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US 2025/0154722 A1Published application
Anisotropic and electronically conducting hydrogel
OwnerMahiar Max HAMEDI, Tobias BENSELFELTinventors
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Abstract
An anisotropic and electronically conducting hydrogel and an actuator or an adjustable membrane including such a hydrogel. The hydrogel is a layered structure including a hydrophilic nanofibril material and electronically conductive elongated nanoparticles, both extending primarily in an x-y plane of the hydrogel. The density of the hydrogel varies in a substantially periodic way along the z-axis providing alternating loose layers and dense layers.
Claims14
1:
- An anisotropic and electronically conducting hydrogel comprising a layered structure, wherein the layers extend in the x-y plane of the hydrogel and are stacked along the z-axis of the hydrogel, and wherein the hydrogel comprises:
- a hydrophilic nanofibril material comprising hydrophilic nanofibrils, wherein a majority of the hydrophilic nanofibrils are extended primarily in the x-y directions of the hydrogel;
- electronically conductive elongated nanoparticles having an aspect ratio above 10, wherein a majority of the electronically conductive elongated nanoparticles are extended primarily in the x-y directions of the hydrogel;
- and
- 50-95 vol % aqueous electrolyte of the total volume of the hydrogel, preferably 70-90 vol % aqueous electrolyte, wherein the density of the hydrogel varies periodically along the z-axis of the hydrogel, providing alternating loose layers and dense layers.
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2:
- The hydrogel according to claim 1, wherein the layered structure has an average pore size of above 20 nm when in a dry state excluding the aqueous electrolyte.
3:
- The hydrogel according to claim 1, wherein the hydrophilic nanofibril material comprises cellulose nanofibrils.
4:
- The hydrogel according to claim 3, wherein 90% of the cellulose nanofibrils have a width of 1.5-3.5 nm, and a length of 0.5-1.5 μm.
5:
- The hydrogel according to claim 1, wherein the electronically conductive elongated nanoparticles are selected from the group consisting of carbon nanotubes (CNTs), graphene, MXene, or any mixture of those.
6:
- The hydrogel according to claim 5, wherein the electronically conductive elongated nanoparticles are CNTs;
- and
- the amount of electronically conductive elongated nanoparticles in the hydrogel is 30-60 wt % of the total weight of the layers.
7:
- The hydrogel according to claim 6, wherein 90% of the CNTs have a width of 4-10 nm and a length of 1.2-2 μm.
8:
- The hydrogel according to claim 1, wherein the hydrophilic nanofibril material is selected from the group consisting of cellulose nanofibrils, protein nanofibrils, chitin nanofibrils, and mixtures of those.
9:
- The hydrogel according to claim 1, wherein the hydrophilic nanofibril material is anionically or cationically charged.
10:
- The hydrogel according to claim 1, wherein the electronically conductive elongated nanoparticles have an average aspect ratio of or above 100.
11:
- The hydrogel according to claim 1, wherein an average thickness of the layers is 200-500 nm.
12:
- An actuator comprising the anisotropic and electronically conducting hydrogel according to claim 1.
13:
- A tunable membrane comprising the anisotropic and electronically conducting hydrogel according to claim 1.
14:
- A method of forming a hydrogel, wherein the method comprises the steps of:
- dispersion of hydrophilic nanofibrils, preferably cellulose nanofibrils, and electronically conductive elongated nanoparticles with an aspect ratio of 10 or higher in water to form a dispersion;
- filtration of the dispersion to form an anisotropic wet sheet;
- drying the wet sheet for a pre-determined time period to form a dried layered structure;
- and
- immersing the dried layered structure in an aqueous electrolyte.
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