Polydiacetylene water sensors

Patent metadata

Field	Value
Publication number	US-2016349223-A1
Application number	US-201515114907-A
Country	US
Kind code	A1
Filing date	Feb 20, 2015
Priority date	Feb 21, 2014
Publication date	Dec 1, 2016
Grant date	—

Abstract

Moisture sensing color change compositions are built of nanofibers of suitable small dimension based on diacetylene monomers that are polymerized in situ in a dried film containing a hygroscopic polymer that is bound to the nanofibers either directly or through crosslinkers.

First claim

1 .- 49 . (canceled)

50 . A method of making a moisture sensor comprising a substrate and an applied moisture sensitive film, the method comprising:
a) combining a monomer with lithium ion in a solution to make a nanofiber suspension; b) combining the nanofiber suspension with a composition comprising a hygroscopic polymer to make a nanofiber/polymer suspension; c) coating the combined suspension of the nanofiber and the hygroscopic polymer of step b) on a substrate; d) optionally dipping the composite polymer coated substrate into a crosslinker solution; e) drying the coating of step d) on the substrate; and f) exposing the dried product of step e) to ultraviolet radiation; wherein the monomer comprises a tail section connected to a head section, wherein the tail section comprises a carbon chain of 10 or more carbon atoms and the head section comprises a hydrophilic organic moiety that promotes formation of nanofibers in the presence of the lithium ion, wherein the carbon chain includes two conjugated triple bonds, and wherein the monomer carries an organic functional group that reacts with the crosslinker to connect the nanofiber to the hygroscopic polymer.

51 . The method according to claim 50 , wherein the tail comprises 18-30 carbon atoms.

52 . The method according to claim 50 , wherein the tail comprises 20-28 carbon atoms.

53 . The method according to claim 50 , wherein the head section comprises an aromatic group.

54 . A method of making a moisture sensor that indicates the presence of water by changing color from blue to red, comprising:
a) combining a suspension of nanofibers with a solution of a polymer that swells upon contact with water; b) coating the product of the step a) onto a substrate; c) dipping the product of the step b) into a crosslinker solution, wherein the crosslinker interacts with functional groups on the nanofibers and with functional groups on the polymer; d) drying the coating on the substrate; and e) exposing the dried coating to ultraviolet radiation; wherein the nanofibers comprise a plurality of monomers containing conjugated triple bonds and characterized by a diameter of less than 50 nanometers.

55 . The method according to claim 54 , wherein the diameter of the nanofibers is 40 nanometers or less.

56 . The method according to claim 54 , wherein the diameter of the nanofibers is 30 nanometers or less.

57 . The method according to claim 54 , wherein the diameter of the nanofibers is about 20 nanometers.

58 . A method of making a suspension of nanofibers, wherein the nanofibers have a diameter less than 50 nanometers, the method comprising combining a monomer composition and a source of lithium ions in solution, wherein the monomer composition comprises a diacetylene monomer of structure

wherein R is a hydrocarbyl group of 10 or more carbon atoms and comprising conjugated triple bonds, L is a direct bond or a divalent aliphatic linking group of 6 non-hydrogen atoms or less, Ar is an aryl ring or aryl ring system, and n is 1 to 5.

59 . A moisture sensitive composition that changes color from blue to red when contacted with water, comprising a dry film comprising polydiacetylene nanofibers of diameter less than 50 nanometers and a hygroscopic polymer that swells upon contact with water.

60 . The moisture sensitive composition according to claim 59 , wherein the hygroscopic polymer is alginate.

61 . The moisture sensitive composition according to claim 59 , wherein the polydiacetylene nanofibers are made by subjecting a diacetylene monomer to polymerization by exposing it to ultraviolet radiation.

62 . The moisture sensitive composition according to claim 61 , wherein the diacetylene monomer has a structure

wherein R is a hydrocarbyl group of 10 or more carbon atoms and comprising conjugated triple bonds, L is a direct bond or a divalent aliphatic linking group of 6 non-hydrogen atoms or less, Ar is an aryl ring or aryl ring system, and n is 1 to 5.

63 . A method of making a sensor that changes color on exposure to moisture, comprising:
coating a solution or a carboxylate salt on a substrate; drying the coated substrate; exposing the dried substrate to a solution of water-soluble polyvinyl alcohol; and irradiating the coated substrate with ultraviolet radiation; wherein the carboxylate salt is a potassium, rubidium, or cesium salt of a carboxylic acid comprising a carboxylate head and an aliphatic tail, and wherein the aliphatic tail comprises two conjugated triple bonds.

64 . The method of claim 63 , wherein the salt is a potassium salt.

65 . The method of claim 63 , wherein the carboxylic acid has 16-30 carbon atoms.

66 . The method of claim 65 , wherein carboxylic acid has 18-28 carbon atoms.

67 . A water sensor that changes color from blue in the dry state to red in the presence of water, comprising:
a substrate; a polymerized diacetylene carboxylate salt coated on the substrate; and a water-soluble polymer disposed on the substrate over the polymerized diacetylene carboxylate salt; wherein the carboxylate salt is a potassium, rubidium, or cesium salt of a carboxylic acid comprising a carboxylate head and an aliphatic tail, and wherein the aliphatic tail comprises two conjugated triple bonds.

68 . The water sensor according to claim 67 , wherein the water-soluble polymer comprises polyvinyl alcohol.

69 . The water sensor according to claim 67 , wherein the carboxylate salt is a potassium salt.

Assignees

• Univ Michigan Regents

Inventors

• Kim Jinsang
• Seo Sungbaek
• Yu Youngchang

Classifications

• B05D1/18

  performed by dipping · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• G01N31/222 Primary

  for investigating moisture content · CPC title

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title

• B05D3/007

  After-treatment · CPC title