KR20200103645A - Non-aqueous encapsulation - Google Patents

Abstract

The non-aqueous encapsulation method for forming an encapsulated hydrophilic material comprises 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, the conjugate acid of the base having a pKa of 1 to 15. A splitting inhibitor component comprising a hydrochloride salt of a 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 at least one hydrophobically modified clay And providing an emulsion system. The method further comprises treating the emulsion system to form at least a continuous phase and an encapsulated dispersed phase, wherein the encapsulated dispersed phase comprises a hydrophilic component enclosed therein and the encapsulated dispersed phase separated from the continuous phase and encapsulated hydrophilicity. Form the material

Description

Non-aqueous encapsulation

Embodiments relate to a non-aqueous emulsion system for encapsulating a material, a method of using a non-aqueous emulsion system for encapsulating a material, and a microcapsule formed with a non-aqueous emulsion system for encapsulating a material.

For example, encapsulation of fine particles is sought to protect the compound of interest by sequencing and/or to allow controlled release of reactive or non-reactive fine particles. For example, encapsulation methods for hydrophilic payloads (materials) such as amines and alcohols are in high demand in many materials, biological and agricultural applications. For example, amine and/or alcohol microcapsules have generated considerable interest in the development of advanced smart materials such as controlled release. However, there are several problems with hydrophilic encapsulation systems such as high water loading in hydrophilic payloads, complex encapsulation techniques and/or poor barrier properties. In this regard, the encapsulation of amines and alcohols is due to the problems of non-scalable production, e.g., substantial solvent residues, poor barrier properties and/or industrial applications, due to emulsion-templated interfacial polymerization, microfluidics ( microfluidics), amine infiltration into hollow microcapsules, solvent evaporation and microfluidics can be difficult to achieve by most conventional encapsulation techniques.

The use of non-aqueous systems for the encapsulation of materials such as amines and alcohols has been proposed, for example, because it is believed that early release of the payload could potentially be promoted by aqueous residues. In addition, many encapsulation systems can react with water to produce unwanted by-products. In addition, designing a non-aqueous system (eg, a water-free system) can reduce the likelihood of and/or avoid the need for an energy-intensive drying step.

Thus, a simplified technique is sought for producing microcapsules (ie, encapsulated materials) characterized by minimal water payload and/or no water payload, high payload loading and/or good barrier properties.

Embodiments include 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 hydrochloride salt of a base having a pKa of 1 to 15 conjugate acids of the base ( partitioning) an emulsion system comprising an inhibitor component, a viscosity modifier component comprising a polyisobutylene polymer having a weight average molecular weight of 300 to 600 kilodaltons, and an emulsifier component comprising at least one hydrophobically modified clay. It can be realized by providing a non-aqueous encapsulation method for forming an encapsulated hydrophilic material comprising the step of providing. The method further comprises treating the emulsion system to form at least a continuous phase and an encapsulated dispersed phase, wherein the encapsulated dispersed phase comprises a hydrophilic component enclosed therein and the encapsulated dispersed phase separated from the continuous phase and encapsulated hydrophilicity. Form the material

1 shows an exemplary process for non-aqueous encapsulation of a hydrophilic material.
Figures 2a, 2b, 2c, 2d, 3a, and 3b show the analysis of splitting inhibitors.
4A, 4B, and 4C show the analysis of emulsifiers.
5A and 5B show the analysis of viscosity modifiers.
6A and 6B show the analysis of Example 1 prepared using DETA as the hydrophilic component.
7 shows the analysis of examples prepared using different hydrophilic components.

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 make polymeric products (eg, polyurethane-based products). Non-aqueous encapsulation is based on an oil-in-oil emulsion system with control of payload segmentation. Typically, capsule formation requires the creation of an emulsion containing at least one aqueous phase. However, water can be harmful to many reaction systems. An embodiment relates to the introduction of a stable and essentially non-aqueous oil-in-oil emulsion system based on phase separation between two organic essentially water-free phases. Emulsion systems include a dispersed phase and a continuous phase. Essentially non-aqueous and free of water means that water is present in an amount of less than 0.5 wt%, 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 small amounts in the ingredients used to form the emulsion system.

Oil-in-oil emulsion systems may be suitable for forming microcapsules (also referred to as encapsulated materials) in a non-aqueous environment. In the case of an emulsion system, a suitable solvent pair is preferred to direct the phase separation into the emulsion. For example, the liquid pairs used in conventional non-aqueous emulsions include combinations of non-polar solvents (eg, hydrocarbons and polymers) and highly polar solvents (eg, methanol, formamide and alcohols). However, polar organic payloads generally split in both phases, potentially disrupting subsequent encapsulation chemistry. Therefore, in the case of an emulsion system for encapsulating a hydrophilic payload, it is preferable to maintain immiscibility with the continuous phase of the payload and to adjust the interfacial polymerization reaction rate. In such emulsion systems, reactive polar payloads such as amines and alcohols tend to split between both emulsion phases, potentially hindering subsequent interfacial polymerization and/or Ostwald ripening (which can significantly reduce emulsion stability). Can be promoted.

The incorporation of efficient splitting inhibitors is a proposed route to keep the active core material inside the emulsion droplets. In addition, undesired reactant delivery can cause local kinetic turbulence to hinder shell growth and/or produce poor quality shell material. It is proposed to maintain a certain level of viscosity for the continuous phase as an efficient way to modify the diffusion rate of the reactants to reduce undesirable kinetic turbulence at the interface.

An exemplary embodiment relates to a non-aqueous emulsion system, which can be referred to as a Pickering emulsion system, meaning an emulsion system established by solid particles absorbed at the interface between both phases. An exemplary diagram of such a Pickering emulsion system is as follows:

For example, in an emulsion system, when two different immiscible solvents (e.g., non-aqueous solvents) are mixed, small droplets of one solvent can be formed and dispersed throughout the system to create two different phases. . Eventually the droplets can aggregate and reduce the amount of energy in the system. However, when solid particles are added to the mixture, the particles can bind to the surface of the interface between the two phases to reduce, minimize and/or prevent the possibility of agglomeration of droplets. Further, according to an exemplary embodiment, the viscosity of the continuous phase can be adjusted from 1500 to 4500 cP at 23° C. (eg, to minimize kinetic turbulence and/or reduce adhesion). The result may be an emulsion system with increased stability of the system, for example with good storage stability at room temperature where the two phases are maintained substantially over a long period of time. In addition, the resulting encapsulated material has good stability (e.g., substantially retained in shell formation) in the continuous phase and/or in other liquids such as formulated systems for forming liquid epoxy resins and/or polyurethane polymers. Can represent. Increased stability (eg, at room temperature and/or higher temperatures) can be realized with an extended pot and/or shelf life for solutions used in industrial applications.

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

The hydrocarbon liquid may contain one or more hydrocarbons having 2 to 100 carbon atoms (eg, 2 to 50 carbon atoms, 2 to 25 carbon atoms). Hydrocarbon liquids may include cyclic hydrocarbons, linear hydrocarbons and/or branched hydrocarbons. In an exemplary embodiment, the hydrocarbon liquid comprises at least one cyclic hydrocarbon and a linear hydrocarbon. Cyclic hydrocarbons and linear hydrocarbons may be present in a weight ratio of 0.5:2.0 to 2.0:0.5 (eg, 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 may 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 may 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 further comprises a splitting inhibitor component comprising at least one splitting inhibitor and a viscosity modifier component comprising at least one viscosity modifier. One or more splitting inhibitors may be in the dispersed phase and one or more viscosity modifiers may be in the continuous phase.

The cleavage inhibitor is the hydrochloride salt of a base, and the conjugate acid of this base has a pKa of 1 to 15 (eg, 5 to 15, 10 to 15, etc.). For example, the hydrochloride salt may not be a salt that reacts violently with an amine. The splitting 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%, and the like relative to the total weight of the hydrophilic component. For example, the amount of the splitting inhibitor component present in the emulsion system is 10 wt% to 100 wt% (e.g., 20 wt% to 100 wt%, 25 wt% to 100 wt%, 25 wt%) relative to the total weight of the hydrophilic component. % To 90 wt%, 30 wt% to 100 wt%, 35 wt% to 100 wt%, 40 wt% to 100 wt%, 50 wt% to 100 wt%, 60 wt% to 100 wt%, etc.) have.

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

The combination of splitting inhibitors such as GuHCl and PIB as viscosity modifiers can produce strong emulsions with stable morphology for several weeks (eg, approximately 3 weeks). A splitting inhibitor such as guanidinium chloride can be incorporated into the hydrophilic payload and act as, for example, a splitting inhibitor to minimize dispersion in the continuous phase. Emulsion droplets can serve as an encapsulation template for interfacial polymerization (e.g., with respect to shell formation) of some of the encapsulated amines and optionally added isocyanates, which at least to form a continuous phase and an encapsulated dispersed phase. It may be part of the machining of the system. Optimizing physical properties with polymer solutes in both the dispersed and continuous phases can improve emulsion stability and control viscosity. An exemplary diagram of such a system is as follows:

According to an exemplary embodiment, shell wall formation can be achieved by interfacial polymerization of polyamines from the droplet core and isocyanates as crosslinking agents that are transferred through the continuous phase. For experimental purposes, diethylenetriamine (DETA) is used as the payload, although the embodiments relate to various hydrophilic payloads such as other amines and alcohols. DETA-loaded microcapsules can be isolated in good yield and exhibit high thermal and chemical stability with extended shelf life even when dispersed in a reactive epoxy resin. The polyamine phase can be compatible with a variety of basic and hydrophilic actives.

The emulsion system further comprises an emulsifier suspension component comprising at least one hydrophobically modified clay and optionally at least one polymeric surfactant. The one or more hydrophobically modified clays are 1 wt% to 10 wt% (e.g., 1 wt% to 8 wt%, 1 wt% to 5 wt%, 1 wt% to 4 wt%, based on the total weight of the emulsion system) %, 1 wt% to 3 wt%, 2 wt% to 3 wt%). For example, the one or more hydrophobically modified clays may be present in an amount of 2.0 to 2.5 wt% based on the total weight of the emulsion system.

Clay minerals can vary depending on the combination of their constituent layers and cations. Hydrophobically modified clay refers to a clay whose surface chemistry has been modified (e.g., prior to being added to an emulsion system) using a clay modifier (e.g., surfactant, silane, or other modifier known in the art). . In an exemplary embodiment, the hydrophobically modified clay is modified by exchange with a surfactant comprising long chain alkylammonium ions, e.g., mono- or di-C ₁₂ -C ₂₂ alkylammonium ions, and , Wherein polar substituents such as hydroxyl or carboxyl are not attached to the long chain alkyl. In an exemplary embodiment, the clay is a silicate clay such as bentonite. In an exemplary embodiment, the hydrophobically modified clay is a bis (hydrogenated tallow alkyl) dimethyl salt with bentonite, a 2-ethylhexyl (hydrogenated tallow alkyl) dimethyl salt with bentonite, and/or a di (hydrogenated tallow alkyl) dimethyl salt with bentonite. Tallow alkyl)methyl.

Hydrophobically modified clays can improve various physical properties of shell formation, such as reinforcement, synergistic flame retardancy, CLTE, barrier properties, and/or improve bending or tensile modulus. In addition, as shown in the examples, the hydrophobically modified clay can provide good dispersion in emulsion systems and/or miscibility with thermoplastic systems.

Referring to Figure 1, in the case of a non-aqueous encapsulation process for forming an encapsulated hydrophilic material in an emulsion system, a mixture comprising a hydrocarbon component, a hydrophilic component, a splitting inhibitor component, a viscosity modifier component, and an emulsifier suspension component is first formed. . The components may be added and mixed in various orders, for example, the first dispersion component may be added and mixed, the second continuous phase component may be added and mixed, and a third emulsifier may be added and mixed. After the components of the emulsion system are added together to the emulsion mixture, the mixture is processed.

The treatment includes exposing the mixture to sonication (eg, applying sound energy to agitate the particles in the mixture at a high wattage number, such as at least 300 W). The treatment further includes, for example, adding one or more isocyanates to the emulsion mixture after exposing the emulsion mixture to sonication. The isocyanate may be an aromatic or aliphatic isocyanate, such as a diisocyanate. An aromatic isocyanate means an isocyanate having an N=C=O group attached directly to an aromatic group. Aliphatic isocyanate refers to an isocyanate that does not have an N=C=O group attached directly to an aromatic group. In an exemplary embodiment, the at least one isocyanate may be an aliphatic isocyanate (eg, sterically hindered aliphatic isocyanate). Exemplary hindered aliphatic isocyanates include 4,4'-methylene dicyclohexyl diisocyanate and tetramethylxylene diisocyanate (TMXDI). The processing of the emulsion mixture allows the formation of interfacial polymerization, for example shell formation around the dispersed phase. In addition, the treatment makes it possible to isolate the dispersed phase from the continuous phase to form an encapsulated hydrophilic material separable from the continuous phase (e.g., separated by shell formation). The isolated encapsulated hydrophilic material can be separated from the continuous phase and used in other systems, for example as an encapsulated component, as described below.

Emulsion systems according to embodiments can be used to effect non-aqueous encapsulation of hydrophobic materials such as amines and alcohols. The emulsion system can be separated from the continuous phase and can produce amine-loaded microcapsules and/or alcohol-loaded microcapsules that can be 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 can function as delayed and/or controlled release of the system. For example, amines and/or alcohols can be released after a period of time (eg, through dissolution of shell formation) and/or upon use of mechanical forces (eg, through use of shear forces). Thus, this non-aqueous encapsulation system can be used to prepare amine-loaded microcapsules or alcohol-loaded microcapsules, which have good barrier properties for long periods of time under contact with other resins such as polyurethane or epoxy resins (e.g. , There is no significant increase in viscosity).

In one embodiment, the amine-loaded microcapsules may contain one or more amine curing agents for an epoxy system. For example, an amine-loaded microcapsule may contain one or more amine curing agents for an epoxy system. Application of shear, heat or other techniques known in the art to allow release through shell formation allows the amine hardener to be released from the shell formation so that the amine hardener can then act as a hardener for the epoxy system.

In another embodiment, the amine-loaded microcapsules may contain one or more amine catalysts for polyurethane systems. For example, amine catalysts can be those known in the art for use in polyurethane systems (eg, for use in formulated polyol systems of polyurethane systems). The application of shear, heat or other techniques known in the art to allow release through shell formation allows the amine catalyst to be released from the shell formation so that the amine catalyst can then act as a catalyst for the formation of the polyurethane polymer. In an exemplary embodiment, shear, heat, or similar methods for release of the amine catalyst may be performed prior to the formulated polyol system comprising amine-loaded microcapsules and mixed with the isocyanate component to form a polyurethane polymer. have.

In another embodiment, the polyol-loaded microcapsules may contain one or more polyols for polyurethane systems. For example, polyols can be those known in the art for use in polyurethane systems (eg, for use in formulated polyol systems of polyurethane systems). Application of shear, heat or other techniques known in the art allows the polyol to be released from the shell formation so that the polyol can then react with the isocyanate for the formation of the polyurethane polymer. In an exemplary embodiment, shear, heat, or similar methods for release of the polyol may be performed prior to the formulated polyol system comprising polyol-loaded microcapsules and mixed with the isocyanate component to form a polyurethane polymer. .

A potential approach to releasing amines and/or alcohols from encapsulation is to use or apply heat to cause the shell formation to decompose so that the amine/alcohol is released from the shell formation. In one exemplary application of heat, it is believed that the composition comprising the encapsulated amine/alcohol is sprayed onto a hot substrate at 100° C., while the shell formation and contact of the hot substrate degrade the shell and allow the release of the amine/alcohol. . Another potential approach to releasing amine/alcohol from 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 can be useful encapsulation techniques for a variety of thermosetting systems. Emulsion systems can be used to make coatings, adhesives and/or sealants. Microencapsulations can eliminate the need for a two-component system to make a hybrid polyurethane coating, which simplifies the transport of chemicals and reduces potential pitfalls while mixing the two-component system.

Example

All parts and percentages are by weight unless otherwise indicated. All molecular weight values are based on weight average molecular weight unless otherwise indicated. Approximate properties, properties, parameters, etc. with respect to the various examples, comparative examples, and materials used in the examples and comparative examples are provided below.

material

All materials and reagents are purchased from commercial suppliers for direct use unless otherwise specified. Diethylenetriamine (DETA), polyethyleneimine (PEI, branched, Mw of 25,000), pentaethylenehexamine (PEHA), guanidinium chloride (GuHCl), fluorescein isothiocyanate isomer I, hexadecane, Decalin, polyisobutylene (500 kilodaltons Mw), 4,4'-diphenylmethane diisocyanate (MDI), polymethylene polyphenyl isocyanate (PMPPI, M _W about 340), isophorone diisocyanate (IPDI) , Hexamethylene diisocyanate (HDI), 4,4'-methylene dicyclohexyl diisocyanate (H ₁₂ MDI) and tetramethylxylene diisocyanate (TMXDI) are available from Sigma Aldrich. Naphthalene 1,5-diisocyanate was purchased from TCI America. Hydrophobically modified clay Cloisite ^® 20 nano-platelets are available from BYK Additives & Instruments. Epoxy resin DER 331 is available from Olin Corporation.

analysis

General measurement information. The viscosity of the microcapsule-epoxy composite is monitored using a Brookfield DV-I PRIME viscometer with 64# spindle at 0.2 Hz for viscosities less than 50000 cps and 0.0167 Hz for higher viscosities. The TGA test is performed using a TA instrument Q50. Fluorescence spectra are obtained using a Zeiss Observer Z1 fluorescence microscope with a 41025 Piston GFP filter set. Intentional rupture and payload release of the microcapsules is achieved using an OMNI GLH homogenizer with a 10 mm X 95 mm Fine Generator Probe for 180 seconds at 167 Hz. ¹ H NMR spectra are obtained using a Varian 500 MHz spectrometer at the University of Illinois' VOICE NMR laboratory.

Payload segmentation characterization by GC-MS. A calibration curve of DETA concentration in hydrocarbon solvents is developed. For the calibration curve, DETA is sonicated for 10 minutes to dissolve in a hydrocarbon solvent (decalin or DH solvent, <12 mg/mL). 1 mL DETA-hydrocarbon solution is mixed with 20 μL dodecane as an internal reference and then applied to GC-MS (Agilent GC 7820A and Agilent MSD 5977 E). The calibration curve is based on the linear correlation between the DETA concentration and the integral ratio of DETA/dodecane as shown below. The calibration curve of GC-MS is based on the linear correlation between the DETA concentration and the integral ratio of DETA/dodecane.

Referring to the above, (A) is a calibration curve for decalin and (B) is a calibration curve for DH solvent.

To quantitatively measure the DETA split concentration, 2 grams of diethylenetriamine (DETA) is mixed with a specific amount of an additive to form a clear solution, and then vigorously stirred with 6 grams of a hydrocarbon solvent to secure split equilibrium. . After precipitation for 5 hours, 200 μL of the hydrocarbon solution phase is diluted with 0.8 mL THF and 20 μL dodecane as an internal reference for the GC-MS test. DETA is observed at a retention time of 4.36 minutes and dodecane at 5.89 minutes.

Contact angle. A clean glass plate is coated with a thin layer of melt-coated polystyrene (M _W , about 3000 to 4000) under continuous heating by a heating gun, and the coating layer is formed upon cooling to room temperature. A droplet of 10 μL DETA-GuHCl solution is transferred to the polystyrene surface with a micropipette and the droplet shape is immediately recorded with a high-resolution camera. Images of droplets on the polystyrene surface are processed by Image J (National Institutes of Health) droplet shape analysis plug-in (LB-ADSA). Water exhibited a contact angle of 86.9 ± 1.6° on this PS surface, indicating the non-polar and hydrophobic surface of the PS coating layer.

Three phase diagram. The three-phase diagram of GuHCl-DETA-DH is constructed based on the weight ratio of the components. A series of samples with different component proportions are precisely weighed on an analytical balance and then subjected to vigorous vortex agitation for 1 minute. The sample is then allowed to settle for evaluation of immiscibility. If the clear boundaries of the two phases appear within 2 minutes, they are labeled as fast phase separation (fast PS in Figure 2d). If it takes more than 2 minutes for the sample to show clear phase separation, it is labeled as slow phase separation (slow PS in Figure 2(d)).

Surface and interfacial tension . Both surface and interfacial tensions are measured through the pendant droplet method. A Nordman Optimum ^® precision tip (#14 Gauge with Φ = 1.83 mm) in combination with a syringe pump is used as a capillary device to generate pendant droplets. Each droplet is 0.2 mL. For the measurement of the surface tension, the image of the droplet is recorded by a high-resolution camera after waiting to reach equilibrium for 1 minute. The measurement of the interfacial tension may take a longer time (5 minutes) to reach equilibrium due to the increased viscosity.

COSMOtherm simulation. The theoretical verification of phase separation in oil-in-oil emulsions is possible using the COSMO-RS theory implemented in COSMOtherm X (COSMOlogic GmbH & Co. KG, Leverkusen, Germany). In simple terms, the COSMO-RS theory calculates the chemical potential of a molecule in solution by the statistical thermodynamics of the electronic structure interactions between different molecules. The screening charge density is generated from the geometrically optimized chemical structure using the TZVP basis set to TURBOMOLE.

Estimation of overlap concentration. The overlapping concentration of PIB is estimated based on Martin's equation log(η _sp /c) = log[η] + K _m [η]c , where η _sp is the specific viscosity , c is the PIB concentration, and Km is the consistency. . To do this, [ η ] is obtained from the intercept. The Huggins and Kraemer equations may not be suitable for this estimation as the PIB wt% is in the semi-dilute-concentration regime.

Encapsulation procedure

The emulsion system of Example 1 was prepared using the following procedure: 1.26 grams of diethylenetriamine (DETA), 0.63 grams of pentaethylene-hexamine (PEHA), 0.30 grams of polyethyleneimine (PEI, branched, Mw. About 25,000), and 0.81 grams of guanidinium chloride (GuHCl) are thoroughly mixed and used as the dispersed phase (DPPG-4213). Then 2.64 grams of hexadecane, 2.64 grams of decalin, and 0.72 grams of polyisobutylene (PIB, Mw about 500,000) are mixed and used as the continuous phase (DHP-012). In addition, 0.09 grams of hydrophobically modified clay nano-platelets (Cloisite ^® 20) are dispersed in 1.71 grams of DHP-012 and used as an emulsifier suspension. Disperse 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 followed by Sonics VCX 500 Watt ultrasound with full size probe (1.27 cm diameter). Treatment is used to sonicate for 75 seconds at 60% power (pause for 1 second after each 5 seconds sonication) to produce a non-aqueous pickering emulsion.

The emulsion system is then diluted with 30 mL DHP-012 and stirred at 16.7 Hz for 20 minutes. Then, 0.6 grams of the crosslinking agent tetramethylxylene diisocyanate (TMXDI) is dissolved in 6 mL DHP-012 and added to the emulsion (stirring at 8 Hz) at an addition rate of 0.5 mL/h. After the isocyanate addition is complete, the encapsulated suspension is slowly heated to 50° C. (0.5° C./min) and stirred for 3 hours. After cooling to room temperature, the capsule suspension is diluted with 150 mL hexane and allowed to settle for 1 hour. The supernatant is carefully decanted and the remaining solid is washed 5 more times with 20 mL hexane. The resulting capsule is transferred to a watch glass and air dried in a fume hood. The isolated yield is approximately 70 wt% for Example 1.

Figure 1 shows an exemplary process of a typical encapsulation procedure with representative microscopic images during each major step: optical images (a) (c), SEM images (e) and corresponding fluorescence images (b) on the same caption area. (d)(f). (Scale bar: 40 μm).

Phase separation screening is carried out as follows:

In an exemplary embodiment, the polar phase of the emulsion system is at least 35 wt% to 50 wt% DETA, 15 wt% to 35 wt% pentaethylenehexamine (PEHA), 5 wt% to 20 wt% branched polyethyleneimine (PEI , M _W about 20 kDa), and 15 wt% to 40 wt% GuHCl. For the composition, it is believed that PEHA and PEI can act as crosslinking agents in subsequent interfacial polymerization to improve barrier performance. Without wishing to be bound by this theory, a preferred composition for an exemplary embodiment of a polar phase is approximately 43 wt%, referred to in the discussion below as DPPG-4213 (DETA-PEHA-PEI-GuHCl, 4:2:1:3 weight ratio) It is believed to be DETA, 20 wt% pentaethylenehexamine (PEHA), 10 wt% branched polyethyleneimine (PEI, M _W about 20 kDa), and 27 wt% GuHCl.

The phase separation of DETA from DH is theoretically evaluated using a liquid extraction module in COSMOtherm X. ²¹ This module provides the final concentration of each compound in both phases by performing iterative resolution and solubility calculations. The final DETA concentration from the DH phase is considered the theoretically predicted partition of DETA into the continuous phase. The effect of various inhibitors on the splitting of DETA is evaluated using the same process. Experimental and theoretical results are not exactly consistent on an absolute basis, but the theoretical predictions coincided very closely with the observed experimental trend (Fig. 2b) with a correlation coefficient R ² =0.75. This theoretical splitting analysis is useful to aid in the identification of splitting inhibitors and other suitable solvent systems for additional payloads of interest.

The viscosity of the continuous phase significantly affects the stability of the emulsion droplets. The polymeric hydrocarbon additive PIB (M _w about 500 kDa) is chosen as a viscosity modifier due to its compatibility and commercial availability. 5A, the viscosity η of the hydrocarbon phase increases from 3 cP (no PIB) to 4085 cP (12 wt% PIB), and a linear correlation between PIB wt% and log η is observed. The improved viscosity results in improved emulsion stability as visualized by light microscopy (FIG. 5A ). In an exemplary embodiment, a stable emulsion is formed when PIB is greater than 4 wt% ( η about 200 cP) and less PIB results in rapid aggregation of the emulsion droplets. Without wishing to be bound by this theory, the PIB content in the continuous phase can exceed 10 wt% ( η about 2000 cP) to maintain a strong emulsion template for subsequent interfacial polymerization. PIB is observed in a semi-dilution regimen of a solution with an estimated overlap concentration of 0.5 g·dL ^-1 (about 0.6 wt%). It is found that PIB does not significantly affect the surface tension or interfacial tension γ of the continuous phase (Fig. 5a, dotted line) between the two emulsion phases (Fig. 5a, solid line), which means that PIB mainly does not interfere with the interfacial energy. It suggests acting as a viscosity modifier.

Referring to Figure 5b, the increased viscosity also extended the shelf life of the emulsion from 5 minutes (4 wt% PIB) to 21 days (12 wt% PIB), while maintaining intact emulsion droplets in a similar shape and size. Without wishing to be bound by this theory, the improved shelf life may be due in part to the reduced diffusion coefficient of the emulsion droplets. According to the Stokes-Einstein equation, the diffusion coefficient is reduced by a factor of 10 ³ by adding PIB from 0 to 12 wt%. These viscous solvents improved emulsion stability by slowing the droplet diffusion rate and reducing the agglomeration of the emulsion.

The increased viscosity can also affect the transport properties and reaction kinetics of the subsequent interfacial polymerization. For example, stable and non-turbulent reactant transfer to the interface during continuous dispersion can allow most interfacial polymerizations to form shell materials with good barrier properties. Stable laminar flows with a low Reynolds number ( R e <200) are believed to be ideal for interfacial polymerization compared to transitional and turbulent flows ( R e> 2000). The efficiency and kinetics of the dispersion process are determined by both the convection method (stirring, mixing, and dispersion) and diffusion. With a typical stirring speed of 500 to 1000 rpm for the most commonly used stirring devices, the viscosity range of the continuous phase can be adjusted to 2000 to 4000 cP (10 to 12 wt% PIB) to maintain a desired laminar flow, The viscosity range is also suitable for producing stable emulsions. Thus, an exemplary embodiment includes an optimized continuous phase containing about 12 wt% PIB and 88 wt% DH (1:1 wt/wt), which was referred to as DHP-012 (DH-PIB, 12 wt%). .

In addition, polar organic payloads can split in both phases and potentially interfere with subsequent encapsulation chemistry. The polyamine, diethylenetriamine (DETA), is determined to be miscible with a 1:1 (wt:wt) mixture of decalin:hexadecane (DH). In particular, this mixture was found to have a dividing factor D _np-p (non-polar-polar phase) of 0.044 with a concentration of 11.3 mg mL ^-1 detected in the continuous phase by GC-MS as discussed above (see Figure 2c). Is determined.

Split inhibitor screening is performed as follows.

The organic acid was first tested as a splitting inhibitor to minimize the dispersion of DETA into the hydrocarbon phase. Referring to FIG. 2A, the DETA split concentration on the non-polar DH phase is plotted for various additives and concentrations, and the control example shows the use of a splitless inhibitor. It has been found that weak organic acids such as acetic acid (HOAc) slightly reduce the DETA resolution. The introduction of ions onto polyamines is one approach to replacing acidic additives. However, the most commonly used sodium, potassium and ammonium salts are believed to be mostly insoluble in amines and possible alcohols. For example, ammonium hexafluorophosphate (NH ₄ PF ₆ ) and guanidinium chloride (GuHCl) are soluble in DETA. It was also found that at certain concentrations, strong organic acids such as trifluoroacetic acid (TFA), ethanesulfonic acid (EtSO ₃ H), NH ₄ PF ₆ , and GuHCL have a relatively better effect in lowering the concentration of DETA in the continuous phase (Fig. 1a). In addition, 65 wt% of TFA (when the weight percent of TFA added relative to 100 wt% of DETA is 65% of the total amount of DETA added) essentially inhibited the dispersion of DETA into the nonpolar phase, whereas strong organic acids It reacted violently and exothermicly with DETA to protonate about 30 mol% of active amino groups in the payload. Similar to TFA, EtSO ₃ H was also found to react violently with amines. In addition, compared to NH ₄ PF ₆ , GuHCl is considered to be relatively more economical and mostly non-reactive to DETA. It is believed that these organic acids will behave in a similar way for alcohols.

Referring to Fig. 2c, D _np-p is reduced from 0.044 to 0 (<0.010, undetectable in GC-MS) with the addition of 65 wt% GuHCl (Fig. 2c), which indicates efficient inhibition of DETA splitting. 2D, a three-phase diagram of GuHCl-DETA-DH is shown, where PS refers to the phase separation configured to obtain a complete overview of the strong polyamine/hydrocarbon phase separation system.

Introduction of the electrolyte into the amine phase significantly altered the phase separation behavior as experimentally revealed by the measurement of the contact angle and the configuration of the phase diagram. The hydrophilicity of the polar phase is improved by adding GuHCl as indicated by the increased contact angle ( θ ) on the hydrophobic polystyrene surface (FIG. 2C, a line inclined upward). For example, when the ratio of GuHCl and DETA ( R _GD , wt/wt) is increased from 0 to 0.65, θ is changed from 48.7° to 71.9°.

As shown in FIG. 2D, GuHCl reached its dissolution limit when R _GD >1 (upper region). For R _GD <1, there is a strong phase separation between the polar (DETA-GuHCl) phase and the non-polar (DH) phase. In general, more GuHCl ( R _GD > 0.5) resulted in faster phase separation (Figure 2d, middle region). When the GuHCl loading is reduced ( R _GD <0.5), the phase separation rate is reduced and takes more than 2 minutes (Fig. 2D, lower region). It is believed that the minimum R _GD to completely inhibit payload segmentation is approximately 0.6. Through extensive experimentation, and not wishing to be bound by this theory, a good composition in the polar phase is approximately 43 wt% DETA, 20 wt% pentaethylenehexamine (PEHA), 10 wt% branched polyethyleneimine (PEI, M _W about 20). kDa), and 27 wt% GuHCl and will be referred to in the discussion below as DPPG-4213 (DETA-PEHA-PEI-GuHCl, 4:2:1:3 weight ratio). PEHA and PEI acted as crosslinking agents in subsequent interfacial polymerization to improve barrier performance.

3A shows the DETA of GC traces present in the hydrocarbon phase when mixed with different amounts of GuHCl. If more GuHCl is present, less DETA is present in the hydrocarbon phase, represented by a smaller peak area at the peak at 4.34. This data is quantified in Figure 2A.

3B depicts the NMR peaks of DETA with and without 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 is carried out as follows:

Polymeric surfactants Brij® 93 (HLB 4), Span® 80 (HLB 4.3), Span® 85 (HLB 1.8) and Tween® 0 (HLB 16.7) can promote the formation or stabilization of oil-in-oil emulsions under various stirring methods. You know you can't. In particular, for the examples, none of them formed stable emulsion droplets under various stirring methods including sonication, homogenization and high speed stirring.

With respect to the embodiments, in a Pickering particles functionalized with hydrophobic clay (Cloisite ^® 20), for example based on a relatively large size enables the generation of stable organic oil-in-water emulsion. In particular, hydrophobically functionalized clays are suitable emulsifiers based on, for example, high stability and relatively large size.

Referring to FIG. 4A, with the combination of hydrophobically functionalized clay, Span® 85 of the four polymer surfactants produces stable emulsion droplets with a uniform shape. In particular, Figure 4a shows a comparison of the stability of the emulsion and functionalized with various combinations of hydrophobic clay (Cloisite ^® 20) and a polymer surfactant Span® 85. It is found that the other three polymeric surfactants (Brij® 93, Span® 80 and Tween® 20) cannot stabilize non-aqueous emulsions. As shown in Figure 4a (scale bar of 40 μm), emulsion stability and particle size can vary depending on the amount of Span® 85. Using 3 wt% Cloisite ^® 20 reduces Span® 85 and improves emulsion stability (bc). With 6 wt% Span® 85, the system does not stabilize the emulsion without forming any droplets. With a reduced amount of Span® 85, an emulsion of large morphology appears, but bursts during the subsequent interfacial reaction, indicating that an unstable emulsion was formed.

Referring to Figure 4b (scale bar of 40 μm), the ratio to the hydrophobically functionalized clay is also evaluated without the use of other polymeric surfactants. Clays functionalized with a greater amount of hydrophobicity produce smaller sized emulsion droplets with improved stability. With the addition of 2 wt% Cloisite ^® 20, no further droplet size reduction is observed visually, and the emulsion is found to be sufficiently stable to survive the subsequent interfacial reaction. If it is not bound by this theory, it is believed to be the functionalized clay Cloisite ^® 20 hydrophobic in order to not add more than necessary the preferred total amount of about 2.0 wt% to 2.5 wt% based on the weight of the total emulsion system. Thus, it is found that the hydrophobically functionalized clay produces smaller sized emulsion droplets with improved stability. In addition, when 2 wt% or more of Cloisite ^® 20 is added, the droplet size is maintained at approximately 6 μm.

Isocyanate screening is carried out as follows:

Aromatic isocyanates generally react faster than aliphatic isocyanates. About the examples; However, most of the commercially available aromatic isocyanates such as naphthalene 1,5-diisocyanate (NDI), 4,4'-diphenylmethane diisocyanate (MDI) and polymethylene polyphenyl isocyanate (PMPPI) are continuous phase DHP- There is a solubility problem at 012. The only miscible aromatic isocyanate was toluene diisocyanate (TDI), which produced only unstable microcapsules. TDI is a highly reactive aromatic isocyanate containing two highly reactive NCO groups (1-NCO and 4-NCO). 4-NCO with less steric hindrance exhibits a relatively high reactivity compared to 1-NCO. Once the 4-NCO reacts with the amino group, the resulting urea product with electron-donating characteristics further reduces the reactivity of 1-NCO to reduce the crosslinking efficiency, which further reduces the barrier properties of the shell wall.

Aliphatic isocyanates are less reactive compared to aromatic isocyanates and are good candidates for better motion control. Most of the commercially available aliphatic isocyanates were miscible with DHP-012 in the non-polar phase, except for isophorone diisocyanate (IPDI) and HDI-oligomer. Of the three commonly used aliphatic isocyanates, hexamethylene diisocyanate (HDI) produced only unstable microcapsules; 4,4'-methylene dicyclohexyl diisocyanate (H ₁₂ MDI) and tetramethylxylene diisocyanate (TMXDI) produced stable microcapsules with good isolation efficiency. Both H ₁₂ MDI and TMXDI are sterically hindered aliphatic isocyanates and exhibit lower reactivity compared to less hindered HDIs with primary NCO groups. It is preferable that an isocyanate having an appropriate reactivity in order to maintain an appropriate polycondensation kinetics achieves the barrier properties of the microcapsules. Hindered aliphatic isocyanates such as H ₁₂ MDI and TMXDI are found to be suitable interfacial crosslinking agents.

The evaluation of the process is carried out as follows:

For Example 1 (see the encapsulation procedure described above), the shape of the entire encapsulation process is monitored by an optical microscope. The size distribution of the initial emulsion droplets is 6.0 ± 1.5 μm. The strong emulsion droplet retained its shape through interfacial polymerization. The isolated DETA-loaded microcapsules show an increased size distribution of 10.2 ± 2.6 μm with slight shape modification after washing with pure hexane.

The thermal stability of DETA-loaded microcapsules is assessed by dynamic thermogravimetric analysis (TGA). The dried microcapsules are heated to 100° C. and held at this temperature for 3 hours to check their thermal stability. The microcapsules maintain a stable weight at 100° C. with only slight weight loss due to the high boiling point solvent residue, which shows good thermal stability and limited permeability. Thereafter, referring to the upwardly inclined line of FIG. 6A, the temperature rose to 650° C. at a heating rate of 10° C./min. For example, there is a rapid weight loss around 150° C. probably due to thermal decomposition of the shell formation (see the downwardly inclined line in Fig. 6A).

The DETA-loaded microcapsules also showed long-term chemical stability in liquid epoxy resins. A mixture of unencapsulated liquid DPPG-4123 and epoxy resin (DER-331) solidified within 2 hours at room temperature, showing an increase in viscosity over several weeks. 6B, the normalized viscosity of the DER-331 epoxy resin formulation containing DPPG-4123 (first line) or DPPG-4123 capsule (second line). The increase in viscosity in the red curve at day 40 was after exposing the formulation to homogenization at 160 Hz for 120 seconds. Without wishing to be bound by this theory, when the DPPG-4213-loaded microcapsules are suspended in an epoxy resin, the normalized viscosity of the epoxy resin is about 40 days of storage compared to a 2 hour cure between the pure payload and the epoxy resin. Increased by a factor of 4, which is believed to indicate a significant improvement in the stability of the DETA-loaded microcapsules in the epoxy resin. This stability is also improved over the previously reported water-based DETA capsule system. After storing the microcapsules in epoxy for 40 days, a high shear force is applied to the microcapsule suspension. The rapid rapid increase in viscosity indicates that the amine payload is still chemically active and the system is triggered to cure by shear.

For exemplary polyurethane systems, the encapsulated diethyltoluenediamine is ISONATE™ 50 O,P (mixture of the 2,4 and 4,4 isomers of MDI) and VORAPEL in the presence of a bismuth/zinc neodecanoate mixture. ™ D3201 polyol and VORANOL™ 360 in a 95:5 weight ratio blend to be added to the prepared prepolymer. The resulting prepolymer with encapsulated diethyltoluenediamine is believed to exhibit 6 month shelf life stability (no significant increase in viscosity) at 40°C.

For the above, an efficient polyamine/hydrocarbon based anhydrous emulsion system suitable for non-aqueous encapsulation of hydrophilic payloads has been demonstrated. Good encapsulation is released by using an emulsion system that includes the incorporation of a splitting inhibitor such as GuHCl and a viscosity modifier such as PIB. The morphology monitoring of the entire encapsulation process can show the high efficiency and feasibility of this non-aqueous encapsulation technique. In addition, the DETA-loaded microcapsules exhibit thermal stability at high temperatures of 100°C and chemical stability in epoxy resins with extended shelf life of up to 4 weeks. The immiscible polyamine/hydrocarbon solvent pair exemplifies a platform anhydrous emulsion system useful for amine/alcohol encapsulation.

Encapsulation of other hydrophilic materials.

According to an exemplary embodiment, other hydrophilic materials can be encapsulated using the methods described herein. Referring to the image of Figure 7, DETA is 1.26 grams of 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), tri(ethylene glycol), glycerol, pyridine, 1-methylimidazole The emulsion system is prepared according to the encapsulation procedure described above, except that, or has been replaced by aniline. All of these formulations formed an encapsulated hydrophilic material and were stable for at least 20 hours.

Claims (10)

A non-aqueous encapsulation method for forming an encapsulated hydrophilic material, 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 whose conjugate acid of the base has a pKa of 1 to 15,
A viscosity modifier component comprising a polyisobutylene polymer having a weight average molecular weight of 300 to 600 kilodalton, and
Providing an emulsion system comprising an emulsifier component comprising at least one hydrophobically modified clay; And
Treating the emulsion system to form at least a continuous phase and an encapsulated dispersed phase, the encapsulated dispersed phase comprising a hydrophilic component enclosed therein;
The non-aqueous encapsulation method, wherein the encapsulated dispersed phase is separated from the continuous phase to form an encapsulated hydrophilic material. The method of claim 1, wherein the hydrocarbon component comprises at least cyclic hydrocarbons and linear hydrocarbons present in a weight ratio of 0.5:2.0 to 2.0:0.5. The non-aqueous encapsulation method according to claim 1 or 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. The non-aqueous encapsulation method according to any one of claims 1 to 3, wherein the splitting inhibitor component is present in an amount of at least 40 wt% relative to 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. The method of any one of claims 1 to 5, wherein the at least one hydrophobically modified clay is present in an amount of 1 wt% to 10 wt% based on the total weight of the emulsion. 7. The method of any one of claims 1-6, wherein treating the emulsion system comprises adding at least one sterically hindered aliphatic isocyanate to the emulsion. A curable epoxy comprising the step of providing at least one epoxy resin and an encapsulated hydrophilic material prepared according to the method claimed in any one of claims 1 to 7, wherein the hydrophilic component comprises the at least one amine. Method of making the composition. The preparation of a composition for forming a polyurethane comprising the step of providing an encapsulated hydrophilic material prepared according to the method claimed in any one of claims 1 to 7, wherein the hydrophilic component comprises the one or more amines. Way. The preparation of a composition for forming a polyurethane comprising the step of providing an encapsulated hydrophilic material prepared according to the method claimed in any one of claims 1 to 7, wherein the hydrophilic component comprises the at least one alcohol. Way.

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