessel.

[0091] In preferred embodiments, the amine borane has a structure of Formula (I). 1R2H

[0092] In some embodiments, R1and R2are each independently selected from the group consisting of: hydrogen, an alkyl group, an aryl group, an ether group, a thioether group, and an amine group.

[0093] In some preferred embodiments, R1and / or R2is an alkyl group. R1and / or R2may be a C1-C10 alkyl, or a Ci-Cs alkyl, or a Ci-Ce alkyl, or preferably a C1-C5 alkyl, or a C1-C4 alkyl, or a C1-C3 alkyl, or a C1-C2 alkyl. In some embodiments, R1and / or R2is an alkyl group that is independently selected from the group consisting of: methyl, ethyl, propyl and butyl. In some preferred embodiments, R1and / or R2is methyl.

[0094] In some preferred embodiments, R1and / or R2is hydrogen. In some embodiments, only one of R1and R2is hydrogen.

[0095] In some embodiments, R1is hydrogen; and R2is independently selected from the group consisting of: hydrogen, an alkyl group, an aryl group, an aryl group, an ether group, a thioether group, and an amine group.

[0096] In some preferred embodiments, R1is hydrogen; and R2is an alkyl group. R1may be hydrogen; and R2may be a C1-C10 alkyl, or a Ci-Cs alkyl, or a Ci-Ce alkyl, or preferably a C1-C5 alkyl, or a C1-C4 alkyl, or a C1-C3 alkyl, or a C1-C2 alkyl. R1may be hydrogen; and R2may be an alkyl group that is independently selected from the group consisting of: methyl, ethyl, propyl and butyl. In some preferred embodiments, R1is hydrogen; and R2is methyl.

[0097] In some embodiments, the catalyst comprises a metal catalyst. In some preferred embodiments, the catalyst comprises a transition metal catalyst.

[0098] The transition metal catalyst may be independently selected from the group consisting of: a ruthenium catalyst, a rhodium catalyst, an iridium catalyst, a cobalt catalyst, and combinations thereof. The transition metal catalyst may be independently selected from the group consisting of: a ruthenium II catalyst, an iridium III catalyst, a rhodium I catalyst, a cobalt II catalyst, and combinations thereof. The transition metal catalyst may comprise a transition metal complex comprising a transition metal ion complexed with one or more ligands, which may be stabilising ligands. At least one ligand may preferably surround the transition metal ion. At least one ligand may be independently selected from the group consisting of: a neutral ligand, an anionic ligand, a cationic ligand, and combinations thereof. At least one ligand may be independently selected from the group consisting of: a monodentate ligand, a bidentate ligand, a polydentate ligand, and combinations thereof. At least one ligand may be independently selected from the group consisting of: an O-donor ligand, an N-donor ligand, an S-donor ligand, a P-donor ligand, and combinations thereof. At least one ligand may be independently selected from the group consisting of: a o-donor ligand, a 71-donor ligand, a 71-acceptor ligand, and combinations thereof. At least one ligand may be independently selected from the group consisting of: an amine ligand, a phosphine ligand, a halide ligand, a 71-system ligand, an alkyl ligand, an aryl ligand, and combinations thereof. In some preferred embodiments, the transition metal catalyst is independently selected from the group consisting of: a compound of Formula (II); a compound of Formula (III); a compound of Formula (IV); a compound of Formula (V), wherein R3is *Pr or Cy; and combinations thereof.

[0099] In some preferred embodiments, the transition metal catalyst is independently selected from the group consisting of: a compound of Formula (II), a compound of Formula (III), a compound of Formula (IV), and combinations thereof. In some embodiments, the catalyst is added to the reaction vessel in a total amount of at least 0.005 mol% relative to the total amount of amine borane added to the reaction vessel, or at least 0.006, 0.007, 0.008, 0.009, or at least 0.01 mol% relative to the total amount of amine borane added to the reaction vessel.

[0100] In some embodiments, the catalyst is added to the reaction vessel in a total amount of no greater than 0.5 mol% relative to the total amount of amine borane added to the reaction vessel, or no greater than 0.4, 0.3, 0.2, or no greater than 0.1 mol% relative to the total amount of amine borane added to the reaction vessel. The catalyst may be added to the reaction vessel in a total amount of between 0.005-0.5 mol% relative to the total amount of amine borane added to the reaction vessel, or between 0.007-0.3 mol% relative to the total amount of amine borane added to the reaction vessel, or between 0.01-0.1 mol% relative to the total amount of amine borane added to the reaction vessel.

[0101] In other embodiments, the catalyst is added to the reaction vessel in a total amount of at least 0.1 mol% relative to the total amount of amine borane added to the reaction vessel, or at least 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or at least 1.0 mol% relative to the total amount of amine borane added to the reaction vessel.

[0102] In some embodiments, the catalyst is added to the reaction vessel in a total amount of no greater than 10.0 mol% relative to the total amount of amine borane added to the reaction vessel, or no greater than 9.0, 8.0, 7.0, 6.0, or no greater than 5.0, 4.0, or no greater than 3.0 mol% relative to the total amount of amine borane added to the reaction vessel.

[0103] In some embodiments, the catalyst is added to the reaction vessel in a total amount of between 0.01-10.0 mol%, or between 0.01-5.0 mol%.

[0104] The catalyst may be added to the reaction vessel in a total amount of between 0.1-10.0 mol% relative to the total amount of amine borane added to the reaction vessel, or between 0.3-7.0 mol% relative to the total amount of amine borane added to the reaction vessel, or between 0.5-5.0 mol% relative to the total amount of amine borane added to the reaction vessel.

[0105] In some embodiments, the method comprises a further step of removing residual catalyst from the polyaminoborane product. Said step may comprise treating a crude polyaminoborane product produced from the dehydropolymerisation with activated carbon and / or silica. In some embodiments, the step may comprise filtering the crude product, preferably when dissolved in a solvent, through activated carbon and / or silica. In some embodiments, the crude product, preferably when dissolved in a solvent, is combined with activated carbon and / or silica to form a mixture, and the polyaminoborane product is then separated from the mixture.

[0106] In embodiments in which the catalyst is a metal catalyst, the method may comprise the step of reducing the residual metal content in the polyaminoborane product to less than 300 ppm, or less than 250 ppm, or less than 200 ppm.

[0107] In some embodiments in which the transition metal catalyst is a rhodium catalyst, such as a compound of Formula (III), the reaction vessel contains air when the catalyst is added to the vessel in step (b).

[0108] In other embodiments, particularly wherein the catalyst is not a rhodium catalyst, the reaction vessel may be substantially free of air when the catalyst is added to the vessel in step (b).

[0109] In some embodiments, the method further comprises the step of adding an amine to the reaction vessel.

[0110] The addition of an amine to the reaction vessel allows for an increase in the activity of the catalyst. Addition of an amine, in particular, enables higher molecular weight polyaminoboranes to be produced.

[0111] The amine may be independently selected from the group consisting of: a primary amine, a secondary amine, a tertiary amine, and combinations thereof. The amine may preferably be a primary or a secondary amine. In some embodiments, the amine may have the structure of Formula (VI), wherein R1and R2are as described in statements of invention above.

[0112] NR^H

[0113] In some preferred embodiments, R1and R2groups of the amine are the same as the R1and R2groups of the amine borane.

[0114] In some embodiments, the amine is independently selected from the group consisting of: methylamine, ethylamine, propylamine, butylamine, and combinations thereof. In some preferred embodiments, the amine comprises methylamine.

[0115] In some embodiments, the amine is added to the reaction vessel in a total amount of at least the same as the amount of catalyst added to the reaction vessel in step (b), or in a total amount of at least 2 times the amount of catalyst added to the reaction vessel in step (b), or at least 3, 4, or at least 5 times the amount of catalyst added to the reaction vessel in step (b). The amine may be added to the reaction vessel in a total amount of no greater than 50 times the amount of catalyst added to the reaction vessel in step (b), or no greater than 40, 30, 20, or no greater than 15 times the amount of catalyst added to the reaction vessel in step (b).

[0116] In some embodiments, the amine is added to the reaction vessel in a total amount of between 1-50 times the amount of catalyst added to the reaction vessel in step (b), or between 1-40, 1-30, or between 1-20 times the amount of catalyst added to the reaction vessel in step (b), or between 1-15 times the amount of catalyst added to the reaction vessel in step (b), or between 1-12, or between 2-12, or between 5-10 times the amount of catalyst added to the reaction vessel in step (b).

[0117] In some embodiments, the amine is added to the reaction vessel after the catalyst is added to the reaction vessel in step (b), preferably immediately after the catalyst is added to the reaction vessel in step (b). In some embodiments, the amine is added to the reaction vessel after the catalyst is added to the reaction vessel and after at least some of the amine borane is added to the reaction vessel. In other embodiments, the amine is added to the reaction vessel after the catalyst is added to the reaction vessel but before any amine borane is added to the reaction vessel. In some embodiments, the amine is added to the reaction vessel at the same time as the catalyst.

[0118] In some embodiments, the dehydropolymerisation reaction is performed in an aprotic solvent.

[0119] The aprotic solvent may be a non-polar aprotic solvent. The non-polar aprotic solvent may be independently selected from the group consisting of: an aliphatic hydrocarbon, an aromatic hydrocarbon, a cycloalkane, a chlorinated hydrocarbon, and combinations thereof. In some embodiments, the non-polar aprotic solvent is independently selected from the group consisting of: hexane, heptane, benzene, toluene, chloroform, cyclohexane, and combinations thereof. In some embodiments, the non-polar aprotic solvent may comprise an aromatic hydrocarbon, which may comprise toluene.

[0120] The aprotic solvent may be a polar aprotic solvent. The polar aprotic solvent may be independently selected from the group consisting of: a nitrile, an ether, an amide, a ketone, a sulfoxide, a sulfone, a nitro compound, a phosphorus compound, a carbonate, a halogenated solvent, and combinations thereof. The polar aprotic solvent may comprise a cyclic ether solvent. The cyclic ether solvent may preferably comprise tetrahydrofuran.

[0121] According to a sixth aspect of the invention, there is provided a method of catalytically dehydropolymerising an amine borane to produce a polyaminoborane, the method comprising the steps of:

[0122] (a) Providing a reaction vessel; and

[0123] (b) Adding a catalyst and an amine borane to the reaction vessel to initiate catalytic dehydropolymerisation of the amine borane, wherein the reaction vessel is maintained at a temperature of between 30 °C and 65 °C, excluding 60 °C, throughout the entire dehydropolymerisation.

[0124] By “throughout the entire dehydropolymerisation”, it is meant from the start to the end of the dehydropolymerisation reaction. The start of the dehydropolymerisation reaction may be when the amine borane and catalyst are added to the reaction vessel or when hydrogen gas is first produced by the reaction. The end of the dehydropolymerisation may be when hydrogen gas production ceases.

[0125] Statements of invention for previous aspects of the invention above may also be applied mutatis mutandis to the sixth aspect of the invention.

[0126] The reaction vessel may be maintained throughout the entire dehydropolymerisation at a temperature of at least 32 °C, or at least 34, 36, 38, or at least 40 °C, or at least 45, or at least 50, or at least 55 °C.

[0127] In some embodiments, reaction vessel may be provided in step (a) at a temperature stated above and maintained at said temperature throughout the entire dehydropolymerisation. According to a seventh aspect of the invention, there is provided a polyaminoborane obtained or obtainable by the method of the first, second, third, fourth, fifth or sixth aspect of the invention.

[0128] Statements of invention for previous aspects of the invention above may also be applied mutatis mutandis to the seventh aspect of the invention.

[0129] The polyaminoborane may have a number average molecular weight (Mn) of at least 20000 g / mol, or at least 40000, 60000, 80000, or at least 100000, 120000, 140000, 160000, or at least 180000 g / mol.

[0130] The polyaminoborane may have an Mnof no greater than 400000 g / mol, or no greater than 350000, 300000, 250000, or no greater than 200000 g / mol.

[0131] The polyaminoborane may have an Mnof between 20000-400000 g / mol, or between 20000-300000, or between 20000-200000, or between 40000-200000, 40000-190000, 50000-180000, or between 60000-170000 g / mol.

[0132] In other embodiments, the polyaminoborane may have an Mnof no greater than 20000 g / mol, or no greater than 18000, 16000, 14000, 12000, or no greater than 10000, 8000, or no greater than 6000 g / mol.

[0133] Mnvalues are preferably obtained using GPC (Gel Permeation Chromatography) relative to polystyrene standards.

[0134] The polyaminoborane may have a polydispersity index (PDI) of no greater than 2.00, or no greater than 1.90, 1.80, 1.70, 1.60, or no greater than 1.50.

[0135] The polyaminoborane may have a weight average molecular weight (Mw) of at least 20000 g / mol, or at least 40000, 60000, 80000, or at least 100000, or at least 150000, 200000, or at least 250000 g / mol. The polyaminoborane may have an Mwof no greater than 400000 g / mol, or no greater than 350000 g / mol.

[0136] The polyaminoborane may have an Mwof between 20000-400000 g / mol, or between 40000-400000, 70000-400000, 90000-400000, 100000-400000, 150000-400000, 200000-400000, or between 250000-400000 g / mol.

[0137] In other embodiments, the poly aminoborane may have an Mwof no greater than 40000 g / mol, or no greater than 30000, 20000, 15000, 10000, 8000, or no greater than 6000 g / mol.

[0138] The polyaminoborane may have a structure of Formula (VII), wherein R1and R2are as described in statements of invention above, and wherein n is a number of repeat units of the polyaminoborane.

[0139] -[-B(H2)-N(R1)(R2)-]n-

[0140] (VII)

[0141] Detailed Description of the Invention

[0142] In order that the invention may be more clearly understood, embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

[0143] Figure 1 shows overlaid GPC traces of polyaminoborane products produced by Reactions 1-10 described below.

[0144] Figure 2nB NMR spectrum (baseline corrected, CDCh, 193 MHz, 298 K) of polyaminoborane product of Reaction 3 described below. Figure 3nB NMR spectrum of aliquot taken of polyaminoborane product of Reaction 4 described below.

[0145] FigurenB NMR spectrum (baseline corrected, CDCh, 193 MHz, 298 K) of polyaminoborane product of Reaction 5 described below.

[0146] Figure 5nB NMR spectrum (baseline corrected, CDCI3, 193 MHz, 298 K) of polyaminoborane product of Reaction 6 described below.

[0147] Figure 6nB NMR spectrum (baseline corrected, CDCI3, 193 MHz, 298 K) of polyaminoborane product of Reaction 7 described below.

[0148] Figure 7nB NMR spectrum (baseline corrected, CDCI3, 193 MHz, 298 K) of polyaminoborane product of Reaction 8 described below.

[0149] Figure 8nB NMR spectrum (baseline corrected, CDCI3, 193 MHz, 298 K) of polyaminoborane product of Reaction 9 described below.

[0150] Figure 9nB NMR spectrum of aliquot taken of polyaminoborane product of Reaction 10 described below.

[0151] Preparation of polyaminoboranes

[0152] General information:

[0153] Unless otherwise stated all experiments were carried out under an argon atmosphere using standard glovebox and Schlenk techniques. Glassware and cannulas were dried overnight at 140 °C. Tetrahydrofuran (THF) (pretreated over AI2O3 then 3 A molecular sieves) was distilled over sodium / benzophenone and degassed by 3 freeze-pump-thaw cycles. All solvents were stored over 3 A molecular sieves. Commercially sourced

[0154] H3B-NH2Me (monomethylamine borane - MMAB) was recrystallised from OEt2 prior to use and stored at -40 °C in the glovebox. All other reagents were obtained from commercial sources and used without further purification unless stated.

[0155] All polymeric materials were analysed by GPC (gel permeation chromatography) measured on a Malvern Viskotec GPCmax together with a Viskotec TDA 305 RI detector. Polymer Mnis referenced to polystyrene standards between Mn= 474-476,500 g mol-1. All samples were passed through 3 columns consisting of a porous styrene divinylbenzene copolymer (column set: 2 x T5000 and 1 x T4000 Malvern columns). The eluent used was GPC grade THF containing [NBu4]Br (2.7 mmol dm-3) and the flow rate was 1 cm3min-1. All polymer samples were dissolved in GPC grade THF [NBu4]Br (2 mg cm-3) and filtered through a PTFE filter (pore size: 45 pm).

[0156] Catalysts used:

[0157] The following transition metal catalysts were used:

[0158] Reaction 1 (inventive - slow MMAB addition and high temperature):

[0159] MMAB (9.00 g, 200 mmol) was dissolved in 30 cm3of THF and loaded into a syringe pump. Separately, MMAB (1.00 g, 22 mmol) and catalyst (III) (0.012g, 0.022 mmol) were added to a round bottomed flask. 15 cm3of THF was then added and the reaction mixture stirred. From the initiation of dehydropolymerisation where the first H2 gas evolution was observed and where the reaction mixture had turned from yellow to colourless, the reaction was held at 60 °C and drop wise addition of MMAB solution from the syringe pump was started. MMAB drop wise addition was performed at an addition rate of 2.20 mmol / min (0.33 mL / min).

[0160] Upon the cessation of H2 gas evolution, the reaction mixture was allowed to cool to room temperature and then poured into -200 cm3of pentane to precipitate the formed polyaminoborane. The resulting polymer was filtered off and dried in-vacuo, obtained as a white solid. The polymer was analysed by GPC (see GPC trace 1 in Figure 1).

[0161] Reaction 2 (inventive - slow MMAB addition and high temperature):

[0162] MMAB (9.00 g, 200 mmol) was dissolved in 30 cm3of THF in an ampoule and loaded into a syringe pump. Separately, MMAB (1.00 g, 22 mmol) and catalyst (III) (0.012g, 0.022 mmol) were added to a round bottomed flask under N2 flow. 15 cm3of THF was then added and the reaction mixture stirred. From the initiation of dehydropolymerisation where the first H2 gas evolution was observed and where the reaction mixture had turned from yellow to colourless, the reaction was held at 40 °C and dropwise addition of MMAB solution, through a suba seal, from the syringe pump was started. MMAB drop wise addition was performed at an addition rate of 2.20 mmol / min (0.33 mL / min).

[0163] Upon the cessation of H2 gas evolution, the reaction mixture was allowed to cool to room temperature and then poured in- air into -200 cm3of pentane to precipitate the formed polyaminoborane. The resulting polymer was filtered off and dried in-vacuo, obtained as a white solid. The polymer was analysed by GPC (see GPC trace 2 in Figure 1).

[0164] Reaction 3 (control):

[0165] MMAB (10.00 g, 222 mmol) and catalyst (III) (0.012g, 0.022 mmol) were added to a round bottomed flask maintained at 20 °C under N2 flow. 45 cm3of THF was then added and the reaction mixture stirred, upon which H2 evolution was observed. Upon the cessation of H2 gas evolution, the reaction mixture was poured in-air into -200 cm3of pentane to precipitate the formed polyaminoborane. The resulting polymer was filtered off and dried in-vacuo, obtained as a white solid. The polymer was analysed by1H,nB NMR spectroscopies and GPC (see GPC trace 3 in Figure 1).

[0166] Reaction 4 (control):

[0167] MMAB (112 mg, 2.5 mmol) was added to a two-neck jacketed Schlenk flask under argon atmosphere in the glovebox. The flask was attached to a circulating cooler which was set to 20 °C. The two-neck jacketed Schlenk flask was attached to an upturned, water filled burette by PTFE tubing. Catalyst (II) (1.5 mg, 2.5 pmol) was dissolved in 1.25 mL THF, then added to the MMAB with stirring set to 400 rpm. H2 production was monitored by the displacement of water from the upturned burette. When the reaction was completed (when H2 production had stopped) an aliquot (0.5 mL) was taken for analysis by1H,31P {1H } andnB NMR spectroscopies. This aliquot was added back into the reaction (in air) then pentane (50 mL) was added, and the reaction stirred vigorously to induce polymer precipitation. The white solid was isolated by filtration and remaining volatiles were removed in vacuo. The polymer was analysed by1H,31P { H } andnB NMR spectroscopies and GPC (see GPC trace 4 in Figure 1).

[0168] Reaction 5 (inventive - slow MMAB addition):

[0169] MMAB (45.00 g, 1002 mmol) was dissolved in 150 cm3of THF in an ampoule and loaded into a syringe pump. Separately, MMAB (5.00 g, 111 mmol) and catalyst (III) (0.060g, 0.112 mmol) were added to a round bottomed flask under N2 flow. 75 cm3of THF was then added and the reaction mixture stirred. From the initiation of dehydropolymerisation where the first H2 gas evolution was observed and where the reaction mixture had turned from yellow to colourless, the reaction was maintained by cooling at 20 °C and dropwise addition of MMAB solution, through a suba seal, from the syringe pump was started. MMAB drop wise addition was performed at an addition rate of 2.20 mmol / min (0.33 mL / min).

[0170] Upon the cessation of H2 gas evolution, the reaction mixture was allowed to cool to room temperature and then poured in-air into -1000 cm3of pentane to precipitate the formed polyaminoborane. The resulting polymer was filtered off and dried in-vacuo, obtained as a white solid. The polymer was analysed bynB NMR and GPC (see GPC trace 5 in Figure 1).

[0171] Reaction 6 (inventive - slow MMAB addition and low temperature):

[0172] MMAB (9.00 g, 200 mmol) was dissolved in 30 cm3of THF and loaded into a syringe pump. Separately, MMAB (1.00 g, 22 mmol) and catalyst (III) (0.012g, 0.022 mmol) were added to a round bottomed flask. 15 cm3of THF was then added and the reaction mixture stirred. From the initiation of dehydropolymerisation where the first H2 gas evolution was observed and where the reaction mixture had turned from yellow to colourless, the reaction was held at 5 °C and dropwise addition of MMAB solution from the syringe pump was started. MMAB drop wise addition was performed at an addition rate of 2.20 mmol / min (0.33 mL / min).

[0173] Upon the cessation of H2 gas evolution, the reaction mixture was allowed to warm to room temperature and then poured into -200 cm3of pentane to precipitate the formed polyaminoborane. The resulting polymer was filtered off and dried in-vacuo, obtained as a white solid. The polymer was analysed bynB NMR and GPC (see GPC trace 6 in

[0174] Figure 1). Reaction 7 (inventive - slow MMAB addition and low temperature):

[0175] MMAB (9.00 g, 200 mmol) was dissolved in 30 cm3of THF and loaded into a syringe pump. Separately, MMAB (1.00 g, 22 mmol) and catalyst (III) (0.012g, 0.022 mmol) were added to a round bottomed flask. 15 cm3of THF was then added and the reaction mixture stirred. From the initiation of dehydropolymerisation where the first H2 gas evolution was observed and where the reaction mixture had turned from yellow to colourless, the reaction was held at 0 °C and dropwise addition of MMAB solution from the syringe pump was started. MMAB drop wise addition was performed at an addition rate of 2.20 mmol / min (0.33 mL / min).

[0176] Upon the cessation of H2 gas evolution, the reaction mixture was allowed to warm to room temperature and then poured into -200 cm3of pentane to precipitate the formed polyaminoborane. The resulting polymer was filtered off and dried in-vacuo, obtained as a white solid. The polymer was analysed bynB NMR and GPC (see GPC trace 7 in Figure 1).

[0177] Reaction 8 (control):

[0178] Catalyst (IV) (0.0182 g, 0.037 mmol) was dissolved in 10 cm3THF with stirring. Separately, MMAB (5.00 g, 111.4 mmol) was dissolved in 100 cm3of THF. The precatalyst solution was then added to the stirring MMAB solution, followed immediately by MeNH2 (200 pl, 0.4 mmol, as 2 mol dm-3solution in THF). After 15 minutes, catalysis initiated and a large amount of H2 gas was produced in under 1 minute accompanied by significant reaction foaming. Upon the cessation of H2 gas evolution, the reaction mixture was allowed to warm to room temperature and then poured into -200 cm3of pentane to precipitate the formed polyaminoborane. The resulting polymer was filtered off and dried in-vacuo, obtained as a white solid. The polymer was analysed bynB NMR and GPC (see GPC trace 8 in Figure 1).

[0179] Reaction 9 (inventive - low temperature):

[0180] MMAB (5.6 g, 125 mmol) was added to a two-neck jacketed Schlenk flask under argon atmosphere in the glovebox. The flask was attached to a circulating cooler which was set to -15 °C, sufficient time was given for the cooler to reach this temperature. The two- neck jacketed Schlenk was attached to an oil bubble to vent the hydrogen produced. Catalyst (II) (65 mg, 0.110 mmol, 0.09 mol%) was dissolved in 12 mL THF, then added to the MMAB with stirring set to 400 rpm. Additionally, 5 equivalents of NFFMe 2 M in THF (3 mL) were added after the catalyst addition. The reaction temperature (-15 °C) was maintained throughout the reaction, until bubbling stopped. When the reaction was completed (H2 production had stopped) an aliquot (0.5 mL) was taken for analysis by1H,31P {1H } andnB NMR spectroscopies. This aliquot was added back into the reaction (no longer taking precautions for the ingress of air) then the reaction mixture poured into pentane (250 mL), and the reaction stirred vigorously to induce polymer precipitation. The white solid was isolated by filtration and remaining volatiles were removed in vacuo. The polymer was analysed by1H,31P {1H } andnB NMR spectroscopies and GPC (see GPC trace 9 in Figure 1).

[0181] Reaction 10 (inventive - slow MMAB addition and low temperature):

[0182] Catalyst (II) (15 mg, 25 pmol) was dissolved in 1 mL THF in a two-neck jacketed Schlenk flask. The flask was attached to a circulating cooler which was set to -15 °C, sufficient time was given for the cooler to reach this temperature. Independently 1.12 g MMAB were dissolved in 10 mL THF, then taken up in two syringes and attached to a syringe pump. 60 pL NH2Me 2 M in THF was added to the catalyst prior to dropwise addition. The slow addition of MMAB was achieved with a syringe pump set to 0.1 mL / min with stirring of the reaction mixture set at 400 rpm. MMAB drop wise addition was performed at an addition rate of 0.25 mmol / min (0.1 mL / min). The reaction temperature (- 15 °C) was maintained throughout the reaction, until bubble formation stopped. When the reaction was completed (H2 production had stopped) an aliquot (0.5 mL) was taken for analysis by1H,31P { H } andnB NMR spectroscopies. This aliquot was added back into the reaction (no longer taking precautions for the ingress of air) then the reaction mixture poured into pentane (150 mL), and the reaction stirred vigorously to induce polymer precipitation. The white solid was isolated by filtration and remaining volatiles were removed in vacuo. The polymer was analysed by1H,31P H} andnB NMR spectroscopies and GPC (see GPC trace 10 in Figure 1).

[0183] Results and Discussion:

[0184] The results of the above reactions 1-10 are displayed in Table 1 below.

[0185] Table 1

[0186]

[0187]

[0188] *Reaction initially set up in air.

[0189] As can be seen from the results in Table 1, reactions 1 and 2 in which higher reaction temperatures are used alongside slow MMAB addition allow for polyaminoboranes to be produced which have lower Mnand Mw, whilst still having a low PDI that is below 2.

[0190] Comparing reactions 3, 4 and 5, which were all conducted at 20 °C, it can be seen that reaction 5 in which slow addition of MMAB was used, produced a polyaminoborane with an Mnthat was around 25000 g / mol higher than the Mnof polymers produced in reactions 3 and 4 where slow MMAB addition was not employed. Similarly, an over 35000 g / mol increase in Mwwas seen for the polymer produced in reaction 5 compared to reactions 3 and 4. However, PDI was surprisingly unaffected, and remained low. Reactions 6 and 7, which are performed at lower temperatures than reaction 5, show that lowering of the reaction temperature acts to further increase Mnand Mwwhilst still keeping PDI low.

[0191] The effect of slow amine borane addition is also seen by comparing reactions 9 and 10, in which slow addition allowed for an around 10000 g / mol increase in Mnand an over 27000 g / mol increase in Mw, whilst still keeping PDI low.

[0192] The above embodiments are described by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims.

Claims

1. CLAIMS1. A method of catalytically dehydropolymerising an amine borane to produce a polyaminoborane, the method comprising the steps of: a. Providing a reaction vessel; and b. Adding a catalyst and an amine borane to the reaction vessel to initiate catalytic dehydropolymerisation of the amine borane, wherein the reaction vessel is maintained at a temperature of between 15 °C and -15 °C throughout the entire dehydropolymerisation.

2. A method as claimed in claim 1 , wherein the reaction vessel is maintained at a temperature of between 0 °C and -15 °C throughout the entire dehydropolymerisation.

3. A method of catalytically dehydropolymerising an amine borane to produce a polyaminoborane, the method comprising the steps of: a. Providing a reaction vessel; and b. Adding a catalyst and an amine borane to the reaction vessel to initiate catalytic dehydropolymerisation of the amine borane, wherein the reaction vessel is maintained at a temperature of between 30 °C and 55 °C throughout the entire dehydropolymerisation.

4. A method as claimed in any preceding claim, wherein step (b) comprises the step of adding at least a portion of the amine borane to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min.

5. A method of catalytically dehydropolymerising an amine borane to produce a polyaminoborane, the method comprising the steps of: a. Providing a reaction vessel; and b. Adding a catalyst and an amine borane to the reaction vessel to initiate catalytic dehydropolymerisation of the amine borane, wherein at least a portion of the amine borane is added to the reaction vessel at an addition rate of between 0.05-5.00 mmol / min.

6. A method as claimed in claim 4 or 5, wherein the at least a portion of the amine borane that is added to the reaction vessel is added at an addition rate of between 0.10-3.00 mmol / min, preferably between 0.20-2.50 mmol / min.

7. A method as claimed in any one of claims 4 to 6, wherein step (b) comprises adding all of the amine borane to the reaction vessel at said addition rate.

8. A method as claimed in any one of claims 4 to 6, wherein step (b) comprises first adding the catalyst and a first portion of the amine borane to the reaction vessel, and then adding the remainder of the amine borane to the reaction vessel at said addition rate.

9. A method as claimed in claim 8, wherein at least 85 mol% of the amine borane is added to the reaction vessel at said addition rate after adding the catalyst and the first portion of the amine borane.

10. A method as claimed in any one of claims 4 to 9, wherein the at least a portion of the amine borane that is added to the reaction vessel at said addition rate is added to the reaction vessel over a total time period of between 60-500 mins.

11. A method as claimed in any one of claims 5 to 10, wherein the reaction vessel is maintained at a temperature of between 65 °C and -15 °C throughout the entire dehydropolymerisation.

12. A method as claimed in claim 11, wherein the reaction vessel is maintained at a temperature of between 15 °C and -15 °C, preferably between 0 °C and -15 °C, throughout the entire dehydropolymerisation.

13. A method as claimed in claim 11, wherein the reaction vessel is maintained at a temperature of between 30 °C and 55 °C throughout the entire dehydropolymerisation.

14. A method as claimed in any preceding claim, wherein the temperature of the reaction vessel does not change by greater than 5 °C throughout the entire dehydropolymerisation, and wherein the temperature of the reaction vessel is preferably kept constant throughout the entire dehydropolymerisation.

15. A method as claimed in any preceding claim, wherein at least a portion of the amine borane is added to the reaction vessel dropwise, optionally using a syringe pump.

16. A method as claimed in any preceding claim, wherein the amine borane has a structure of Formula (I), wherein R1is hydrogen and R2is a C1-C5 alkyl, and preferably methyl. ^H17. A method as claimed in any preceding claim, wherein the catalyst comprises a transition metal catalyst, and wherein the transition metal catalyst is preferably independently selected from the group consisting of: a ruthenium catalyst, a rhodium catalyst, an iridium catalyst, a cobalt catalyst, and combinations thereof.

18. A method as claimed in claim 17, wherein the transition metal catalyst is independently selected from the group consisting of: a compound of Formula (II), a compound of Formula (III), a compound of Formula (IV), a compound of Formula (V), and combinations thereof.(IV) (V)19. A method as claimed in claim 18, wherein the transition metal catalyst is a compound of Formula (III), and wherein the reaction vessel contains air when the catalyst is added to the vessel in step (b).

20. A method as claimed in any preceding claim, wherein the method further comprises the step of adding an amine to the reaction vessel, preferably a primary amine.

21. A method as claimed in claim 20, wherein the amine is added to the reaction vessel in a total amount of between 1-50 times the amount of catalyst added to the reaction vessel in step (b).

22. A method as claimed in claim 20 or 21, wherein the amine is added to the reaction vessel immediately after the catalyst is added to the reaction vessel in step (b).

23. A method as claimed in any preceding claim, wherein the dehydropolymerisation reaction is performed in an aprotic solvent, optionally a polar aprotic solvent, optionally comprising tetrahydrofuran.

24. A method of catalytically dehydropolymerising an amine borane to produce a polyaminoborane, the method comprising the steps of: a. Providing a reaction vessel; and b. Adding a catalyst and an amine borane to the reaction vessel to initiate catalytic dehydropolymerisation of the amine borane, wherein the reaction vessel is maintained at a temperature of between 30 °C and 65 °C, excluding 60 °C, throughout the entire dehydropolymerisation.

25. A polyaminoborane obtained or obtainable by the method of any preceding claim.

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