Understanding Polymers: Properties and Applications

i have this things though and then i will i will say this polymer polyethylene right polyethylene has has a melting temperature right and then you have a thermal so thermal property is very important for us to to know uh so i guess so you you care about thermal property and how people measure those thermal properties such as a TGTM and also what is known as degradation temperature. This is one of the things that polymer, if you make the polymers and you put it into an instrument that can heat up the sample not just 100 or 200 degrees C, it can go up to 1000 degrees C, see when the polymer sample thermally degrade burns okay in other words burns right this is an organic polymer typically so unless you have inorganic polymers that has a different story typical organic polymer has a degradation temperature so thermal property probably what you want to know one thing what kind of other property do you think that is you want to know about this density hydrophobicity how flexible the polymer is the physical strength All right, so the one that I want to go after is actually mechanical properties, right? And the word, something flexible, hard, stiff, tough. I'm just kind of putting these all kinds of different one. And then this mechanical property should be, we also need to know. And there's a section in the later in the class, I kind of introduced the different kinds of ways of how people measure the mechanical properties and then the mainly what is called the stress strength. It is a very common, this section is very kind of closer to what has been learned, what we have learned from the studying the metals in the past. that's a metallurgy and the metal properties ceramics and these are the material science. Polymer has a lot of strong ties to the material science in its academic and study platforms. And somebody says molecular weight. Okay and I will say the molecular weight I want to say molecule somebody you're going to say instead of saying molecular weight I want you to say we are talking about molecular weight distribution okay so it is a if for example if I just graphically draw it to you this is your molecular weight and then then this is a I guess a weight fraction of timer so this is I guess a number of mers so this is an eye And then more typical polymer has this kind of distribution, molecular weight distribution. So think about some polymer has a narrow molecular weight distribution, very narrow. Some polymer has a very broad molecular weight distribution. They do not have the same physical property, mechanical property, even thermal property cannot be the same. So molecular weight distribution is something that we need to know and, you know, the we are we are talking about number average weight average and uh what is called the mw over mn and this is called the dispersity polydispersity and this is a the measure of how broad the molecular weight distribution and let's see density let's go viscosity there we go this is not like i like so those who are asking this is viscosity i'd like to highlight okay so viscosity is i put our emphasis on the uh understanding the viscosity because the why people see that polymers is a useful material is because it's a Processability. Polymers are easier to process compared to the metals and the ceramics. So therefore, the understanding the viscosity is very important because you want to easily kind of make this polymer softened up and pushing through the nozzles and then extrude them out, make a fiber spin, or also you want to make the injection molding to make a lot of parts. so the processability is actually the part that i was not able to cover most of the case although it's very important in this portion of the class but i can certainly talk about the viscosity itself this is something that we want i want to update in my class content in the future adding a little bit about what kind of different types of processing polymers people has done in the past Okay, density hydro for V, city hydro city. Yep. So that's that's also another 1, but let me kind of asking asking you a question on this continue to do to do this. Is polyethylene that you, you see here right? And, but you, you have heard about high density, Paul, the low density, Paul. Lead a low density polyethylene. the list goes on and on these are even these two are separate recycling code that we have right do you know how they are different their densities are different certainly for sure but in from the molecular sense anyone we talked about this the high density polyethylene is polymer chain looks so it is a it is a ch2 that's forever okay so there's thousands of thousand is actually not enough you have about let's say 10 000 repeating units of of those the low low density polyethylene on in in contrast they have a chain but there is a branching okay and that branching has a branching and that branching has a branching so branches on a branches so this is a chain looks like chemically identical but the high density is a linear chain architecture this is a branch okay so this is a branch to change so um another concept that it will be also useful to know is in you call the chain architecture like architecture Also, we can just simply say as a branching because from the experience, high density, low density as a physical outcome is a difference in density, but real molecular differences, their chain architecture differences, whether it's a branched or not. Some people in the research is actually they want to make a ring polymer. how the ring polymers are different from the linear polymers and so on. So that's something that will be related to. Okay, and this chain architecture branching is actually related to once again, the processability. How easy to process this and so on. And then the chain architecture is among other things. Okay, so far so good. Okay, branching. Yeah. And then I want you to think about one other thing that has been covered in your class, which is coal polymer. Was it covered in your class? Right? the random copolymerization was covered in your class. And the reason is not only just making polymer using two different monomer unit, not just because of that, we want to actually make the polymer in the industry scale so that they can have something more better property without, in a way, without by making new kinds of monomer as a So, 1, very famous example is this, this is a polystyrene and then this is what they call the acrylonitrile. So it's called a PAN and this is a PS. Polystyrene we are using as it is making styrofoam cups and sometimes clear plastic covering because it's very cheap monomers that we can easily make and you you and then that's become one of the main change on polymers. This PAN is the polymer coming from acrylonitrile. ch2 bubble bond ch with this it is one of the kind of odd monomers uh it is expensive monomers and not only that it is very difficult to process that this ornaments into once you make the polymers this is a very difficult uh to process it so what uh what happened was uh this is 1 has a very nice desirable chemical. Uh, resistance, although is very difficult to process at 100%, but if you make this 1 into. What is corn is a random copolymer so instead of making this random copolymers, people are using this notation very likely instead of using the square bracket. They are using. This. this normal simple bracket and then they they said these are the repeating with let's say molar composition is x and one minus x or something so that they have a random copolymer and this one itself has a random copolymer called pan and that we call the s a and this is a industrially produced polymers uh to have a in a way better property than the polystyrene itself but we do not want to reinvent the new kinds of structures so they make this uh sand components and on top actually has anyone heard about abs abs plastics it's used in 3d printing that's right not only that before three 3d printing is even like 3d printing have you heard about lego right the lego block that is made out of the abs it is very nice polymer uh and the abs is uh a is that's right a and s i don't somehow they got this name coming from but abs is coming from this acrylonitrile and styrene copolymers are being grafted onto the rubber, which is a butadiene. So it is a butadiene grafted by styrene acrylonitrile copolymers. And instead of using the, there is one called the high impact polystyrene, which is in a way uh i can say that that's like butadiene with a styrene graft okay and this one is a butadiene polymer with acrylitrile and sam what it looks like in the molecular sense you have a butadiene and this one is grafted yeah polystyrenes are grafted on polybutadiene polybutadiene is one of the rubbers right see it looks like this and there is a very flexible uh polymers one of the main source of the rubber so the rubber typically made into small kinds of particles and then then they actually put the styrenes And then they are being drafted here, whereas the is more like. This point with a lot of. And the reason that Lego is actually, if you look at the Lego is pretty tough. It's pretty good. It has a pretty much. Good mechanical property compared to the polystyrene because of the not only. It has a unidine naked making making me more soft about impact absorbing material, but also the acronym natural making more chemical resistance. so it is a lot of engineering has been went into a play and this is also acrylonitrile group making more easy to be colored i just keep this one in my mind that i just have to say this because uh this one just keep on bothering me so this one is one of the thing that do you know chemically why people call this one this is a cyanide right So, you can say that this is the policy. And that doesn't sound great, right? If you want to sell the product that cyanide is a poison, so you don't want to sell it. So they actually come up with a name called. And so that they can they people general public do not know he has the same chemical structure that is a sign. I just poison anyway. Why am I saying about the copolymer is the. We want to this is 1 of the things that I want to say. Copolymer or is just essentially. You have a, you have a, you have a B. You want to combine those properties together. Okay. If you want to combine those 2 properties, somehow you can probably hopefully you can have a property. In between those 2, and the 1 way is you use a monomer stage. Making it to a random component that's a 1 strategy and. Sometimes working sometimes doesn't work. I cannot imagine making random of a star in with. Something like nylon that doesn't work. Nylon has a very different chemistry with a star in. So. You know the some. chemistry are compatible for making a random copolymer some chemistry you cannot do so then then what people usually think about as we learn from the metal uh we just simply making what they call alloy you mix them together and make a polymer blend so that's a one way is making a copolymer or making a polymer blend you mix those two polymers Unfortunately, it doesn't work that easily. If the polymer blend is just like a works like a charm, then we don't have to worry about making different grade of polymers. Probably polymer scientists will run out of their business because it's so easy to tune the material property by mixing those polymer A that is hard and polymer B that is a soft and then you mix them together to kind of dilute the property. that doesn't work that way because polymer a and b are easily immiscible they are not recycled oil and water it looks like a chemical structure is the same one one good easy grandpa is actually you see the high density and low density polyethylene they are not miscible you put that in they will phase separate into two separate domains so you know chemically looks the the same only difference is their branching degrees And if the branching degrees are so different, and they have its own domains of 2 different melting temperatures and optically, they looks very different. So, polymer miscibility polymer blend is something that I also talked about in the later in my lectures. That we can talk about your questions when you after you look at this. And then then there is another question something called a. block b so you make a and you make a b so you make it into the chain so when we put in a different color it's a traditional block of polymers so you make blue chain and the red chain making a black component and then this black polymer can Although the A and B would like to face separate, but they are tied together to the chain. So it does not form this big, large segregated domains, but they what we call the self sample into a very nano scale structures. And these are the old polymers. There are examples actually polymer blends are being commercially used. Uh, in multi, you know, millions of tons of years are being used and there are black polymers are being used in the industry. Multi. uh millions tons a year multi hundreds of million tons a year so i mean in a bulk scale production is as possible and the copolymers polymer blend the black copolymer but it has its own system that has been seen successful it's not all the system that is always being successful so this first thing effort is understanding that we have a polymer that can have a different thermal properties and the second one is now you know the option that yeah we can make the polymer into a even more than what they call the is a copolymer is a chemically heterogeneous mixtures how you're going to control the structures of this copolymer is another big theme in the polymer material design why people are putting so much emphasis on copolymers uh in the not in the class in the industry is because you don't want to invent a new hill okay the one another viable option for you is make up come up with a new monomers means new chemistry new monomer chemistry making a new monomer into a larger scale structures uh productions and then develop its own processing technique those are the very kind of big problem to deal with so to kind of go around the problem is okay i know we know how to handle a polymer we know how to handle the b polymers making a larger scale how about combining those two to see if you can kind of solve the problem to have the property that you can these days we are facing a different problem because of the polymers are so well made we want to even now degrade the polymers and you know, recycled polymers and this is one of the big things that people are talking and think about solving the problem. Okay, so I want to talk to you about the polymer as a material, new materials, and here is a diagram of what people used to think that as a materials, okay, and there are two materials historically in the material. Okay, 1 is the other is. I mean, if you go go to the really old days, there is only 1 material. As a ceramics, right? These are the, the, the ages. I don't know. 5,000 years ago. We don't even know there is a metal. So we only use a stone to to to kill the animals. And. I guess the people to survive. But now the eras of metal came in as a material and the material diversity really boost of our civilization to go. And then the polymers, this is a before 1950s. Is actually during the World War II is one of the big boost in the I think the 1950s is a little bit too hard, so I will say 1940s. Okay, so people start to know that there is a kind of viscous gummy material as a product that is a failed organic synthesis. And that's what, again, my organic synthesis friend is saying that, oh, I have a polymer at the bottom, so my reaction is failed. So they have to try, try again and again to make some something that is not valuable. but now the polymer becomes a very useful material and then becomes now one of the one of the new new materials and the metals are still very important ceramics is all important and the ceramics ceramics silicon computers right information ages so there is no doubt that is but now the polymers plastics are important and people this one has its own kind of the the area that used to be the people used to have a cup right people used to have all kinds of uh the household you that used to be made by the metals and the ceramics all replace it i mean the cup is a very good example uh yeah polymers are being replacing those area and then this is because of the polymer has a the pros and cons so let's talk about why polymers are being accepted and we are using it uh two thousands now this is no doubt that polymers are important part of the our daily lives you guys can Imagine the life without polymers from when you wake up in the morning until you go to bed. We just have so much dependence. We just want to be a little bit more responsible when we're using these polymers, but polymers are very good. And why people like polymer is a new material for the modern society. So let's talk about the pros. As I guess a new material, I guess I'm talking about properties. So what's good thing about polymer over metals? Anyone can can put anything in the chatting box where you can say anything. I mean, it does have a better quote unquote better property than metals and ceramics. That's why. The people use partners, right? So is anything that you, you kind of heard of. uh corrosion okay but you know the somebody say corrosion but the corrosion itself can be uh i mean metal people was pre working hard yet and it still has a corrosion issues uh it has a but they can make it a different different alloys to make the corrosion to handle the corrosion but that's corrosion yeah that's that is good i can i can give you that any any others yes somebody say lighter right lighter material this is a very big okay lighter less dense and the uh the new airplane the new i think the boeing 7 797 or dreamliner and that's the one that is being the material is a lighter so that lighter airplane consume less fuels so more economic and then that's what this whole airplane from the new boeing was made of the composite epoxy composite if the whole thing is a one molecule actually and then they and then they put the engines in and and so it has a comparable mechanical properties it could have an engineer to have a comparable mechanical properties and metals it can be much like somebody say more somebody say cheaper yeah okay cheaper yep cheaper can be also true and the reason is because of but i think that it can be cheaper too right the metals can be cheaper as well but certainly the lighter is a big portion and somebody say more flexible that's also actually important flexible one of the thing that polymers are uniquely have as a material is you have a rubber band right rubber band is a really the one of the unique one if you stretch the rubber band you can stretch 200 300 can you imagine doing that with the ceramics or the way right you it's very fragile and also what about metal metal is not flexible so the flexible rubber band is a tire i have actually one class video or class a slide that i made it before during the world war ii there was a shortage of the natural rubber and because of the without rubber the country, the United States cannot be functional because you cannot drive the car, you cannot fly the airplane, right? So there's a big campaign that... do not drive around too much is not because there's a shortage of the fuel there's a shortage of the actual rubber supplies and then a lot of synthetic rubbers are being produced and that is actually what we use in in some of the ways um you guys have a nail print nail print rubber is a nail means a new rubber and that was invented by one of the famous scientists named carothers who's an inventor of the nylon title easier to produce there you go who said that easier to william wow who's williams williams glasso grassa william that's that's a good answer easier to process this is actually the to me the this is the there are two answers that i was looking for Is material properties that pretty much many people know there is a lighter material, but easier to process. And that makes essentially the most important properties is is a mass production. So that's why this mass production. It can be made it into a cheaper ways to make. A massive amount of material. certainly the original monomer surprises is not so expensive but remember that the when the nylon first came out as a nylon stocking it is more expensive than the silk stocking because people love it it lasts it's very very strong and lasts for a long time and yep it's an insulator not conductive as metal that is true so that's why we are using the polymer as a insulating wires to to kind of the to insulate this some the metals but you know this always a new opportunity comes out uh there's something called a conductive polymer This is also when you to think about as a new ideas, conductive polymers. Is possible that it was a kind of a curiosity. Okay. So people know that it's a formally. Not the family, but it's actually formally also very insulating, but. Electrically, not is insulating material, but you can make electrical electrically. conductive or semi-conductive polymers and which is easier to process and which is also bendable right you know everything together is comes to a one one word flexible electronics right so there are people uh pushing this idea to the uh making these polymers to be easy to be used you can dissolve it in and you can put it into a more electronic component and then they they want to make the led polymers there's a flexible conductors and you can use that one for but you know if you're actually looking at the foldable phone that you recently probably saw in the new new products This is actually not using polymer flexible, flexible polymer, flexible conducting polymers, but they're just simply using the silicon that is actually conductive. When you have a silicon, it's very amazing that the property of material, we all know that silicon is very brittle, ceramics are very brittle, but if you make it thinner and thinner and thinner, it can be made it into a very flexible. So that they're using that kind of dimension dependency of the overall mechanical property and to make this one so i think that we but you know i kind of find out uh is the usual two uh two or three one that i've been want to emphasize this but there's a there's a bad thing about polymers right not as good as the metals What is not as good as metal? I mean, this is all good, so you should replace the metals. there is a place that we cannot use plastics because of anyone because because in the kitchen right if you go to the kitchen there is always metals in the kitchen that's right somebody said temperature right temperature so eventually it will melt but i i argue that i mean to me the degradation is a main main problem of the polymer as a material because we cannot use this one for high temperature applications but you know but there is a what is called the inorganic polymer to be made into the ceramic precursors And the people studying on inorganic polymer, such as a silicon base and. And other kinds of polymers, and they are using this. To make this a high temperature application. And which has an application in NASA and aerospace. And the defense a lot of like, you know. The area that they don't care about the, he said the performance is the most. important criteria for their material selection. And so there's a lot of opportunities actually. People are still looking into new problem. But remember that this is the most significant problem that you want to remember that when it comes down to. And maybe it's hard to dispose of plastic because it's harmful to the environment. This is a, this is a, that is also recycled how to recycle the polymer is a really big problem it ties into the what i said before a and b not miscible as we learn from the there's a whole thermodynamics we understand now Large molecule, large molecule mixture is very different from small molecule mixtures. You know, waters and ethanol is easily to be mixed, right? But if you have a water version of, let's say, polyvinyl alcohol, and then there is another one. Yeah, I mean, for example, like I said, polyethylene, high density, low density, they are not miscible. polypropylene polyethylene there's only methyl branch difference i mean it should be not that hard right they they super hate each other they don't they don't miscible at all right so think about not just the hydrophobicity hydrophilicity even what seems like all hydrocarbon-based polymers they are not miscible and trying to people trying to cycling it there's a lot of idea How can we actually, instead of recycle, means you are kind of using it again or kind of similar one, but how you can actually chemically convert it into the different kinds of it. It's called upcycle. What I have in mind, and I'm trying to find, many people are trying to find a solution of kind of producing a value-added product by degrading the polymers and using as a polymer as a feedstock. for making new chemicals this is just at the initial stage i don't think it has people as any big

I'm just kind of putting these all kinds of different one. And then this mechanical property should be, we also need to know. And there's a section in the later in the class, I kind of introduced the different kinds of ways of how people measure the mechanical properties and then the mainly what is called the stress strength.

It is a very common, this section is very kind of closer to what has been learned, what we have learned from the studying the metals in the past. that's a metallurgy and the metal properties ceramics and these are the material science. Polymer has a lot of strong ties to the material science in its academic and study platforms.

And somebody says molecular weight. Okay and I will say the molecular weight I want to say molecule somebody you're going to say instead of saying molecular weight I want you to say we are talking about molecular weight distribution okay so it is a if for example if I just graphically draw it to you this is your molecular weight and then then this is a I guess a weight fraction of timer so this is I guess a number of mers so this is an eye And then more typical polymer has this kind of distribution, molecular weight distribution. So think about some polymer has a narrow molecular weight distribution, very narrow.

Some polymer has a very broad molecular weight distribution. They do not have the same physical property, mechanical property, even thermal property cannot be the same. So molecular weight distribution is something that we need to know and, you know, the we are we are talking about number average weight average and uh what is called the mw over mn and this is called the dispersity polydispersity and this is a the measure of how broad the molecular weight distribution and let's see density let's go viscosity there we go this is not like i like so those who are asking this is viscosity i'd like to highlight okay so viscosity is i put our emphasis on the uh understanding the viscosity because the why people see that polymers is a useful material is because it's a Processability.

Polymers are easier to process compared to the metals and the ceramics. So therefore, the understanding the viscosity is very important because you want to easily kind of make this polymer softened up and pushing through the nozzles and then extrude them out, make a fiber spin, or also you want to make the injection molding to make a lot of parts. so the processability is actually the part that i was not able to cover most of the case although it's very important in this portion of the class but i can certainly talk about the viscosity itself this is something that we want i want to update in my class content in the future adding a little bit about what kind of different types of processing polymers people has done in the past Okay, density hydro for V, city hydro city. Yep. So that's that's also another 1, but let me kind of asking asking you a question on this continue to do to do this.

Is polyethylene that you, you see here right? And, but you, you have heard about high density, Paul, the low density, Paul. Lead a low density polyethylene. the list goes on and on these are even these two are separate recycling code that we have right do you know how they are different their densities are different certainly for sure but in from the molecular sense anyone we talked about this the high density polyethylene is polymer chain looks so it is a it is a ch2 that's forever okay so there's thousands of thousand is actually not enough you have about let's say 10 000 repeating units of of those the low low density polyethylene on in in contrast they have a chain but there is a branching okay and that branching has a branching and that branching has a branching so branches on a branches so this is a chain looks like chemically identical but the high density is a linear chain architecture this is a branch okay so this is a branch to change so um another concept that it will be also useful to know is in you call the chain architecture like architecture Also, we can just simply say as a branching because from the experience, high density, low density as a physical outcome is a difference in density, but real molecular differences, their chain architecture differences, whether it's a branched or not.

Some people in the research is actually they want to make a ring polymer. how the ring polymers are different from the linear polymers and so on. So that's something that will be related to. Okay, and this chain architecture branching is actually related to once again, the processability. How easy to process this and so on.

And then the chain architecture is among other things. Okay, so far so good. Okay, branching.

Yeah. And then I want you to think about one other thing that has been covered in your class, which is coal polymer. Was it covered in your class? Right? the random copolymerization was covered in your class.

And the reason is not only just making polymer using two different monomer unit, not just because of that, we want to actually make the polymer in the industry scale so that they can have something more better property without, in a way, without by making new kinds of monomer as a So, 1, very famous example is this, this is a polystyrene and then this is what they call the acrylonitrile. So it's called a PAN and this is a PS. Polystyrene we are using as it is making styrofoam cups and sometimes clear plastic covering because it's very cheap monomers that we can easily make and you you and then that's become one of the main change on polymers.

This PAN is the polymer coming from acrylonitrile. ch2 bubble bond ch with this it is one of the kind of odd monomers uh it is expensive monomers and not only that it is very difficult to process that this ornaments into once you make the polymers this is a very difficult uh to process it so what uh what happened was uh this is 1 has a very nice desirable chemical. Uh, resistance, although is very difficult to process at 100%, but if you make this 1 into.

What is corn is a random copolymer so instead of making this random copolymers, people are using this notation very likely instead of using the square bracket. They are using. This.

this normal simple bracket and then they they said these are the repeating with let's say molar composition is x and one minus x or something so that they have a random copolymer and this one itself has a random copolymer called pan and that we call the s a and this is a industrially produced polymers uh to have a in a way better property than the polystyrene itself but we do not want to reinvent the new kinds of structures so they make this uh sand components and on top actually has anyone heard about abs abs plastics it's used in 3d printing that's right not only that before three 3d printing is even like 3d printing have you heard about lego right the lego block that is made out of the abs it is very nice polymer uh and the abs is uh a is that's right a and s i don't somehow they got this name coming from but abs is coming from this acrylonitrile and styrene copolymers are being grafted onto the rubber, which is a butadiene. So it is a butadiene grafted by styrene acrylonitrile copolymers. And instead of using the, there is one called the high impact polystyrene, which is in a way uh i can say that that's like butadiene with a styrene graft okay and this one is a butadiene polymer with acrylitrile and sam what it looks like in the molecular sense you have a butadiene and this one is grafted yeah polystyrenes are grafted on polybutadiene polybutadiene is one of the rubbers right see it looks like this and there is a very flexible uh polymers one of the main source of the rubber so the rubber typically made into small kinds of particles and then then they actually put the styrenes And then they are being drafted here, whereas the is more like. This point with a lot of.

And the reason that Lego is actually, if you look at the Lego is pretty tough. It's pretty good. It has a pretty much.

Good mechanical property compared to the polystyrene because of the not only. It has a unidine naked making making me more soft about impact absorbing material, but also the acronym natural making more chemical resistance. so it is a lot of engineering has been went into a play and this is also acrylonitrile group making more easy to be colored i just keep this one in my mind that i just have to say this because uh this one just keep on bothering me so this one is one of the thing that do you know chemically why people call this one this is a cyanide right So, you can say that this is the policy. And that doesn't sound great, right?

If you want to sell the product that cyanide is a poison, so you don't want to sell it. So they actually come up with a name called. And so that they can they people general public do not know he has the same chemical structure that is a sign.

I just poison anyway. Why am I saying about the copolymer is the. We want to this is 1 of the things that I want to say.

Copolymer or is just essentially. You have a, you have a, you have a B. You want to combine those properties together. Okay.

If you want to combine those 2 properties, somehow you can probably hopefully you can have a property. In between those 2, and the 1 way is you use a monomer stage. Making it to a random component that's a 1 strategy and.

Sometimes working sometimes doesn't work. I cannot imagine making random of a star in with. Something like nylon that doesn't work. Nylon has a very different chemistry with a star in. So.

You know the some. chemistry are compatible for making a random copolymer some chemistry you cannot do so then then what people usually think about as we learn from the metal uh we just simply making what they call alloy you mix them together and make a polymer blend so that's a one way is making a copolymer or making a polymer blend you mix those two polymers Unfortunately, it doesn't work that easily. If the polymer blend is just like a works like a charm, then we don't have to worry about making different grade of polymers.

Probably polymer scientists will run out of their business because it's so easy to tune the material property by mixing those polymer A that is hard and polymer B that is a soft and then you mix them together to kind of dilute the property. that doesn't work that way because polymer a and b are easily immiscible they are not recycled oil and water it looks like a chemical structure is the same one one good easy grandpa is actually you see the high density and low density polyethylene they are not miscible you put that in they will phase separate into two separate domains so you know chemically looks the the same only difference is their branching degrees And if the branching degrees are so different, and they have its own domains of 2 different melting temperatures and optically, they looks very different. So, polymer miscibility polymer blend is something that I also talked about in the later in my lectures.

That we can talk about your questions when you after you look at this. And then then there is another question something called a. block b so you make a and you make a b so you make it into the chain so when we put in a different color it's a traditional block of polymers so you make blue chain and the red chain making a black component and then this black polymer can Although the A and B would like to face separate, but they are tied together to the chain.

So it does not form this big, large segregated domains, but they what we call the self sample into a very nano scale structures. And these are the old polymers. There are examples actually polymer blends are being commercially used.

Uh, in multi, you know, millions of tons of years are being used and there are black polymers are being used in the industry. Multi. uh millions tons a year multi hundreds of million tons a year so i mean in a bulk scale production is as possible and the copolymers polymer blend the black copolymer but it has its own system that has been seen successful it's not all the system that is always being successful so this first thing effort is understanding that we have a polymer that can have a different thermal properties and the second one is now you know the option that yeah we can make the polymer into a even more than what they call the is a copolymer is a chemically heterogeneous mixtures how you're going to control the structures of this copolymer is another big theme in the polymer material design why people are putting so much emphasis on copolymers uh in the not in the class in the industry is because you don't want to invent a new hill okay the one another viable option for you is make up come up with a new monomers means new chemistry new monomer chemistry making a new monomer into a larger scale structures uh productions and then develop its own processing technique those are the very kind of big problem to deal with so to kind of go around the problem is okay i know we know how to handle a polymer we know how to handle the b polymers making a larger scale how about combining those two to see if you can kind of solve the problem to have the property that you can these days we are facing a different problem because of the polymers are so well made we want to even now degrade the polymers and you know, recycled polymers and this is one of the big things that people are talking and think about solving the problem.

Okay, so I want to talk to you about the polymer as a material, new materials, and here is a diagram of what people used to think that as a materials, okay, and there are two materials historically in the material. Okay, 1 is the other is. I mean, if you go go to the really old days, there is only 1 material.

As a ceramics, right? These are the, the, the ages. I don't know. 5,000 years ago. We don't even know there is a metal.

So we only use a stone to to to kill the animals. And. I guess the people to survive.

But now the eras of metal came in as a material and the material diversity really boost of our civilization to go. And then the polymers, this is a before 1950s. Is actually during the World War II is one of the big boost in the I think the 1950s is a little bit too hard, so I will say 1940s. Okay, so people start to know that there is a kind of viscous gummy material as a product that is a failed organic synthesis.

And that's what, again, my organic synthesis friend is saying that, oh, I have a polymer at the bottom, so my reaction is failed. So they have to try, try again and again to make some something that is not valuable. but now the polymer becomes a very useful material and then becomes now one of the one of the new new materials and the metals are still very important ceramics is all important and the ceramics ceramics silicon computers right information ages so there is no doubt that is but now the polymers plastics are important and people this one has its own kind of the the area that used to be the people used to have a cup right people used to have all kinds of uh the household you that used to be made by the metals and the ceramics all replace it i mean the cup is a very good example uh yeah polymers are being replacing those area and then this is because of the polymer has a the pros and cons so let's talk about why polymers are being accepted and we are using it uh two thousands now this is no doubt that polymers are important part of the our daily lives you guys can Imagine the life without polymers from when you wake up in the morning until you go to bed.

We just have so much dependence. We just want to be a little bit more responsible when we're using these polymers, but polymers are very good. And why people like polymer is a new material for the modern society.

So let's talk about the pros. As I guess a new material, I guess I'm talking about properties. So what's good thing about polymer over metals? Anyone can can put anything in the chatting box where you can say anything. I mean, it does have a better quote unquote better property than metals and ceramics.

That's why. The people use partners, right? So is anything that you, you kind of heard of. uh corrosion okay but you know the somebody say corrosion but the corrosion itself can be uh i mean metal people was pre working hard yet and it still has a corrosion issues uh it has a but they can make it a different different alloys to make the corrosion to handle the corrosion but that's corrosion yeah that's that is good i can i can give you that any any others yes somebody say lighter right lighter material this is a very big okay lighter less dense and the uh the new airplane the new i think the boeing 7 797 or dreamliner and that's the one that is being the material is a lighter so that lighter airplane consume less fuels so more economic and then that's what this whole airplane from the new boeing was made of the composite epoxy composite if the whole thing is a one molecule actually and then they and then they put the engines in and and so it has a comparable mechanical properties it could have an engineer to have a comparable mechanical properties and metals it can be much like somebody say more somebody say cheaper yeah okay cheaper yep cheaper can be also true and the reason is because of but i think that it can be cheaper too right the metals can be cheaper as well but certainly the lighter is a big portion and somebody say more flexible that's also actually important flexible one of the thing that polymers are uniquely have as a material is you have a rubber band right rubber band is a really the one of the unique one if you stretch the rubber band you can stretch 200 300 can you imagine doing that with the ceramics or the way right you it's very fragile and also what about metal metal is not flexible so the flexible rubber band is a tire i have actually one class video or class a slide that i made it before during the world war ii there was a shortage of the natural rubber and because of the without rubber the country, the United States cannot be functional because you cannot drive the car, you cannot fly the airplane, right?

So there's a big campaign that... do not drive around too much is not because there's a shortage of the fuel there's a shortage of the actual rubber supplies and then a lot of synthetic rubbers are being produced and that is actually what we use in in some of the ways um you guys have a nail print nail print rubber is a nail means a new rubber and that was invented by one of the famous scientists named carothers who's an inventor of the nylon title easier to produce there you go who said that easier to william wow who's williams williams glasso grassa william that's that's a good answer easier to process this is actually the to me the this is the there are two answers that i was looking for Is material properties that pretty much many people know there is a lighter material, but easier to process. And that makes essentially the most important properties is is a mass production.

So that's why this mass production. It can be made it into a cheaper ways to make. A massive amount of material.

certainly the original monomer surprises is not so expensive but remember that the when the nylon first came out as a nylon stocking it is more expensive than the silk stocking because people love it it lasts it's very very strong and lasts for a long time and yep it's an insulator not conductive as metal that is true so that's why we are using the polymer as a insulating wires to to kind of the to insulate this some the metals but you know this always a new opportunity comes out uh there's something called a conductive polymer This is also when you to think about as a new ideas, conductive polymers. Is possible that it was a kind of a curiosity. Okay.

So people know that it's a formally. Not the family, but it's actually formally also very insulating, but. Electrically, not is insulating material, but you can make electrical electrically.

conductive or semi-conductive polymers and which is easier to process and which is also bendable right you know everything together is comes to a one one word flexible electronics right so there are people uh pushing this idea to the uh making these polymers to be easy to be used you can dissolve it in and you can put it into a more electronic component and then they they want to make the led polymers there's a flexible conductors and you can use that one for but you know if you're actually looking at the foldable phone that you recently probably saw in the new new products This is actually not using polymer flexible, flexible polymer, flexible conducting polymers, but they're just simply using the silicon that is actually conductive. When you have a silicon, it's very amazing that the property of material, we all know that silicon is very brittle, ceramics are very brittle, but if you make it thinner and thinner and thinner, it can be made it into a very flexible. So that they're using that kind of dimension dependency of the overall mechanical property and to make this one so i think that we but you know i kind of find out uh is the usual two uh two or three one that i've been want to emphasize this but there's a there's a bad thing about polymers right not as good as the metals What is not as good as metal? I mean, this is all good, so you should replace the metals. there is a place that we cannot use plastics because of anyone because because in the kitchen right if you go to the kitchen there is always metals in the kitchen that's right somebody said temperature right temperature so eventually it will melt but i i argue that i mean to me the degradation is a main main problem of the polymer as a material because we cannot use this one for high temperature applications but you know but there is a what is called the inorganic polymer to be made into the ceramic precursors And the people studying on inorganic polymer, such as a silicon base and.

And other kinds of polymers, and they are using this. To make this a high temperature application. And which has an application in NASA and aerospace.

And the defense a lot of like, you know. The area that they don't care about the, he said the performance is the most. important criteria for their material selection.

And so there's a lot of opportunities actually. People are still looking into new problem. But remember that this is the most significant problem that you want to remember that when it comes down to.

And maybe it's hard to dispose of plastic because it's harmful to the environment. This is a, this is a, that is also recycled how to recycle the polymer is a really big problem it ties into the what i said before a and b not miscible as we learn from the there's a whole thermodynamics we understand now Large molecule, large molecule mixture is very different from small molecule mixtures. You know, waters and ethanol is easily to be mixed, right? But if you have a water version of, let's say, polyvinyl alcohol, and then there is another one. Yeah, I mean, for example, like I said, polyethylene, high density, low density, they are not miscible.

polypropylene polyethylene there's only methyl branch difference i mean it should be not that hard right they they super hate each other they don't they don't miscible at all right so think about not just the hydrophobicity hydrophilicity even what seems like all hydrocarbon-based polymers they are not miscible and trying to people trying to cycling it there's a lot of idea How can we actually, instead of recycle, means you are kind of using it again or kind of similar one, but how you can actually chemically convert it into the different kinds of it. It's called upcycle. What I have in mind, and I'm trying to find, many people are trying to find a solution of kind of producing a value-added product by degrading the polymers and using as a polymer as a feedstock. for making new chemicals this is just at the initial stage i don't think it has people as any big

Transcript for:Understanding Polymers: Properties and Applications

Transcript for:
Understanding Polymers: Properties and Applications