Webinar: The Surface Properties and Water Adsorption Behaviour of Hair Fibers

Hello everyone and thank you for joining us for today's webinar. The topic we will be exploring this afternoon is the surface properties and water absorption behavior of hair fibers. This topic will be explored by Surface Measurement Systems very own Dr. Damiano Cattaneo. He is the Senior Instrumentation Scientist for SMS and obtained his PhD in Chemistry at the University of St. Andrews in December 2015. His research project was focused on using porous materials for biomedical applications. He also gained a Master's Degree in Medicinal Chemistry from the Universita Deglisturio di Milano in Italy. During the last year of his masters he also worked as a researcher on drug discovery and total synthesis on anti Parkinson's drugs at the Department of Pharmaceutical Sciences, Pietro Pratesi in Milan, Italy. Since joining SMS in 2016, he has worked on the development of advanced in situ experimental surface science techniques using molecules as probes for studying catalysts, zeolites, MOFs polymers, pharmaceuticals, composites and cement materials under relevant industrial conditions. Dr. Catenao has also helped with the development, testing and launch of a range of new products including the DVS Adventure, DVS Resolution and the DVS endeavor. So without further ado, I will hand over to Dr. Catanea to begin his presentation.

In the presentation of today I would like to highlight a few details in regard to the DVS instrumentation. So I'm going to give you a quick introduction in regard to the instrumentation itself and then we are going to move to the main topic of application for hair fiber. So water absorption modification and damaging fiber and how it affect the measurement and in DVs. And lastly a couple of example of application which we use two comparative method which is Raman plus DVS to understand the water uptake capability of materials. So starting from my introduction we're going to talk about the way molecule interact with samples. Specifically we don't talk about water molecule mainly. We're going to have a little bit of introduction about organic solvent, but we're going to talk about water molecule mainly. So the way molecule interact with the sample is we introduce a certain amount of molecule around the sample itself and those molecules can adsorb on the surface of the sample or they can absorb through the bulk of the material. Now this is the two condition in which the molecule can locate themselves and obviously when we reduce the concentration of molecule around the sample then we can measure the desorption property if there is desorption and the reversibility of the sample itself. Now if we highlight the two conditions that we just described, we have two different phenomena. We have Adsorption and we have absorption. The absorption itself can be identified to different parameter, which is physisorption and chemisorption. Now physisorption is a weak type of interaction. So it's a weak type of bonding in which the molecule will pile up on the surface of the sample and is, because it's such a weak interaction is usually reversible. Which means that if we go up, for example in relative humidity or partial pressure, the molecule will just absorb on the surface. As soon as we move down in relative humidity or partial pressure, those molecules will dissolve. Now this is an important factor whenever we look at property of the surface of the material. So surface area, pore size, surface roughness, surface energy, heat of absorption and free energy are all calculated using the parameter of absorption, that is pure physisorption. Now chemisorption on the other hand, is a stronger bonding. We have sites that specifically interact with the surface of the molecule that we are using as a probe. The process can be reversible or irreversible, but it really depends on the energy involved in the interaction and the property of the material that we use. Usually those materials are specifically engineered to establish a bond with the molecule that we are introducing. So titrate or acid base, catalyst dispersion, those are the type of material that usually have specific chemisorption. Much more relevant for this type of study that we are going to look at is bulksorption, which is a phenomenon of absorption itself. So in this case what we have is molecule of solvent not only piling up on the surface of the material, but also penetrating through the bulk of the material. And in this case we are talking about diffusion. The kinetic process of uptake of molecule depends not only on the ability of the molecule to absorb on the surface, but but also to penetrate through the bulk. And we are going to specifically look into these parameters, specifically glass transition and specifically diffusion coefficient, which are two parameters that can be measured using DBS experiment. And the last phenomenon of absorption is the absorption into the lattice structure. This is mainly common for molecules that change structure in presence of specific type of sorbet. So if you think about an anhydrous form of a molecule, when introduce water, it can move to a hydrate form for a solvent. For example, if we add acetone, we can generate a solvent form of that material depending on the type of material. In this case we have reversible or irreversible solvate or hydrate. And we can have stoichiometric or non stoichiometric hydrate or Solvent. By that definition, if we are able to count the number of molecules that are ending up in the structure of our material. For example, if we say it's an hexahydrate, then in that case it's a stoichiometric interaction. If you're not able to exactly define the number of molecules that end up in destruction, then is usually defined as non stoichiometric. So how do we develop a DVS experiment? How did the DBS experiment came to be? The main concept of DBS come from an older method defined as a JAR method. A JAR method uses a series of desiccator that contains a saturated solution of a salt. At the bottom of the desiccator, we introduce our sample and we leave the sample to reach equilibrium over a certain amount of time. We measure the initial mass of the sample at dry form. Then we measure the mass of the sample after a certain period of time in each desiccator. And each desiccator will have a different salt in it. And a different salt will generate a different point of vapor pressure. So we will have lithium chloride for example, as a saturated solution will generate 11% relative humidity. Then you can have potassium nitrate which is 55%. Then you can have sodium chloride which is 75%. And every single desiccator represents a point of equilibrium that can be used for the calculation. This is more of a manual method for the measurement of the absorption. The DVS is an instrumentation that basically fully automate this process and allow us to measure the uptake, absorption or desorption by using a balance and constantly measure the mass change while using mass flow controller to generate the correct amount of humidity over time. So what is the difference between the two methods? Now when you do a method that is a manual method like the JAR method, you require quite a significant amount of sample. The higher is the amount of sample is and the more accurate is going to be the experiment. Less prone to error by manual interaction. In a DVS, we do not interact with the sample most of the time. We load the sample and we perform the entire experiment automatically through the instrumentation. So we can use milligrams of sample compared to grams which we will use. In a JAR method, the condition of the equilibrium are different. In a JAR method we use a static mode so the molecule migrate throughout diffusion from a point of lower concentration to a port to sorry, from a point of higher concentration to a point of lower concentration. In a DVS experiment we use a carrier gas, about 200 milliliters per minute of nitrogen or Air to push molecular water or organic solvent on top of the sample itself. And in that way we will measure the uptake of the sample in more dynamic mode. This gives us a faster response because we push the equilibriums toward. We push the kinetic towards an equilibrium condition, but it also gives a more accurate measurement of the equilibrium condition. The other difference is obviously time requirement. The JAR metric can require weeks to collect the full set of data. In a comparative cycle. A DVS can require a couple of days maximum to collect the same level of quality of data and the same amount of data. And the last parameter that we want to mention is obviously cross contamination. Whenever you want to measure the sample that you have in a jar, you need to remove it using a standard balance to remove the sample, measure it and put it back in. Every single time you do this process, you're obviously exposing it to a different level of humidity and different level of temperature. Consequentially you can introduce systematic error in the measurement when you do it. In a DBS experiment, the entire process of absorption and desorption is automatically measured inside the system in a balance. Consequentially we have no cross contamination. Here is an example of the two experiments of the same material. On the left side is done on a JAR method and it takes about 300 days. On the right side is done on a DVS and it takes about four days. The other important parameter that you see here is that the JAR method only give you 0.4 absorption while the DVS allows you to generate a specific step, whatever step you desire. But in specific step, which means that we can measure the full absorption and the full dissoption. Which means that if we plot the isotherm plot which is the equilibrium condition at each stage. For the JAR method we only have an absorption cycle. For the DBS we can measure the absorption and desorption cycle which much more useful for the analysis of the property of the material. So how does a DVS work from a point of view of the functioning of the instrumentation? So here you can see the schematic of a standard DBS experiment or a standard DBS instrumentation. We have two side of generation which are controlled by mass flow controller which are basically very capable valve. They open and close dependent on the amount of flow that we require for that specific generation. Those valves are connected to technically two reservoir. One reservoir which we call dry which will be our cylinder of gas, could be air, could be nitrogen. And then we have a wet reservoir which is basically the headspace of a bottle of water or organic Solvent. Depending on what type of experiment you're running, let's say we are doing an experiment and we are doing the first stage, which is usually a drying stage. So your target relative humidity or partial pressure will be zero. So in that case, these two valves will control the flow coming through the reservoir and it will have 100% dry open, 0% wet open. If you are requiring for example 80% relative humidity, then your dry will be open 20% and your wet will be open 20, 80%. The 2 flow generated by those mass flow controller then mixed and the humidity is read by a sensor, in this case a humidity sensor. And then the gas flow is pushed towards a sample and a reference chamber that you can see over here. Those sample reference chamber are two identical symmetrical chamber that are directly connected to micro balance, which can be pictured if you want to identify this balance as a two plate or the pharmacist balance, which has a sample side and a reference side. The sample and reference are perfectly identical. So we have the same pan, the same end and wire, the same type of chamber. So why, what's the difference? The difference between the sample and reference size is the fact that you load the sample of one of the two sides. Why do we need this symmetrical setup when we are doing an experiment of dbs? Let's say we are doing an experiment with water. When we introduce molecule of water into the chambers, the molecule of water are uncontrollable, they absorb everywhere. They absorb on the, on the sample obviously, but they always absorb also on the pan, on the end of wire and on the side chambers. Now we want to measure accurately only the mass change related to the presence of the sample and the sample uptake. So to make it accurate, we make it symmetrical. So if there is no sample, the left and right side are perfectly symmetrical. So if I introduce molecule of water in both sides, they absorb water in the same way. So I don't measure any mass change. If I load a sample, the only mass difference that I'm measuring is dependent on the presence of the sample itself, which makes it more accurate and more reliable. So how does a standard DBS experiment work? This is fairly straightforward. We start from a dry sample or we dry the sample in a DBS experiment and then we introduce molecule of water into the chamber and we measure the uptake at equilibrium conditions. So we wait for the sample to reach equilibrium and then we move to the next stage and we go up in uptake with the absorption and we go back down in this option. Now this is a standard experiment. We can modify this experiment and do different stages or different temperature condition. But generally the most basic is absorption and desorption. We look at the plot data of the kinetic data which is the equilibrium condition at each stage. And and if we consider the mass at equilibrium condition at this stage, we can then plot it versus relative humidity. And we can get the isotherm plot which is the measurement of pure uptake in percentage mass change of the sample over relative humidity. So this is the way we run the experiment. So how does the data look like? Here is an example of a very very basic Dr. DVS experiment on a sample of food material, in this case rice. This is a kinetic plot. So it's a plot of time over percentage mass change, which is your red line and target relative humidity, which is in this case your blue line. So we start from a massive equilibrium condition and then we increase and decrease the relative humidity in 10% step from zero to 90, back to zero. And in this case we are doing two cycle experiments. We have an initial dry condition right here and then we have absorption and desorption and we are doing two cycle experiment on these specific setup. So what type of information do we get from these initial plot before we look at the isotope? So the first thing we can see here is that the material has about 20% over 20% mass change. So in material is definitely have a very very high affinity for water, Very very high uptake of water. We have a drying curve here and also we can see that the material go back to the initial mass every time we go back to zero. This is particularly important because it is telling us that this material is perfectly reversible. We can absorb up to over 20% of water. And then once we dry the sample, it goes back to the initial condition. So the sample is very stable in presence of water, even though it has a very very high uptake of water. Now if we take each equilibrium condition at each partial pressure stage and we plot it versus the relative humidity, we can see here that we get our isotope plot. So what extra information do we get from this specific plot? You can see here there is a nice gap of hysteresis between the absorption and desorption, which usually indicates that the sample is having a bulk absorption. Which means is that the material have a very very high affinity for water. And so water tends to penetrate through the sample and try to stay inside the sample as much as possible. One of the interesting thing is basically showing you here that if I go for example to a certain level of relative humidity during the absorption cycle. So this 50% for example step and I look at the partial pressure change to get to more or less the same mass change during the desorption cycle, I need to go to almost 10% less relative humidity. Just because the water likes to stay inside the sample, is really absorbed inside the sample. This experiment was done at 25 degrees Celsius and obviously there is thermodynamic involved in the process of desorption. What I would expect, for example, is that if we repeat the same experiment at higher temperature, I would expect this gap of hysteresis to close progressively because we are providing more energy to the water molecule that are trapped inside the sample and we are pushing the equilibrium condition towards the dissolution stage. So this is the general introduction about the technique. Now we are going to look specifically into our application and we're going to talk about hair fiber specifically. So from a point of view of application, why are we interested in this specific type of application? We are interested specifically in treatment that can be applied to hair fiber. And we are going to highlight a few examples of how we can study water uptake or even organic solvent uptake and how different treatment on hair fiber can affect the absorption capacity but also the response of presence of water on top of the sample. There are other type of information that we can get to DBs related to personal care. Today I'm going to focus specifically on hair, but we can also look at diffusion retain retention of water or diffusion permeability parameter, for example, if you're looking at skin treatment or for membrane or polymer, for example for contact lensing or for absorbate polymer absorbate specifically. Today we are going to focus mainly on hair product. So the main concept of what we are looking at here is the evolution of the functionality of what hair provide us as a species obviously, but also how it's changed the way we treat hair over time and how that affected the performance or let's say the water uptake of hair itself. So if we look at the concept of what our hair is used for, or what we are technically using right now is obviously for insulation and that is historically. And protection obviously if you think about hair or on the surface of your skin. But there is a component of appearance as well that has a predominant value in hair care product as well. So what information do we get from dvs specifically? How do we use DVS to study this type of parameter? So what we are looking at specifically is absorption capacity and penetration of molecules throughout this sample. Not only we're going to look at what is the Total uptake. So how much water can hair absorb, let's say at 25 degrees C when they are undamaged, and how the damage affect the uptake. And second, we are going to look at how fast is the uptake of water. This is the phenomenon of diffusion, obviously for specifically for absorption. And, and the other part that we are going to focus specifically on is how changes in the structure of the hair, damaged hair for example, or modified structure of the hair, can affect the total water uptake and can affect the equilibrium condition of this water uptake. So here we have a look at the sample of untreated hair, so undamaged untreated hair, and we are looking at what is the water uptake of, of this specific sample. So this material has approximately 20% mass change at equilibrium condition. This experiment is performed at 25 degrees Celsius. And if we look at the isoturn plot, we can clearly see our nice gap of hysteresis. And this is specifically done on a branch of hair called European hair. The equilibrium condition in this specific case will use it as a stage time rather than at the mdt. So what it means by that is rather than using the equilibrium condition of the balance to decide when to move to the next stage of the experiment, we use a fixed time in our method. Basically we say every 400 minutes more move from a lower humidity condition up to a higher humidity condition until you get to 90% relative humidity. Once you get to the 90% relative humidity, step it down, back to 0, 10% step, 400 minutes per stage. The experiment can be done in different way. We can do the experiment as a DMDT condition or we can do the experiment as a fixed time. And this experiment specifically was done as a fixed time. So this give us a standard introduction to the basic information. Our standard hair, untreated hair, will have 20% mass change at 25 degrees Celsius. Now a little bit more of an advanced experiment will be evaluating transition phases in for example, hair product, but in general, any product. This is a schematic that allows me to show what I'm going to show you on the example of hair. I'm using here a product, a material that is not hair specifically, but it allows me to highlight you how we run this experiment so far. I, I showed you experiment called step experiment. What I mean by that is I generate a certain level of relative humidity, let's say 10%, I wait for the sample to reach equilibrium and then I move to the next stage. The experiment that I'm doing here It's a ramp experiment. It's not a step. What you see here is the blue line is my relative humidity. The red line is my mass change. So what I'm doing here is taking a sample of amorphous material and I'm recording the mass of the equilibrium condition at dry stage. And then I increase progressively the relative humidity and I look the way the mass respond to the change in relative humidity. Now if you picture something that has no class transition, no actual transition in the structure picture, for example, silica gel, the more water I expose the sample, the more the mass will be uptake. So if I picture this sample as, let's say, silica gel, I would expect that my humidity increase and my mass increase perfectly as a parallel line, no deviation from the linearity until I reach a certain plateau, let's say 90%. And then my mass change will flat out at some point. Every deviation from these parallel line will indicate obviously that there is a transition happening. And this transition is affecting the way the water is uptake by the sample. And in this case we see this hump condition, which is actually our glass transition point for this specific sample. Now, this glass transition is not universal. It obviously depends on the temperature at which I'm doing the experiment on the concentration of relative humidity which I can measure, because I can just draw the line here and find a point of glass transition. But the third parameter which is also important is the ramp rate, the speed at which the humidity is increased over time. That will affect the total uptake of the sample, but also the shape of this curve. Now that is true to a certain degree. The main point is that if we measure the ramp, the glass transition at different ramp rate for this specific sample, we can actually obtain a graph like this. So you see here, this is the grass transition point, the value that we just read. And this is a plot of the glass transition point versus ramp speed 2, 4, 6, 8 and 10. Now it's a linear plot. We expect to be a linear plot, but this also give us an extra information. If we draw this line back to the Y axis, we find approximately 20, 30%. That is a glass transition point. The relative humidity of glass transition, which is independent on the ramp rate and consequentially that give us a critical value of relative humidity at which the glass transition happened for this sample at this temperature, which is different from the value that you get. For example, for dsc, DSC will give you a value of temperature. Here we are giving you a value of relative humidity at a constant temperature. Now we have done this set of experiments into looking into the glass transition point and using different ramp speed on hair sample. And you can see here, we are using different ramp rate to identify the ground transition point and we are increasing the ramp speed the more this line progressively goes down. Now, one of the interesting things that you see over here is the fact that when you go to 10% ramp rate, you basically do not see the hump typically related with the glass transition point. So something that you need to be aware of when we are identifying a glass transition point is obviously that not only the concentration of humidity and the temperature which we're doing the experiment are important, but in if you speed up the ramp rate too fast, you might miss the point of grass transition because the mass uptake increases too quickly and it covers the value. So obviously the ramp rate has a significant factor in the moisture uptake. But also that is much more evident the point of grass transition when we are looking at condition in which the ramp rate is much slower. Just to highlight you the point, we're talking about a glass transition point which happened around 65% relative humidity, fairly constant depending on the ramp rate. But more or less this is the grass transition point at 25 degrees Celsius. So let's have a look at what happened when we look at damaged hair specifically that has been treated. And what are we talking about when we're speaking about treatment? We are going to specifically look at different treatment with different molecules, specifically ammonia on one side, which can be one of the components used for hair treatment, and then monoethylenamine. I'm going to give you a quick example of type of study that were done in, let's call it wet chemistry. So a pure treatment on sample that has tension, stress, tension on the sample. And then we are going to specifically mainly focus on DVS experiment and how to measure changes that are specifically applied to the sample after the treatment. For example, with MEA and ammonia itself, we are talking about lower concentration. So usually we are going to look at about 3 to 5% between ammonia and methylamide. So I was speaking exactly about a quick example of wet chemistry. And you can see over here, this is a project that was carried out in collaboration with Imperial College in London on the specific response of hair treatment, in this case from untreated hair, which is your blue line, and then two versions of treated hair, 5% MEA, which is your green line, which is the lower point of stress, strain, performance and and then the ammonia, which is about the orange lunch, which is your 3% from a point of view of stress tensile property of the hair and from a point of view of surface, this is with the SEM, you can definitely see that the virgin hair, so the untreated hair and the hair treated with ammonia are much closer to each other, while the sample treated with MEA are definitely completely change the tensile property and they are also showing surface damage. If we want to look at from a point of view of physical analysis of the sample with sea, the interesting data we can measure actually are also applied to dvs. So if we want to have a look at the data from a point of view of absorption, what we are going to do now is compare the specifically the water uptake and the speed at which the water uptake and also the solvent uptake is affected after treatment of the sample with ammonia of mea. So the way we are going to do this experiment is basically to set up a diffusion experiment. And the diffusion experiment is again slightly different from what we are looking at from a point of view of pure step experiment. We are not going to do a full ramp of absorption and desorption, but what we are going to look at is a single stage. We are going to dry our sample and then expose to a constant level of relative humidity or partial pressure in case we are using solvent. And what we are going to look at is the speed at which this ramp rate increase. And if the sample is able to reach equilibrium over a certain amount of time. Why are we interested in this parameter? This parameter allows us to understand how quickly the sample absorbs water, but also allows us to do a pure calculation of the diffusion coefficient. And specifically, the way we measure the diffusion coefficient is by using a fitting of this plot and by knowing the distance of travel or the molecule of water. So if I look at this plot, I can identify mainly two points that will allow me to determine this parameter of my equation. Mt will be the mass uptake at the initial condition. So when we are starting to ramp up the relative humidity and M infinite will be the mass uptake at the equilibrium condition. So we identify two points at a certain amount of time of MT and M infinite. And we are going to compare it between pure sample untreated hair and untreated hair. And the other parameter that we need to understand obviously is the distance of travel of the molecular water or organic solvent. And that's a physical parameter that we can measure for fiber. In this case, we just measure the radius of the fiber and that represents the distance of travel of the molecule of water. We're Going to talk about powder, because we're going to talk about air that has been grounded and in per powder sample. Usually we define the particle size of the power as the distance of travel. So once we know the flux, the mt over nth infinite, and once we know the distance of travel of this molecular water, we can automatically calculate the diffusion coefficient for that sample for that solvent at a specific temperature. One last thing before I move to the data itself, in case you are interested in reproducing this type of data on a dbs, if you already have a dbs. One of the important factors that we want to highlight is the fact that we request to run the experiment with one second data collection. These experiments are relatively short in time required for the experiment itself, but we want as many points as possible to get the best fitting, especially for the mt, especially for this part. So usually we recommend to run diffusion experiment using one second data collection. So let's have a look at the data here. We have a water absorption experiment, three different sample. We have our untreated hair, which is our red line, and then we have damaged hair after treatment, which is our yellow line. And then we have the same untreated hair, but that being grounded as a powder. And what you can see here is not only that, there is a significant difference obviously in speed of the uptake. Whenever we ground the hair to a powder condition, you can see that the material immediately uptake most of the amount of water required and then it plateaus, it reaches equilibrium. So we are obviously increasing the total surface area of the sample, but we are decreasing the bulk absorption capacity, decreasing the total mass uptake that the sample is capable of. On the other hand, our damaged hair has a much higher uptake of water in total, a much higher uptake of water at the end. So that's an interesting factor. Sorry, didn't mean to skip forward. You can see here that the sample actually have a much higher residue water at the end of the experiment compared to the untreated hair. And there is a slightly higher speed in the initial uptake in the diffusion coefficient of the damaged hair compared to the untreated hair. We can compare this data also using less polar solvent, let's say methanol for example. And you can see here the massive difference that the use of a different solvent doesn't. The powder, the grounded hair obviously has a very, very similar uptake between water and organic solvent, but in this case the virgin hair, actually the untreated hair has a higher uptake of methanol, but it also plateaus in reach equilibrium, faster in the uptake, higher in the total chemisorption. On the other hand, the damaged hair is much slower in the uptake, much lower uptake at the end of the equilibrium condition. And obviously, because we have this set of data which help us do a general comparison between these property and this material, we can also use this data for the direct calculation of the diffusion coefficient. And here you can see the difference in diffusion coefficient, the fact that the powder hair obviously had the lowest diffusion coefficient compared to the untreated hair. And then the difference, for example, between when you look at the untreated hair and treated hair, the presence of treated treatment. Actually, sorry, the untreated hair slow down in the diffusion when you move to a less polar solvent in comparison to the damaged hair, which slows down as well, but much less compared to the untreated hair. I just mentioned the fact that we are using organic solvents. So I would like to take just a second to mention how we measure organic solvent. You can purchase instrumentation that allows you to measure relative humidity. Quite simply, they're available in the market. But if you want to measure organic solvent, it's a little bit more complicated. For that reason, we had to develop our own sensor to measure concentration of solvent in a carrier gas. For example, in this experiment of methanol, we use our proprietary sensor which measures time of flight. And we use time of flight to measure the speed of sound of carrier gas, for example nitrogen. And then we measure the change in speed of sound, the change in time of flight of a mixture of carrier gas plus solvent, so nitrogen plus methanol. And the change depends on the density, which depends on the concentration. So we can relate back the change in time of light ratio to the change in concentration of the solvent itself. And this allows us to measure very, very accurately the concentration of a series of volcanic solvent. But it also is very quick because time of flight takes few milliseconds to measure. We can have a constant live measurement of all the data point that we want and all the concentration that we want. So this is just to give you an idea how we did the experiment using the organic solvent version. Here is another example of what we can do as water uptake and difference between water uptake, specifically between treated and untreated hair, but also hair coming from a different area of the world. So you can see here that the green and blue line are Caucasian hair, undamaged and damaged, and they are fairly close to each other from the point of view of total uptake and reversibility. However, if you look at the red line, those are undamaged Asian hair. And in that case you can see the uptake of water is much more defined, is much higher, and it's also much faster during the desorption stage of the experiment. So not only we have to consider the version of the hair that we're using, if it's been treated or not be treated, but also the origin of the hair that we're using for this type of study. So this is the summary of what we just highlighted. The measurement of diet, of obesity, of hydrophilicity. The identification of a point of glass transition and the use of a ramp method for the measurement of ground transition. The relationship of using water and potentially organic solvent to measure and establish the uptake and the speed of the uptake of this sample. And, and the ability to measure OSHO diffusion and permeability compensation. Before I would like to conclude this talk, I would like to show you an example of what we can do as an institute study of characterization of sample. So we talked a lot about water absorption and measurement of water resolution and we talked about the fact that the presence of water can cause structural changes, sometimes a reversible structural change, but nonetheless a structure. So one of the things that we try to develop is also a comparative measurement between dvs and a spectroscopic technique, for example, DVS with Raman. So you can see here this setup that we currently can provide with our DVS instrument, which we have our chamber for our DVS with a glass pan that you can see over here. And then we have a Raman port Raman probe that we mount on top of the sample itself. Now this is a fully automated system that will allow the user to run an experiment with TVS and also to correct Raman data automatically throughout the experiment. So the way the system work is that we measure the absorption and the absorption of the sample. And as soon as the sample reach equilibrium, the system automatically triggers Arama spectra. And so we will end up having the comparative study between the two techniques. And here I can show you an idea of what's the difference between the two sets of data and how we can use the difference between these two sets of data. You can see here a study of absorption and desorption in two cycle experiments on a sample that have a significant mass uptake, about 11% mass change. And obviously we are able to correct Raman data for each condition, for each partial pressure of relative humidity. So what type of information do we get? So if we look at the data collected on these DVs and we look at the Raman data specifically for any step of partial pressure at which there is water in it, we can see that the Raman data are perfectly overlapping this. The sample is very stable in presence of water as we know about the DBS data, but it doesn't have doesn't show any change in structural of the material. It doesn't show any new peak, it doesn't show any shift on the existing peak. Now if we want to look at the same set of samples, but we look at the data collected at the end of the drying stage in these two sections, we can definitely see that there are significant changes in the Raman position of formation, new peak and shift in the peak position in pre existing peak. Now this is particularly interesting because if we look at the way the sample behave and the amount of time required for the sample to dry. If I have a bulk of sample and I want to identify if my sample is perfectly dry or wet, I can technically give an extra time of drying for example if I want to to just be 100% sure that it's perfectly drawn dry. Or I could simply collectorama spectra which takes about a few seconds, 30 seconds in total for this specific setup and immediately know by the spectra in this case if the sample contains any residue of water, for example, if I have this area of the peak or if the sample is perfectly dry, for example if I have the other peak. And that allows us to identify different condition of the sample but but also follow the structural changes of the sample. So all the data that I showed you so far are being collected in our line of flow instruments, specifically DVS adventure for the water only experiment and DVS resolution for the water plus organic solvent and Raman experiment. We can also technically run this same type of experiment on a high throughput system. For example a DBS endeavor which allows you to run the same type of experiment that you would run in a DBS resolution but with five samples at the same time. The system is equipped with five balances so will allow you to run five samples at the same time. So with that I would like to thank you all for your attention and I would like to know if you have any question or if you need any more information in regard to my presentation.

Thank you Damiano for a great presentation. Yes, as Damiano mentioned, we please invite you all to submit any queries or questions you have for the speaker in the questions panel. Just to kick things off, we have a first question here, Damiano, and that is is it possible to use a mixture of solvents in the system.

Absolutely, yes. So in the DBS resolution or in the DBS Endeavor, we can set up experiment in which we run a single component, a single solvent. For example, the data that I showed you so far. So just water by itself or just methanol as an organic solvent by itself. But you can also run experiment using the mixture of two solvents, for example water plus an organic solvent or two organic solvent at the same time. Some of the experiments that we could potentially run is to measure for example the methanol uptake in presence of a residue of constant water or how the presence of two solvent affect the uptake of the sample.

Okay, great. Thank you. A question from Heinz Roberta. And they ask what is the high operating temperature limit? Sure.

For the DVS Adventure Resolution, which are the single balance system which I show you right here, the DVS adventure resolution can go up to 85 degrees Celsius. The DVS endeavor, which is the high throughput system, can go up to 70 degrees Celsius for pretreatment. So if you are interested only in drying the sample, we can provide an accessory called preheater which mounts in the chamber and it can locally increase the temperature of the sample up to 200 degrees C as a pre treatment, As a drying stage for the sample itself. But for main generation 85 is the maximum temperature generation for adventure resolution 70 for DBS endeavor.

Great. Alexander Murr asks how are you sure that there is a glass transition Just based on the higher mass increase in the ramp experiments.

So if I have a look at the generals to this set of data, the first parameter obviously is more or less, you know, the chemistry related to the type of material that you're running. So if I run a porous material or if I run a material that is fairly stable, I would expect to see phenomena like glass transition or phenomena of recrystallization. But in general, whenever we have a deviation from a linearity plot, whenever, for example, my mass uptake creates, this type of hump is usually related to a change in the way the sample respond to, to the presence of relative humidity or to the presence of an organic solvent. Now, there are different effect, different phenomenon that can cause a deviation. For example, bulksorption or recrystallization or expansion of the pore of a structure of the material in presence of higher concentration. Those can all relate back to these type of phenomena. However, by knowing the type of material that we're running, we can sort of predict what type of behavior this sample will have. If for example, I take this is A sample that I'm looking at here of crystalline, sorry, amorphous lactose. Amorphous lactose. A phenomenon of glass transition and recrystallization. And if I look at the same sample in crystalline form, crystalline lactose will not have a glass transition. So first I wouldn't expect to have any deviation and second, if I have a deviation, it's probably due to the fact that there is a contaminant in it. For our hair sample, we identify a point of deviation of the linearity plot of the data as the glass transition point and we know the sample can go through glass transition. Now, it is correct to say that by looking purely at if I didn't know what the sample is and I don't know anything about the material that I'm loading into the instrumentation, I can never exclude other phenomena. However, the main point is the fact that when you're running a DBS experiment, the only parameter that you're measuring is mass change in change of relative humidity or partial pressure. So other technique can corroborate the data provided by dvs. In general, if you're looking at samples that are known in type of behavior, you can then associate that change to a specific type of transition. If someone gave me an incognito a general sample I don't know anything about, I will be a little bit more careful to assign changing mass to specific phenomena that the sample is having.

Great. A question here from Chad Pavlis. They ask what is the optimal size to cut hair fibers to to get a real world result, does one end need to be sealed?

Not necessarily. So the, the way we are looking at the measurement is the main part of the absorption. The surface of absorption is really the length of the air. So that dimension will always be higher compared to the part that you cut at the top at the bottom. So that part will influence much less in the water uptake capacity compared to thinking about exactly if I cut it, let's say 2 centimeter or 10 centimeter, the influence or the change because of the increase on the total surface area is partially marginal. Now if you grind the hair, if you go to a powder for that, then it's significant difference in the structure, in the surface area, in the particle size. So in that case it does make a difference. But if you are reducing the size of hair only partially to adjust for the measurement, it's not a particular influence is not the surface area change is not significant enough to affect your set of data because the increase in surface area is so marginal compared to the rest of the total surface of the air.

Great. And I think we have time for one more question. So Ron Gray has asked, what was the last sample you showed with the Raman spectra?

Oh, this is not a hair sample. This is food material. Specifically this customer. I'm using this sample to just highlight the type of information that we can get from the use of DVS Raman. The sample itself is actually perfectly reversible food material. And the interesting thing for this specific material is that the manufacturer that provided us with this sample stores their material at 50% relative humidity. That's the general storage condition of their loading. And they want to know how stable will be the sample if they cycle it up and down in temperature, or if they have to dry it specifically before shipping after storage. And one of the interesting things that was very useful for that type of study is the fact that, yes, they want to dry it, but they also want to know how quickly they can dry it. So we have done the experiment in on about 10 milligrams of sample, which is very small amount of sample. But if you look at a very big amount of sample, then you have to scale up the amount of drying that you have to do to reduce to the normal condition of the sample. However, to shorten the time to check that the sample is perfectly dry, you can easily dry as quickly as possible and then run around on Spectra for about 30 seconds and, and see where it ends up in the spectra. And you know, immediately, okay, it's dry, so it's ready to be stored, it's ready to be sealed or ready to be posted or it's still wet, I need to dry even more. So the study was specifically done here to look at the water exposure from one side, but also look at the way to identify different condition of water exposure and to know it not only from a point of microscopic point of view, so a small amount of sample, but also from a bulk point of view when they're running a much higher amount of sample.