CN111491724A

CN111491724A - Non-aqueous encapsulation

Info

Publication number: CN111491724A
Application number: CN201880080416.5A
Authority: CN
Inventors: 吕晓村; J·S·卡茨; A·K·施密特; J·S·穆尔
Original assignee: University of Illinois; Dow Global Technologies LLC; Rohm and Haas Co
Current assignee: University of Illinois; Dow Global Technologies LLC; Rohm and Haas Co
Priority date: 2017-11-06
Filing date: 2018-10-29
Publication date: 2020-08-04
Also published as: BR112020008828A2; JP2021511195A; KR20200103645A; WO2019089406A1; EP3706896A1

Abstract

A non-water encapsulation process for forming an encapsulated hydrophilic material comprising providing an emulsion system comprising a hydrocarbon component comprising one or more hydrocarbons, a hydrophilic component comprising at least one selected from one or more amines and one or more alcohols, a partitioning inhibitor component comprising a hydrochloride salt of a base having a pKa of 1 to 15 for the conjugate acid of the base, a viscosity modifier component comprising a polyisobutylene polymer having a weight average molecular weight of 300 to 600 kilodaltons, and an emulsifier component comprising one or more hydrophobically modified clays. The method also includes treating the emulsion system to form at least one continuous phase and an encapsulated dispersed phase, the encapsulated dispersed phase comprising a hydrophilic component encapsulated therein and the encapsulated dispersed phase separating from the continuous phase to form an encapsulated hydrophilic material.

Description

Non-aqueous encapsulation

Technical Field

Embodiments relate to a non-aqueous emulsion system for encapsulating materials, a method of encapsulating materials using the non-aqueous emulsion system, and microcapsules formed with the non-aqueous emulsion system for encapsulating materials.

Background

Encapsulation of microparticles is sought, for example, to protect related compounds by sequestration and/or to allow controlled release of reactive or non-reactive microparticles. For example, many materials, biological and agricultural applications place a high demand on encapsulation methods for hydrophilic payloads (materials), such as amines and alcohols. For example, amine microcapsules and/or alcohol microcapsules have attracted considerable interest in developing advanced smart materials, such as controlled release. However, hydrophilic encapsulation systems suffer from several problems, such as high water content in the hydrophilic payload, complex encapsulation techniques, and/or poor barrier properties. In this regard, encapsulation of amines and alcohols can be difficult to achieve by most conventional encapsulation techniques, such as emulsion templated interfacial polymerization, microfluidics, penetration of amines into hollow microcapsules, solvent evaporation, microfluidics, and the like, e.g., due to large solvent residues, poor barrier properties, and/or problems that are not amenable to scale-up (e.g., for industrial applications).

The use of non-aqueous systems to encapsulate materials such as amines and alcohols has been proposed, for example, because it is believed that water residues may promote premature release of the payload. Further, many encapsulation systems may react with water, which may lead to undesirable byproducts. Further, designing a non-aqueous system (e.g., a system without the addition of water) may reduce the likelihood of and/or avoid the need for an energy intensive drying step.

Accordingly, a simplified technique is sought to produce microcapsules (i.e., encapsulating materials) with minimized and/or no water payload, high payload loading, and/or good barrier properties.

Disclosure of Invention

Embodiments may be realized by providing a non-aqueous encapsulation method for forming an encapsulated hydrophilic material, the method comprising providing an emulsion system comprising a hydrocarbon component comprising one or more hydrocarbons, a hydrophilic component comprising at least one selected from one or more amines and one or more alcohols, a partitioning inhibitor component comprising a hydrochloride salt of a base having a pKa of 1 to 15 for the conjugate acid of the base, a viscosity modifier component comprising a polyisobutylene polymer having a weight average molecular weight of 300 to 600 kilodaltons, and an emulsifier component comprising one or more hydrophobically modified clays. The method also includes treating the emulsion system to form at least one continuous phase and an encapsulated dispersed phase, the encapsulated dispersed phase comprising a hydrophilic component encapsulated therein and the encapsulated dispersed phase separating from the continuous phase to form an encapsulated hydrophilic material.

Drawings

Fig. 1 illustrates an exemplary process for non-aqueous encapsulation of hydrophilic materials.

Fig. 2A, 2B, 2C, 2D, 3A and 3B show an analysis of partitioning inhibitors.

Fig. 4A, 4B and 4C show the analysis of the emulsifiers.

Fig. 5A and 5B show analysis of viscosity modifiers.

Fig. 6A and 6B show an analysis of example 1 prepared using DETA as the hydrophilic component.

Fig. 7 shows an analysis of an example prepared using other hydrophilic components.

Detailed Description

Embodiments relate to non-aqueous encapsulation of hydrophilic materials, such as amines, alcohols, and other reactive or non-reactive additives that may be used to produce polymeric products (e.g., polyurethane-based products). Non-water encapsulation is based on oil-in-oil emulsion systems, achieved by controlling the payload distribution. Generally, capsule formation requires the production of an emulsion containing at least one aqueous phase. However, water can be detrimental to many reaction systems. The examples relate to stable substantially water-free oil-in-oil emulsion systems that incorporate phase separation between two organic, substantially water-free phases. The emulsion system comprises a dispersed phase and a continuous phase. By substantially nonaqueous and anhydrous is meant that water is present in an amount less than 0.5 weight percent based on the total weight of the emulsion system. For example, water may not be added separately to the emulsion system, but may be present in minor amounts in the components used to form the emulsion system.

Oil-in-oil emulsion systems may be well suited for forming microcapsules (also referred to as encapsulating materials) in nonaqueous environments. For emulsion systems, a suitable solvent pair is required to drive the phase separation into an emulsion. For example, the liquid pair used in conventional non-aqueous emulsions comprises a combination of a non-polar solvent (such as hydrocarbons and polymers) and a highly polar solvent (such as methanol, formamide and alcohols). However, polar organic payloads are typically distributed in both phases, potentially interfering with subsequent encapsulation chemistry. Thus, for emulsion systems used to encapsulate hydrophilic payloads, it is desirable to maintain the immiscibility of the payload with the continuous phase and to adjust the interfacial polymerization kinetics. In such emulsion systems, reactive polar payloads such as amines and alcohols may tend to partition between the two emulsion phases, potentially interfering with subsequent interfacial polymerization and/or promoting Ostwald ripening (which may significantly reduce emulsion stability).

Incorporation of effective partitioning inhibitors is one proposed approach to keep the active core material within the emulsified droplets. Further, adverse reactant transport may create local dynamic turbulence, leading to disruption of shell growth and/or production of low quality shell material. It is suggested to maintain the viscosity of the continuous phase at a certain level as an efficient means of modifying the diffusion rate of the reactants to reduce unwanted dynamic turbulence at the interface.

Exemplary embodiments relate to non-aqueous emulsion systems, which may be referred to as Pickering emulsion systems, which refer to emulsion systems built up of solid particles adsorbed on the interface between two phases. An exemplary diagram of such a Pickering emulsion system is as follows:

for example, in an emulsion system, if two different immiscible solvents (e.g., non-aqueous solvents) are mixed, small droplets of one solvent can form and be dispersed throughout the system, resulting in two different phases. Eventually, the droplets coalesce together, reducing the energy in the system. However, if solid particles are added to the mixture, the particles will bind to the surface of the interface between the two phases and reduce the likelihood of droplet coalescence, minimize droplet size and/or prevent droplet coalescence. Further, according to exemplary embodiments, the viscosity of the continuous phase may be adjusted between 1500-. The result may be an emulsion system with increased system stability, e.g., good storage stability at room temperature, where the two phases are substantially maintained over an extended period of time. Further, the resulting encapsulant material can exhibit good stability (e.g., substantially remaining in the shell configuration) in the continuous phase and/or in another liquid (e.g., a liquid epoxy resin and/or a formulation system used to form the polyurethane polymer). Increased stability (e.g., at room temperature and/or higher temperatures) may be achieved for extended pot life and/or shelf life of solutions used in industrial applications.

In exemplary embodiments, the emulsion system comprises an immiscible hydrocarbon-amine pair liquid and/or an immiscible hydrocarbon-alcohol pair liquid. The hydrocarbon component comprises one or more hydrocarbons. The amine and/or alcohol form a hydrophilic component comprising at least one selected from the group consisting of one or more amines and one or more alcohols. The hydrocarbon component and the hydrophilic component can be present in a weight ratio of 0.5:2.0 to 2.0:0.5 (e.g., 0.7:1.5 to 1.5: 0.7). The emulsion system also includes the incorporation of a partitioning inhibitor component, a viscosity modifier component, and an emulsifier component. The partitioning inhibitor, viscosity modifier, and/or emulsifier may be a solid at room temperature before being added to the emulsion system.

The hydrocarbon liquid may comprise one or more hydrocarbons having from 2 to 100 carbon atoms (e.g., from 2 to 50 carbon atoms, from 2 to 25 carbon atoms). The hydrocarbon liquid may comprise cyclic, straight chain and/or branched hydrocarbons. In exemplary embodiments of the hydrocarbon liquid, at least one of cyclic hydrocarbons and linear hydrocarbons is included. The cyclic hydrocarbon and the linear hydrocarbon may be present in a weight ratio of 0.5:2.0 to 2.0:0.5 (e.g., 0.7:1.5 to 1.5: 0.7).

The hydrophilic component liquid may comprise one or more amines and/or one or more alcohols having a weight average molecular weight of 50 daltons to 30 kilodaltons. For example, the one or more amines can have a weight average molecular weight of 50 daltons to 1000 daltons, 50 daltons to 500 daltons, 50 daltons to 250 daltons, and the like. The one or more alcohols can have a weight average molecular weight of 50 daltons to 1000 daltons, 50 daltons to 500 daltons, 50 daltons to 250 daltons, and the like.

The emulsion system also includes a dispensing inhibitor component comprising one or more dispensing inhibitors and a viscosity modifier component comprising one or more viscosity modifiers. The one or more partitioning inhibitors may be in a dispersed phase and the one or more viscosity modifiers may be in a continuous phase.

Partitioning inhibitors are hydrochloride salts of bases whose conjugate acids have a pKa of 1 to 15 (e.g., 5 to 15, 10 to 15, etc.). For example, the hydrochloride salt may not react violently with the amine. The dispensing inhibitor component may be present in an amount of at least 10 wt.%, at least 31 wt.%, at least 40 wt.%, at least 50 wt.%, at least 60 wt.%, at least 65 wt.%, etc., relative to the total weight of the hydrophilic component. For example, the partitioning inhibitor component can be present in the emulsion system in an amount of 10 to 100 wt% (e.g., 20 to 100 wt%, 25 to 90 wt%, 30 to 100 wt%, 35 to 100 wt%, 40 to 100 wt%, 50 to 100 wt%, 60 to 100 wt%, etc.) relative to the total weight of the hydrophilic component.

The viscosity modifier is polyisobutylene having a weight average molecular weight of 300 to 600 kilodaltons (e.g., 400 to 600 kilodaltons, 450 to 550 kilodaltons, etc.). In exemplary embodiments, the emulsion system comprises incorporation of at least guanidine hydrochloride (GuHCl) as a partitioning inhibitor in the dispersed phase and Polyisobutylene (PIB) as a viscosity modifier in the continuous phase. The viscosity modifier can be present in an amount of at least 1 weight percent, at least 2 weight percent, at least 3 weight percent, at least 4 weight percent, at least 10 weight percent, etc., based on the total weight of the hydrocarbon component and the viscosity modifier component. For example, the amount of viscosity modifier present in the emulsion system can be 1 to 50 wt% (e.g., 4 to 50 wt%, 1 to 40 wt%, 4 to 40 wt%, 1 to 30 wt%, 4 to 30 wt%, 1 to 20 wt%, 4 to 20 wt%, 1 to 15 wt%, 4 to 15 wt%, 1 to 13 wt%, 4 to 12 wt%, 10 to 12 wt%, etc.) relative to the total weight of the hydrocarbon component and the viscosity modifier component.

The combination of a partitioning inhibitor, such as GuHCl and PIB, as a viscosity modifier can produce a firm emulsion with a stable morphology for several weeks (e.g., about 3 weeks). A partitioning inhibitor, such as guanidine hydrochloride, can be incorporated into the hydrophilic payload as a partitioning inhibitor, e.g., to minimize dispersion in the continuous phase. The emulsion droplets may serve as an encapsulation template for interfacial polymerization (e.g., with respect to shell architecture) of some of the encapsulated amine and optionally the added isocyanate, which may be part of the emulsion system processing to form at least a continuous phase and an encapsulated dispersed phase. Optimization of physical properties using polymeric solutes in both the dispersed and continuous phases can enhance emulsion stability and adjust viscosity. An exemplary diagram of such a system is as follows:

according to an exemplary embodiment, the formation of the shell wall may be accomplished by interfacial polymerization of isocyanate as a crosslinking agent and polyamine from the droplet core, the crosslinking agent being transported through the continuous phase. For experimental purposes, Diethylenetriamine (DETA) was used as the payload, although the examples refer to various hydrophilic payloads, such as other amines and alcohols. DETA-loaded microcapsules can be isolated in good yield, show high thermal and chemical stability, and have an extended shelf life even when dispersed in reactive epoxy resins. The polyamine phase is compatible with a wide variety of basic and hydrophilic actives.

The emulsion system also includes an emulsifier suspension component comprising one or more hydrophobically modified clays and optionally one or more polymeric surfactants. The one or more hydrophobically modified clays can be present in an amount of 1 to 10 weight percent (e.g., 1 to 8 weight percent, 1 to 5 weight percent, 1 to 4 weight percent, 1 to 3 weight percent, 2 to 3 weight percent), based on the total weight of the emulsion system. For example, the one or more hydrophobically modified clays can be present in an amount of 2.0 to 2.5 weight percent based on the total weight of the emulsion system.

Clay minerals may differ by their composition layers and the combination of cations. Hydrophobically modified clay refers to clay whose surface is chemically modified (e.g., prior to addition to the emulsion system) by the use of a clay conditioning agent (e.g., surfactants, silanes, or other conditioning agents known in the art). In exemplary embodiments, the hydrophobically modified clay is prepared by reaction with a surfactant comprising a long chain alkyl group, such as a long chain alkylammonium ion (e.g., mono-or di-C)₁₂-C₂₂Alkylammonium ion) exchange, wherein a polar substituent such as a hydroxyl group or a carboxyl group is not attached to a long-chain alkyl group. In an exemplary embodiment, the clay is a silicate clay, such as bentonite. In exemplary embodiments, the hydrophobically modified clay comprises a bis (hydrogenated tallow alkyl) dimethyl salt of bentonite, a 2-ethylhexyl (hydrogenated tallow alkyl) dimethyl salt of bentonite, and/or a bis (hydrogenated tallow alkyl) methyl salt of bentonite.

Further, as shown in the examples, the hydrophobically modified clays can provide good dispersibility in emulsion systems and/or miscibility with thermoplastic systems.

Referring to fig. 1, for a non-water encapsulation process for forming an encapsulated hydrophilic material of an emulsion system, a mixture is first formed that includes a hydrocarbon component, a hydrophilic component, a partition inhibitor component, a viscosity modifier component, and an emulsifier suspension component. The components may be added and mixed in a different order, for example, the components of the dispersed phase may be added and mixed first, the components of the continuous phase may be added and mixed second, and the emulsifier may be added and mixed again. After the components of the emulsion system are added together to form the emulsion mixture, the mixture is processed.

The treatment comprises exposing the mixture to ultrasonic treatment (e.g., applying sonic energy to stir particles in the mixture at a high wattage (e.g., at least 300W)). The treatment also includes, for example, adding one or more isocyanates to the emulsion mixture after exposing the emulsion mixture to ultrasonic treatment. The isocyanate may be an aromatic or aliphatic isocyanate, such as a diisocyanate. Aromatic isocyanates refer to isocyanates having an N ═ C ═ O group directly attached to an aromatic group. Aliphatic isocyanates refer to isocyanates having an N ═ C ═ O group directly attached to an aromatic group. In exemplary embodiments, the at least one isocyanate may be an aliphatic isocyanate (e.g., a sterically hindered aliphatic isocyanate). Exemplary sterically hindered aliphatic isocyanates include 4,4' -methylenedicyclohexyl diisocyanate and tetramethylxylene diisocyanate (TMXDI). The process of emulsion mixing allows interfacial polymerization to form, for example, a shell structure around the dispersed phase. Further, the treatment allows the dispersed phase to be separated from the continuous phase (e.g., by shell formation), thereby forming an encapsulated hydrophilic material that can be separated from the continuous phase. The isolated encapsulated hydrophilic material can be separated from the continuous phase and used as an encapsulating component in other systems, for example, as described below.

The emulsion system according to the embodiments can be used to perform non-aqueous encapsulation of hydrophobic materials such as amines and alcohols. The emulsion system may produce amine-loaded microcapsules and/or alcohol-loaded microcapsules that may be separated from the continuous phase and used in other systems, such as epoxy and/or polyurethane systems. When amine-loaded microcapsules and/or alcohol-loaded microcapsules are used in other systems, they may act as delayed release and/or controlled release of the system. For example, the amine and/or alcohol may be released over a period of time (e.g., by dissolution of the shell structure) and/or upon the use of mechanical force (e.g., by the use of shear forces). Thus, such non-water encapsulation systems may be used to prepare amine-loaded microcapsules or alcohol-loaded microcapsules, which may exhibit good barrier properties (e.g., without significant viscosity increase) over extended periods of contact with other resins (e.g., polyurethane or epoxy resins).

In one example, the amine-loaded microcapsules may contain one or more amine hardeners for the epoxy system. For example, the amine-loaded microcapsules may contain one or more amine hardeners for epoxy systems. The amine hardener may be allowed to release from the shell construction using shear, heat, or other techniques known in the art that allow release through the shell construction, which would then enable the amine hardener to act as a curing agent for the epoxy system.

In another example, the amine-loaded microcapsules may include one or more amine catalysts for use in polyurethane systems. For example, the amine catalyst can be a catalyst known in the art for use in polyurethane systems (e.g., a formulated polyol system for use in polyurethane systems). The application of shear, heat, or other techniques known in the art that allow release through the shell architecture can allow the amine catalyst to be released from the shell architecture, which will subsequently enable the amine catalyst to act as a catalyst for the formation of the polyurethane polymer. In exemplary embodiments, the shearing, heating, etc. methods for releasing the amine catalyst may be performed prior to mixing the formulated polyol system with the isocyanate component to form the polyurethane polymer, the formulated polyol system comprising the amine-loaded microcapsules.

In another example, the polyol-loaded microcapsules may comprise one or more polyols for use in a polyurethane system. For example, the polyol can be a polyol known in the art for use in polyurethane systems (e.g., a formulated polyol system for use in polyurethane systems). Application of shear, heat, or other techniques known in the art will allow the polyol to be released from the shell structure, which will subsequently react the polyol with the isocyanate to form the polyurethane polymer. In exemplary embodiments, the shearing, heating, etc. methods for releasing the polyol may be performed prior to mixing the formulated polyol system with the isocyanate component to form the polyurethane polymer, the formulated polyol system comprising the polyol-loaded microcapsules.

One potential method of releasing the amine and/or alcohol from the encapsulation is to use heat to degrade the shell structure, resulting in the release of the amine/alcohol from the shell structure. In an exemplary heating application, the composition comprising the encapsulated amine/alcohol is sprayed onto a hot substrate at 100 ℃, and contact of the shell configuration with the hot substrate is believed to degrade the shell and allow release of the amine/alcohol. Another potential method of releasing the amine/alcohol from the encapsulation is to use shear forces. In one exemplary application of shear, the composition comprising the encapsulated amine/alcohol is sprayed using a high pressure/high shear spray gun, and the shell may break during the spraying process and/or upon impact with the substrate.

Epoxy and/or polyurethane materials formed using amine and/or alcohol loaded microcapsules and/or polyol loaded microcapsules may be useful encapsulation techniques for various thermoset systems. The emulsion system can be used to make coatings, adhesives, and/or sealants. Microcapsules can eliminate the need for a two-component system to make mixed polyurethane coatings, which simplifies the transport of chemicals and reduces potential defects during mixing of the two-component system.

Examples of the invention

All parts and percentages are by weight unless otherwise indicated. All molecular weight values are based on weight average molecular weight unless otherwise indicated. The following are provided with respect to various working examples, comparative examples, and approximate properties, characteristics, parameters, and the like of materials used in the working and comparative examples.

Material

Unless otherwise indicated, all materials and reagents were obtained from commercial suppliers for direct use. Diethylenetriamine (DETA), polyethyleneimine (PEI, branched, Mw 25,000), pentaethyleneHexamine (PEHA), guanidine hydrochloride (GuHCl), fluorescein isothiocyanate isomer I, hexadecane, decahydronaphthalene, polyisobutylene (Mw 500 kilodaltons), 4' -diphenylmethane diisocyanate (MDI), polymethylene polyphenyl isocyanate (PMPPI, M)_w340), isophorone diisocyanate (IPDI), Hexamethylene Diisocyanate (HDI), 4' -methylenedicyclohexyl diisocyanate (H)₁₂MDI) and tetramethylxylene diisocyanate (TMXDI) are available from Sigma Aldrich. Naphthalene 1, 5-diisocyanate was purchased from TCI America. Hydrophobically modified clays

20 nanoplatelets available from ByK chemical assistants and instruments&Instruments). Epoxy resin d.e.r.331 is available from Olin Corporation (Olin Corporation).

Analysis of

General instrumental information the viscosity of the microcapsule-epoxy composition was monitored at 0.2Hz with a Brookfield DV-I PRIME viscometer with 64# shaft below 50000cps and at 0.0167Hz with higher viscosity TGA testing was performed with TA instruments Q50 fluorescence spectroscopy was obtained using a Zeiss Observer Z1 fluorescence microscope and 41025Piston GFP filter bank intentional rupture and payload release of microcapsules was achieved at 167Hz for 180 seconds using an OMNI G L H homogenizer with 10mm × 95mm sawtooth (fine) generator probe.¹The H NMR spectra were obtained using a Varian 500MHz spectrometer at VOICE NMR laboratory, university of Illinois.

For this calibration curve, DETA was dissolved in hydrocarbon solvent (decalin or DH solvent, <12mg/m L) by sonication for 10 min. A1 m L DETA hydrocarbon solution was mixed with 20 μ L dodecane as an internal reference, followed by GC-MS (Agilent GC 7820A and Agilent MSD 5977E). the calibration curve is based on a linear correlation between DETA concentration and DETA/dodecane integral ratio, as shown below.

Referring to the upper panel, (A) is a calibration curve of decalin, and (B) is a calibration curve of DH solvent.

To quantitatively determine the DETA partition concentration, 2 grams of Diethylenetriamine (DETA) were mixed with a specific amount of additive to form a clear solution, then vigorously stirred with 6 grams of hydrocarbon solvent to ensure partition equilibrium after 5 hours of precipitation, the 200 μ L hydrocarbon solution phase was diluted with 0.8m L THF and 20 μ L dodecane as internal references for GC-MS testing.

The contact angle. A clean glass plate is coated with a thin layer of polystyrene (M)_WApproximately 3000-4000) which were melt-coated under continuous heating with a heating gun and the coating formed upon cooling to room temperature a drop of 10 μ L solution of DETA-GuHCl was transferred to a polystyrene surface by a micropipette and the drop shape was immediately recorded with a high resolution camera an Image of the drop on the polystyrene surface was treated with a drop shape analysis insert (L B-ADSA) of Image J (national institute of health, usa) water showed a contact angle of 86.9 ± 1.6 ° on this PS surface, indicating that the PS coating was a non-polar hydrophobic surface.

Ternary phase diagram. According to the weight ratio of the components, a GuHCl-DETA-DH ternary phase diagram is established. A series of samples of different component ratios were accurately weighed on an analytical balance and then subjected to vigorous vortex stirring for 1 minute. The samples were then allowed to settle for immiscibility assessment. If a clear boundary of two phases occurs within 2 minutes, it is marked as a fast phase separation (fast PS in FIG. 2D). If the sample shows clear phase separation requiring more than 2 minutes, it is marked as slow phase separation (slow phase PS in FIG. 2 (D)).

Surface and interfacial tension. Both surface and interfacial tension are measured by the pendant drop method. Nordman

Cartridge (precision tip) (#14Gauge, where φ is 1.83mm) and injectionThe pump acts in combination as a capillary device to produce pendant drops, 0.2m L each to measure surface tension an image of the drop is recorded with a high resolution camera after waiting 1 minute to reach equilibrium.

COSMOtherm simulation theoretical verification of phase separation in oil-in-oil emulsions was achieved by using COSMO-RS theory implemented in COSMOtherm X (COSMOlogic GmbH & co. kg, germany.) briefly, COSMO-RS theory calculates the chemical potential of molecules in solution by statistical thermodynamics of the interaction of electronic structures between different molecules.

Overlap concentration estimation according to Martin equation log (η)_sp/c)＝log[η]+K_m\[η]c estimating the overlap concentration of PIB, wherein η_spIs the specific viscosity, c is the PIB concentration, and Km is the consistency [ η ]]Is obtained from the intercept. The Huggins and Kraemer equations may not be suitable for this estimation because PIB wt% is at half-dilute concentration.

Encapsulation procedure

The emulsion system of working example 1 was prepared using the following procedure: 1.26 g of Diethylenetriamine (DETA), 0.63 g of Pentaethylenehexamine (PEHA), 0.30 g of polyethyleneimine (PEI, branched, Mw. about.25,000) and 0.81 g of guanidine hydrochloride (GuHCl) were mixed thoroughly and used as the disperse phase (DPPG-4213). Then, 2.64 g of hexadecane, 2.64 g of decalin and 0.72 g of polyisobutylene (PIB, Mw. about.500,000) were mixed and used as the continuous phase (DHP-012). Further, 0.09 g of hydrophobically modified clay nanoplatelets (a)

20) Dispersed in 1.71 g of DHP-012 and used as an emulsifier suspension. The dispersed phase (DPPG-4213, 3.0 grams), continuous phase (DHP-012, 6.0 grams) and emulsifier suspension (1.8 grams) were mixed in a glass vial and then sonicated at 60% power for 75 seconds (1 second pause after every 5 seconds sonication) with a sonic VCX 500 watt sonicator with a full size probe (diameter 1.27cm) to produce a nonaqueous electrolytePickering emulsion.

The emulsion system was then diluted with 30m L DHP-012 and stirred at 16.7Hz for 20min, then 0.6 g of the crosslinker tetramethylxylene diisocyanate (TMXDI) was dissolved in 6m L DHP-012 and added to the emulsion at an addition rate of 0.5m L/h (stirred at 8 Hz), after completion of the isocyanate addition, the encapsulation suspension was slowly heated to 50 ℃ (0.5 ℃/min) and stirred for 3 hours, after cooling to room temperature, the capsule suspension was diluted with 150m L hexane and allowed to settle for 1 hour, the supernatant was carefully decanted, and the remaining solids were further washed five times with 20m L hexane, the resulting capsules were transferred to a sight glass and air dried in a fume hood, the isolation yield of example 1 was approximately 70 wt%.

Fig. 1 shows an exemplary process of a general encapsulation procedure for a representative microscope image during each key step: optical image (a) (c), SEM image (e) and corresponding fluorescence image (b) (d) (f) on the same header area. (scale bar: 40 μm).

Phase separation screening was performed as follows:

in exemplary embodiments, the polar phase of the emulsion system comprises at least 35 to 50 wt% DETA, 15 to 35 wt% Pentaethylenehexamine (PEHA), 5 to 20 wt% branched polyethyleneimine (PEI, M)_WAbout 20kDa) and 15 to 40 wt.% of GuHCl. In terms of composition, it is believed that PEHA and PEI can be used as crosslinkers in subsequent interfacial polymerization to improve barrier properties. Without intending to be bound by this theory, the good composition of the exemplary embodiment of the polar phase is believed to be about 43 wt% DETA, 20 wt% Pentaethylenehexamine (PEHA), 10 wt% branched polyethyleneimine (PEI, M)_WAbout 20kDa) and 27 wt.% GuHCl, referred to as DPPG-4213(DETA-PEHA-PEI-GuHCl in a weight ratio of 4:2:1:3) in the following discussion.

The phase separation of DETA from DH was theoretically evaluated using the liquid extraction module of cosmoterm X.²¹This module performs iterative partitioning and solubility calculations to give the final concentration of each compound in both phases. The final DETA concentration of the DH phase is considered the theoretical predictive distribution of DETA to the continuous phase. By the same procedureThe effect of various inhibitors on DETA partitioning was evaluated. Although the experimental and theoretical results do not match exactly on an absolute basis, the theoretical predictions are very close to the observed experimental trends (fig. 2B), with a correlation coefficient R²0.75. This theoretical partitioning analysis helps to aid in identifying other suitable solvent systems and partitioning inhibitors to obtain relevant other payloads.

The viscosity of the continuous phase significantly affects the stability of the emulsion droplets. Polymeric Hydrocarbon additive PIB (M)_wAbout 500kDa) was selected as a viscosity modifier due to its compatibility and commercial availability, referring to FIG. 5A, the viscosity of the hydrocarbon phase η increased from 3cP (no PIB) to 4085cP (12 wt% PIB), and a linear correlation between PIB wt% and log η was observed^-1(about 0.6 wt%). PIB was found not to have much influence on the surface tension of the continuous phase (fig. 5A, dashed line) or the interfacial tension γ between the two emulsion phases (fig. 5A, solid line), indicating that PIB is mainly used as a viscosity modifier without interfering with the interfacial energy.

Referring to fig. 5B, the increased viscosity also extended the shelf life of the emulsion from 5min (4 wt% PIB) to 21 days (12 wt% PIB), maintaining intact emulsion droplets with similar morphology and size. Without intending to be bound by this theory, the extended shelf life may be due in part to a reduction in the diffusion coefficient of the emulsion droplets. When PIB was added in an amount of 0 to 12% by weight, the diffusion coefficient was reduced by 10 according to the Stokes-Einstein equation³And (4) doubling. Such viscous solvents enhance emulsion stability by slowing droplet diffusion rates and reducing emulsion coalescence.

The viscosity increase may also have an effect on the transport properties and reaction kinetics of the subsequent interfacial polymerization. For example, during continuous dispersion, stable and non-turbulent reactant delivery to the interface may allow most of the interface to polymerize to form a shell material with good barrier properties. Stable laminar flow with low reynolds numbers (Re <200) compared to transition flow and turbulent flow (Re >2000) is considered to be a desirable choice for interfacial polymerization. The efficiency and kinetics of the dispersion process are determined by the convection method (stirring, mixing and dispersion) and diffusion. For the most commonly used stirring equipment, a typical stirring rate is 500-. Thus, the exemplary embodiment comprises an optimized continuous phase comprising approximately 12 wt% PIB and 88 wt% DH (1:1 wt/wt), referred to as DHP-012(DH-PIB, 12 wt%).

Further, the polar organic payload may partition in both phases, potentially interfering with subsequent encapsulation chemistry. Diethylene glycol triamine (DETA) is a polyamine that is identified as miscible with a 1:1 (wt.: wt.) mixture of Decalin and Hexadecane (DH). In particular, the partition coefficient D of this mixture was detected in the continuous phase by GC-MS, as described above_np-p(nonpolar-polar phase) was 0.044 (see FIG. 2C) and the concentration was 11.3 mg. m L^-1。

Partition inhibitor screening was performed as follows:

organic acids were first tested as partitioning inhibitors to reduce the diffusion of DETA into the hydrocarbon phase. Referring to fig. 2A, DETA partition concentrations of various additives and concentrations in a non-polar DH phase are shown, where the control example involves the use of no partition inhibitor. Weak organic acids such as acetic acid (HOAc) were found to slightly reduce DETA partitioning. The introduction of ions into the polyamine phase is one method of replacing the acidic additive. However, the most commonly used sodium, potassium and ammonium salts are believed to be largely insoluble in amines and possibly alcohols. For example ammonium hexafluorophosphate (NH)₄PF₆) And guanidine hydrochloride (GuHCl) are soluble in DETA. It has further been found that strong organic acids (e.g., trifluoroacetic acid (TFA), ethanesulfonic acid (EtSO)₃H)、NH₄PF₆And GuHC L) had relatively good results in reducing DETA concentration in the continuous phase at certain concentrations (graph)1A) In that respect Further, while 65 wt% TFA (relative to 100 wt% DETA, such that the weight percent of TFA added is 65% of the total amount of DETA added) substantially inhibited DETA dispersion into the nonpolar phase, the strong organic acid reacted strongly exothermically with DETA, protonating approximately 30 mol% of the active amino groups in the payload. Similar to TFA, EtSO was also found₃H reacts violently with amines. Further, with NH₄PF₆In contrast, GuHCl is considered relatively more economical and the response to DETA is not obvious. It is believed that these organic acids behave in a similar manner to alcohols.

Referring to FIGS. 2C, D_np-pFrom 0.044 to 0: (<0.010, undetectable in GC-MS), addition of 65 wt.% GuHCl (fig. 2C), indicating effective suppression of DETA partitioning. Referring to FIG. 2D, a ternary phase diagram of GuHCl-DETA-DH is shown, wherein PS refers to phase separation and is constructed to obtain a complete overview of the strong polyamine/hydrocarbon phase separation system.

As experimentally revealed by the measurement of the contact angle and the construction of the phase diagram, the introduction of the electrolyte in the amine phase significantly changed the phase separation behavior. The hydrophilicity of the polar phase was enhanced by the addition of GuHCl, as indicated by the increase in contact angle θ on the hydrophobic polystyrene surface (FIG. 2C, upward sloping lines). For example, when GuHCl to DETA ratio (R)_G-DWeight/weight) increased from 0 to 0.65, θ changed from 48.7 ° to 71.9 °.

When R is shown in FIG. 2D_G-D>1 (upper region), GuHCl reaches its solubility limit. For R_G-D<1, there is a strong phase separation between the polar (DETA-GuHCl) and nonpolar (DH) phases. Generally, more gas GuHCl (R)_G-D>0.5) results in faster phase separation (fig. 2D, middle zone). With decreasing GuHCl content (R)_G-D<0.5), the speed of phase separation decreases and it takes more than 2min (fig. 2D, lower zone). Minimum R for complete forbiddance of payload allocation_G-DIs considered to be about 0.6. Through a number of experiments, and without intending to be bound by this theory, a good composition of the polar phase is believed to be about 43 wt% DETA, 20 wt% Pentaethylenehexamine (PEHA), 10 wt% branched polyethyleneimine (PEI, M)_WAbout 20kDa) and 27 wt.% GuHCl, and will be referred to as DPPG-4213(DETA-PEHA-PEI-GuHCl, in a weight ratio of 4:2:1:3) in the following discussion. PEHA and PEI act as cross-linkers in subsequent interfacial polymerization to improve barrier properties.

Fig. 3A shows GC traces of DETA present in the hydrocarbon phase when mixed with varying amounts of GuHCl. When more GuHCl is present, less DETA is present in the hydrocarbon phase, represented by the smaller peak region of the peak at 4.34. This data is quantified in fig. 2A.

Fig. 3B shows the NMR peaks of DETA with and without the presence of 65 wt.% GuHCl. When GuHCl is present, the peak shifts to higher ppm, indicating higher polarity and interaction of GuHCl with DETA.

Emulsion stabilizer (emulsifier) screening was performed as follows:

discovery of polymeric surfactants

93(HLB 4)、

80(HLB 4.3)、

85(H L B1.8) and

20(H L B16.7) do not promote the formation or stabilization of oil-in-oil emulsions under various agitation methods, specifically, none of these examples formed stable emulsified droplets under various agitation methods including sonication, homogenization, and high speed agitation.

For illustration, hydrophobically functionalized clay: (

20) As Pickering particles, stable oil-in-oil emulsions can be produced, for example, on the basis of their relatively large size. In particular, hydrophobically functionalized clays are suitable emulsifiers, e.g. based on their high stability andrelatively large in size.

Referring to FIG. 4A, in combination with a hydrophobically functionalized clay, of four polymeric surfactants

85 produce stable emulsion droplets with a uniform morphology. In particular, fig. 4A shows a hydrophobically functionalized clay (ii) ((iii))

20) And a polymeric surfactant

85, respectively. Three other polymeric surfactants were found: (

93、

80 and

20) the non-aqueous emulsion could not be stabilized. As shown in FIG. 4A, emulsion stability and particle size (40 μm on a scale bar) may depend on

85, to be specific. Using 3% by weight of

20, emulsion stability is enhanced, but

85 less (error | no reference source found.

b-c). For 6% by weight of

85, the system does not stabilize the emulsion without forming any droplets. With following

85, showing an emulsion with good morphology but breaking during the subsequent interfacial reaction, indicating that a reliable emulsion was formed.

Referring to fig. 4B (scale bar 40 μm), the ratio of hydrophobically functionalized clay was also evaluated without the use of other polymeric surfactants. Larger amounts of hydrophobically functionalized clay result in smaller sized emulsified droplets with enhanced stability. 2% by weight of a solvent

After 20, no further reduction in droplet size was observed with the naked eye and the emulsion was found to be sufficiently stable to withstand subsequent interfacial reactions. Without intending to be bound by this theory, it is believed that the hydrophobically functionalized clay, based on the total weight of the total emulsion system, allows for the addition of no more than the necessary amount

The amount of 20 is about 2.0 wt% to 2.5 wt%. Thus, it was found that hydrophobically functionalized clays produce emulsion droplets of smaller size with enhanced stability. Further, by adding 2% by weight or more

20, the droplet size was kept at about 6 μm.

Isocyanate screening was performed as follows:

aromatic isocyanates generally react faster than aliphatic isocyanates. With respect to the examples; however, most of the commercially available aromatic isocyanates (error! no reference source is found.

) Such as naphthalene 1, 5-diisocyanate (NDI), 4' -diphenylmethane diisocyanate (MDI) and polymethylene polyphenyl isocyanate (PMPPI) in a continuous phase DHP-012There are solubility problems. The only miscible aromatic isocyanate is Toluene Diisocyanate (TDI), which only produces unstable microcapsules. TDI is a high-reactivity aromatic isocyanate containing two NCO groups (1-NCO and 4-NCO) with different reactivity. The less sterically hindered 4-NCO exhibits relatively high reactivity compared to 1-NCO. Once the 4-NCO group reacts with the amino group, the resulting urea product with electron donating properties further reduces the reactivity of the 1-NCO group, resulting in a reduced crosslinking efficiency, which further reduces the barrier properties of the shell wall.

Aliphatic isocyanates are less reactive than aromatic isocyanates and are good candidates for better kinetic control. With the exception of isophorone diisocyanate (IPDI) and HDI oligomers, most of the commercially available aliphatic isocyanates are miscible with the nonpolar phase DHP-012. Of the three commonly used aliphatic isocyanates, Hexamethylene Diisocyanate (HDI) only produces unstable microcapsules; 4,4' -methylenedicyclohexyl diisocyanate (H)₁₂MDI) and tetramethylxylene diisocyanate (TMXDI) produced stable microcapsules with good separation yields. H₁₂MDI and TMXDI are sterically hindered aliphatic isocyanates which exhibit lower reactivity compared to low hindered HDI with primary NCO groups. Isocyanates with the proper reactivity to maintain moderate polycondensation kinetics are desirable to achieve the barrier properties of the microcapsules. Sterically hindered aliphatic isocyanates such as H were found₁₂MDI and TMXDI are suitable interfacial crosslinking agents.

The process evaluation was performed as follows:

with respect to example 1 (see encapsulation procedure above), the morphology of the entire encapsulation process was monitored by light microscopy. The size distribution of the initial emulsion droplets was 6.0. + -. 1.5. mu.m. The robust emulsion droplets retain their morphology through interfacial polymerization. After washing with pure hexane, the isolated DETA-loaded microcapsules showed an increased size distribution of 10.2 ± 2.6 μm and a slight shape deformation.

The thermal stability of the DETA loaded microcapsules was evaluated by dynamic thermogravimetric analysis (TGA). The dried microcapsules were heated to 100 ℃ and held at this temperature for 3 hours to check their thermal stability. The microcapsules retain a stable weight at 100 ℃ with only a slight weight loss due to the high boiling solvent residue, indicating good thermal stability and limited permeability. Then, referring to the upwardly inclined line of FIG. 6A, the temperature was raised to 650 ℃ at a heating rate of 10 ℃/min. A drastic weight loss occurs around 150 c, for example, possibly due to thermal degradation of the shell structure (see downward sloping lines of fig. 6A).

DETA loaded microcapsules also show long term chemical stability in liquid epoxy resins. The mixture of unencapsulated liquid DPPG-4123 and epoxy resin (DER-331) cured within 2 hours at room temperature, showing a viscosity increase within weeks. Referring to FIG. 6B, the standard viscosity of DER-331 epoxy formulations containing DPPG-4123 (first line) or DPPG-4123 capsules (second line). After homogenization of the formulation at 160Hz for 120s, the viscosity in the red curve jumps at 40 days. Without intending to be bound by this theory, it is believed that when DPPG-4213 loaded microcapsules are suspended in epoxy resin, the standard viscosity of the epoxy resin increases only about four times during 40 days of storage compared to the 2h cure time between the pure payload and the epoxy resin, indicating a significant increase in stability of the DETA loaded microcapsules in epoxy resin. This stability is even improved over previously reported water-based DETA capsule systems. After 40 days of storage of the microcapsules in the epoxy resin, high shear forces were applied to the microcapsule suspension. The rapid sharp increase in viscosity indicates that the amine payload is still chemically active and that the system cures through shear triggering.

For an exemplary polyurethane system, encapsulated diethyltoluenediamine may be added using ISONATE in the presence of a bismuth/zinc neodecanoate mixture^TM50O, P (mixture of 2,4 and 4,4 isomers of MDI) and 95:5 weight ratio of VORAPE L^TMD3201 polyol and VORANO L^TM360 polyol mixture. It is believed that the resulting prepolymer with encapsulated diethyltoluenediamine showed shelf-life stability of 6 months at 40 ℃ (without significant increase in viscosity)

With respect to the above, an effective polyamine/hydrocarbyl anhydrous emulsion system suitable for non-aqueous encapsulation of hydrophilic payloads has been demonstrated. Good encapsulation can be released by using an emulsion system comprising a partitioning inhibitor (e.g. GuHCl) and incorporating a viscosity modifier (e.g. PIB). Morphological monitoring of the entire encapsulation process can demonstrate the high efficiency and feasibility of this non-water encapsulation technique. Further, the DETA loaded microcapsules show thermal stability at temperatures up to 100 ℃ and chemical stability in epoxy resins, with shelf life extended to four weeks. The immiscible polyamine/hydrocarbon solvent pair illustrates a platform anhydrous emulsion system for amine/alcohol encapsulation.

Encapsulation of other hydrophilic materials.

According to exemplary embodiments, other hydrophilic materials may be encapsulated using the methods described herein. Referring to the image in fig. 7, an emulsion system was prepared according to the encapsulation procedure described above, except that DETA was replaced with 1.26 grams of 1, 5-diazabicyclo [4.3.0] non-5-ene (DBN), tri (ethylene glycol), glycerol, pyridine, 1-methylimidazole, or aniline. All these formulations formed encapsulated hydrophilic materials, stable for at least 20 hours.

Claims

1. A non-water encapsulation process for forming an encapsulated hydrophilic material, the process comprising:

providing an emulsion system comprising:

a hydrocarbon component comprising one or more hydrocarbons,

a hydrophilic component comprising at least one selected from one or more amines and one or more alcohols,

a partitioning inhibitor component comprising a hydrochloride salt of a base having a pKa of the conjugate acid of 1 to 15,

a viscosity modifier component comprising a polyisobutylene polymer having a weight average molecular weight of 300 to 600 kilodaltons, and

an emulsifier component comprising one or more hydrophobically modified clays; and

treating the emulsion system to form at least one continuous phase and an encapsulated dispersed phase comprising the hydrophilic component encapsulated therein;

the encapsulated dispersed phase is separated from the continuous phase to form the encapsulated hydrophilic material.

2. The method of claim 1, wherein the hydrocarbon component comprises at least a cyclic hydrocarbon and a linear hydrocarbon in a weight ratio of 0.5:2.0 to 2.0: 0.5.

3. The method of claim 1 or claim 2, wherein the hydrocarbon component and the hydrophilic component are present in a weight ratio of 0.5:2.0 to 2.0: 0.5.

4. The method of any one of claims 1 to 3, wherein the partitioning inhibitor component is present in an amount of at least 40 wt.%, relative to the total weight of the hydrophilic component.

5. The method of any one of claims 1 to 4, wherein the viscosity modifier component is present in an amount of at least 1 wt.%, based on the total weight of the hydrocarbon component and the viscosity modifier component.

6. The method of any one of claims 1 to 5, wherein the one or more hydrophobically modified clays are present in an amount of 1 to 10 weight percent based on the total weight of the emulsion system.

7. The method of any one of claims 1 to 6, wherein the treatment of the emulsion system comprises adding one or more sterically hindered aliphatic isocyanates to the emulsion.

8. A method of preparing a curable epoxy composition, the method comprising providing one or more epoxy resins and an encapsulated hydrophilic material prepared according to the method of any one of claims 1 to 7, and the hydrophilic component comprising one or more amines.

9. A process for preparing a polyurethane-forming composition, the process comprising providing an encapsulated hydrophilic material prepared according to the process of any one of claims 1 to 7, and the hydrophilic component comprising one or more amines.

10. A process for preparing a polyurethane-forming composition, the process comprising providing an encapsulated hydrophilic material prepared according to the process of any one of claims 1 to 7, and a hydrophilic component comprising the one or more alcohols.