[Music] [Music] hello my name is Chris Harris and I'm from Alawis chemistry and welcome to this video on OCR a polyesters and polyimides so this video is dedicated to the OCR a specification so if you are studying OCR a chemistry then this video will have everything you need to know for this particular topic and nothing more so it is specifically designed for you and the video is part of a long series of different videos for osha a four year one and two and the full series is available for free on my Alawis chemistry youtube channel all I ask is that you just subscribe just subscribe to the video you get all the updates and it just shows you support for the channel as well and I will keep on making them for as long as people show an interest and subscribe to the channel and if you want your own private copy of these slides that have created here you can purchase them from the tear shop so if you click on the link in the comments box of the description box so he's in the description box at the bottom of the video and you'll be able to get ahold of them they're they're great for revision great value you can use it on your tablet smartphone on the move really easy and allows you to scroll through our to your leisure and and like I say the videos here are designed for revision only and you do need to integrate this into your other work that you do with your school or college or if you're doing it if you're doing it on your own and also you need to integrate it with an exam technique yeah because it's one thing knowing the content but there's another thing actually sitting the exam and doing it and just because you go through this doesn't mean you can answer the questions and luckily I have got some videos on on the channel that allows you to basically I walk through the some past papers and go through some of the techniques and spotting spotting some potential pitfalls that the examiners may throw at you so yeah so this they could say this video is dedicated to OSHA a and it meets the specification points that are taken from the specification obviously okay so let's make a start and let's look at different types of polymers so we're gonna start with addition polymers first so alkenes are the monomers that make up addition polymers so addition polymers as the name suggests is where you add something together and you make the long polymer and so you've got to remember you would have seen addition polymers in module four and I do have videos I'm a year yeah one sides cuz module falls in year one so if you have a look in the year 1 play list and you can find them there if you need a bit of a refresher so to make poly propane we need the monomer propene so it's the alkene and add a few of these together to make your polymer which is poly propane so there's your monomer propane and the double bond opens up and that forms the the polymer chain which is there as you can see and remember n at the end of the bracket means it's many repeat units so this is what we call of a PT unit so it's the it's the part of the polymer that repeats over and over and over again and n is just however many that may be and they go so this is a repeat unit and obviously the double bond is not in the repeat unit because this is a section of the polymer that repeats over and over again under the feature as well that we've got to be aware of is we have trailing bonds no trailing bonds extend beyond the bracket and basically that shows that there are more units that are repeating left and right of this repeat unit so it is important to put these extra long bonds in and so this was shown to repeat units so it's just showing you what a repeat U and it is and how this how this reoccurs obviously that can go on that can go on and on but just make sure that cuz the exam board may ask you the examiners may ask you to write down a specific number of repeat units so make sure you're doing it correctly and always draw trailing bonds and leaving a square bracket as well so poly alkenes are what we call saturated molecules and they're normally nonpolar and they're very unreactive generally because there's no there's no elements here where you can get attacking molecules to break this up so as a result they don't degrade well in landfill so if you think of plastics that made from these types of polymers they're not very biodegradable and that's not good for the environment because they just sit under the ground for years and years and years so obviously scientists are looking at ways in which we can develop plastics which are biodegradable and effectively better for the environment so and so these are addition polymers okay the other type of polymer is a condensation polymer so condensation polymers are comprised of two main two main types you got poly amide and you've got polyesters and hence the name of this PowerPoint so the name of the video should I say so condensation polymer polymerization is where we get two different monos with at least two functional groups and these react together and we get a link that's made now to see the name ID or an ester link that's made and we call it condensation polymerization because water is eliminated when we join these two monomer units together so the link really determines the type of polymer that's produced so I can say there's two types of polymer poly amides is formed by reacting diamines and dicarboxylic acids together and polyesters and you can see a poly amide there which is this bit on the bottom so that's example of poly amide so it'd be used in for example a rope towing world garden and rope and polyesters are formed by reacting a diol which is just a double-car oxalic acid but you'll see this in a moment and the sorry a double alcohol and then we react it with a dicarboxylic acid which does have two carboxylic acids at either end of the group and we add them together but we'll see some examples all the way through this this video this is an example of polyester which is commonly used in fibers most you'll find if you look on their labels of your clothing you'll see that it is likely to say polyester honest as well okay so let's look at some poly amides first so polyamides are formed by reacting dicarboxylic acids and dye a means together so amide links are formed when dicarboxylic acids react with diam and we have to use dicarboxylic acids and diamines as they are functional groups either side of the molecule and we need that because if we didn't have that we wouldn't be able to form chains either side of that monomer unit okay so let's have a look here's a dicarboxylic acid and you can see what it has is it's just a molecule but whatever this R group is it could be anything but it must have two carboxyl groups either side of the molecule so that's all the dicarboxylic acid is the diamine is just exactly the same it's just we've got two amine groups either side of an R group that's in the middle and this forms your poly a mine too now you can see here when we react a carboxylic acid and an and an amine together we get an amide and you would have seen that in the a means an amides topic in module six so if you're unsure on them types of reactions and go and have a look at that video but basically this is just the same type of reaction but because this is a dicarboxylic acid gonna diamine we form a a name I'd link but also you can see here we have another opportunity for this and to bond with another carboxylic acid later on so that's why they've got to be diamonds and dicarboxylic acids and we form poly amide and there's our amide link and because it's condensation polymerization what we've removed to form that link is water and so the waters you can see is formed there that's eliminated and that's why we call it condensation so let's have a look at an example you don't need to know these specifically for the exam but it's just showing you an example of a of a poly amide so Kevlar is one of them use for bulletproof vests car tires sports equipment because it's lightweight but really really strong so Kevlar is made from benzene 1-4 dicarboxylic acid and one for diamine or benzene so it's made from an diamine and dicarboxylic acids so this is just here is an example you don't need to know these specific ones and but benzene there's your dicarboxylic acid there but the benzene molecule in the middle and there's your diamino benzene which is on there so you can see these look quite horrendous when you look at these molecules but you just looking at the Bruce and this is really why I'm showing you this and it forms Kevlar there you can see we still have our link that's in the middle there we are okay so we still have our link that's in the middle and this is the formula for Kevlar but you can see this is also the repeat unit so this this unit here will repeat and repeat and repeat and keep on repeating to form to form the Kevlar molecule but it's just to show you that it may look complicated but it's the same process okay let's look at another example which is nylon 6-6 this is another example of a poly amide used in carpets and clothes and except this time we use in hexane dioic acid and 1-6 diamine or hexane but it's exactly the same process okay so there's our dicarboxylic acid and there's our diamine this is just to show you that the process is exactly the same and there we have it so we have whoops so we have our nylon 6-6 which is there and this is our repeat unit so it might look very complicated but if you see how that's been formed from this and this and we've just lost the water from the middle bit here we've joined them two together there's your amide link so there might give you complicated molecules like this and there might be expecting you to then use the two molecules they give you to form a repeat unit so just make sure you are comfortable with that don't worry about how complicated it may look okay so polyesters and are formed by using a dye carboxylic acid in the dial so just like before we have carboxylic acid reacting with an s reacts with an alcohol you form an ester okay if you're not too sure on that there is a video that are talking to talking to talk about carboxylic acid is reacting with alcohols to form esters so this is just the same we're just using die carboxylic us and dials so ester links are formed when they react and here's an example so there's a dichotic silica acid which we've seen before and there's our dial so a dial has two alcohol groups left and right exactly the same principle so then we're going to react these to form a polyester and we have a wrestler link in the middle as you can see there so there's no difference there but again we have removed water so there it is so remove and remove water so there's no difference between polyester and polyamide were still removing the water from the middle and join them together except in this example or forming a polyester okay so let's have a look at a pot example of a polyester so terylene again you don't need to know the exact formulas for these it's just here as an example because polymers can be quite complicated so it's just to show you how simple it can be to to actually spot the actual join and what you're writing down so it's made from benzene one for dye carbocylic acid and ether in one two Dyer so here's our benzene one for dicarboxylic acid so we still got the two carboxylic acids either side and there's our dial there and we're going to react on them two together to form your terylene so there's terror in there so you can see that's your repeat unit it looks looks complicated but it's not too it's not too bad hopefully and but again when you're looking at your trailing bonds make sure you're losing the awaits there and you're losing the hydrogen there because you must lose water that's how you know where your trailing bonds go because this is a condensation polymerization okay let's look at hydrolysis so condensation polymers can be hydrolyzed so remember just like with in the esters topic that you would have seen and you can hydrolyze an ester hydrolysis means hydro means water lysis means to break so hydrolysis is to break using water that's all it means sounds complicated but it's not so to produce the original monomers we have to break the polymer chain using hydrolysis so it's just the reverse of polymerization so it's not too complicated so you can see here here's our poly amide and what we're going to do is react that with water okay and what we're going to do is produce our two products are two monomers that we use to make the polymer in the first place so we've got a dicarboxylic acid and we've got a diamine now you can see we've done is we've concluded in black where the OHS come from and that comes from the two molecules water and that's why we need two molecules of water to complete our monomer and monomer chains or monomer units so here we are there we are so to determine the monomer units what we've got to do is break the bond in the middle of the amide or ester link in the repeat unit so that's what you need to do is find where that amide is to link is and then what we do is we add Oh H and H to each of the monomer units as I've just shown you there just before so remember for polyester you must produce a dicarboxylic acid and a dial okay and for poly amide as you can see there we must produce a dicarboxylic acid and a diamine so we must produce them two products you can't produce anything else okay so look and get back to addition polymers we need to try and do the same as well and we can actually work out which monomer units are used to fall to form the polymer that's in front of you so they might give you a polymer chain and say right which monomers we use to make this so a monomer units can be determined by finding the repeating unit which will always have at least two carbon backbone it must have at least that and four K because there's gonna be a double bond and double bond Aloni exists between two carbons so the monomer can be found in addition polymers by removing the bonds between the repeat units and inserting a double bond between the two carbon atoms okay so you'll see and see what I mean here so here's a section of an addition polymer which is there so what got to do is try and find out which monomer units were use to make that so notice this is one repeat unit but notice the absence of the double bond so we haven't included a double bond here all we've done is segregated one of the repeat units so that's what we've done there so that's the first thing to find out the repeat unit write it down segregate it then once we've done that we then need to put that double bond in between the two carbons that make up the backbone of the repeat repeat unit so there's the two carbons there there is a carbon there but that's acting as a branch we always write alkenes like this so spot the two carbons put your double bond in and there it is and there's your your monomer unit that's been used to make that so in this case and this is the alkyne which is propane that's used to make this polymer okay and we can work out the repeat units from the monomer as well so for example here is the monomer this is a different monomer we're going to use just to add a bit of spice to it so we're going to work out the repeat unit so what we need to do is draw down the two carbon atoms first and instead of the double bond we're going to place a single bond like you can see there and then we're going to add in the groups there we are so these are the groups that make it up so we've just removed the double bond we've drawn is like a letter hitch because it's easier to see polymers that way okay so we've just stretch them bonds out again and then finally we need to add our trailing bonds and that make up the backbone of our polymer so that's very important and there we are we've we've formed our repeat unit so it's fairly straightforward but you're just looking for the two carbon backbone everything else can be added as side groups okay and we can do exactly the same we can work out the monomer from a polymer chain for condensation polymers as well so the monomer can be determined by finding the repeat unit but it's in a condensation polymer so we're looking for either an amide link or an ester link in our in our molecules so here you can see polyester we've got our ester link there which is in the middle and the monomer can be found by breaking the bonds between the ester link or the M I'd link depending what you're what you're reacting it with and then we add H or Oh H to either end and of both molecules that we formed so there it is okay so that's what we're doing so we're looking particularly for the ester link and looking where we can actually break that that chain there okay condensation polymers can be more complicated and can contain a Meyde and ester link so we can have we can have both types in there so molecules are they mean and alcohol groups can react with dicarboxylic acids cuz that's the common denominator they're all reacting with dicarboxylic acids and this forms a more complicated condensation polymer so you can see here we've got our die carboxylic acid and we've got an alcohol and an A and a mean group on one of the molecules there so that's this one here okay so you can see that there so then what we can do is form our more complicated to polymer so effectively we've got and I've color-coded it so you can see so you can see what's going on here so you can see we've got the still got our amide link here but we can form s the links as well later on down the line but it's just showing that there can be a bit more complicated okay so there's your ami link and so the S link will appear at the end of the repeat units as you can see okay so they can be formed from one type of monomer as well in some cases so all the examples we've seen here was multiple types of monomer so molecules with carboxylic acid in either end of an alcohol and a main group can react with itself to form a more complicated condensation monomer polymer sorry so here we go and you can see here this is just one monomer we're not using to hear the same monomer and we're just going to react them with each other to form your amide link so it's just the same the same type of monitoring unit so they do exist as well and that's it so that's the topic on polyesters and polyamides the best thing with these is just to try and keep their practice in them making sure that you can spot the amide links and where to break them and please subscribe to the channel so all the videos are on here are all free I'll keep on making them as long as people keep subscribed to the channel I'll keep on making them the powerpoints like I say are available to purchase if you click on the link in the description box you'll be able to get ahold of them there but that's it bye bye