interesting read: Long-term stability of CdSe/CdZnS quantum dot encapsulated in a multi-lamellar microcapsule .
Park SY1, Kim HS, Yoo J, Kwon S, Shin TJ, Kim K, Jeong S, Seo YS.
Abstract
We developed a novel and easy encapsulation method for quantum dots (QDs) using a partially oxidized semi-crystalline polymeric material which forms a micron-sized granule with a multi-lamellar structure from a dilute solution. The QDs were highly dispersed in the granule in such a way that they were adsorbed on the lamella with ∼12 nm spacing followed by lamellar stacking. The QDs were heavily loaded into the granule to 16.7 wt% without aggregation , a process which took only a few minutes. We found that the quantum yield of the QDs was not degraded after the encapsulation. The encapsulated QD-silicone composite exhibited excellent long-term photo- and thermal stability with its initial photoluminescence intensity maintained after blue LED light radiation for 67 days and storage at 85 °C and 85% relative humidity for 119 days.
http://www.ncbi.nlm.nih.gov/pubmed/26080682
http://www.ncbi.nlm.nih.gov/pubmed/?term=Park...d=26080682
[0098] Further, when the high-molecular-weight polymer is included, since the high-molecular-weight polymer has a higher average molecular weight than the polymer having a polar functional group in the side chain, a melt viscosity of the polymer matrix 15 may be enhanced. In this case, it is determined that a denaturalization of the quantum dot 11 due to heat may be suppressed. That is, when the quantum dot-polymer composite 10 is subject to a high temperature environment of hundreds of degrees, such as heat generated upon operation of a light emitting diode, the polymer matrix 15 may melt, however a degree of flow may be decreased upon melting by adding the high-molecular-weight polymer. In this case, a form stability of the quantum dot-polymer composite 10 may be increased, and thus, the quantum dot 11 may not be exposed to the outside, and accordingly, heat transfer to the quantum dot 11 may remain blocked. Accordingly, by suppressing the damage to the quantum dot 11 due to heat, thermal resistance or thermal stability of the quantum dot-polymer composite 10 may be improved. However, the present invention is not limited to this theory. As described above, when the polymer additionally includes a crosslinkable substituent, the polymer matrix 15 may pass through a curing process, and the crosslinkable substituent may be cured during the curing process, and thus moisture barrier properties and thermal resistance are further improved , thereby more effectively preventing damage to the quantum dot 11.
[0196] According to embodiments of the present invention, in a process of cooling a mixed solution of a polymer solution and a quantum dot suspension, when polymers form microcapsules through self-assembling, polar functional groups positioned in side chains of the polymers may increase interaction with quantum dots, and thus, the quantum dots may be captured in a polymer matrix or a self-assembled structure, and at the same time, the quantum dots may also be dispersed and positioned stably. Also, the polymer matrix in a microcapsular quantum dot-polymer composite may protect the quantum dots from an oxidizing environment such as oxygen or moisture, and from high temperature conditions . Furthermore, the microcapsules may be dispersed easily in various polymer or resin solutions, and various polymer or resin melts, and thus dispersibility may be maintained even after removing a solvent, cooling, or curing. As a result, quantum efficiency may be maintained stably for a long term.
http://patents.com/us-20150072092.html
......interesting read; then I think about QDX tm
Looking Forward
Park SY1, Kim HS, Yoo J, Kwon S, Shin TJ, Kim K, Jeong S, Seo YS.
Abstract
We developed a novel and easy encapsulation method for quantum dots (QDs) using a partially oxidized semi-crystalline polymeric material which forms a micron-sized granule with a multi-lamellar structure from a dilute solution. The QDs were highly dispersed in the granule in such a way that they were adsorbed on the lamella with ∼12 nm spacing followed by lamellar stacking. The QDs were heavily loaded into the granule to 16.7 wt% without aggregation , a process which took only a few minutes. We found that the quantum yield of the QDs was not degraded after the encapsulation. The encapsulated QD-silicone composite exhibited excellent long-term photo- and thermal stability with its initial photoluminescence intensity maintained after blue LED light radiation for 67 days and storage at 85 °C and 85% relative humidity for 119 days.
http://www.ncbi.nlm.nih.gov/pubmed/26080682
http://www.ncbi.nlm.nih.gov/pubmed/?term=Park...d=26080682
[0098] Further, when the high-molecular-weight polymer is included, since the high-molecular-weight polymer has a higher average molecular weight than the polymer having a polar functional group in the side chain, a melt viscosity of the polymer matrix 15 may be enhanced. In this case, it is determined that a denaturalization of the quantum dot 11 due to heat may be suppressed. That is, when the quantum dot-polymer composite 10 is subject to a high temperature environment of hundreds of degrees, such as heat generated upon operation of a light emitting diode, the polymer matrix 15 may melt, however a degree of flow may be decreased upon melting by adding the high-molecular-weight polymer. In this case, a form stability of the quantum dot-polymer composite 10 may be increased, and thus, the quantum dot 11 may not be exposed to the outside, and accordingly, heat transfer to the quantum dot 11 may remain blocked. Accordingly, by suppressing the damage to the quantum dot 11 due to heat, thermal resistance or thermal stability of the quantum dot-polymer composite 10 may be improved. However, the present invention is not limited to this theory. As described above, when the polymer additionally includes a crosslinkable substituent, the polymer matrix 15 may pass through a curing process, and the crosslinkable substituent may be cured during the curing process, and thus moisture barrier properties and thermal resistance are further improved , thereby more effectively preventing damage to the quantum dot 11.
[0196] According to embodiments of the present invention, in a process of cooling a mixed solution of a polymer solution and a quantum dot suspension, when polymers form microcapsules through self-assembling, polar functional groups positioned in side chains of the polymers may increase interaction with quantum dots, and thus, the quantum dots may be captured in a polymer matrix or a self-assembled structure, and at the same time, the quantum dots may also be dispersed and positioned stably. Also, the polymer matrix in a microcapsular quantum dot-polymer composite may protect the quantum dots from an oxidizing environment such as oxygen or moisture, and from high temperature conditions . Furthermore, the microcapsules may be dispersed easily in various polymer or resin solutions, and various polymer or resin melts, and thus dispersibility may be maintained even after removing a solvent, cooling, or curing. As a result, quantum efficiency may be maintained stably for a long term.
http://patents.com/us-20150072092.html
......interesting read; then I think about QDX tm
Looking Forward
