Continuous manufacturing process for high-purity polyhedral oligomeric silsesquioxane compositions

Abstract

A process is disclosed for manufacturing polyhedral oligomeric silsesquioxane (POSS) compounds using a non-methanol solvent that allows the desired product to selectively crystallize while co-formed species remain in solution, thereby enabling isolation without washing. The process may be carried out in a batchwise mode, allowing control over crude product melting point and melt viscosity profiles by adjusting reaction conditions, or in a continuous mode, in which the reaction media is reused and rebalanced to produce POSS at 99% purity. In certain embodiments, ethanol is generated in situ from triethoxysilane hydrolysis, with excess ethanol optionally collected. These methods provide efficient POSS manufacture with tunable intermediate properties and compatibility with continuous operation.

Description

CONTINUOUS MANUFACTURING PROCESS FOR HIGH-PURITY POEYHEDRAE OEIGOMERIC SIESESQUIOXANE COMPOSITIONSInventors: Dr. Sukhendu B. Hait; Mr. Zack Kemp; Mr. Gary Moody;Dr. Joseph D. LichtenhanCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Application No. 63 / 775,712, titled “Continuous Manufacturing Process for High-Purity Polyhedral Oligomeric Silsesquioxane Compositions,” filed March 21, 2025, which is hereby incorporated by reference in its entirety.BACKGROUND

[0002] Polyhedral oligomeric silsesquioxanes (POSS) constitute a family of molecules comprising a silica-like core surrounded by a shell of organic groups. The chemical composition of POSS represents a hybrid intermediate between that of silica (SiO2) and silicone (R2SiO). Silsesquioxane is the IUPAC name for a range of polycyclic compounds consisting of a hydrocarbon, a silicon, and an average of 1.5 oxygen atoms. The nomenclature derives from siloxane, where "sil" denotes silicon, "sesqui" (Latin meaning one and a half) combined with "oxane" denotes an average of 1.5 oxygens per silicon atom, and "ane" denotes that each silicon is also attached to an organic group. The terms "polyhedral" and "oligomeric" describe the rigid three-dimensional shape and topology of these compounds and their intermediate sizes between monomers and polymers.

[0003] Poly silsesquioxanes are materials represented by the formula [RSiOi.5]x where x represents the molar degree of polymerization and R represents an organic substituent, which may include hydrogen, siloxy groups, cyclic, aliphatic, olefinic, or aromatic groups that may additionally contain reactive functionalities such as alcohols, isocyanates, esters, amines, ketones, olefins, ethers, mercapto groups, polyethylene glycol chains, or halides. Polysilsesquioxanes may be either homoleptic or heteroleptic. Homoleptic systems contain a single type of R group while heteroleptic systems contain more than one type of R group distributed in a statistically random manner on the cage structure.1#111408012vl

[0004] Conventional manufacturing approaches for POSS compounds have commonly employed methanol as the reaction medium, in part because it can promote precipitation or crystallization of desired cage products. However, methanol has also been observed to interfere with the intended transformation under certain conditions, thereby functioning as a poisoning agent in practice. This dual role complicates reaction control and contributes to variability in isolation outcomes, particularly the purity of the desired POSS product. Moreover, methanol-based systems have not allowed the reaction media to be effectively reused, as the solvent is typically discarded after each batch due to impurity buildup and solvent-related interference — a limitation that has hindered efforts to develop a viable continuous manufacturing process.

[0005] Conventional batchwise methods typically address the impurity of the desired POSS product through post-isolation washing and additional purification operations, including sublimation, exhaustive extraction, solvent recrystallization, and media filtration. While these techniques can improve purity, they are inherently multi-step and resource-intensive, adding time, cost, and solvent consumption. The challenge is exacerbated by the narrow solubility differences between targeted cage products and co-formed silicon-containing intermediates and byproducts, which limits the effectiveness of simple crystallization-based separations.

[0006] Because conventional methods prioritize post-isolation washing to address purity, less attention has been paid to the inherent, process-dependent properties of the crude material at the point of isolation. However, the melting behavior and melt viscosity of POSS compositions are central to applications in polymer processing. Prior work has generally not recognized that impure, intentionally characterized crude compositions can function as useful, property-defined intermediates, whose melting-point intervals and rheological profiles can be measured, directed, and leveraged to inform and improve subsequent processing steps.

[0007] Accordingly, there remains a need for a manufacturing approach that eliminates complications associated with methanol use, recognizes and leverages the utility of impure, property-defined compositions (including their melting-point and rheological characteristics), and enables reuse of the reaction media to support a continuous process capable of delivering high-purity POSS materials with improved efficiency.2#111408012vlSUMMARY

[0008] The invention disclosed herein is directed to processes for manufacturing polyhedral oligomeric silsesquioxane (POSS) compounds using non-methanol solvent systems that overcome the limitations of methanol-based media and enable selective crystallization of the desired product while retaining other reaction species in solution. The processes may be carried out in batch or continuous modes, allowing operators to tailor crude-product properties — such as melting point and melt viscosity — through adjustment of reaction conditions, or to reuse and rebalance the reaction media over multiple cycles to achieve high-purity output.

[0009] In a particular embodiment exemplifying the principles of the invention, a method of manufacturing polyhedral oligomeric silsesquioxane is disclosed. A reaction medium comprising a non-methanol solvent, a base, and water may be provided. I-butyl trialkoxysilane may then be added into the reaction medium. The i-butyl trialkoxysilane and the reaction medium may then be heated to elicit a condensation reaction. A reaction mixture comrpsigin an alcohol byproduct, one or more silicon-containing intermediates, and one or more i-butyl-substituted polyhedral oligomeric silsesquioxane (POSS) cage compounds may be formed via the condensation reaction. The one or more i-butyl-substituted polyhedral oligomeric silsesquioxane (POSS) cage compounds may then be separated and removed from the reaction mixture. The one or more silicon-containing intermediates and the alcohol byproduct may be retained in the reaction medium after the separating step. The steps may be repeated one or more times, using the reaction medium containing the retained one or more silicon-containing intermediate and the alcohol byproduct.

[0010] In another embodiment exemplifying principles of the present invention, a continuous method of manufacturing polyhedral oligomeric silsesquioxane is disclosed. A reaction medium comprising ethanol, water, and a base many be provided. I-butyl triethoxysilane may be added to the reaction medium. The i-butyl triethoxysilane may be reacted in the reaction medium to form [(i-BuSiO1.5)8]S8, one or more silicon-containing intermediates, and ethanol byproduct. The [fi-BuSiOl ,5)8]Z8 may be crystallized from the reaction medium while the one or more silicon-containing intermediates remain soluble in the reaction medium. The crystallized [(i-BuSiO1.5)8]S8 may be collected via filtration. The reaction medium may be recharged with additional i-butyl triethoxysilane and water. The steps may be repeated to continuously produce [(i-BuSiO1.5)8]S8 at a purity of at least 99%.3#111408012vl

[0011] In yet another embodiment exemplifying the principles of the present invention, a composition comprising an impure solid that includes an i-butyl-substituted polyhedral oligomeric silsesquioxane (POSS) cage compound and one or more silicon-containing intermediates is disclosed. The composition may be characterized by a melting point as determined by differential scanning calorimetry (DSC) that is intentionally adjustable by selection of reaction conditions.

[0012] In yet another embodiment exemplifying the principles of the present invention, a composition comprising an impure solid that includes an i-butyl-substituted polyhedral oligomeric silsesquioxane (POSS) cage compound and one or more silicon-containing intermediates is disclosed. The composition may be characterized by a melt viscosity as determined by rheometry, wherein the melt viscosity is intentionally adjustable by selection of reaction conditions.

[0013] The above summary is not intended to describe each illustrated embodiment or every possible implementation. These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views, which are not true to scale, and which, together with the detailed description below, are incorporated in and form part of the specification, serve to illustrate further various embodiments and to explain various principles and advantages in accordance with the present invention:FIG. 1 depicts a chemical reaction scheme for synthesis of polyhedral oligomeric silsesquioxane compounds from an i-butyl trialkoxysilane precursor, according to aspects of the present disclosure.FIG. 2 depicts the chemical reaction scheme of FIG. 1, conducted with ethanol as the solvent, according to aspects of the present disclosure.FIG. 3 depicts a flowchart for a single batch process method for preparation of POSS cages, according to aspects of the present disclosure.FIG. 4 depicts a flowchart for a double batch process for manufacturing POSS cage compounds, according to aspects of the present disclosure.4#111408012vlFIG. 5 depicts a flowchart for a continuous process for manufacturing POSS cage compounds, according to aspects of the present disclosure.FIG. 6 depicts a graph showing percentage average product yield versus cycle number for recovery of high-purity [(i-BuSiOi.5)s]s8 prepared by the continuous process, according to aspects of the present disclosure.FIG. 7 depicts a differential scanning calorimetry thermogram of high-purity [(i-BuSiOi.5)s]s8 prepared by the continuous process, according to aspects of the present disclosure.FIG. 8 depicts a differential scanning calorimetry thermogram of lower-purity [(i-BuSiOi.5)s]s8 prepared by the batch process, according to aspects of the present disclosure.FIG. 9 depicts a high-performance liquid chromatography chromatogram comparing samples of [(i-BuSiOi.5)s]s8 prepared by the continuous process and the batch process, according to aspects of the present disclosure.FIG. 10 depicts silicon-29 nuclear magnetic resonance spectra comparing low-purity i-butyl POSS compositions prepared by the batch process and high-purity i-butyl POSS compositions prepared by the continuous process, according to aspects of the present disclosure.FIG. 11 depicts a graph showing a complex viscosity profile for high-purity [(i-BuSiOi.5)s]s8 prepared by the continuous process as a function of angular frequency, according to aspects of the present disclosure.FIG. 12 depicts a graph showing complex viscosity profiles for i-butyl POSS cage mixture compositions prepared by the batch process as a function of shear rate, according to aspects of the present disclosure.FIG. 13 depicts representative cage compositions of polyhedral oligomeric silsesquioxanes showing melting, solubility, and use characteristics, according to aspects of the present disclosure.FIG. 14 depicts a graph showing heteroleptic composition viscosity profiles relative to temperature, according to aspects of the present disclosure.DETAILED DESCRIPTION

[0015] Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which 5#111408012vlcan be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Alternate embodiments may be devised without departing from the spirit or the scope of the invention. Further, the terms and phrases used herein are not intended to be limiting; but rather, to provide an understandable description of the invention. While the specification concludes with claims defining the features of the invention that are regarded as novel, it is believed that the invention will be better understood from a consideration of the following description in conjunction with the drawing figures, in which like reference numerals are carried forward.

[0016] As used herein, the terms “a” or “an” are defined as one or more than one. The term “plurality,” as used herein, is defined as two or more than two. The term “another,” as used herein, is defined as at least a second or more. The terms “comprises,” “comprising,” or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but may include, other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “comprises” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. The terms “including,” “having,” or “featuring,” as used herein, are defined as comprising (i.e., open language). The term “coupled,” as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically. As used herein, the term “about” or “approximately” applies to all numeric values, whether or not explicitly indicated. These terms generally refer to a range of numbers that one of skill in the art would consider equivalent to the recited values (i.e., having the same function or result). In many instances these terms may include numbers that are rounded to the nearest significant figure. Relational terms such as first and second, top and bottom, right and left, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. As used herein, the term “cycle” refers to a sequence within a continuous manufacturing process that includes introduction of additional organosilane into a retained reaction medium, formation of additional polyhedral oligomeric silsesquioxane (POSS) cage compounds, and separation of the formed POSS product, while the reaction medium remains in continuous or semi-continuous use. Although the process may 6#111408012vlinvolve multiple cycles, the overall manufacturing operation constitutes a single continuous process.

[0017] Polysilsesquioxanes may be represented by the formula [RSiOi.5]x where x represents the molar degree of polymerization and R represents an organic substituent. The organic substituent R may include hydrogen, siloxy groups, cyclic groups, aliphatic groups, olefinic groups, or aromatic groups. These organic substituents may additionally contain reactive functionalities such as alcohols, isocyanates, esters, amines, ketones, olefins, ethers, mercapto groups, polyethylene glycol groups, or halides. Polysilsesquioxanes may be either homoleptic or heteroleptic. Homoleptic systems contain one type of R group while heteroleptic systems contain more than one type of R group distributed in a statistically random manner on the cage.

[0018] POSS nanostructure compositions may be represented by the formula [(RSiOi.5)n]s# for homoleptic compositions and [(RSiOi.5)n(R'SiOi.5)m]s# for heteroleptic compositions, where R is different from R'. The symbols m and n refer to the stoichiometry of the composition. The symbol S indicates that the composition forms a well-defined nanostructure and the symbol # refers to the number of silicon atoms contained within the nanostructure. The value for # is the sum of m+n, where n may range from 1 to 24 and m may range from 1 to 12. The symbol S# describes the overall nanostructural characteristics of the system, also referred to as cage size, and is not a multiplier for determining stoichiometry.

[0019] The invention disclosed herein is directed to processes for manufacturing polyhedral oligomeric silsesquioxane (POSS) that eliminate the use of methanol to address the longstanding limitations of methanol-based media. Instead, the process employs a nonmethanol solvent that enables formation and crystallization of the desired POSS product while retaining co-formed intermediates and byproducts in solution, thereby permitting isolation of the desired POSS product without washing or further post-reaction processing. Although methanol is undesirable within the system, the process can still be practiced with methanolgenerating reactants provided that the selected solvent is non- azeotropic with methanol so that the methanol can be removed during operations.

[0020] In some embodiments, the disclosed process may be carried out in a batchwise manner, wherein the reaction is allowed to proceed for a selected duration and is then stopped to permit isolation of the product. Conducting the process in this way enables the operator to7#111408012vlintentionally direct the composition of the crude solid that is obtained following removal of the reaction medium. Because the relative amounts of the desired POSS compound and residual silicon-containing intermediates vary in response to reaction conditions — such as solvent composition, temperature, reactant ratios, and residence time — the melting-point range and melt-viscosity profile of the isolated solid can be selectively controlled by appropriately adjusting these parameters. This batchwise mode therefore provides a means to obtain property-defined intermediates whose thermal and rheological characteristics are tailored through control of the reaction itself.

[0021] In some embodiments, the disclosed process may be carried out in a continuous manner, in which the reaction medium is retained within the system and repeatedly cycled while fresh reactants are introduced. Because non-methanol solvent systems — such as ethanol — retain silicon-containing intermediates and byproducts in solution while permitting selective crystallization of the octameric cage compound, the medium can be rebalanced and recharged over multiple cycles without degradation. Conducting the process in this way enables the reaction media to be reused rather than discarded, maintaining a stable solvent environment and supporting formation of the desired POSS product at 99% purity. This continuous mode therefore provides a means to increase functional yield as the system approaches steady-state operation, with soluble intermediates being progressively converted in subsequent passes. The continuous process also remains compatible with ethanol-generating reactants, and the ethanol formed in situ sustains the reaction while any excess ethanol can be collected as a valuable item of commerce.

[0022] Accordingly, the present ethanol-based approach provides a means to eliminate complications associated with methanol use, recognize and leverage impure, property -defined intermediates whose melting-point and melt- viscosity profiles are tunable via process controls, and enable continuous manufacture while maintaining high product quality and process efficiency.

[0023] Herein various embodiments of the present invention are described. To avoid redundancy, repetitive description of similar features may not be made in some circumstances.

[0024] Referring to FIG. 1, a chemical reaction scheme depicts the synthesis of polyhedral oligomeric silsesquioxane compounds from an i-butyl trialkoxysilane precursor. The starting material comprises an i-butyl group bonded to a silicon atom, which is further bonded to three8#111408012vlalkoxy groups designated as OR, where R may be methyl or ethyl. The reaction proceeds in the presence of a solvent, a catalytic base, and water, with the release of an alcohol byproduct designated as ROH.

[0025] With continued reference to FIG. 1, the chemical reaction may generate multiple product types including cage structures of varying silicon atom counts. The S notation following each product formula indicates the total number of silicon atoms in each cage structure. A homoleptic octameric cage compound having the formula [(i-BuSiOi.5)s]s8 contains eight silicon atoms. A homoleptic decameric cage compound having the formula [(i-BuSiOi.5)io]sio contains ten silicon atoms. A homoleptic dodecameric cage compound having the formula [(i-BuSiOi.5)i2]si2 contains twelve silicon atoms. The process may be adjusted to prepare cages that comprise a distribution of silicon-cage sizes including eight, ten, twelve, fourteen, and higher silicon atoms. A heteroleptic cage compound having the formula [(i-BuSiOi.5)m(i-BuHOSiOi)n]s(m+n) may also be formed, where the heteroleptic cage compound contains a total of m plus n silicon atoms distributed within the cage framework.

[0026] Having described the reaction chemistry in general terms, reference is now made to FIG. 2, which illustrates an embodiment of the reaction conducted in ethanol. Although conventional methanol-based approaches assumed that methanol would promote precipitation or crystallization of the desired product, it has been observed that methanol can act as a poisoning agent under the reaction conditions. Ethanol, by contrast, provides a solvent environment that maintains the higher cage structures and resin byproducts in solution while enabling crystallization of the octameric cage compound [(i-BuSiOi.5)s]s8, allowing for isolation of the octameric cage compound [(i-BuSiOi.5)s]s8 and re-use of the reaction media.

[0027] As shown in FIG. 2, the chemical reaction may include i-butyl triethoxysilane reacting with water in the presence of a base catalyst, releasing ethanol as a byproduct, to form an octameric POSS cage structure having the formula [(i-BuSiOi.5)s]s8. The octameric POSS structure comprises a three-dimensional cage with silicon atoms at the vertices connected by oxygen bridges, with i-butyl groups attached to each silicon atom. The reaction also produces silicon-containing intermediates such as higher cages and resin which remain soluble in ethanol.9#111408012vl

[0028] The reaction shown in FIG. 2 may utilize alternative solvent media in addition to ethanol. C2 and higher alcohols, ethers including dioxane, ketones, or carbonates may be utilized as a solvent medium provided the solvent medium solubilizes the silicon-containing intermediates and affords crystallization of the octameric cage compound [(i-BuSiOi.5)s]s8. The selection of solvent medium may be based on the solubility characteristics that permit the octameric cage compound to crystallize from the reaction medium while higher cage structures and silicon-containing intermediates remain dissolved.

[0029] A wide range of bases can be used in the process illustrated in FIG. 2, including but not limited to: hydroxide, alkoxide, carboxylate, amides, imides, carboxamides, carbanions, carbonate, sulfate, phosphate, biphosphate, phosphorus ylides, nitrate, borate, cyanate, fluoride, hypochlorite, silicate, stannate, basic metal oxide, amines, amine oxides, and organometallics.

[0030] In other embodiments, the chemical reaction may utilize methoxy-containing i-butyl silanes with the ethanol reaction medium. During the hydrolysis of i-butyl trimethoxysilane, methanol is generated as a byproduct. Methanol- generating reagents such as i-butyl-trimethoxysilane may be utilized in conjunction with solvents that do not form methanol azeotropes, thereby allowing for the removal of methanol from the cage assembly process. High boiling solvents such as dioxane, dimethylsulfoxide, and dimethylformamide are non-azeotropic with methanol and do not readily solubilize the desired octameric cage compound [(i-BuSiOi.5)s]s8. The selection of non-azeotropic solvents may permit the separation of methanol from the reaction medium during the manufacturing process while maintaining the solubility characteristics that favor crystallization of the targeted octameric product.

[0031] Referring to FIG. 3, a flowchart illustrates a single batch process method for preparation of POSS cages. The process begins with an initial start-up phase that involves the addition of several components to a reaction vessel, including solvent, silane, water, and base. These components are combined and directed into a stirred and refluxed reaction vessel where the cage assembly reaction takes place. The reaction vessel operates under stirring and reflux conditions to facilitate the condensation reaction for POSS cage formation.

[0032] With continued reference to FIG. 3, following the reaction, the process proceeds to product collection and removal, which may be accomplished via two alternative methods:10#111408012vlfiltration or evaporation of the reaction medium. After product isolation, the reaction medium is directed to disposal. The flowchart depicts a linear process flow characteristic of batch manufacturing, where the reaction medium is used once and then discarded rather than being recycled for subsequent production cycles. The process may be utilized as a batch method by stopping the reaction, discarding the reaction media, and isolating the product after one run.

[0033] This single batch approach produces a crude product composition that is dependent upon the specific process conditions employed, including solvent type, concentrations, temperature, and base type. The crude product composition is an impure solid comprising the octameric cage compound [(i-BuSiOi.5)s]s8 together with higher cage structures or silicon-containing intermediates. Although the reaction media is removed prior to isolation of the crude material, it has been found that the manner in which the reaction is conducted — including the use of ethanol as the solvent — affects the physical properties of the resulting crude product composition. In particular, the crude material exhibits a melting-point range and melt- viscosity profile that are responsive to the reaction conditions and can be intentionally adjusted.

[0034] Referring to FIG. 4, a flowchart illustrates a double batch process for manufacturing POSS cage compounds. The process begins with an initial start-up phase, which involves the addition of solvent, silane, water, and base to establish the reaction medium. From the initial start-up phase, the process proceeds to a first stirred and refluxed reaction vessel where the condensation reaction occurs. The first reaction vessel includes a product collection step where the product is collected and removed via filtration.

[0035] With continued reference to FIG. 4, the process then continues to a recharge step where consumed ingredients, specifically silane and water, are replenished. The recharged reaction medium flows to a second stirred and refluxed reaction vessel where additional reaction occurs. The second reaction vessel similarly includes a product collection step where product is collected and removed via filtration. Following the second batch run, the process concludes with reaction medium disposal. The flowchart demonstrates a sequential two-run approach where the reaction medium is utilized twice before being discarded, with product isolation occurring after each reaction run through filtration.

[0036] The double-batch process yields the octameric cage compound [(i-BuSiOi.5)s]Ss at about 97% purity, while trace higher-order cages or other silicon-containing intermediates may remain due to entrainment through successive filtration steps. The composition and resulting physical behavior of the isolated solid are influenced by how the two stages are executed —11#111408012vle.g., temperature setpoints, concentration profiles, and solvent selection. In particular, employing ethanol during the reaction alters the impurity profile of the octameric cage compound [(i-BuSiOi.5)s]Ss such that the melting-point interval and melt-viscosity characteristics of the product can be directed to desired ranges.

[0037] FIG. 5 illustrates an embodiment of a continuous process flow for manufacturing the octameric cage compound [(i-BuSiOi.5)s]Ss. In the start-up phase, solvent, silane, water, and base are introduced into the system. The amount of base may be sufficient to establish a basic reaction medium having a pH of approximately 8.1 to 14. Water may be supplied in an amount that provides the oxygen stoichiometry required for formation of the cage structure. The organosilane feed may be delivered uniformly over a period of about two hours. These components enter a reaction vessel, where the reaction medium may be stirred and heated to a temperature adequate to promote the condensation reaction, typically within a range from 24 °C to 101 °C.

[0038] As shown in FIG. 5, the reaction mixture proceeds from the reaction vessel to an in-line collection step in which the product is isolated by filtration. The octameric cage compound [(i-BuSiOi.5)s]Ss may be obtained using filtration equipment such as in-line filters or filter-dryers. This single-step isolation method avoids the additional purification operations or disposal requirements associated with batch-based techniques such as sublimation, exhaustive liquid-liquid extraction, solvent recrystallization, or post-reaction media filtration.

[0039] As further shown in FIG. 5, an optional slip-stream of soluble components may be removed from the circulating reaction medium and directed to a separate operation for manufacturing silanol-functional POSS materials. Following removal of this stream, the reaction medium may be replenished with consumed components, including silane and water, and returned to the reaction vessel, thereby maintaining the continuous cycle.

[0040] In certain embodiments, the concentrations of reactants may be controlled within ranges effective for maintaining reaction performance. For example, the silane concentration may range from about 2 M to 0.2 M, with a preferred range from about 1.1 M to 0.9 M. The water concentration may range from about 5 M to 0.5 M, with a preferred range from about 4 M to 3.75 M. The base concentration may range from about 0.25 M to 0.1 M, with a preferred range from about 0.6 M to 0.46 M. These concentrations may be maintained during continuous operation by appropriate adjustment of feed streams and recycle flows.12#111408012vl

[0041] The continuous process may be operated under reflux conditions. As the reaction proceeds, ethanol may be produced in situ through hydrolysis of i-butyl triethoxysilane. The ethanol generated in this manner maintains the solubility of silicon-containing intermediates while enabling crystallization and subsequent isolation of the octameric cage compound [(i-BuSiOi.5)s]Ss. To maintain an appropriate balance between solubility and precipitation, ethanol may be removed during operation to regulate the concentration of silicon-containing intermediates. When ethanol levels become excessively dilutive, excess solvent may be withdrawn via reflux to restore the desired composition of the reaction medium.

[0042] The continuous process not only affords the octameric cage compound [(i-BuSiOi.5)s]Ss at 99% purity but also exhibits progressively higher product yields as the system advances toward steady-state conditions. As the reaction medium is recycled and recharged over successive cycles, the composition of soluble silicon-containing intermediates stabilizes, enabling more efficient conversion to the desired octameric cage compound. The result is an increase in overall yield with each addition of organosilane until the process reaches a steady operating regime. Once the process reaches steady-state conditions, the process can proceed with continuous addition of organosilane, continuous recycling of the reaction media, and continuous filtration of the [(i-BuSiOi.5)s]Ss at 99% purity.

[0043] Referring to FIG. 6, a line graph depicts the percentage average product yield versus cycle number for the recovery of 99% pure [(i-BuSiOi.5)s]s8 from successive additions of i-butyl triethoxysilane via the continuous manufacturing process. The vertical axis represents the percentage average product yield ranging from approximately 40% to 100%, while the horizontal axis represents the continuous cycle number from the first cycle through the eighth cycle.

[0044] With continued reference to FIG. 6, the graph displays a curve that begins at approximately 41% yield at the first cycle. The yield increases progressively through subsequent cycles as the continuous process reaches steady-state conditions. The yield rises to approximately 60% at the second cycle, approximately 70% at the third cycle, and approximately 80% at the fourth cycle. A 90% yield of [(i-BuSiOi.5)s]s8 is reached by the fifth cycle.

[0045] As further shown in FIG. 6, the curve plateaus after the fifth cycle, maintaining approximately 90% yield through the sixth cycle before showing a slight increase to13#111408012vlapproximately 91% at the seventh cycle. The steady-state yield of approximately 90% or greater achieved by the fifth cycle may be maintained through subsequent cycles. The reaction media remains suitable for reuse in subsequent cycles while producing product at 99% purity. The [(i-BuSiOi.5)s]s8 isolated from each cycle may exhibit 99% purity, and the reaction media may be recharged with additional i-butyl triethoxysilane for the next cycles without degradation of the reaction medium or reduction in product purity.

[0046] The progressive increase in yield from approximately 41% at the first cycle to approximately 90% by the fifth cycle may be attributed to the accumulation of silicon-containing intermediates in the reaction medium. As the continuous process proceeds through successive cycles, the concentration of higher cage structures and hydroxylated oligomers in the reaction medium may increase. These silicon-containing intermediates may be converted into the octameric cage compound [(i-BuSiOi.5)s]s8 during subsequent reaction cycles, thereby contributing to the increased yield observed in later cycles. The solubility of the silicon-containing intermediates in the ethanol-based reaction medium may permit their retention and subsequent conversion while the octameric cage compound crystallizes and is removed via filtration.

[0047] The ASTM E928-19 method was utilized to assess the thermal transitions of the 99% purity [(i-BuSiOi.5)s]s8 from the continuous method and the process-dependent compositions from the single- and double-batch method.

[0048] Referring to FIG. 7, a differential scanning calorimetry (DSC) thermogram depicts the thermal behavior of high-purity [(i-BuSiOi.5)s]s8 prepared by the continuous process. The horizontal axis represents temperature in degrees Celsius, ranging from approximately -50°C to 300°C. The vertical axis represents heat flow in watts per gram (W / g), ranging from approximately -2.0 to 0.5. The thermogram displays two distinct endothermic peaks appearing as downward deflections from the baseline.

[0049] With continued reference to FIG. 7, a first endothermic transition occurs at an onset temperature of approximately 60.08°C and exhibits a peak minimum at 61.40°C. This first thermal transition has an associated enthalpy of 18.65 J / g. This lower temperature transition may be attributed to changes in the molecular conformation of the isobutyl groups and their crystalline habitat.14#111408012vl

[0050] As further shown in FIG. 7, a second endothermic transition occurs at an onset temperature of approximately 264.03°C and exhibits a peak minimum at 267.49°C. This second thermal transition has an associated enthalpy of 37.61 J / g. The second endothermic peak corresponds to the melting behavior of the [(i-BuSiOi.5)s]s8 compound.

[0051] The high-purity [(i-BuSiOi.5)s]s8 shows sharp thermal transition maxima at 61.40°C and 267.49°C as measured by DSC. The sharpness of these thermal transitions provides evidence of the 99% or greater purity level achieved by the continuous process. In contrast to lower-purity material prepared by batch processes, which exhibits broader thermal transitions and depressed melting points, the high-purity compound prepared by the continuous process exhibits well-defined thermal behavior with maximal thermal temperature values at each transition.

[0052] Referring to FIG. 8, a differential scanning calorimetry (DSC) thermogram depicts the thermal behavior of lower-purity [(i-BuSiOi.5)s]s8 prepared by the batch process. The graph plots heat flow in watts per gram on the vertical axis against temperature in degrees Celsius on the horizontal axis, with the temperature range extending from approximately -50°C to 300°C. The thermogram displays an initial decrease in heat flow from approximately 0.6 W / g at -50°C, followed by a gradual stabilization through the lower temperature region.

[0053] With continued reference to FIG. 8, a first endothermic peak appears at 53.69°C with an associated enthalpy of 16.26 J / g. The onset temperature for this first thermal transition is indicated at 49.51 °C. This lower temperature transition may be attributed to changes in the molecular conformation of the isobutyl groups and their crystalline habitat, similar to the conformational transition observed in high-purity material. However, the peak temperature of 53.69°C is lower than the corresponding transition at 61.40°C observed in high-purity [(i-BuSiOi.5)s]s8 prepared by the continuous process.

[0054] As further shown in FIG. 8, the heat flow remains relatively stable through the intermediate temperature range from approximately 100°C to 200°C. A second endothermic peak occurs at 266.30°C with an associated enthalpy of 34.78 J / g. The onset temperature for this second thermal transition is indicated at 259.63°C. This second endothermic peak corresponds to the melting behavior of the [(i-BuSiOi.5)s]s8 compound.15#111408012vl

[0055] The thermal transitions observed in the lower-purity batch process material exhibit broader peak profiles compared to the sharp, well-defined peaks observed in high-purity material prepared by the continuous process. The broader thermal transition maxima at 53.69°C and 266.30°C in the batch process material contrast with the sharper thermal transition maxima at 61.40°C and 267.49°C observed in the high-purity continuous process material.

[0056] The presence of higher cage structures such as decameric, dodecameric, and tetradecameric cage compounds, as well as ill-defined silicon species, within the batch-manufactured [(i-BuSiOi.5)s]s8 composition may contribute to the observed melting point depression and broader thermal transitions. These silicon-containing byproducts may become entrained or co-crystallized with the octameric cage compound during the filtration step of the batch process, resulting in a composition with reduced purity compared to material prepared by the continuous process.

[0057] The enthalpy values associated with the thermal transitions in the lower-purity batch process material are also reduced compared to the high-purity continuous process material. The first thermal transition in the batch process material exhibits an enthalpy of 16.26 J / g compared to 18.65 J / g for the corresponding transition in the high-purity material. The second thermal transition in the batch process material exhibits an enthalpy of 34.78 J / g compared to 37.61 J / g for the corresponding melting transition in the high-purity material. These reduced enthalpy values may reflect the presence of impurities that disrupt the crystalline structure of the octameric cage compound.

[0058] Chromatographic analysis provides an additional method for assessing product purity beyond differential scanning calorimetry. Referring to FIG. 9, a high-performance liquid chromatography (HPLC) chromatogram compares two samples of [(i-BuSiOi.5)s]s8 prepared by different manufacturing processes. The vertical axis represents normalized intensity ranging from 0 to approximately 500, while the horizontal axis represents retention time in minutes ranging from 13 to approximately 20 minutes. A first trace corresponds to lower-purity [(i-BuSiOi.5)s]s8 prepared by a batch process, and a second trace corresponds to high-purity [(i-BuSiOi.5)s]s8 prepared by a continuous process.

[0059] With continued reference to FIG. 9, both traces exhibit a primary peak at approximately 17.5 minutes retention time, corresponding to the octameric cage compound [(i-BuSiOi.5)s]s8. Both traces show a peak height of approximately 505 normalized units at this 16#111408012vlretention time. The similarity in peak height at the primary elution time indicates that both samples contain the octameric cage compound as the predominant species.

[0060] As further shown in FIG. 9, the first trace displays an additional peak at approximately 16.5 minutes retention time with a peak height of approximately 115 normalized units. This additional peak corresponds to i-butyl silicon intermediates present in the batch-manufactured material. The first trace also shows a smaller peak at approximately 17 minutes retention time with a peak height of approximately 25 normalized units. This smaller peak corresponds to larger sized i-butyl cages, specifically decameric and dodecameric species having the formulas [(i-BuSiOi.5)io]sio and [(i-BuSiOi.5)i2]si2, produced via the batch process.

[0061] The second trace exhibits a single sharp peak without the additional intermediate peaks observed in the red trace. The absence of peaks at approximately 16.5 minutes and 17 minutes retention time in the first trace demonstrates the higher purity achieved through the continuous manufacturing process. The single sharp elution profile of the second trace indicates that the continuous process produces [(i-BuSiOi.5)s]s8 with minimal contamination from silicon-containing intermediates such as larger cage structures.

[0062] The breadth and number of peaks in the elution profiles may be used to distinguish between high-purity material prepared by the continuous process and lower-purity material prepared by batch processes. The presence of multiple elution peaks in the batch-manufactured material correlates with the broader thermal transitions and depressed melting points observed in the DSC analysis of the same material.

[0063] 29Si NMR analysis provides a complementary method for assessing product purity in addition to differential scanning calorimetry and high-performance liquid chromatography. Referring to FIG. 10, two silicon-29 nuclear magnetic resonance (29Si NMR) spectra compare low-purity and high-purity i-butyl POSS compositions. The horizontal axis represents chemical shift in parts per million ranging from -56 ppm to -79 ppm. The upper spectrum corresponds to a high-purity [(i-BuSiOi.5)s]s8 labeled as Pure Compound i-Butyl POSS and displays a single sharp peak at approximately -67 ppm. The lower spectrum corresponds to a low-purity [(i-BuSiOi.5)s]s8 labeled as i-Butyl Composition Mixture of Cages and displays multiple peaks across the chemical shift range from approximately -60 ppm to -70 ppm.17#111408012vl

[0064] With continued reference to FIG. 10, the high-purity [(i-BuSiOi.5)s]s8 shows a sharp single product peak at 6 = -67.1 ppm in CeDe as measured by29Si NMR. The sharpness and singularity of this peak indicates that the silicon atoms within the octameric cage structure occupy equivalent chemical environments. The presence of a single resonance at this chemical shift is characteristic of a homoleptic octameric cage compound wherein all eight silicon atoms are bonded to identical i-butyl organic substituents and are connected through equivalent Si-O-Si linkages within the cage framework.

[0065] As further shown in FIG. 10, the lower spectrum corresponding to the i-Butyl Composition Mixture of Cages exhibits multiple peaks with notable resonances appearing near -61 ppm, -66 ppm, -67 ppm, -68 ppm, and -69 ppm. The presence of multiple peaks in the lower spectrum indicates the presence of various cage structures and reaction byproducts characteristic of batch-manufactured material. These additional resonances may arise from decameric, dodecameric, and tetradecameric cage compounds, as well as from ill-defined hydroxylated oligomers and silicon-containing intermediates that remain in the batch-manufactured composition.

[0066] The contrast between the single sharp peak in the upper spectrum and the multiple peaks in the lower spectrum illustrates the difference in purity between high-purity product manufactured via the continuous process and lower-purity product containing a mixture of cage sizes and other silicon-containing intermediates. The spectroscopic distinction between high-purity and lower-purity [(i-BuSiOi.5)s]s8 compositions correlates with the thermal and chromatographic differences observed between materials prepared by continuous and batch manufacturing processes.

[0067] A phenomenon similar to melting point depression may be operative upon the viscous and viscoelastic characteristics of POSS. Referring to FIG. 11, a graph depicts the complex viscosity profile for high-purity [(i-BuSiOi.5)s]s8 heated to 305°C as a function of angular frequency. The vertical axis represents complex viscosity in Pascal- seconds, ranging from 0 to approximately 12000 Pa-s. The horizontal axis represents angular frequency in radians per second, ranging from approximately 0 to 50 rad / s. The graph displays a curve with data points connected by a line, where the curve exhibits a characteristic decrease in complex viscosity as angular frequency increases.18#111408012vl

[0068] With continued reference to FIG. 11, at low angular frequencies nearing 0 rad / s, the complex viscosity reaches values of approximately 11000-12000 Pa-s. As the angular frequency increases, the complex viscosity decreases, demonstrating shear-thinning behavior characteristic of the high-purity [(i-BuSiOi.5)s]s8 compound in the molten state. The viscosity drops to approximately 6700 Pa-s at around 2 rad / s, then to approximately 3800 2200 Pa-s at around 3 rad / s, and continues to decrease to approximately 2200 Pa-s at around 6 rad / s.

[0069] As further shown in FIG. 11, the curve continues to decline at higher frequencies, reaching approximately 1400 Pa-s at around 10 rad / s, approximately 1000 Pa-s at around 17 rad / s, approximately 600 Pa-s at around 33 rad / s, and approaching values near 200-400 Pa-s at frequencies above 40 rad / s. The high-purity [(i-BuSiOi.5)s]s8 heated to 305°C shows a relatively linear viscoelastic range over the 20-50 rad / s frequency range. This relatively linear viscoelastic behavior over the 20-50 rad / s range indicates that the compound may be amenable to viscous mixing during compounding operations.

[0070] The viscosity of the high-purity [(i-BuSiOi.5)s]s8 compound in the molten state at 305°C may be lower than that of most thermoplastics. The [(i-BuSiOi.5)s]s8 may be used as a rheological flow additive, also referred to as a diluent, for polyolefins and related polymers during melt compounding. The addition of the high-purity [(i-BuSiOi.5)s]s8 compound during compounding may produce a rheological diluative effect. The melting point of the high-purity [(i-BuSiOi.5)s]s8 compound at approximately 267°C falls within the 200-300°C range at which commodity, engineering, and higher performance thermoplastics melt or begin to melt, thereby allowing the compound to melt at polymer processing temperatures and provide low viscosity during melt processing operations.

[0071] Referring to FIG. 12, a graph depicts the complex viscosity profile for processdependent i-butyl POSS cage mixture compositions as a function of shear rate. The vertical axis represents viscosity q in units of Pa-s, ranging from approximately -10 to 60 Pa-s. The horizontal axis represents shear rate y in units of 1 / s, ranging from 0 to 100 1 / s. Four data series are presented corresponding to measurements at different temperatures including 25°C, 50°C, 100°C, and 190°C.

[0072] With continued reference to FIG. 12, the i-Butyl POSS Cage Mixture at 25°C exhibits the highest viscosity values among the four temperature conditions. At low shear rates,19#111408012vlthe viscosity starts at approximately 65 Pa-s and decreases in a shear-thinning manner to approximately 2 Pa- s at high shear rates. The pronounced shear-thinning behavior observed at 25°C indicates that the process-dependent composition exhibits non-Newtonian flow characteristics at this temperature.

[0073] As further shown in FIG. 12, the i-Butyl POSS Cage mixture at 50°C displays relatively constant viscosity values of approximately 7 Pa-s across the shear rate range with a slight decrease at higher shear rates. The i-Butyl POSS Cage Mixture at 100°C shows viscosity values of approximately 1 Pa-s that remain relatively constant across the measured shear rate range. The i-Butyl POSS Cage Mixture at 190°C exhibits the lowest viscosity values near 0 Pa-s across the entire shear rate range. The compositions at higher temperatures display more Newtonian-like behavior with relatively constant viscosity across the shear rate range.

[0074] The process-dependent compositions from batch methods show lower viscosity profiles at lower temperatures than the high-purity compound [(i-BuSiOi.5)s]s8. The high-purity compound heated to 305°C as shown in FIG. 11 exhibits viscosity values ranging from approximately 12000 Pa-s at low frequencies to approximately 100-200 Pa-s at higher frequencies. In contrast, the process-dependent i-butyl POSS cage mixture compositions exhibit viscosity values below 65 Pa-s even at 25°C, which is substantially lower than the viscosity of the high-purity compound at 305°C.

[0075] The inclusion of higher cage structures and ill-defined silicon species into the [(i-BuSiOi.5)s]s8 compositions may reduce both melting point and viscosity. The processdependent compositions containing decameric, dodecameric, tetradecameric, and higher cage structures, as well as hydroxylated oligomers, may exhibit depressed melting points and reduced viscosity compared to the high-purity octameric cage compound.

[0076] The lower viscosity profiles of the process-dependent compositions at lower temperatures may be of utility for applications involving thermoplastics that melt at the lower temperature end of the 200-300°C range. Polyvinyl chloride (PVC), copolymers of polyolefins, and hot melt adhesives may benefit from the use of process-dependent i-butyl POSS compositions that exhibit low viscosity at temperatures below the melting point of the high-purity [(i-BuSiOi.5)s]s8 compound. The ability to adjust melting point and viscosity characteristics through control of the manufacturing process conditions may provide flexibility20#111408012vlin tailoring the rheological properties of i-butyl POSS compositions for specific polymer processing applications.

[0077] The continuous process may be amenable to the manufacture of heteroleptic cages bearing i-butyl groups and small molar amounts of different silanes. Heteroleptic cages may be manufactured by controlling the stoichiometry of two or more silane coupling agent feedstocks utilized in the continuous process. The silane coupling agent feedstocks may include vinyl silanes, octyl silanes, i-octyl silanes, phenyl silanes, and methyl silanes in addition to i-butyl silanes. The molar ratios of the different silane feedstocks may be adjusted to produce heteroleptic cages with targeted compositions and corresponding physical properties. Heteroleptic cages are analogous to polyolefin copolymers and terpolymers such as those formed between ethylene and octene, wherein the different organic functionalities are distributed in a statistically random manner on the cage structure. Whilst the formation of heteroleptics via a continuous process is feasible, care must be taken to ensure the solubility characteristics of the heteroleptic POSS are amenable to crystallization and filtration recovery from the reaction medium.

[0078] The selection of silane feedstock combinations and their stoichiometric ratios may be based on the desired melting point, solubility, and functional characteristics of the resulting heteroleptic cage composition. I-butyl heteroleptics containing 1-2 moles of i-octyl, n-octyl, or vinyl melt at a lower temperature than the homoleptic octameric cage compound [(i-BuSiOi.5)s]s8. The incorporation of i-octyl, n-octyl, or vinyl substituents into the i-butyl cage framework may disrupt the crystalline packing of the cage molecules, thereby reducing the melting point compared to the homoleptic i-butyl composition. The longer alkyl chains of i-octyl and n-octyl substituents may introduce conformational flexibility that reduces intermolecular interactions within the crystalline structure. In contrast, i-butyl heteroleptics containing 1-2 moles of phenyl or methyl melt at a higher temperature than the homoleptic octameric cage compound [(i-BuSiOi.5)s]s8. The phenyl substituents may contribute to increased intermolecular interactions through aromatic stacking effects, while the smaller methyl substituents may permit tighter crystalline packing compared to the branched i-butyl groups. The ability to increase or decrease the melting point of i-butyl-based heteroleptic cages through selection of the second organic functionality provides flexibility in tailoring the thermal properties of POSS compositions for specific applications.21#111408012vl

[0079] Referring to FIG. 13, representative cage compositions of polyhedral oligomeric silsesquioxanes illustrate the relationship between cage structure, organic substituent composition, and physical properties including melting point and solubility. A phenyl homoleptic decamer structure comprises a silica-oxygen cage core with ten silicon atoms, where each silicon atom is bonded to a phenyl group extending outward from the cage. The phenyl homoleptic decamer exhibits a melting point of 364°C and minimal solubility. The high melting point of the phenyl homoleptic decamer reflects the rigid aromatic character of the phenyl substituents and their contribution to intermolecular interactions within the crystalline structure.

[0080] With continued reference to FIG. 13, a phenyl, methyl, vinyl heteroleptic octamer structure comprises a silica-oxygen cage core with eight silicon atoms bearing a mixture of phenyl groups, methyl groups, and vinyl groups distributed on the cage. The vinyl groups are depicted with double bonds extending from the silicon atoms. The phenyl / methyl / vinyl heteroleptic octamer exhibits a melting point of 150°C, which is substantially lower than the 364°C melting point of the phenyl homoleptic decamer. The heteroleptic octamer also exhibits high solubility and crosslinkable characteristics, and may serve as a compatibilizer for polyolefin blends.

[0081] As further shown in FIG. 13, the comparison between the phenyl homoleptic decamer and the phenyl / methyl / vinyl heteroleptic octamer illustrates how the composition of organic groups on the cage affects the melting point and solubility characteristics of POSS compounds. The heteroleptic composition containing mixed organic functionalities demonstrates a substantially lower melting point than the homoleptic phenyl composition. The presence of multiple different organic substituents on the heteroleptic cage may disrupt the crystalline packing efficiency, thereby reducing the melting point and increasing solubility compared to homoleptic compositions bearing a single type of organic substituent.

[0082] Heteroleptics with 1-3 molar equivalents of vinyl or a related olefin may be suited for use as secondary crosslink points. The vinyl groups present on the heteroleptic cage may participate in crosslinking reactions that can be produced using peroxide cure or electron beam (e-beam) cure. The crosslinking of polyolefins using peroxide or e-beam cure is commonly employed to improve the durability and flammability characteristics of wire coatings. The incorporation of vinyl-containing heteroleptic POSS into polyolefin formulations may provide22#111408012vldiscrete crosslink sites distributed throughout the polymer matrix, where the rigid cage structure serves as a multifunctional crosslink junction.

[0083] Referring to FIG. 14, a graph depicts heteroleptic composition viscosity profiles as a function of temperature for various POSS compositions. The vertical axis represents viscosity r| in Pa-s using a logarithmic scale ranging from 0.01 to 1E+10. The horizontal axis represents temperature T in degrees Celsius ranging from 20.00 to 110.00. Five distinct data series are presented corresponding to different heteroleptic cage compositions.

[0084] With continued reference to FIG. 14, a first data series corresponds to [(PhSiOi.5)2(VinylSiOi.5)6]s8-i4, which is a phenyl / vinyl heteroleptic composition. This phenyl / vinyl heteroleptic exhibits the highest viscosity values among the five compositions, starting near 1E+09 Pa-s at 20°C and decreasing to approximately 50 Pa-s at 110°C. The high initial viscosity of the phenyl / vinyl heteroleptic may be attributed to the aromatic character of the phenyl substituents and their contribution to intermolecular interactions at lower temperatures.

[0085] As further shown in FIG. 14, a second data series corresponds to [(i-octylSiOi.5)i(VinylSiOi.5)7]s8-i4, which is an i-octyl / vinyl heteroleptic composition. This i-octyl / vinyl heteroleptic shows viscosity values beginning around 6000 Pa-s at 20°C and decreasing to approximately 0.7 Pa-s at 110°C. A third data series corresponds to [(i-butylSiOi.5)4(MeSiOi.5)4]s8-!4, which is an i-butyl / methyl heteroleptic composition with equal molar ratios of i-butyl and methyl substituents. This i-butyl / methyl heteroleptic displays viscosity values starting near 4000 Pa- s at 20°C and decreasing to approximately 0.6 Pa- s at 110°C.

[0086] A fourth data series corresponds to [(i-butylSiOi.5)6(MeSiOi.5)2]s8-!4, which is an i-butyl / methyl heteroleptic composition with a higher proportion of i-butyl substituents. This i-butyl / methyl heteroleptic exhibits viscosity values beginning around 50 Pa-s at 20°C and decreasing to approximately 0.5 Pa-s at 110°C. A fifth data series corresponds to [(i-octylSiOi.5)2(hexadecylSiOi.5)6]s8-!4, which is an i-octyl / hexadecyl heteroleptic composition. This i-octyl / hexadecyl heteroleptic shows the lowest viscosity values among the five compositions, starting near 40 Pa- s at 20°C and decreasing to approximately 0.2 Pa- s at 110°C.23#111408012vl

[0087] All five heteroleptic compositions demonstrate decreasing viscosity with increasing temperature. The rate of viscosity decrease varies among the different heteroleptic compositions, with the phenyl / vinyl heteroleptic exhibiting the steepest decrease in viscosity over the measured temperature range. The i-octyl / hexadecyl heteroleptic maintains the lowest viscosity values across the entire temperature range, which may be attributed to the long alkyl chains of the i-octyl and hexadecyl substituents that provide conformational flexibility and reduce intermolecular interactions.

[0088] The incorporation of the octameric cage compound [(i-BuSiOi.5)s]s8 and heteroleptic cages may serve to reduce the interfacial tension between blends of polyolefins with other commodity or engineering resins. Commodity and engineering resins are typically of higher polarity than polyolefins, and the POSS cage structures may act as compatibilizers at the interface between the immiscible polymer phases. The silica-like core of the POSS cage may interact with polar polymer phases while the organic substituents on the cage periphery may interact with nonpolar polyolefin phases, thereby reducing interfacial tension and improving blend compatibility.

[0089] Flow enhancements in polyolefins from the addition of POSS may arise from parts per million (ppm) loading levels wherein the cages access the volume between polymer chain entanglements. The region between polymer chain entanglements is referred to as the polymer web. The POSS cages may penetrate into the polymer web and reduce the number of entanglements or facilitate easier disentanglement of the polymer chains. Fewer entanglements or easier disentanglement of the polymer chains may result in increased rheological flow during melt processing operations. In the case of fibers or blown-film applications, disentanglement of the polymer web may result in higher orientation effects, thereby giving rise to anisotropic properties in the processed polymer articles.

[0090] Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art having the benefit of the teaching presented in the foregoing description and associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.24#111408012vl

Claims

CLAIMS1. A method of manufacturing polyhedral oligomeric silsesquioxane, comprising:(a) providing a reaction medium comprising a non-methanol solvent, a base, and water; (b) adding i-butyl trialkoxysilane to the reaction medium;(c) heating the i-butyl trialkoxysilane and the reaction medium to elicit a condensation reaction that forms a reaction mixture comprising: (i) an alcohol byproduct; (ii) one or more silicon-containing intermediates; (iii) and one or more i-butyl- substituted polyhedral oligomeric silsesquioxane (POSS) cage compounds; (d) separating the one or more i-butyl-substituted polyhedral oligomeric silsesquioxane (POSS) cage compounds from the reaction mixture.

2. The method of claim 1, further comprising:(e) retaining, after the separating step (step (d)), the alcohol byproduct and the one or more silicon-containing intermediates in the reaction medium; and (f) repeating steps (b) - (e) one or more times using the reaction medium containing the retained one or more silicon-containing intermediates and the alcohol byproduct.

3. The method of claim 1 or 2, wherein the non-methanol solvent is selected from the group consisting of a C2 or higher alcohol, an ether, a ketone, or a carbonate.

4. The method of claim 3, wherein the non-methanol solvent is ethanol.

5. The method of claim 1 or 2, wherein in step (c), heating the i-butyl trialkoxysilane and the reaction medium comprises heating the i-butyl trialkoxysilane and the reaction medium to a temperature in a range of 24°C to 101°C.

6. The method of claim 1 or 2, wherein the one or more i-butyl-substituted polyhedral oligomeric silsesquioxane (POSS) cage compounds is homoleptic and comprises [(i-BuSiO1.5)8]S8.

7. The method of claim 1 or 2, wherein the one or more i-butyl-substituted polyhedral oligomeric silsesquioxane (POSS) cage compounds is heteroleptic and comprises i-butylsiloxy units in combination with one or more additional siloxy units bearing non-i-butyl substituents.25#111408012vl8. The method of claim 7, wherein the non-i-butyl substituents are selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, cyclohexyl, phenyl, benzyl, and substituted phenyl groups.

9. The method of claim 1 or 2, wherein the i-butyl trialkoxysilane is i-butyl triethoxysilane and the alcohol byproduct is ethanol byproduct.

10. The method of claim 1 or 2, wherein the i-butyl trialkoxysilane is i-butyl trimethoxysilane, the alcohol byproduct is methanol byproduct, and the non-methanol solvent is non-azeotropic with the methanol byproduct.

11. A continuous method of manufacturing polyhedral oligomeric silsesquioxane, comprising:(a) providing a reaction medium comprising ethanol, water, and a base;(b) adding i-butyl triethoxysilane to the reaction medium;(c) reacting the i-butyl triethoxysilane in the reaction medium to form [(i- BuSiO1.5)8]S8, one or more silicon-containing intermediates, and ethanol byproduct;(d) crystallizing the [(i-BuSiO1.5)8]S8 from the reaction medium while the one or more silicon-containing intermediates remain soluble in the reaction medium; (e) collecting the crystallized [(i-BuSiO1.5)8]S8 via filtration;(f) recharging the reaction medium with additional i-butyl triethoxysilane and water;and(g) repeating steps (c) - (f) to continuously produce [(i-BuSiO1.5)8]S8 at a purity of at least 99%.

12. The method of claim 11, wherein a yield of the [(i-BuSiO1.5)8]S8 increases across successive cycles of steps (b) - (e) as the process approaches steady-state operation.

13. The method of claim 12, wherein the yield of the [(i-BuSiO1.5)8]S8 reaches at least 90% by a fifth cycle of steps (b) - (e).

14. The method of claim 11, further comprising removing at least a portion of the ethanol byproduct from the reaction medium between repetitions of step (f) to maintain a concentration of the i-butyl triethoxysilane within a predetermined range.26#111408012vl15. The method of claim 1 or 11, wherein the base is selected from the group consisting of hydroxide, alkoxide, carboxylate, amides, imides, carboxamides, carbanions, carbonate, sulfate, phosphate, biphosphate, phosphorus ylides, nitrate, borate, cyanate, fluoride, hypochlorite, silicate, stannate, basic metal oxide, amines, amine oxides, and organometallics.

16. The method of claim 1 or 11, wherein the one or more silicon-containing intermediates comprise at least one of [(i-BuSiO1.5)10]S10, [(i-BuSiO1.5)12]E12, [(i-BuSiO1.5)14]E14, [(i-BuSiO1.5)16]S16, [(i-BuSiO1.5)18]S18, and [(i-BuSiO1.5)20]S20.

17. The method of claim 1 or 11, wherein the reaction medium has a pH in a range of 8.1 to 14.

18. The method of claim 1 or 11, wherein a concentration of the water in the reaction medium is in a range of 0.5M to 5M.

19. The method of claim 1 or 11, wherein a concentration of the base in the reaction medium is in a range of 0.1M to 0.25M.

20. A composition comprising an impure solid that includes an i-butyl-substituted polyhedral oligomeric silsesquioxane (POSS) cage compound and one or more silicon-containing intermediates, the composition being characterized by a melting point as determined by differential scanning calorimetry (DSC), wherein the melting-point is intentionally adjustable by selection of reaction conditions.

21. The composition of claim 20, wherein the melting point is greater than 266°C.

22. A composition comprising an impure solid that includes an i-butyl-substituted polyhedral oligomeric silsesquioxane (POSS) cage compound and one or more silicon-containing intermediates, the composition being characterized by a melt viscosity as determined by rheometry, wherein the melt viscosity is intentionally adjustable by selection of reaction conditions.

23. The composition of claim 22, wherein the melt viscosity at 25°C is from 56 Pa-s to 2 Pa-s.

24. The composition of claim 22, wherein the melt viscosity at 50°C is from 5 Pa-s to 8 Pa-s.

25. The composition of claim 22, wherein the melt viscosity at 100°C is less than 5 Pa- s.27#111408012vl26. The composition of claim 20 or 22, wherein the reaction conditions comprise one or more of solvent composition, temperature, reactant ratios, and residence time.

27. The composition of claim 26, wherein the solvent composition comprises ethanol.

28. The composition of claim 26, wherein the temperature is in a range of 24°C to 101°C.

29. The composition of claim 26, wherein the reactant ratios comprise the ratio of two or more silane coupling-agent feedstocks selected from vinyl silanes, octyl silanes, i-octyl silanes, phenyl silanes, methyl silanes, and i-butyl silanes.

30. The composition of claim 20 or 22, wherein the one or more silicon-containing intermediates comprise at least one of [(i-BuSiO1.5)10]S10, [(i-BuSiO1.5)12]E12, [(i-BuSiO1.5)14]S14, [(i-BuSiO1.5)16]S16, [(i-BuSiO1.5) 18]S18, and [(i-BuSiO1.5)20]S20.28#111408012vl

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