FIELD OF THE INVENTION

[0001] The present invention relates to a microscale reactor and methods for small scale synthesis and rapid screening conditions for the preparation of materials, such as inorganic nanopartic!es, nanocrystals, heterostructured nanomaterials, and colloidal materials.

BACKGROUND OF THE INVENTION

[0002] Developing reliable and reproducible methods for reaction processes is often a technical challenge. For example, a large scale process would usually require long wait times during a heating and cooling cycle of the process. The reaction may take a few hours to equilibrate at very high temperatures, and a few more hours to cool to room temperature. If an error occurs during this large scale reaction, for instance, if the reaction is a multi-step process, then not only is a significant amount of material wasted, but there is also an undesirable loss of time and expenses. Moreover, these large scale reactions often require the use of a traditional thermocoupled heating mantle, which in itself can also have problems due to the thermocouple.

[0003] These challenges also occur when performing reactions on a very small reaction scale, which is typically required if using expensive inorganic precursor complexes, or if requiring screening of multiple reactions conditions. Again, if a multiple step "colloidal total synthesis" is used (i.e., using colloidal, nanoparticie reagents to conduct multi-step synthesis), then this problem particularly requires reliable microscale synthetic processes since an error in any step would require that the entire process to be repeated, which would incur unwanted expenses and loss of time. Further still, there is the issue of weighing out reagents required for microscale synthesis, which is commonly complicated by requiring amounts too small to be accurately weighed out using analytical balances.

[0004] The present invention resolves these problems by providing for systems and methods that enable microscale reactions. Sn particular, the present invention allows for synthesis of inorganic nanoparticies and colloidal materials in the microscale. [0005] Any feature or combination of features described herein are included within the scope of the present invention provided that the features included in any such combination are not mutually inconsistent as will be apparent from the context, this specification, and the knowledge of one of ordinary skill in the art. Additional advantages and aspects of the present invention are apparent in the following detailed description and claims.

SUMMARY OF THE INVENTION

[0006] The subject disclosure features system and methods that provide reliable heating/cooling and mixing, coupled with uniform delivery of reagents at microscaie sizes, as specified in the independent claims. Embodiments of the invention are given in the dependent claims. Embodiments of the present invention can be freely combined with each other if they are not mutually exclusive.

[0007] According to another embodiment, the present invention features a system for synthesizing a material in a microscaie process. The system may comprise a microreactor vessel having one or more ports configured for receiving reagents and venting, a parficulate-fiiled heating mantle having a cavity configured to hold the microreactor vessel, and a grinder for grinding solid reagents.

[0008] According to one embodiment, the present invention features a method for synthesizing a material in a microscaie reaction. In one embodiment, the method may comprise providing a microreactor vessel, providing a particulate-filied heating mantle, providing one or more solid reagents required for synthesizing the material, weighing each solid reagent in an amount sufficient to provide an accurate reading on a large scale weighing device and also complying with a scaled ratio of the reaction, mixing the weighed solid reagents to form a solids mixture, grinding the solids mixture, weighing a desired amount of the ground solids mixture into the microreactor vessel as required for the microscaie reaction, placing the microreactor vessel containing the ground solids mixture directly on the particulate-filied heating mantle, and heating the microreactor vessel containing the ground solids mixture using the particulate-filied heating mantle.

[0009] According to another embodiment, the present invention may comprise a method of performing a microscaie reaction. The method may comprise providing a microreactor vessel, providing a particulate-filied heating mantle having a mantle cavity configured to hold the microreactor vessel, providing the reagents required for synthesizing the material, adding the reagents into the microreactor vessel in amounts required for the microscale reaction, thereby forming a reaction mixture, placing the microreactor vessel containing the reaction mixture directly on the mantle cavity of the parficulate-fiiled heating mantle, and heating the microreactor vessel containing the reaction mixture via the pa rti cu ί ate-fi 11 ed heating mantle. In some embodiments, the reagents may comprise a ground solids mixture, one or more liquid reagents, or a combination thereof. In other embodiments, the amount of the reagents complies with a scaled ratio of the reaction.

[0010] One of the unique and inventive technical features of the present invention is the use of a microreactor that is heated in a carbon-containing packing medium, which can accelerate a reaction time required for making inorganic nanomateriais based on, for example, semiconductor nanocrystals and colloids that typically require very high temperatures (T - 150-400 °C). Due to the same scale of the microreactor, reactions can be conducted without the use of traditional thermocoupled heating mantles. Without wishing to limit the invention to any theory or mechanism, it is believed that the technical feature of the present invention advantageously provides for heating and cooling cycles that are about 4-5 times more rapid than that of large scale reactors, which greatly shortens the reaction time require for these reactions.

[0011] Another unique and inventive technical feature of the present invention is the premixing of solid reagents in larger quantities for ease of weighing out on analytical balances, and ball milling of said solids to provide for a homogeneous solid mixture. Without wishing to limit the invention to any theory or mechanism, the technical feature of the present invention advantageously provides a uniform mixture that can be weighed out is amounts as required for a microscale reaction, while also being of sufficiently large amounts to enable facile and accurate weighing of these reagents. None of the presently known prior references or work has the unique inventive technical features of the present invention.

[0012] The present invention is shown to be universal and applicable to a broad range of inorganic nanoparticie materials. Embodiments will be described herein, for exemplary purposes, in connection with the preparation of semiconductor nanocrystals possessing desirable optica! and optoelectronic properties based on "Quantum Dots". However, the present invention is applicable with any microscale reaction.

[0013] The features and advantages of the present invention will become apparent from a consideration of the following detailed description presented in connection with the accompanying drawings in which:

[0014] F!G. 1A shows a non-limiting example of a microscale reactor system.

[0015] FIG. 1 B depicts a relative size of a microscale reactor according to an embodiment of the invention.

[0016] FIG. 2 shows a non-limiting example of a scheme for synthesizing PbSe nanowires using the microscale reactor system.

[0017] FIG. 3 shows a non-limiting example of a scheme for synthesizing PbSe quantum dots using the microscale reactor system.

[0018] FIG. 4 shows non-limiting examples of semiconductor nanomateriais prepared using the microscale reactor and process.

[0019] Following is a list of elements corresponding to a particular element referred to herein:

[0020] 1 10 microreactor vessel

[0021] 1 12 chamber portion of the microreactor vessel

[0022] 1 15 port of the microreactor vessel

[0023] 120 heating mantle

[0024] 125 cavity of heating mantle

[0025] As used herein, the terms "micro" and "microscale" refers to a size on the order of micro- (1 G ^~6 ) to milligrams when referring to mass measurements, or micro- to milliliters when referring to volume measurements.

As used herein, the microreactor may be alternatively termed a "Kawaii Reactor", pronounced "kah-wah~ee", which is Japanese for "a state of cuteness".

[0027] As used herein, a large-scale weighing device can be an analytical scale or balance that is accurate to 1 Q ^~4 g (ten-thousandth of a gram). [0028] As used herein, a scaled ratio of a reaction refers to a proportional adjustment, e.g. linear, of the mole ratio of the reaction. For example, for a 1 : 1 mol ratio of a reaction that is reduced by half, the scaled ratio is 0.5:0.5. As another example, for a 1 :2 mol ratio of a reaction that is scaled by 1/4, the scaled ratio is 0.25:0.5. As another example, for a 1 :3 mo! ratio of a reaction that is doubled, the scaled ratio is 2:6.

[0029] Referring to FIGs, 1-5, in one embodiment, the present invention features a method for synthesizing a material in a microscale reaction. The synthesized material can be an inorganic nanoparticle, a nanocrystal, a heferosfructured nanomaterial, or a colloidal material. Sn some embodiments, the method may comprise providing a microreactor vessel (1 10), providing a particulate-filled heating mantle (120), providing one or more solid reagents required for synthesizing the material, weighing each solid reagent to an amount sufficient to provide an accurate reading on a large-scale weighing device and also complying with a scaled ratio of the reaction, mixing the weighed solid reagents to form a solids mixture, and grinding the solids mixture, e.g. ball-milling, to form a homogeneously mixed ground solids mixture. In other embodiments, the method may further comprise providing one or more liquid reagents required for synthesizing the material, and adding the ground solids mixture and one or more liquid reagents into the microreactor vessel in amounts required for the microscale reaction, thereby forming a reaction mixture.

[0030] In some embodiments, the method may further comprise placing the microreactor vessel (1 10) containing the reaction mixture directly on the particulate-filled heating mantle (120), and heating the microreactor vessel (1 1 10) containing the reaction mixture using the particulate-filled heating mantle (120), thereby producing the material. In preferred embodiments, the ground solids mixture and the one or more liquid reagents react to produce the material. Without wishing to limit the invention to a particular theory or mechanism, the method allows for the reaction mixture to be heated to a desired temperature at a rate that is about 4-5 times faster than that of a larger scale reaction.

[0031] In some embodiments, the ground solids mixture is weighed to an amount required for the microscale reaction. In other embodiments, the one or more liquid reagents may comprise solvents that are added to the ground solids mixture either prior to heating or after heating of the ground solids mixture. If the liquid reagents are added after heating of the ground solids mixture, then further heating of the reaction mixture to a desired temperature may be performed. In other embodiments, the method may further comprise cooling the microreactor vessel after the reaction occurs. For example, when a reaction product is formed during heating, the product may be rapidly cooled, i.e. quenched, while in the microreactor vessel. As another example, the reaction may be cooled, and then re-heated.

|0032] In yet other embodiment, the method may further comprise mixing the reaction mixture while heating. For instance, a magnetic stir-bar that is sufficiently sized to fit in the chamber portion (1 12) of the microreactor vessel may be used for mixing. In still further embodiments, the method may comprise extracting the synthesized material. The synthesized material can be extracted via filtering or centrifugation and decanting, in order to obtain the desired solid material.

[0033] In one preferred embodiment, the microreactor vessel (1 10) may comprise a chamber portion (1 12) having one or more ports (1 15) projecting outwardly therefrom. Preferably, the one or more ports (1 15) may be configured to receive the ground solids mixture and the one or more liquid reagents. In an exemplary embodiment, the ports may be arranged such that each port is disposed at an angle with respect to each other. In another embodiment, the one or more ports (1 15) may be further configured to vent gases, such as inert gases for flushing the vessel or those produced during the reaction.

[0034] In some embodiments, the chamber portion (1 12) is spherical or conical in shape. For example, the chamber portion (1 12) may be a microscale round bottom flask or Erienmeyer flask, !n some embodiments, the microreactor vessel (1 10) can have a maximum dimension ranging from about 1 -4 cm. For instance, the maximum dimension may be the maximum diameter of the chamber portion (1 12), such as the diameter of the round bottom flask or the diameter of Erienmeyer flask base. In preferred embodiments, the microreactor vessel (1 10) is configured to hold a maximum volume ranging from about 1 mi to 30 mi, for example, about 1-10 ml, 10-20 ml, or 20-30 ml.

[0035] In a further embodiment, the heating mantle (120) may be a sand-type heating mantle having a mantle cavity (125) for holding the microreactor vessel. For example, the heating mantle may be filled with carbon-glass particulates that function as a heating medium [0036] According to another embodiment, the present invention may comprise a method of performing a microsca!e reaction. In one embodiment, the method may comprise providing a microreactor vessei (1 10) comprising a chamber portion (1 12) and one or more ports (1 15) projecting outwardly from the chamber portion (1 12), and configured for receiving reagents and venting gases, and providing a particulate-filled heating mantle (120) having a mantle cavity (125) configured to hold the chamber portion (1 12) of the microreactor vessel (1 10).

[0037] In another embodiment, the method may further comprise providing the reagents required for synthesizing the material, adding the reagents into the microreactor vessel (1 10) in amounts required for the microsca!e reaction, thereby forming a reaction mixture, placing the microreactor vessel (1 10) containing the reaction mixture directly on the mantle cavity (125) of the particulate-filled heating mantle (120), and heating the microreactor vessei (1 10) containing the reaction mixture via the particulate-filled heating mantle (120). Without wishing to limit the invention to a particular theory or mechanism, the reaction mixture is heated to a desired temperature at a rate that is about 4-5 times faster than that of a large scale reaction.

[0038] In preferred embodiments, the reagents may comprise a ground solids mixture, one or more liquid reagents, or a combination thereof. In other preferred embodiments, the amount of the reagents complies with a scaled ratio of the reaction. The reagents of the reaction mixture can react to produce the material, which may be an inorganic nanoparticle, a nanocrystal, a heterostructured nanomaterial, or a colloidal material.

[0039] In an exemplary embodiment, the ground solids mixture may prepared by providing one or more solid reagents; weighing each solid reagent to an amount sufficient to provide an accurate reading on a large-scale weighing device; mixing the one or more weighed solid reagents to form a solids mixture; and grinding the solids mixture using a grinder to form a homogeneously mixed ground solids mixture. In one embodiment, the solids mixture may be grinded by ball milling.

[0040] In some embodiments, the method may further comprise mixing the reaction mixture while heating, for example, using a magnetic stir-bar that is sufficiently sized to fit in the chamber portion (1 12) of the microreactor vessei. In other embodiments, the method may further comprise cooling the microreactor vessel (1 10). For instance, the reaction mixture may be cooled after heating, or cooled and then re-heated as required by the reaction.

[0041] !n one embodiment, the one or more ports (1 15) may be configured to receive the ground solids mixture and the one or more liquid reagents. In an exemplary embodiment, the ports may be arranged such that each port is disposed at an angle with respect to each other. In another embodiment, the one or more ports (1 15) may be further configured to vent gases, such as inert gases for flushing the vessel or those produced during the reaction.

[0042] In some embodiments, the chamber portion (1 12) is spherical or conical in shape. For example, the chamber portion (1 12) may be a microscale round bottom flask or Erlenmeyer flask. In some embodiments, the microreactor vessel (1 10) can have a maximum dimension ranging from about 1 -4 cm. For instance, the maximum dimension may be the maximum diameter of the chamber portion (1 12), such as the diameter of the round bottom flask or the diameter of Erlenmeyer flask base. In preferred embodiments, the microreactor vessel (1 10) is configured to hold a maximum volume ranging from about 1 mi to 30 mi, for example, about 1-10 ml, 10-20 ml, or 20-30 ml.

[0043] In yet another embodiment, the heating mantle (120) may be a sand-type heating mantle having a mantle cavity (125) for holding the microreactor vessel. For example, the heating mantle may be filled with carbon-glass particulates that function as a heating medium.

[0044] In alternative embodiments, at least two microreactor vessels may be use in any of the methods described herein. For example, one microreactor vessel may be used for preparing, e.g. mixing and reacting, one group of reactants, and another microreactor vessel may be used for preparing, e.g. mixing and reacting, another group of reactants. Further still, the first group of reactants may be combined with the second group of reactants in one of the microreactor vessels or in a third microreactor vessel, !n another embodiment, additional reactants may be added to the combined groups of reactants. Without wishing to limit the invention to a particular theory or mechanism, any number of microreactor vessels may be used in the present invention. [0045] In other alternative embodiments, at least two heating mantles may be use in any of the methods described herein, i.e. one heating mantle may be used for heating each microreactor vessel. For example, two heating mantles may be used to heat two microreactor vessels, where one heating mantle heats one microreactor vessel, and the desired temperature of each heating mantle may be different from each other, !n still other alternative embodiments, one heating mantle may comprise two or more mantle cavities. For example, one mantle cavity may be used for heating each microreactor vessel, i.e. one heating mantle may be used to heat two or more microreactor vessels simultaneously, !n further alternative embodiments, at least two heating mantles, each having two or more mantle cavities, may be use herein.

[0046] According to another embodiment, the present invention features a system for synthesizing a material in a microscaie process. The system may comprise a microreactor vessel (1 10) having one or more ports (1 15) projecting outwardly from the chamber portion (1 12) and configured for receiving reagents and venting, a particulate- fiiled heating mantle (120) having a mantle cavity (125) configured to hold the the chamber portion (1 12) of the microreactor vessel (1 10), and a grinder for grinding solid reagents. Without wishing to limit the invention to a particular theory or mechanism, the system may be effective for use in synthesizing inorganic nanoparticies, nanocrystals, heterostructured nanomaterials, or colloidal materials.

[0047] In some embodiments, the microreactor vessel is a glass vessel having one or more ports (1 15) configured for receiving the reagents and venting. Non-limiting examples of the glass vessel is a modified round bottom flask or Erienmeyer flask. The vessel may have one, two, or three ports disposed at or near the top the chamber portion and projecting outwardly from the chamber portion. The ports may be used for venting of gases produced during a reaction. The ports may be arranged such that each port is disposed at an angle with respect to each other. As shown in FIG. 1 B, the two ports are arranged to form a V-shape. As another example, one port may be disposed on top of the chamber, and another port disposed near the top such that an angle between the ports ranges from about 15° to 45°.

[0048] In other embodiments, the microreactor vessel can have a maximum dimension ranging from about 1-4 cm. For example, the maximum dimension is a diameter of the chamber portion. As another example, the maximum dimension may be the diameter of the base of the chamber portion, !n sti!i other embodiments, the microreactor vessel is configured to hold a maximum volume ranging from about 1 ml to 30 ml. An exemplary embodiment of the microreactor vessel is a glass reactor with an external diameter measuring 10-20 mm (1-4 mL total volume) and one or more ports, for use in nanomaterials syntheses, such as l!-VI and lll/IV semiconductors, which include cadmium chalcogenides, lead chalcogenides, and hierarchical structures prepared from these materials. As shown in FIG. 1 B, an exemplary embodiment of the main chamber of the microreactor vessel is spherical in shape and slightly smaller than a coin.

[0049] !n a preferred embodiment, the ground solids mixture is homogeneously mixed. A technique of grinding of the solids mixture may involve grinding with a ball mill; however, other suitable grinding techniques may be used. For one exemplary reaction, as described in Example 4, a novel blend of initial powdered reactants was synthesized into a CdSe@CdS tetrapod material, which is termed Tetrapod Media, for specific use with the Kawaii reactor. The reactants were bail milled together to ensure a homogenous mixture, and then added to the flask ail together, as opposed to individually, which is standard practice in the field. Without wishing to limit the inventions to a particular theory or mechanism, this may serve to significantly ease weighing out the materials into this small scale reaction vessel, while still allowing for precise control of precursor quantities.

[0050] According to one embodiment, the heating mantle may be a sand-type heating mantle. The mantle may have a cavity disposed thereon for holding the microreactor vessel. For example, the cavity may be an indentation disposed on a top section of the mantle. In another embodiment, the heating mantle may be filled with carbon-glass particulates that functions as a heating medium. In an exemplary embodiment, a heating media can have a tunable conductivity to facilitate rapid heating and cooling of the reaction vessel. Without wishing to limit the inventions to a particular theory or mechanism, this may aid to increase the rate of the reactions ran in the Kawaii reactor relative to larger scale procedures. For example, this medium may comprise a mixture of graphite/sand, in ratios of about 90:10 weight percent (graphite:sand) to 50:50 weight percent (graphite:sand), with higher percentages of sand serving to aid in reactions requiring greater insulation. [0051] EXAMPLES. The following experimental procedures are for exemplary purposes only, and are not intended to limit the invention to the examples described herein. Equivalents or substitutes are within the scope of the invention.

[0052] EXAMPLE 1. Synthesis of PbSe Nanowires, as shown in FIG. 2,

[0053] The methods have been adapted from Murray et al., Designing PbSe Nanowires and Nanorings through Oriented Attachment of Nanoparticles, 2005.

[0054] Preparation of a trioctylphosphine (TOP):Se stock solution: To a 20 mL scintillation vial was added a stir bar along with 26.38 mg of Se powder. The vial was vacuumed and back-filled with Ar 3x to remove air. Then 2 mL of TOP (97%) was added and the vial was sonicated to for a TOP:Se solution.

[0055] Flask 1 : To 1 mL 2-neck round bottom Kawaii flask equipped with a Teflon 10mm stir bar and reflux condenser was added iead(H) acetate trihydrate (72.2 mg), diphenyl ether (0.95 mL), and oleic acid (0.19 mL). The flask was evacuated of air and replaced with Ar, and subsequently heated to 150°C under Ar for 30 minutes for the formation of lead oieate. Flask 2 was prepped during this time. After cooling to 60°C, 0.38 mL of the previously prepared TOP:Se solution was added to the lead oieate mixture, and allowed to recover to 60 ^C C. The contents of flask 1 were drawn up in a syringe and quickly injected into flask 2. The temperature is expected to drop to about 200°C or slightly lower (but not below 180°C), whereupon the nanowires are allowed to grow for 60 seconds. After the growth period, the reaction was quenched as quickly as possible by acetone spray.

[0056] Flask 2: To a 50 mL 3-neck round bottom flask equipped with a Teflon ½" stir bar and reflux condenser was added n-tetradecylphosphonic acid (19mg) along with diphenyl ether (1 .425 mL). The flask was evacuated with air and then heated to 250°C under Ar.

[0057] Workup: The crude solution was mixed with an equal volume of hexane, and the nanowires were centrifuged at 10,000 rpm for 5 minutes. The precipitated nanowires were then redispersed in chloroform.

[0058] EXAMPLE 2. Synthesis of PbSe Quantum Dots, as shown in FIG. 3. [0059] The methods have been adapted from Lifshitz et al., PbSe/PbS and PbSe/PbSe _x Si- _x Core/She!! Nanocrystals, 2005.

[0060] Preparation of a TOP:Se stock solution: To a 20 mL scintillation vial was added a stir bar along with 0.155 g of Se powder (99.995%). The vial was vacuumed and backfilled with Ar 3x to remove air. Then 2 mL of TOP (97%) was added and the vial was sonicated to form a TOP:Se solution,

[0061] Flask 1 : To a 1 mL 2-neck round bottom Kawaii flask equipped with a Teflon 10mm stir bar and reflux condenser was added lead(ll) acetate trihydrate (46.15 mg), diphenyl ether (0.13 mL), oleic acid (0.098 mL). The flask was evacuated of air and replaced with Ar, and then 0.52 mL of TOP (tech grade, 90%) was added to the flask. The Kawaii reactor was subsequently heated to 1 10-120 ^C C under vacuum for 60 minutes, then placed under Ar and kept at 45°C. Next, 0.1 1 mL of TOP:Se was added into the flask. The temperature was allowed to stabilize at 45°C whereupon the contents of flask 1 were rapidly injected into the contents of flask 2 using a glass syringe wrapped in cotton. The temperature of flask 2 is expected to drop from 180-210°C to 100-130°C after injection. As the temperature stabilizes at 100-130°C, particles should form within the first 15 minutes of growth time. After the growth period, the reaction was quenched as quickly as possible by acetone spray.

[0062] Flask 2: To a 1 mL 2-neck round bottom Kawaii flask equipped with a Teflon 10mm stir bar and reflux condenser was added diphenyl ether (0.65 mL). The flask was heated to 1 10-120°C under vacuum for 1 hour, and then subsequently heated to 180- 210°C under Ar for the injection of flask 1 's contents.

[0063] EXAMPLE 3. Platinum Tipping of Nanomate iais using Kawaii Reactor.

[0064] Oleic acid (0.03 mL, 9.12 ^χ 10 ^~5 mol), o!eylamine (0.03 mL, .51 ^χ 10 ^"5 mo!), 1 ,2- hexadecanedio! (0.00645 g, 2.49 * 10 ^"5 mol) and 1 .5 mL diphenyl ether were loaded into a Kawaii Reactor with a condenser, 1 cm stir bar and thermocouple. The reaction mixture was then heated to 80" ^" 'C under vacuum for 3 min at 300 RPM to deoxygenate the reaction mixture and remove adventitious moisture from the vessel. The reaction mixture was then heated to 225°C under argon before injecting the Pt precursor and nanorods in dichlorobenzene. Separately, Pt(l!) acetylacetonate (0.00375 g. 9.54 ^χ 10 ^" mo!) was added to a dispersion of nanomaterials (3.75 mg in 0.15 mi dichlorobenzene) and the orange mixture was sonicated for 5 minutes to promote dissolution of the Pt precursor. The Pt/nanomateriai dispersion was then injected via syringe into the reaction mixture therrnostated at 225 °C under Ar. After 4 minutes the reaction had turned completely black and was removed from the heating mantle. Toluene (1.0 roL was injected upon cooiing to beiow 80 ^C C.

[0065] EXAMPLE 4. Kawaii Scale Synthesis of lnP@ZnS Nanoparticles (ln:P:MA:Zn:S = 1 :1 :4.3:1 :1 ), with added water-free steps,

[0066] TrisftrimethylsiivQphosphine/QDE Stock Prep: In a glove box, an ampule of tris(trimethylsilyl)phosphine (P(TMS) ₃ ) was opened carefully. 9.68 L of P(TMS) ₃ (8.36 mg, 0.0333 mmol) was added via syringe to a flame-dried vial. 0.5 mL of 1-octadecene (stored under molecular sieves) was added to the vial and then the vial sealed with a septum.

[0067] Synthesis of indium myristate Ini MA Indium acetate (29,20 mg, 0.1 mmol, dried en vacuo at 80°C for 1 hr) was added to a flame-dried 2 mL 2-neck round bottom Kawaii Reactor equipped with a 10 mm PTFE stir bar and condenser, along with myristic acid (98.20 mg, 0.43 mmol, dried en vacuo at 80°C for 1 hr) and 1-octadecene (ODE, 1 mL, stored under molecular sieves). The flask was subjected to three 5-minute vacuum and Argon back-filling cycles, and then the reaction was heated to 100 ^o C-120°C for 1 hr under vacuum to obtain an optically clear solution. The reaction flask was then backfilled with Ar and cooled to room temperature.

[0068] Synthesis of InP/ZnS core/shell nanocrystais: To a flame-dried 2 mL 2-neck round bottom Kawaii Reactor equipped with a 10 mm PTFE stir bar and condenser was added 0.913 mL of ODE (stored under molecular sieves), 0.167 mL of the previously- prepared lni(MA) ₄ .3 / ODE solution (corresponding to 0.0167 mmol Indium and 0.7167 mmol MA), along with 10.54 mg Zinc Stearate (0.0167 mmol, dried en vacuo at 80°C for 1 hr), 3.97 μί dodecanethiol (DDT, 0.0167 mmol, stored under molecular sieves). The flask was subjected to three 5-minute vacuum/Ar-back-filling steps while stirring at 300RP to remove air/water. Then, 0.25 mL of the P(T S) ₃ in ODE stock (0.0167 mmol, 4.84 μί P(TMS)3) was carefully added to the reaction mixture. The reaction mixture was then heated to 300°C at a heating rate of 2°C/s (i.e. 137.5 seconds to get to 300°C; 2 min 18 seconds) and allowed to grow at 300°C for 30 minutes. During the heating steps, a color change from colorless to green was observed at 80-80°C, indicative of formation of InP nanoparticies. The reaction was quenched by taking the flask out of the graphite bath and swirling the mixture.

[0069] EXAMPLE 5. Procedures for CdSe@CdS Tetrapods using a Kawaii Reactor with ultra-water-free conditions.

[0070] Preparation of cubic-CdSe seed stock solution: The vial containing the stock solution was flame-dried, the sulfur used was dried en vacuo, and the TOP 97% was stored under molecular sieves. The stock solution was also made the same day to avoid water accumulation.

[00711 Tetrapod Media Preparation: 0.060 g CdO (0.4672 mmoi), 0.160 g octadecylphosphonic acid (ODPA) (0.4784 mmol), and 3.05 g trioctyiphosphine oxide (TOPO) (7.888 mmol) were added together and ball milled at 35 Hz for 5 minutes to form a thoroughly-mixed, light purple solid composition.

[0072] Synthesis of CdSe@CdS Tetrapods: To a flame-dried 2 mL Kawaii Reactor flask equipped with a 10mm PTFE magnetic stir bar and a condenser was added 0,654 g of Tetrapod Media (which consists of TOPO, CdO, ODPA), and the flask and tetrapod media were dried en vacuo at 70°C for 15 minutes. The flask was then heated to T = 150 °C under vacuum in a graphite/sand bath and stirred at this temperature for 10-15 minutes for degassing. The reaction temperature was increased to T = 350 °C. Upon reaching ~350°Ο, 0.14 mL of TOP (97 %, stored under molecular sieves) was added via syringe, and the reaction mixture was subjected to 1 high temperature vacuum/Ar backfilling cycle. Then, oleic acid (OLAC, 90%, 0.12 mL, stored under molecular sieves) was added via syringe, and the reaction mixture was allowed to recover to 350°C. The flask was washed with the reaction mixture to incorporate any cadmium still stuck to the wails of the flask, after which the solution should be a transparent, slightly yellow solution. The flask was wrapped with cotton for 15 minutes of stabilization at 350°C, after which a stock solution of "cubic"-CdSe quantum dots (0.09 mL) was injected to the reaction mixture and the reaction mixture was again allowed to reach T = 350 °C during the 5 minutes of growth. Once the 5 minutes were done, the heating mantle was quickly removed. The reaction mixture was allowed to cool to100°C, and toluene (1 mL) was added, and the mixture was fully cooled to room temperature.

[0073] Purification: A crude sample of the final mixture was taken before purification: 0.1 ml_ of solution was added to 1 mL of toluene for this sample. To a 15 mL centrifuge was added the reaction mixture and diluted with methanol. The resulting mixture was centrifuged at 9000 rpm for 9 minutes to give a supernatant with precipitate. After centrifugation at 9000 rpm for 9 minutes, this supernatant was decanted and the precipitate was dried at T = 50 °C under vacuum for overnight to produce a solid.

|0074] As used herein, the term "about" refers to plus or minus 10% of the referenced number.

[0075] Various modifications of the invention, in addition to those described herein, will be apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fail within the scope of the appended claims. Each reference cited in the present application is incorporated herein by reference in its entirety.

[0076] Although there has been shown and described the preferred embodiment of the present invention, it will be readily apparent to those skilled in the art that modifications may be made thereto which do not exceed the scope of the appended claims. Therefore, the scope of the invention is only to be limited by the following claims. Reference numbers recited in the claims are exemplary and for ease of review by the patent office only, and are not limiting in any way. In some embodiments, the figures presented in this patent application are drawn to scale, including the angles, ratios of dimensions, etc. In some embodiments, the figures are representative only and the claims are not limited by the dimensions of the figures. In some embodiments, descriptions of the inventions described herein using the phrase "comprising" includes embodiments that could be described as "consisting of, and as such the written description requirement for claiming one or more embodiments of the present invention using the phrase "consisting of is met.