The disclosure discloses a method of preparing electric and temperature dual-control bi-stable color-changing dyes and microcapsules, belonging to the technical fields of fine chemicals and materials science. According to the disclosure, after an electrolyte, a leuco dye and an organic solid material are mixed according to 1:(2-10):(15-50), a series of electric and temperature dual-control bi-stable color-changing dye compounds having a color change temperature range of −5° C. to +80° C. can be prepared. The dye compounds change color under cooperative control of electricity and temperature, and can be continuously stable at a certain color change state according to different conditions, and finally achieve controllable color change conditions and controllable color change stable states. When being driven by voltage and temperature, the dual-control bi-stable color-changing microcapsules prepared according to the disclosure achieve controllable color change performance and color change stable states, and have the driving voltage being lower than 10 V (much lower than the human body safety voltage 36 V).

A semiconductor nanoparticle includes a core and a shell covering a surface of the core. The shell has a larger bandgap energy than the core and is in heterojunction with the core. The semiconductor nanoparticle emits light when irradiated with light. The core is made of a semiconductor that contains M.sup.1, M.sup.2, and Z. M.sup.1 is at least one element selected from the group consisting of Ag, Cu, and Au. M.sup.2 is at least one element selected from the group consisting of Al, Ga, In and Tl. Z is at least one element selected from the group consisting of S, Se, and Te. The shell is made of a semiconductor that consists essentially of a Group 13 element and a Group 16 element.

A temperature-indicator product comprising a visual indicator comprising a thermochromic colour-memory composition and comprising an electron-donating colouring organic compound (A), an electron-accepting colouring organic compound (B) and reaction medium compound (C). The visual indicator comprises a first portion comprising a first thermochromic colour-change composition in its lower temperature state and a second portion comprising a second thermochromic colour-change composition in its higher temperature state. The product is useful as a tamper-evident indicator or as a freeze indicator.

The invention relates to an apparatus for producing a droplet assembly, which apparatus comprises a droplet generator. A process for producing a droplet assembly, using an apparatus comprising a droplet generator is also described. The invention also relates to droplet assemblies comprising a plurality of droplets. Various uses of the droplet assemblies are also described.

A semiconductor nanoparticle includes a core and a shell covering a surface of the core. The shell has a larger bandgap energy than the core and is in heterojunction with the core. The semiconductor nanoparticle emits light when irradiated with light. The core is made of a semiconductor that contains M.sup.1, M.sup.2, and Z. M.sup.1 is at least one element selected from the group consisting of Ag, Cu, and Au. M.sup.2 is at least one element selected from the group consisting of Al, Ga, In and Tl. Z is at least one element selected from the group consisting of S, Se, and Te. The shell is made of a semiconductor that consists essentially of a Group 13 element and a Group 16 element.

A semiconductor nanoparticle includes a core and a shell covering a surface of the core. The shell has a larger bandgap energy than the core and is in heterojunction with the core. The semiconductor nanoparticle emits light when irradiated with light. The core is made of a semiconductor that contains M.sup.1, M.sup.2, and Z. M.sup.1 is at least one element selected from the group consisting of Ag, Cu, and Au. M.sup.2 is at least one element selected from the group consisting of Al, Ga, In and Tl. Z is at least one element selected from the group consisting of S, Se, and Te. The shell is made of a semiconductor that consists essentially of a Group 13 element and a Group 16 element.

[Problems] To provided are a reversibly thermochromic composition that shows black during color development by using a fluoran derivative having a specific structure as an electron-donating color-developing organic compound, turns colorless during decoloration, and is excellent in light resistance and a microcapsule pigment encapsulating the reversibly thermochromic composition.

[Solution] Disclosed is a reversibly thermochromic composition including: (a) a fluoran derivative having a specific structure as an electron-donating color-developing organic compound; (b) a compound having a specific structure as an electron-accepting compound; and (c) a reaction medium which reversibly induces an electron transfer reaction between the component (a) and the component (b) in a specific temperature range, and a reversibly thermochromic microcapsule pigment encapsulating the reversibly thermochromic composition.

The disclosure discloses a method of preparing electric and temperature dual-control bi-stable color-changing dyes and microcapsules, belonging to the technical fields of fine chemicals and materials science. According to the disclosure, after an electrolyte, a leuco dye and an organic solid material are mixed according to 1:(2-10):(15-50), a series of electric and temperature dual-control bi-stable color-changing dye compounds having a color change temperature range of −5° C. to +80° C. can be prepared. The dye compounds change color under cooperative control of electricity and temperature, and can be continuously stable at a certain color change state according to different conditions, and finally achieve controllable color change conditions and controllable color change stable states. When being driven by voltage and temperature, the dual-control bi-stable color-changing microcapsules prepared according to the disclosure achieve controllable color change performance and color change stable states, and have the driving voltage being lower than 10 V (much lower than the human body safety voltage 36 V).

The invention relates to a water-soluble receptacle which is suitable for accommodating an additive or an additive composition and is filled with an additive or an additive composition comprising at least one dye or at least one dye composition, wherein the water-soluble receptacle has a wall thickness in the range from 5 to 50 .Math.m, and wherein the water-soluble receptacle comprises a water-soluble polymer composition or consists of a water-soluble polymer composition, wherein the polymer composition comprises: a) at least one polyvinyl alcohol copolymer P1 having a degree of hydrolysis in the range from 75 to 95 mol%, wherein the polyvinyl alcohol copolymer P1 is a copolymer which comprises vinyl alcohol repeating units, vinyl ester repeating units and repeating units of at least one comonomer, wherein the at least one comonomer is selected from pentaerythritol acrylate and pentaerythritol acrylate derivatives and also optionally acrylic acid; and/or b) at least one polyvinyl alcohol P2 having a degree of hydrolysis in the range from 87 to 95 mol%; wherein, in addition to the at least one polyvinyl alcohol copolymer P1 and/or the at least one polyvinyl alcohol P2, the polymer composition can additionally optionally contain additive substances; wherein the polymer composition, in the case in which it comprises at least one polyvinyl alcohol copolymer P1 and no polyvinyl alcohol P2, has a content of repeating units of the at least one comonomer in a range from in total 10% to 20% by weight, based on the total weight of polyvinyl alcohol copolymer P1; and wherein the polymer composition, in the case in which it comprises at least one polyvinyl alcohol copolymer P1 and at least one polyvinyl alcohol P2, has a content of repeating units of the at least one comonomer in a range from in total 10% to 20% by weight, based on the total weight of polyvinyl alcohol copolymer P1 and polyvinyl alcohol P2. The water-soluble receptacle can advantageously be used in a method for producing a coloured aqueous alkali metal cyanide solution. To this end, the water-soluble receptacle can be provided together with an alkali metal cyanide compound in the form of a composition Z1. The invention also relates to a method for producing said composition Z1 and to the use of said composition for producing a coloured aqueous alkali metal cyanide solution (composition Z2).

In various embodiments, the present invention is directed to a supraparticle for use in producing structural colors comprising a plurality of core/shell nanoparticles having a melanin or synthetic melanin core and a silica shell having a plurality of silanol groups on its outer surface and a poly(ethylene glycol) (PEG) crosslinker. In various embodiments, the structure of these these crosslinked supra particles is reinforced by hydrogen bonds formed between the silanol groups on the core-shell nanoparticles and mechanical, solution phase, and dry state stability.