Electrically conductive smart papers
The present disclosure describes a method for preparing a paper nanocomposite, including: continuously providing a first suspension that includes lignocellulosic pulp fibers, cellulose nanofibrils, carbon nanotubes, and a cationic surfactant; continuously adding a second suspension to the first suspension to provide a slurry, the second suspension includes lignocellulosic pulp fibers, cellulose nanofibrils, carbon nanotubes, and an anionic surfactant; depositing the slurry comprising the first and second suspensions onto the substrate; and dewatering the slurry to form the paper nanocomposite.
1 . A method for preparing a paper nanocomposite by continuous flow processing, the method comprising:
continuously providing a first liquid suspension comprising a first plurality of lignocellulosic pulp fibers, a first plurality of cellulose nanofibrils, a first plurality of carbon nanotubes, and a cationic surfactant, wherein the first plurality of carbon nanotubes have a positive charge, and wherein the first plurality of carbon nanotubes are adsorbed to the first plurality lignocellulosic pulp fibers via the first plurality of cellulose nanofibrils to form a first cellulosic unit;
continuously adding a second liquid suspension to the first liquid suspension to provide a slurry, the second liquid suspension comprising a second plurality of lignocellulosic pulp fibers, a second plurality of cellulose nanofibrils, a second plurality of carbon nanotubes, and an anionic surfactant, wherein the second plurality of carbon nanotubes have a negative charge, and wherein the second plurality of carbon nanotubes are adsorbed to the second plurality lignocellulosic pulp fibers via the second plurality of cellulose nanofibrils to form a second cellulosic unit;
filtering the slurry comprising the first and second liquid suspensions on a membrane to provide a filtered mat, wherein the filtered mat is an anisotropic sheet comprising alternating layers of the first cellulosic unit and the second cellulosic unit; and
removing the liquid from the filtered mat to form the paper nanocomposite.
2 . The method of claim 1 , wherein the first plurality of carbon nanotubes are functionalized with a group capable of forming hydrogen bonds with the first plurality of lignocellulosic pulp fibers and/or the first plurality of cellulose nanofibrils.
3 . The method of claim 1 , wherein the first plurality of carbon nanotubes comprise multi-walled carbon nanotubes functionalized with a hydroxy or a carboxy group.
4 . The method of claim 1 , wherein the first plurality of carbon nanotubes have a length of from 10 μm to 20 μm and/or a mean diameter of from 8 nm to 100 nm.
5 . The method of claim 1 , wherein the first plurality of lignocellulosic pulp fibers are selected from a group consisting of bleached Kraft softwood (SW) pulp, bleached Kraft hardwood (HW) pulp, and a combination thereof.
6 . The method of claim 1 , wherein the first plurality of cellulose nanofibrils are synthesized by a TEMPO-mediated oxidation of wood pulp.
7 . The method of claim 1 , wherein a carbon nanotube to cellulose nanofibrils ratio in the first and second liquid suspensions is independently from about 1:1 to about 10:1 by weight.
8 . The method of claim 1 , further comprising collecting first and/or second unbound cellulose nanofibrils as collected free cellulose nanofibrils after filtering the slurry on the membrane, and/or collecting first and/or second carbon nanotubes as collected free carbon nanotubes after filtering the slurry on the membrane.
9 . The method of claim 8 , further comprising introducing the collected free cellulose nanofibrils and/or collected free carbon nanotubes to the first or second liquid suspension, or a combination thereof.
10 . The method of claim 1 , wherein the anionic surfactant is selected from the group consisting of alkali lignin (AL), sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), alkylphenol ethoxylates (APEO), or any combination thereof.
11 . The method of claim 1 , wherein the cationic surfactant is selected from the group consisting of cetyl-trimethylammonium bromide (CTAB), cetylpyridinium chloride (CPC), dodecyltrimethylammonium bromide (DTAB), cationic polycarboxylate (C-PCE), or a combination thereof.
12 . The method of claim 1 , wherein the first liquid suspension and/or second liquid suspension independently have a carbon nanotubes content of 1 wt % to 20 wt %, relative to the weight of the first liquid suspension and/or the second liquid suspension, respectively.
13 . The method of claim 1 , wherein the first liquid suspension and/or second liquid suspension independently have a carbon nanotubes content of 5 wt % at a 2:1 carbon nanotubes: surfactant ratio.
14 . A paper nanocomposite formed by a method of claim 1 .
15 . The paper nanocomposite of claim 14 , wherein the carbon nanotubes are bound to lignocellulosic pulp fibers via the cellulose nanofibrils.
16 . The paper nanocomposite of claim 14 , wherein the cellulose nanofibrils and/or the carbon nanotubes are further associated with the cationic surfactant, the anionic surfactant, or both the cationic surfactant and the anionic surfactant.
17 . The method of claim 1 , wherein cellulose nanofibrils of the first plurality of cellulose nanofibrils and of the second plurality of cellulose nanofibrils have a mean length of about 650 nm and a mean diameter of about 2 nm.
18 . A paper nanocomposite, comprising lignocellulosic pulp fibers, cellulose nanofibrils, carbon nanotubes, an anionic surfactant, and a cationic surfactant, wherein the paper nanocomposite is an anisotropic sheet comprising alternating layers of a first cellulosic unit and a second cellulosic unit, wherein the first cellulosic unit comprises a first plurality of positively charged carbon nanotubes adsorbed to a first plurality of lignocellulosic pulp fibers via a first plurality of cellulose nanofibrils, and wherein the second cellulosic unit comprises a second plurality of negatively carbon nanotubes adsorbed to the second plurality of lignocellulosic pulp fibers via a second plurality of cellulose nanofibrils.