In the past years, the cost of CNTs has gone down radically while their purity has gone up. CNTs can be expected to far outstrip carbon fiber in their strength to weight ratio. Of course, making a speaker cone out of CNTs (only) directly is not practical because CNTs don't stick together well. However, CNTs are known for as much as doubling the strength of other materials. Common articles assert that only 2-3% CNTs by weight is required for drastic improvements. So I purchased some CNTs that I intend to include in a coating for speaker cones. It was like $75 for 100 grams whereas early on they were more like $50/gram ballparkish. .. clearly enough to do many cones. .. The challenge according to articles is that CNTs don't dissolve like solutes. They have to be dispersed using special solvents and usually stirring and ultrasonics. Otherwise, they clump up and cause more trouble than gain. So I haven't tried this yet, but I think it would be more fun to toss some ideas around. Articles have indicated that multi-wall tubes work better for strengthening other materials so that's what I got. I'm planning on sanding just a little paper off of some paper cones and then replacing with a thinned CNT based coating .. Polyurethane is on the list of possibilities as experiments have been done with it already. So let's see if anyone has any cool ideas about the best way to do this so I can make the best decisions before taking little risks. I intend to do trial runs on useless paper or cardboard.
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I have some tangential work experience with other nanoparticles. Typically they need to be functionalized to maintain reasonable stability over time. pH alone can be used for some materials, but that tends to break down faster once you're in a full formulation.
Aggregates of nanoparticles can be quite stubborn. Typical ultrasonic baths and normal stirring methods aren't sufficient for many applications like this. Wand-based or flow-through sonicators are often used to try to break aggregates apart, but in our case even that didn't do it. For the titania-based ones we were dealing with, they needed to be functionalized at synthesis to keep them apart. I didn't have direct input on that project, but from a distance saw university professors and very bright Ph.D. students struggle to synthesize and stabilize materials for a couple years.
From a stirring standpoint, high speed dispersers can be tried. Those generate far greater shearing forces than typical mixing. But they also run the risk of aerosolizing what you're stirring (as do ultrasonic wands), and I have no interest in inhaling manmade nanoparticles.
A mini ball mill might do it also, since your application isn't likely to require tight control of particle size distribution.
Aggregates of nanoparticles can be quite stubborn. Typical ultrasonic baths and normal stirring methods aren't sufficient for many applications like this. Wand-based or flow-through sonicators are often used to try to break aggregates apart, but in our case even that didn't do it. For the titania-based ones we were dealing with, they needed to be functionalized at synthesis to keep them apart. I didn't have direct input on that project, but from a distance saw university professors and very bright Ph.D. students struggle to synthesize and stabilize materials for a couple years.
From a stirring standpoint, high speed dispersers can be tried. Those generate far greater shearing forces than typical mixing. But they also run the risk of aerosolizing what you're stirring (as do ultrasonic wands), and I have no interest in inhaling manmade nanoparticles.
A mini ball mill might do it also, since your application isn't likely to require tight control of particle size distribution.
The solvent is a mixture of butyl acetate and ethylene glycol butyl ether. Based on our lab experimental results from numerous dispersants screened out, it is particularly suitable for carbon nanotubes to be dispersed in ester solvents such as ethyl acetate, butyl acetate, and the liquid epoxy resin.
Carbon nanotubes (CNTs) can be dissolved or dispersed in various solvents, including polar and nonpolar organic solvents, as well as some acid solvents. While some solvents can help dissolve CNTs, others are better suited for dispersion. Solvent choice depends on the specific application and the desired properties of the final CNT dispersion.
Here's a more detailed look at some common solvents used for CNTs:
Polar Organic Solvents:
Generative AI is experimental. (google)
I am wondering if a little simple soap with alcohol or alcohol/acetone would do it ... those are pretty easy to get. Acetone should be compatible with polyurethane whereas alcohol probably not unless it's water based. Checking compatibility with dilute polyurethane first or other coating may be the first step. Talk about epoxy is useless .. won't be able to apply a thin coating of epoxy.
I'm thinking soap/alcohol/water based polyurethane or acetone with solvent based polyurethane and check and see how soap/alcohol behaves with that.
I found REW last night to compare impulse and frequency response. https://www.roomeqwizard.com/features.html
Carbon nanotubes (CNTs) can be dissolved or dispersed in various solvents, including polar and nonpolar organic solvents, as well as some acid solvents. While some solvents can help dissolve CNTs, others are better suited for dispersion. Solvent choice depends on the specific application and the desired properties of the final CNT dispersion.
Here's a more detailed look at some common solvents used for CNTs:
Polar Organic Solvents:
- N-methyl-2-pyrrolidone (NMP): A popular solvent for CNT dispersion, known for its good dispersion quality and stability, especially when used with dispersants.
- N,N-dimethylformamide (DMF): Another frequently used solvent, particularly for suspending CNTs in microdroplets for nanoelectronic applications.
- Tetrahydrofuran (THF): A solvent that can also be used to disperse CNTs.
- Dichloromethane: Used in the preparation of CNT dispersions for inks and paints.
- Acetone: A common solvent for CNT dispersion, although other solvents may be preferred in some cases.
- Toluene: Used in mixtures with other solvents like acetone for CNT dispersion.
- Chloroform: Another solvent used in CNT dispersions, particularly in halogenated solvent systems.
- Methanol and Ethanol: Can be used in conjunction with other solvents for CNT dispersion.
- Methanesulfonic acid (MSA) and p-toluenesulfonic acid (pToS):
These low-corrosivity acid solvents can create stable CNT solutions at high concentrations, suitable for various applications like thin-film deposition and 3D printing. - Chlorosulfonic acid and oleum:
These superacid-strength solvents are also used for acid solutions of CNTs, but their use in extrusion techniques can be challenging due to chemical compatibility.
- Dispersants:
Dispersants, such as surfactants, can be added to solvents to improve the dispersion of CNTs, especially in aqueous solutions.
- Functionalization:
Functionalizing CNTs with specific groups can enhance their solubility and dispersion in certain solvents.
- Mechanical Methods:
Methods like bead milling and high-shear homogenization can also be used to disperse CNTs in solvents.
- Methods for dispersing carbon nanotubes for nanotechnology ...
Jan 2, 2019 — Fig. 2. 2D structures of selected solvents for carbon nanotubes. From top left: DMF; acetone; diethyl ether; ethanol; p...
SpringerLink
- Doping of carbon nanotubes by halogenated solvents | Scientific Reports
Apr 29, 2022
Nature
- WO2002088025A1 - Method for dissolving carbon nanotubes
[0016] Once the carbon nanotubes are dissolved in these aromatic amines, the carbon nanotubes can be readily dissolved in other po...
- Show all
Generative AI is experimental. (google)
I am wondering if a little simple soap with alcohol or alcohol/acetone would do it ... those are pretty easy to get. Acetone should be compatible with polyurethane whereas alcohol probably not unless it's water based. Checking compatibility with dilute polyurethane first or other coating may be the first step. Talk about epoxy is useless .. won't be able to apply a thin coating of epoxy.
I'm thinking soap/alcohol/water based polyurethane or acetone with solvent based polyurethane and check and see how soap/alcohol behaves with that.
I found REW last night to compare impulse and frequency response. https://www.roomeqwizard.com/features.html
maybe to avoid aerosolizing, a special container is required ... agreed, I don't want CNTs in my lungs at all ever.
Yes, a container with lid where the probe or shaft just barely fits through can be useful.
I don't have direct experience with carbon nanotubes, but my gut feel is dispersing them well is going to be a primary challenge. It's easy to focus on the solvent package and dispersants when what you may need is more energetic mixing. I would focus on coming up with a mixing method you're comfortable with, that works quickly and reasonably well with aggregates (not simple stirring), is easy to clean, etc. The faster and easier your experiments are, the more of them you'll try. If it takes too long or feels like too much of an investment, it's harder to do what you need to do to optimize things.
Figuring out how you want to measure the resultant solution will also be important if you want to quantify what's going on. While individual nanotubes are typically too small to visualize with an optical microscope, aggregates may be viewable.
I'd also get used to the idea that whatever you do to disperse them might only last a few hours if you're using simple methods. Accepting a very short shelf life might simplify your task. I would keep the component count as low as possible in initial tests (like start with just your polyurethane, the CNTs, a good mixing method, and nothing else). For the touchier ones we do at work, there's only a 90-day shelf life, and that was after a lot of work by very smart people with heavy chemistry backgrounds. There are a zillion additives and solvents you could use, but testing them all could take you a lifetime. Chemistry tends to be less predictable than other development projects if you aren't following someone else's methods precisely.
No idea what your chemistry experience is like, so I'll throw out a couple points for some items I have knowledge of:
THF - my favorite solvent smell (not that I encourage inhaling them for fun), but also one that has recently come under scrutiny for long-term storage/peroxide formation issues. Not one I'd casually have around the house.
Acetone - pretty easy to acquire. Vapors are heavier than air, so they collect in open containers like garbage cans. When you know what's in the garbage can and someone else doesn't, may lead to a flaming garbage can. Been there; though comical after the fact, I don't recommend it. Acetone evaporates pretty rapidly, but if you aren't that worried about open container stability, may not be a problem.
Methanol - poisonous through multiple routes. Not one I'd play with casually unless it's really necessary.
Ethanol - drinkable, so of the ones you have listed, would be a pretty safe place to start. If you want high purity and undenatured, pure grain alcohol from the liquor store is a good source. Leads to amusement at the office when you have a legitimate excuse for having it around.
For the others, go to Sigma Aldrich and read the SDS's for them. Once you get used to reading SDS's, it's pretty easy to spot things you don't want to mess with.
I don't have direct experience with carbon nanotubes, but my gut feel is dispersing them well is going to be a primary challenge. It's easy to focus on the solvent package and dispersants when what you may need is more energetic mixing. I would focus on coming up with a mixing method you're comfortable with, that works quickly and reasonably well with aggregates (not simple stirring), is easy to clean, etc. The faster and easier your experiments are, the more of them you'll try. If it takes too long or feels like too much of an investment, it's harder to do what you need to do to optimize things.
Figuring out how you want to measure the resultant solution will also be important if you want to quantify what's going on. While individual nanotubes are typically too small to visualize with an optical microscope, aggregates may be viewable.
I'd also get used to the idea that whatever you do to disperse them might only last a few hours if you're using simple methods. Accepting a very short shelf life might simplify your task. I would keep the component count as low as possible in initial tests (like start with just your polyurethane, the CNTs, a good mixing method, and nothing else). For the touchier ones we do at work, there's only a 90-day shelf life, and that was after a lot of work by very smart people with heavy chemistry backgrounds. There are a zillion additives and solvents you could use, but testing them all could take you a lifetime. Chemistry tends to be less predictable than other development projects if you aren't following someone else's methods precisely.
No idea what your chemistry experience is like, so I'll throw out a couple points for some items I have knowledge of:
THF - my favorite solvent smell (not that I encourage inhaling them for fun), but also one that has recently come under scrutiny for long-term storage/peroxide formation issues. Not one I'd casually have around the house.
Acetone - pretty easy to acquire. Vapors are heavier than air, so they collect in open containers like garbage cans. When you know what's in the garbage can and someone else doesn't, may lead to a flaming garbage can. Been there; though comical after the fact, I don't recommend it. Acetone evaporates pretty rapidly, but if you aren't that worried about open container stability, may not be a problem.
Methanol - poisonous through multiple routes. Not one I'd play with casually unless it's really necessary.
Ethanol - drinkable, so of the ones you have listed, would be a pretty safe place to start. If you want high purity and undenatured, pure grain alcohol from the liquor store is a good source. Leads to amusement at the office when you have a legitimate excuse for having it around.
For the others, go to Sigma Aldrich and read the SDS's for them. Once you get used to reading SDS's, it's pretty easy to spot things you don't want to mess with.
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Good point. All of the nanoparticles we use at work are liquid based to minimize exposure risks.
We do use powdered dyes though, and Holy Mother do they spread when people do bad things with them. Had a new cleaning service person spread red dye all over the building recently.
And I personally was terribly stupid with a graphite spray in the house once. I was tempted to just move.
Obviously many solvents should be used in well-ventilated areas at a minimum.
We do use powdered dyes though, and Holy Mother do they spread when people do bad things with them. Had a new cleaning service person spread red dye all over the building recently.
And I personally was terribly stupid with a graphite spray in the house once. I was tempted to just move.
Obviously many solvents should be used in well-ventilated areas at a minimum.
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