Okay. I think we're going to go ahead and get started. So welcome to those of you here and those online on YouTube to the nano tech seminar series for April 5th. Just a quick word about our next seminar before I introduce today's speaker. So our final seminar for this spring semester will be in three weeks from today on April 26th. And our speaker will be Professor Sarkar from the Department of Biomedical, Biomedical Engineering here at Georgia Tech. So it's a pleasure to have with us today, Professor Carson Meredith. Carson got his bachelor's degree here at Georgia Tech in chemical engineering, and then went to UT Austin to get his PhD also in chemical engineering. And then did a post-doctoral stint at the National Institute for Standards and Technology, nist at, before coming to Georgia Tech in 2000, where he is currently a Professor of Chemical and Biomolecular Engineering, as well as James Harris, Faculty Fellow and also Executive Director for the renewable bio products Institute, as you can see on the slide. And until recently was editor in chief of the journal emergent materials. And we kind of joke before the seminar. Carson last spoke at this seminar series in 2008. So I think probably most of you were not at that last seminar. Even Mikkel, I don't think you were at that last seminar. So with that, I'll turn it over to Professor Meredith. Hey, thanks for the introduction. David. And everyone can hear fine. That sounds like it's good. All right. So I do appreciate the invitation to talk to and noaa tech. And indeed it was 14 years ago. So it's good to still be here and and talk to you today. So today I want to talk to you some about the work that my group does in cellulose nanomaterials, utilizing them in applications for renewable or sustainable materials. And so, first of all, what are cellulose nano materials? So for the uninitiated, if you look at the structure in a, in a plant, which includes trees, algae. Algae are technically not plants, but they're very similar. Trees, plants and algae all produce cellulose and these molecules hydrogen bond and form crystals. The crystals become segments in a kind of febrile, elementary nano febrile that contains alternating crystalline and amorphous domains. So if these, these fibers go into making larger micron size fibers and they become part of the plant cell wall. So when you, when you liberate the cellulose, for example, in the pulping process, like craft pulping or an OR of mechanical refining process. You can produce these essentially from these elementary syllables. You can produce fibrillation cellulose, which is sometimes known as cellulose nanofiber bowls or C and F. Or you can treat, treat them with acid and hydrolyze the amorphous sections and you, you just get the crystalline segments. So these are Nano rods, all right. And the, the dimensions are of the elementary crystals are about three to five nanometers in width and maybe 20 to 50 nanometers long. Alright. So they're, they're of interest because their length and aspect ratio makes them, makes them useful in modifying the properties of materials as, as well as their high crystallinity. They are quite strong there, very high modulus. So the modulus and tensile strength of the individual crystals is close to that of Kevlar polymer. And of course, factors like the source and the abstract your method can, can affect the length and the yield and things like that. So in most of the work we'll talk today about using crystalline cellulose. All right? And I want to talk about two applications. One is in waterborne coatings. So aqueous, aqueous based codings that we've used to C and C's to enable. Low VOCs. I'll explain what that means in a second. And the other application I'll talk about as renewable barrier packaging. So in the first one, the waterborne acrylic formulations. These are essentially found in many types of coatings and all types of latex paint, most, most types of latex paints. So if you look at a latex paint as an example, it contains polymers plus water plus a number of additives. So these going to include coalescence, which we'll talk about in a minute. Pigments, rheology modifiers, deformers, antimicrobials. And the polymer is in the presence is generally as a latex. So these are particles that are in a one hundred, two hundred nanometer size range, usually in many of the commercial paints. So the polymers are distributed as discrete dispersed phase materials in water. And most of these formulations have both non volatile and volatile coalescence in them. So the coalescence job is to keep they partition into the latex and they keep it soft so that when it forms a film, the particles are nice and soft and can fuse together. So as it dries, of course the water dries, but the other thing that happens as so you paint on your your paint and it's maybe 40 or 50 percent solids. As it dries, the water dries out and they begin to pack together in a close-packed arrangement. And then as they're packing and they derive further, they begin to squish essentially together. And they form polygon like geometries as the particles to form. And ultimately you have entered diffusion at the particle interfaces to wear it. It dries into a continuous solid film and that's your, your paint. So it's desired that this end product, when it dries, be relatively hard and scratch resistant. And it's also desire that this it develop hardness and scratch resistance really early. So after a few hours of drying, typically, you want it to begin to develop hardness. Otherwise, particles from the air starts to stick in it and they screw up the finish and the paint doesn't work like it's supposed to do. So. But even though you need hardness in the end property, you need soft enough for this process to happen. So, so basically, for that, as you add coalescent, these are additives, oily additives that go into the polymer and allow it to stay soft and fuse together. They eventually, most of the volatile coalescence will, will actually slowly evaporate off even after the water is gone. And they add to the volatile organic compounds or VOC burden of the paint. So early paints, we're mostly solvent based and had 40 or 50 percent solvent. Now, many low VOC solve the paints have maybe 2.5 weight percent solvent. Some of them even lower, but there really aren't that many commercially useful paints that have no VOCs and them. So one of the challenges is how can you keep them soft for the initial drying stage to film form, to form the film without adding these organic volatile coalescence. Then how do you have them transition to being hard as early as possible, you know, within the first day of drying. So all right. So we're going to use cellulose nanocrystals to help develop this type of property. And in this case, we're just using the binder part of the paint, the latex particles, so there's no pigment or anything in there since this is a scientific study. But the crystalline cellulose, this is similar to the other slide. That lets you know it's the C and C's or cellulose nanocrystals that we're using and belong to the next slide. What we're doing with the C and C's is we have two acrylic latex materials that were prepared by Dao. Dao was a partner on this project and they make a large quantity of these latex binders that, that other companies buy and make paint out of. So so the, the latex binder has 60 percent, around 60 percent butyl AC relate, 35 percent methyl methacrylate and then 5% Meth acrylic acid. So these are all vinyl acral 8. Polymer monomers and they're copolymer eyes into a random co-polymer. And we just had to, that differed and their methacrylate acid composition. So the acid is the really hydrophilic component that we added to this as part of the study. The methacrylate acid helps the particles to be swollen with water. So the water itself is the coalescent and we're not adding an organic coalescent, if that makes sense. But, and these particles are around a 116 nanometers to this latex. What we do is we add and C's and dispersion form. They're both aqueous dispersions and mix in a very simple way with a vortex mixer in the lab. So it's not an intense or sophisticated type of mixing. But we mix and we dry. And this gives you lengthen height or width characteristics of the height from the AFM measurement really means width of the cellulose nanocrystals. So what ends up happening is the cellulose will distribute itself in the water there. They're negatively charged. And the latex is also somewhat negatively-charged. But we found later in the study that the cellulose really isn't hydrophobic enough to go into the latex particles and the latex particles aren't hydrophilic enough to allow the cellulose to go in so they stay out in the water phase and ultimately they dry. They kinda get the C and C's get squished together and the interstitial and or droplet regions. So we'll look at what happens. These are images of what the latex dispersions look like. Before, before and after adding 13, 5% of the C and C's. And we actually added up to 15 weight percent. And you can see here, this is just a photograph of two dried films. And you can see there they're transparent. That the haze or the mat is a little bit different. They're a little bit more flat looking terms of the gloss. When you have the C and C's and them. But they're, they're completely transparent. And that's because this is just the solid material that you would find in a pain or a coding. But it doesn't have any pigment or binder pigment or color or anything like that. So so as I said, what we expected and indeed what we observed is that the C and C's, because it's cellulose, they're covered with a hydroxyl groups and they also have sulfate ester groups on them and are negatively charged. So they remain and the water phase and do not enter the polymers water drying. But as the polymers, as the water dries and the solids concentration goes up and it forces the particles together. And then a rod-like nanoparticles are essentially forced together between the latex particles. So one of the things that we, we're worried about or interested to, to discover is can these five, Can these particles still fuse together and form a film? When their, their exterior in what's remaining of the water phase is filled with these other solids. So can the acrylic soft polymers essentially wrap around the cellulose nanocrystals and connect to the other latex particle and fused together. So that was one of the significant questions. And as well as how are they confirming how they are distributed in the film. So it turns out that this is a, these are SEM images, these are actually polarized light microscope images of just transmission through the films. So you expect to see completely dark images if there's no birefringence and no evidence of crystalline material. Okay, So the neat acrylics are not expected to be highly crystalline and, and under polarization with crossed polarizer, the Indeed you don't see any birefringence. But as soon as you start adding the C and C's, you begin to see birefringence showing up. So brightness is a result of the crystalline CNC cellulose domain. And what's interesting is you at this length scale, this is a 100 micron length scale. They look pretty well distributed. So it's with a light microscope, it's pretty difficult to tell that there's any real structure there at the micro meter size domain. So when we go to S, so this is good news. So there aren't any giant aggregates of cellulose nanocrystals there. So if we look at with SEM. At cryo fractured cross section. So he took the films and fractured them and look at the cross section. You can see the, these are the two neat surfaces. So there is a little bit of, of structure and roughness there on the neat acrylic. But at five and 15 percent cellulose, you began to see these, these domains that they appear white and the SEM. And I have the average size that we analyze there between say, 37 to 47 or 48 nanometers, depending on the image. So they're essentially under 50 nanometer domains where you're seeing these cellulose nanocrystals show up as, as small, small aggregates. All right? And that tells us that if you, if you look at the distance between each of those little dots, it of course varies quite a lot, but they're separated by distances of it, of at least 100 up to several 100 nanometers. And if you remember, the original latex particles were around a 116 nanometers. The original C and C's were much, much smaller with a width of six nanometers. So it appears that they're at least spaced out by about the size of one of the original latex particles. So they got stuck between the particles as they were drying. But these formed really nice film so the CNC do not impede the formation of a film. And so we have, at this stage, we have a nice film forming latex binder that is pretty close to a commercial composition that has no volatile organic compounds in it. So the next question then becomes, well, what's the minimum filmed temperature that it can form a film. We found that that was about 0 Celsius. So even at close to the freezing point of water, this can still form a film. The next question is, what are the mechanical properties? Did we actually increase the modulus to be actually increase the hardness? And so when we look at ultimate tensile strength, strain at break. And the data here that from which these are derived, you can see that going from a neat material up to the 15 weight percent. Indeed, you see increases and tensile strength. The increases are essentially higher for that, for the material that contains more acrylic acid. And that makes it a little bit of sense and that it's, it's, those acid groups on the polymer are likely interacting well with the sulfate ester groups on the, and the, uh, currently the OH groups on the C and C, the strain rate goes down so they become less flexible, which is also associated with hardness. And of course, you can see that there's a large increase in the initial modulus as these dry. And as you add C and C content. So this is all good news. We also looked at nanoindentation. So this was, was done. So you look at the neat material to the 15 weight percent for our two different 510 weight percent acrylic acid and roughly the result is the same. They they become much more, much higher loads at peak as you increase the amount of C and C regardless of the initial loading force. So from this data, we can actually use a model and estimate the hardness. And you can see that, that the hardness increases really dramatically on going from the really soft, neat material to the 15 weight percent loading. Another, another way. Paint and latex are qualitatively scored and hardness is called pencil hardness. It's a test where literally kind of pencil is used to write on the film and the characteristics of the line are used to grade. And so basically, the higher the letter is in the alphabet, the higher hardness. So this is a significant jump from F to H. And finally, one of the tests the industry uses is called Konig's hardness or the conic pendulum test. It's a, it's a swinging pendulum that essentially touches the film as it swings by n. If the film is soft and tacky, it will slow the pendulum down. And it will, you'll have a fewer number of seconds of pendulum swinging. This is a very empirical type industry test. If the film gets harder and less tacky, then the pendulum swings longer, there's less friction. So, so you can see that as we add, this is looking at Day 1 and Day 7. As we add the C and C material, indeed, it gets harder. And this, and it's about the same hardness on day one as it is on day 7, which is really good news. Meaning that it develops its max hardness on the first day. So the benchmark is actually an industrial formulation that we used, that, that does have volatile organic components in it. And you can see how it starts slightly below this number. And when it ends up, it ends up a little bit above that one. But it shows that we're in this range of a VOC containing binder with no VOCs. So the conclusion of this part of the talk or that we looked at the effect of cellulose nanocrystal addition on the mechanical properties of coalescent free ambient film forming latex and CNC did not impede film formation and they were confined to these interstitial regions. And we got significant enhances, enhancement and the tensile strength modulus and hardness. And that the timescale of that hardness was, was very, was successful. So it was, after one day it had reached its hardness. So this, the student who perform this work, ESG, Dogan Gunnar, is, she's now back and Turkey. But she finished her PhD last year and published this work in progress and organic coatings. The, so, one question you might be thinking, well, we looked at adding C and C to the outside of the latex. All right, so we had seen Z is confined to the water phase outside of the hydrophobic polymer. Well, what would happen if you could put the c and c is n to the latex. And remember around the length size direction they're about the same size as the latex particles. So we looked at this and her thesis. And this actually did quite a bit of work on getting the cellulose nanocrystals, which are hydrophilic. Getting the modified to be hydrophobic so that they would go into the latex particles during the production and then looked at the film properties. And I'm not going to tell all of that story because it ended up being really some interesting chemistry to do the polymerization and modification, but it didn't. I'm not working quite as well as the original method. And so there's no, This is the most interesting part of the story. Really. Just throw them in the water and you have a nice harder film. But to do this modification, as he did use a, something called Isiah Nado ethyl methacrylate, which is a, a bifunctional, has an isocyanate group that will react with hydroxyls on the surface of the cellulose nanocrystal, and then it leaves a pendant acrylic groups. So this vinyl carbon carbon bond becomes active when you, you can cope polymerize this with those butyl lack relate methyl methacrylate monomers. So she, she did that modification work and ended up figuring out how to do what's called a mini emulsion polymerization and dispersing. You essentially take surfactant and you create droplets with the monomers and the cellulose nanocrystals up here. You end up with tiny droplets. And then you polymerize inside of the droplets and end up with final droplets. They're about the same size as your original liquids. So she did this successfully and was able to get really nice dispersion of the C and C's and the latex. But again, like I said, the mechanical properties were much better, just doing it the original way. So why not do it the simple way? But ended up being the first person to actually do a mini emulsion polymerization that they've actually got the CFCs in the particles. So alright, so this, this work, this part of the work was funded by a public-private partnership called P3 nano, which is a combination of the US Endowment for forestry and communities and USDA. That's the public part and that's the private part. So Misha softener in Material Science and Engineering was quite helpful on this work. As well as Stan Brownell at Dow and Greg gentleman, who's a scientist at the Forest Service Forest Products Laboratory in Madison, Wisconsin. They they have a pilot plan and make the CFCs for us. All right, so the next the next story I want to talk about is changing gears to another kind of film base material. And this is looking at functional barriers in packaging. So if you look at many of the types of food packaging. That we, that we use, which are considered flexible packaging. These are of course, critical to our food supply, particularly when you look at. So it's not just snack foods, but it's also fresh foods, meat and cheese. And it's very, very important to provide an oxygen barrier to protect against spoilage. But there, the problem with these things is that they are multi materials. So you end up with multilayers to create the oxygen barrier and the other types of properties like moisture barrier and sealing properties and print ability. But typically they're designed like this where there's an oxygen barrier on the inside. Now there are adhesive tie layers and then there are moisture barriers on the outsides. And other layers can be added as well. But the minimum is usually about five layers if you include the adhesives as a layer. And if you look at 2017, flexible packaging was 40% of packaging types. Rigid packaging was another 27 percent. And these end up just flexible packaging alone ends up being about 1 trillion pieces of plastic annually that's generated. So there would be, there's a lot of interest in making these kinds of materials from biomass, bio-based components because they are biodegradable and soil generally and compostable. And if it's cellulose in general, you can recycle it in a manner similar to paper recycling. So if you look at this diagram, this is oxygen permeability. It's the rate of oxygen transport through a film in terms of volume per square meter per day. And then it's normalized with the film thickness and the partial pressure of oxygen, which is usually 21 kilopascals. So this value of one in these units is a pretty close one plus or minus, you know, going from about 0.5 to about five or 10. That's, that's the range of interest in commercial packaging. So all of the materials and blue are conventional materials, most of them petroleum derived, and they are typically combined. You have really good oxygen barriers like ethylene vinyl alcohol will be the internal oxygen barrier and then outer, outside it will often be poly olefin or PET polyethylene terephthalate. So these are typically combined to get you in this range for the total constructed film. Finally, what we're interested in or biomass options. So if you look at two of these materials, Here's the cellulose nanocrystal that, that shows up around 10. So it's already pretty close to the range that we're interested in. There's also another one called chitin. Chitin nanofibers. It's even better, gets right in the center of that range. So I want to tell you the story of how we took cellulose nanocrystals, combine them with these chitin nanofibers and produced a really nice functional oxygen barrier that is fully biodegradable. So the orange values here, the challenges, this was preliminary data actually from other studies are not from our group. Where they, they, they do these in a lab where the solvent cast from water and let these dry really, really slowly. It takes a week for them to dry. So typically you have at most one weight percent solids and 99 percent water. And wait for that water to dry, you can get nice films of cellulose or chitin that have good barrier properties. But how did, how can you do this in a manufacturable way where they dry in a few minutes at most. So chitin is very similar to cellulose, so it's a polysaccharide also. So molecular, the base molecule is essentially identical to cellulose except it has what's called an acetamide group substituted on one of the hydroxyls. But like cellulose chitin forms nanofiber roles that are several nanometers wide. And these also form larger nanofibers where you have amorphous crystalline, amorphous crystalline domains. So chitin generally does not come from plants, it comes from other, other parts in nature. So they're available from industrial food processing waste so that the external shell or exoskeleton of crustaceans contains large amounts of chitin, which is the, that's the image that this is drawn from the cuticle. And also from fungi. Mushrooms for example, a and from insects. Those are the major sources of chitin and the natural world. So it can be extracted through a process that involves G-protein or deprotonation. So removing the proteins, demineralization and then sometimes doing what's called deacetylation, which is stripping off some of those acetyl groups, which replaces them with an amine, NH2 primary amine group. So it's a chemical treatment. You get a nice milky looking dispersion and water. And these, you have to add a little acetic acid to keep them positively-charged. So the chitin, because of its nitrogen group, can be protonated and positively charged. These are mechanically sheared to produce a clarified suspension that has nanofibers. So there are two too rough groups of materials we derive. One we call chitin nanofibers or CH and Fs, which typically they're long fibers and they contain more of the amorphous content. Then they're there. They're zeta potential is about plus 32 millivolts. The, the shorter ones have been the acetylated much more extensively, which allows us to come out a shorter nano whiskers, or some people call them nanocrystals to what we call them CH and w's. And there are about, they're, they're more highly charged plus 55 millivolts. And of course shorter on the order of one hundred, two hundred nanometers or so. So what we're exploring here is combining cellulose nanocrystals and chitin nanofibers and taking advantage of the negative charge and positive charge interactions. So one of the ways that where we're looking at combining them is through layering, where you build up layer by layer the film and they essentially associate with one another through electrostatic attraction. And this just gives structures where you have sulfate groups on the site, the C and C's and you have these amine NH2 groups on chitin and that's what leads to their, their negative and positive charge. So one of the studies that we did early in the group was to look at layering. So we use polylactic acid as a renewable substrate just to support the materials. And we started layering chitin cellulose, chitin cellulose and so on. And looked at the barrier properties. And what we found is that the permeability for oxygen, it actually decreased considerably when we added these chitin nanofiber and cellulose on top of that. But it didn't decrease when we added one layer of chitin or one layer of cellulose, it decreased when we add two layers. So they went through a step change. As long as you have a bi-layer of both materials, you get a lower permeability. If you keep adding to those layers, it doesn't really change the inherent permeability because we're normalizing with thickness. So having that first chitin cellulose interface seems to be very important. In producing better barrier properties. We ended up roughly in this range depending on how they are. These were spray coated. So how their spray coated and other properties you get in this range roughly with the chitin nanofibers. But the very best ones got pretty close to PET, which was exciting to us. And when we began to think about, well, are there ways to optimize this chitin and strip off more of these acetamide groups and have more amine. Therefore, they could get higher, higher charge and they could be lower, lower size, and pack better into denser structures. So that's where we went into switching modes into the chitin nano whiskers. And if you look at that work. So we did a study recently at the process intensity. If you start with carbon nanofibers and you intensify the deacetylation process, strip off more and more of those amine groups. You sequentially begin to lower the oxygen barrier, the oxygen permeability. So here we're looking at the same structure of chitin cellulose bi-layers. But we're just modifying the chitin nano whisker chemistry, making them more highly charged and shorter. And eventually you get to. Properties that are equal to polyethylene terephthalate. And then we also looked at a at an addition of kiddos. And so how does Zen is a product that's formed when you strip off almost all of these acetamide groups, strip off the asset fuel groups and you're left with primary means. And that ends up being a very strong cationic poly electrolyte, fully soluble in water. So the Katas and even added one to one with the chitin nano whiskers drops the permeability even farther. So two below that achievable with PET. So this was also a nice success and we're very happy with this result. And so this is where we get with the nano whiskers. We also were working on a project where our goal here was to move from spray coating towards other types of roll-to-roll coding processes. So the idea is to take a substrate. In this case we use cellulose acetate. So it would all be polysaccharide based and use a roll to roll coding process known as slot dye coating to produce these on a more continuous manufacturing method. And this involved a number of faculty here at Georgia Tech. So the slot layering and particular Harris's lab and EMI looks something like this where we use this specialized dual slot layer die. It's simultaneously deposits the chitin and cellulose in one pass. And it also apply shear in a way the spray coating doesn't and subsequently gets that are barrier properties in general. And finally, one last thing I will, we'll take a look at. I think I will say one thing about this slide. This is what John Reynolds in chemistry. In addition to thinking about food packaging, we also were thinking about other products that are packaged and one of them is electronic devices. And so John, if you know his lab, creates electrochromic polymers and uses them for electrochromic displays. So this is just a test of switching the color of the two polymers with a bias voltage. But typically these, these types of displays would use glass or PET as a barrier films. So we were looking at making these printable circuits in a way that, that not only replaces the ITO electrodes, but also replaces the barrier package on the outside so it's compostable or recyclable. And we found out that essentially here's our benchmark. Glass at the top. This is photo stability. So we took the devices, put them in a son test chamber, and irradiated them for a number of days. Of course, glass works the best at protecting against oxidative damage. Under exposure to light. Cellulose acetate by itself, it doesn't work well at all. But when we take our cellulose acetate and put the chitin cellulose barrier films on them. We get performance that, that varies depending on on the coding. We put down, the thicknesses and the quality of the coding. But it actually performs kind of like PET. And one of them even performed as well as glass. The duly or the dual layer chitin cellulose films. So one last thing I will say is we also looked at the direct blending approach. So if layering them individually works well, well, why not blend them where you take both components, put them into a single suspension, and then those as a film. So here you expect immediate aggregation of the two. These are oppositely charged. They do immediately aggregate. But it turns out they form really nice dense films and they have really attractive barrier properties when you do that. So this is just contrasting a c and c only film to one that has three to one sea and C's versus chitin nanocrystals nanofibers. And it's kind of hard to tell C and C's or they're really short ones. And what we think we're seeing here is there's a long chitin nanofiber in here and there's another one there. And the C and C's are basically attached to the exterior of the chitin nanofibers. So in conclusion, we've, we've worked on biomass derived materials that promise circular functional barrier packaging. Continually move towards lower O2 barrier, so better barrier targets. And this can be achieved with, with layering and blending. I am not showing the data right now, but these, we did confirm these are biodegradable and soil and R are quotable on that could be coded on water barrier substrates. So I didn't talk much about moisture barrier in this talk, but we'll talk more about that next week when I, when I talk at the eye Matt symposium. But you could actually coat these on a substrate like PET and get a, a combination of a nice water barrier. And then PET itself is recyclable. So and finally, and an acknowledgment, I would like to acknowledge the students who are still here at Georgia Tech who did this latter part of the word UAG in my lab and TJ Jiang and the Harris group. And of course faculty collaborators and a number of alumni from the group over the years. So thank you very much. We have time for questions. Well, I have question about the modify the 50 assembly code to inside is some water, so P does a pump do I don't know how you make data happen. Uh-huh. Yeah. That's a good question. So the go back to that part, the first part of the talk. So how do we get them embedded in the latex? That what you mean? So the way you, the way to do that is to start from the very beginning at the stage where the latex particles are polymerized. So they're typically what happens is you have this yellow or orange phase is the organic monomer. And then you have water with surfactant and these are emulsified. So typically there would be no no cellulose nanocrystals present. And then you would initiate this emulsion to begin polymerizing. So it's a free radical polymerization and depolymerization would occur inside the droplets. So in order to get the silos nanocrystals in the droplets, you essentially have to, you have to get them in the monomer droplets first before you polymerize them. So that's what we, what we did is we added the cellulose nanocrystals to this organic phase after they were modified with this acrylic surface modifier. And so we found that if you get a high enough coverage of this group, the cellulose nanocrystal, they will partition into the organic phase. So they, the organics are the monomer, the methyl methacrylate of butyl accurately monomer. The CFCs, we'll go into that monomer instead of the water. If you modify them. And then you emulsify it with high-energy like ultrasound. And you have droplets with the C and C's embedded. And then you can kick off the the polymerization and the polymer forms around the CFCs. That's how it works. So I have two questions, actually, one of which is difficult to talk about this next week, I can wait till next week stock. Okay. If you could expand more about what, a moisture barrier or oxygen barrier, I would think one would do the purpose of the other. Editors. Second question was, I think in that same slide you also talk about how the oxygen permeability. So the materials degrade. And I wasn't anything to comment more about the degradation process. All right. So typically materials that are good, oxygen barriers are usually the chemistry of blocking oxygen. And general is such that they end up usually being somewhat sensitive to water. So this ethylene vinyl alcohol is kind of the industry workhorse for polymeric water, I'm sorry, oxygen barriers. Polyvinyl chloride, PVD C is also a good one, but it's being phased out because of the chlorine content. But this one is still a workhorse and it's a really incredibly good oxygen barrier. But it's very, very sensitive to water. So if you, if you get this exposed to anything above 50 percent humidity, it, it loses its oxygen permeability properties. And what happens is water will swell the polymer and it no longer has the density required to block oxygen gas. So there is kind of a trade off between high oxygen barrier and high water barrier kind of usually not found in the same material. And that's that's why they're layered like this. So the other question was about the degradation. So current materials, really, they don't degrade in any appreciable timescale. And there's not a recycling infrastructure commercially available to send this type of multi-component waste, so it gets landfilled. So we are, our concept is the, the layers were forming actually are composed of cellulose or chitin. So even the substrate itself and all of them are known to be biodegradable. So they all have a polysaccharide backbone and so they undergo hydrolysis. So organisms, microbes that would essentially eat these and the soil have enzymes that can hydrolyze the cellulose chain. And they degrade and two sugar like monomers and are consumed by the bacteria. That make sense? Yeah. If you have eye that, I may miss the question. What's the purpose for the CNC inside? So it looks like most improved them mechanical poverty, while the Isaac kind of function where you provide. So the mechanical hardness and modulus was the target we were after. But other properties that could be improved are the barrier properties. So if you were to get a high enough loading of the cellulose nanocrystal. You could, you can improve the barrier properties of the coating. In our case, we we didn't really get to high enough loading where that became obvious. But that was the main, the main property of interest. I have kind of somewhat of a trivial question going back to the, to the first part of the talk about the latex paint gnomes. Sure. You'd mentioned that the under SEM you were seen domains of less than 30 to 40 nanometers or so. But if I recall correctly, the actual cellulose nanocrystals are a 135 nanometers in length. So how how does that how does that work? Yeah, that's a good question. I'm not sure I have a great answer to that, to be honest. It was a thought we had as well. And some of the, some of the, the little domains were larger. So there was a kind of distribution and domain sizes. What we, what we expect, what we suspect is that it's just the way that these were cleaved. The ones that you end up seeing are the ones that are not not oriented towards the side but oriented more towards the end. This is something that others have seen as well when they take C and C campaigning composites and fracture them. It's a similar observation. So okay. So I wasn't crazy but you're not crazy? I really don't understand. They're they're hard to see to begin with and SEM, because there's no contrast really between the acrylic and the carbohydrate, C and C. And you end up seeing some other kind of feature like some roughness or something that gets picked up by the SEM, I think. And for whatever reason that's not good at seeing if there are those that are there. Where you're looking at the edge of the length, you're just you just can't see them. Not in the SEM. I think kind of building off of that, the picture that you showed where you had the hydrophobic versus hydrophilic kind of crossing around the latex. With these, is there, is there a potential for like wicking? Or is the crystalline structure different than like a cellulose fiber where maybe is not going to wick water or something, right? I think if these were fiber mats that didn't contain the polymer binder, they would definitely wick water. But if they were, say, a non-woven kind of matte that had porosity. But once they once they dry with the latex binder in there, that that just doesn't happen because the pores are filled at that point. So it's possible that there's some kind of wicking action that happens as they're drying and you have the softened to latex polymers. They might get drawn into this little cellulose bundle and they may get worked in, and maybe that's helped. Maybe that's how they, they, they form films through some type of capillary action that, that, that could be true. Actually, I hadn't thought of that. That's an interesting idea. All right. I think we're at the top of the hour, so I want to thank Professor murder one more. Thank you. Thanks.