RAPID MERCURY-FREE PHOTOCHEMICAL MICROENCAPSULATION/NANOENCAPSULATION AT AMBIENT CONDITIONS

Abstract

A method of mercury-free photochemical micro-/nano-encapsulation of an active material is a process for obtaining micro-/nano-capsules by means of curing by UV LED radiation at ambient or even cold temperatures. A stirrer photo-reactor made from glass or transparent plastics can be used but mixed flow reactor could be also employed. Appropriate mixing is sufficient to expose all droplets, which contain an active material surrounded by curable-shell materials in the emulsion to the LED radiation. Using the optimum light intensities and reactions' times is critical for encapsulating the active material with a high efficiency and producing a high quality micro-/nano- capsules, Solar monochromator device can also be used as long as it generate the same radiation with a narrow/single wavelengths as the LED device. Light emitted diode (LED) is a mercury-free UV radiation source with a long operating life time and an instant ON-Off. it has a high efficiency, a very low cooling requirements and cost-efficient in photochemical encapsulation. It reduces the time of microencapsulation from 6 hours to a less than 5 minutes. It has a significant decrease in manufacturing cost, waste-water, unconverted monomers, and leftover active phase change material (PCM) compared to other methods. Conversion of more than 90% of monomers can be achieved, and encapsulation efficiency can reach 100% at optimum conditions. This is in addition to the ability of this invented technology for encapsulate volatile and heat sensitive active materials at ambient as well as low temperatures. Normal glass or transparent plastics can be used as a reactor material. Only the matched useful wavelength radiation is emitted by LED without having other wavelengths which might have a bad impact on the encapsulation process.

Claims

1. (canceled)

2. An LED stirrer photoreactor for the photochemical microencapsulation or nanoencapsulation of a phase change active material with a curable material at an ambient or cold temperature for five minutes or less wherein the curable material comprises a mono-functional monomer and wherein the photoreactor comprises: (a) a transparent tube equipped with a helix stirrer that can be fit inside the tube; and (b) at least one LED lamp with adjustable light intensities.

3. The photoreactor of claim 2, further comprising a light reflector.

4. The photoreactor of claim 2, comprising more than one LED light.

5. The photoreactor of claim 4, wherein each LED light has a different light wavelength.

6. The photoreactor of claim 4, wherein each LED light has a similar light wavelength.

7. The photoreactor of claim 4, wherein each LED light has a different light intensity.

8. The photoreactor of claim 4, comprising two LED lamps wherein each has a wavelength of 365 nm and a radiation intensity of 0.6 W/cm.sup.2.

9. The photoreactor of claim 4, comprising two LED lamps wherein each has a wavelength of 365 nm and a radiation intensity of 1.2 W/cm.sup.2.

10. The photoreactor of claim 2, wherein the curable material further comprises a second mono-functional monomer or a di-, tri-, or poly-functional monomer.

11. The photoreactor of claim 2, wherein the transparent tube is rounded or square.

12. The photoreactor of claim 2, wherein the transparent tube is plastic or glass.

13. The photoreactor of claim 12, wherein the transparent tube is glass and is 3.5 cm in diameter.

14. The photoreactor of claim 2, for the microencapsulation or nanoencapsulation at an ambient or cold temperature for five minutes.

15. The photoreactor of claim 2, for the microencapsulation or nanoencapsulation at an ambient or cold temperature for less than five.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG. 1: photochemical stirrer reactor for micro-and nano-encapsulation.

[0043] FIG. 2: Heat of Fusion of PCM Microcapsules drying at 55° C. for 12 hours and then, after drying at 55° C. for 20 days. Irradiation at 1.2 W/cm.sup.2 for 4 minutes.

[0044] FIG. 3: photochemical thin-film flow reactor for micro-and nano-encapsulation

[0045] FIG. 4: DSC thermogram of pure PT 20.

[0046] FIG. 5A: DSC measurements of microcapsules treated at 450 W UV intensity for 1 min.

[0047] FIG. 5B: DSC measurements of microcapsules treated at 450 W UV intensity for 2 min.

[0048] FIG. 5C: DSC measurements of microcapsules treated at 450 W UV intensity for 5 min.

[0049] FIG. 5D: DSC measurements of microcapsules treated at 450 W UV intensity for 10 min.

[0050] FIG. 6: Thermogravimetric analysis of samples treated at UV intensity of 450 W.

[0051] FIG. 7: Weight analysis of PT 20 microcapsules stored at 50° C. over a span of 40 days.

[0052] FIG. 8: Influence of Radiation intensity on encapsulation efficiency for 2 minutes reaction time at wavelength of 365 nm.

[0053] FIG. 9: Influence of irradiation time on encapsulation efficiency without using the mixer in the photoreactor at a wavelength of 365 nm and a radiation intensity of 1.2 W/cm.sup.2.

[0054] FIG. 10: Influence of irradiation time on encapsulation efficiency at a wavelength of 365 nm and a radiation intensity of 12 W/cm.sup.2 (maximum light intensity of the LED lamps).

[0055] FIG. 11: Influence of irradiation time on encapsulation efficiency at a wavelength of 365 nm and a radiation intensity of 0.6 W/cm.sup.2.

LIST OF TABLES

[0056] Table 2: Chemical recipe of ingredients for emulsion preparation

[0057] Table 2. Encapsulation efficiency at decreasing and increasing light intensities for total irradiation of 6 minutes, which is divided into two stages.

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