Nanostructured phase change materials for solid state thermal management

Abstract

Nanostructured phase change materials (PCMs) which are heterogeneous materials having at least two phases, at least one of the phases having at least one of its dimensions in the nanoscale, and comprising a first agent that undergoes an endothermic phase transition at a desired temperature and a second agent that assists in maintaining a nanostructure, are provided. There are also provided methods for manufacturing such PCMs, and applications thereof for providing thermoregulatory coatings and articles containing such coatings for use in a wide range of applications, such as cooling textiles, wipes, packaging, films, walls and building materials.

What is claimed is: 
     
         1 . (canceled) 
     
     
         2 . A phase-change material (PCM) nanoemulsion, the PCM nanoemulsion comprising a dispersed phase and a continuous phase, the dispersed phase comprising a phase-change material that undergoes an endothermic phase transition at a desired transition temperature, wherein at least about 50 J/g of heat is absorbed or released during the endothermic phase transition, and the continuous phase assisting in maintaining a nanostructure in the PCM nanoemulsion, wherein:
 the continuous phase comprises an emulsifier, a surfactant, a film-forming polymer, or a combination thereof; and   the phase-change material comprises PEG, hydroxypropyl cellulose (HPC), poly(2-ethyl-2-oxazoline) (PEtOx), poly(vinyl acetate) (PVA), a mixture of fatty acid polymers, or a combination thereof.   
     
     
         3 . The PCM nanoemulsion of  claim 2 , wherein the PEG is PEG400, PEG500, PEG600, PEG650, PEG800, PEG900, PEG950, PEG1000, PEG1050, PEG1500, PEG2000, PEG2500, PEG3000, or PEG3500. 
     
     
         4 . The PCM nanoemulsion of  claim 2 , wherein the dispersed phase further comprises a nanocrystalline filler having a high aspect ratio, wherein heat absorption of the phase-change material is not substantially adversely affected by the nanocrystalline filler or is increased by the nanocrystalline filler. 
     
     
         5 . The PCM nanoemulsion of  claim 2 , wherein the nanocrystalline filler comprises nanocrystalline cellulose (NCC), a carbon nanotube, a nanoclay, a clay, or a combination thereof. 
     
     
         6 . The PCM nanoemulsion of  claim 5 , wherein the clay is montmorillonite, bentonite, kaolinite, hectorite, or halloysite. 
     
     
         7 . The PCM nanoemulsion of  claim 4 , wherein the endothermic phase transition is a solid-solid phase transition. 
     
     
         8 . The PCM nanoemulsion of  claim 4 , wherein the PCM nanoemulsion has solid or solid-like properties. 
     
     
         9 . The PCM nanoemulsion of  claim 8 , wherein the PCM nanoemulsion remains solid or solid-like when heated to the desired transition temperature. 
     
     
         10 . The PCM nanoemulsion of  claim 4 , wherein the PCM nanoemulsion is solid when dried. 
     
     
         11 . The PCM nanoemulsion of  claim 2 , wherein the phase-change material undergoes a solid-solid phase transition at about 30-39° C., 35-37° C., 20-24° C., 20-25° C., 25-30° C., 25-40° C., or 33-40° C. 
     
     
         12 . The PCM nanoemulsion of  claim 7 , wherein about 50-200 J/g, at least about 100 J/g, or at least about 150 J/g of heat is absorbed or released during the solid-solid phase transition. 
     
     
         13 . The PCM nanoemulsion of  claim 2 , wherein the PCM nanoemulsion comprises Tween, sodium dodecyl sulphate (SDS), pectin, egg lecithin, Span, sodium caseinate, poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP), nanocrystalline cellulose (NCC), hydroxypropyl cellulose (HPC), chitosan, or a combination thereof. 
     
     
         14 . A thermoregulatory coating on a substrate comprising the PCM nanoemulsion of  claim 2 . 
     
     
         15 . The thermoregulatory coating of  claim 14 , wherein the substrate is a foam, a plastic, or a packaging material. 
     
     
         16 . An article comprising the PCM nanoemulsion of  claim 2 , wherein the article is a material for food packaging. 
     
     
         17 . The article of  claim 16 , wherein the material for food packaging is a material for packaging chocolate. 
     
     
         18 . The article of  claim 16 , wherein the material for food packaging is a paper or a cardboard box or a plastic.