 Third type, if I remove the scluidine and add phenyl group like this one, CH2 double bond CH and here we have the benzene ring. So polymerization of this gives, the name of this compound is styrene and the polymerization of this gives what? polystyrene polystyrene okay, the use of this is, I am not drawing the structure here again but can you tell me what is the repeating unit of this? CH2 single bond CH CH2 single bond CH phenyl ring and open bond both side N, correct? like that you can draw the structure, I am not drawing it here again because we know how to draw this another example you see, we remove this benzene ring and we attach CN here, cyanide this molecule we call it as acrylonitrile A-C-R-Y-O nitrile and on polymerization this gives what? polyacrylonitrile these are homopolymers, this we also call it as orlone the name of polyacrylonitrile is orlone orlone polyacrylonitrile we use for the formation of fibres uses it fifth one, if I remove all the hydrogen atom and add fluorine CF2 double bond CF2 polymerization this compound is tetrafluoro ethylene the monomer and polymerization of this gives you the compound we call it as teflon and the teflon that use of this is the formation of non-pupil even mouse feet is made of teflon yes sir so these 4-5 examples you must remember all these are examples of homopolymers not copolymers now the next thing is what are the polymerization techniques we have that is reaction what reactions involved in polymerization write down the reaction involved in so 2 types of polymerization reaction we have so heading is polymerization reaction like I said 2 types of polymerization reaction we have the first one is addition polymerization addition polymerization leave some space here and the second one we write down condensation polymerization addition polymerization also we have 3 types the first one is free radical polymerization the second one is cationic polymerization polymerization and the third one is anionic polymerization condensation polymerization what happens into this the molecules like molecules like water NH3, HCl, etc. goes out, eliminates and the 2 molecules combined so these are the 2 types of reaction we have first of all we will see free radical polymerization so next heading you write down free radical because cationic and anionic we will not go into that detail I will just give you the idea how it forms basically the difference in these 3 reactions is what the intermediate or free radical cation and anion that is the only difference ok so reaction part is not that important but free radical we will see that write down the first one free radical polymerization free radical polymerization free radical polymerization this mechanism involves the formation of free radical ok and that is why this we also call it as chain growth polymerization because in free radical mechanism we know that initiation step then chain propagation then chain termination this we also call it as chain growth polymerization growth polymerization and since free radical involves in this so these kind of reaction is very difficult to stop difficult to stop difficult to stop means we do not have any control on this reaction any control on this reaction ok so that's why we most probably will get very complex structure into it if we try to control it it's not possible because intermediate is free radical which is highly reactive and we know in free radical reactions we do not have any control into that ok that is one thing now for this reaction since it involves free radical so this reaction actually requires a free radical agent ok which forms free radical generally so for this reaction we need a free radical agent free radical agent are those molecules or compounds which helps in the formation of free radical ok it helps in the formation of free radical like for example we can take any peroxide or oxygen O2 as a catalyst we can take or we can take any peroxide for this purpose in general we use benzoil peroxide as free radical agent so benzoil peroxide if you look at the structure the structure of benzoil peroxide is this pH C double bond O and then we have a peroxide linkage C double bond O and pH so what happens with this benzoil peroxide all these peroxy compounds where we have this linkage peroxy linkage are generally not that stable and when you heat this slightly this bond dissociates and it forms radical which is pH C double bond O O radical plus pH C double bond O O radical why this happens because because these two oxygen ok has lone pair of electron on it and that's why we have very high lone pair lone pair repulsion and hence the dissociation of this bond is easier so one of the electron here is taken up by this oxygen and another one is taken up by this oxygen and it forms a free radical like this we also know that this free radical has property to eliminate neutral molecule neutral molecule and forms new free radical so in this what happens two CO2 molecule eliminates I am writing down for both one one CO2 from this, one CO2 from this eliminate and we will get two phenyl radical I should write down this we will get two phenyl radical got it? yes sir so this is the first step of the reaction and this is step like I said we call it as chain initiation step free radical mechanism chain initiation step ok next step is what? chain propagation in chain propagation what happens this phenyl radical in the next step this phenyl radical has a free radical here it reacts with the ethylene that you have and with a suitable pressure temperature catalyst so here this one electron comes over here and these two joints like this so the product is this CH single bond CH2 radical like this only the chain propagates we have another molecule also CH2 double bond CH2 combines with this here and we will get a long chain so in short if I write down n times if this steps goes then it gives ph CH2 CH2 CH2 CH2 radical this is suppose n times like this compound we will get CH2 radical ok and finally what happens this one and this one club together because we have this kind of many compounds are there so all these clubs together and it forms ph ph2 ph2 ph the whole thing suppose this is x number of times like this only ok and finally this ph ph goes out and we will get a long chain compound here so basically this reaction involves so this last step is chain termination when all the free radical combines together this step is chain termination from here to here it is chain propagation and till here it is chain initiation ok so like you see free radical involves in this reaction the structure of the polymer that you get here is very complex it is there is no proper arrangement order arrangement here why because the intermediate is free radical which is highly reactive and we do not have any control in such reaction copy it down the repeating unit is just ph2 ph2 right both the ph2 monomer is that only you know ph2 double bottom ph2 so with that only we will get the repeating unit for homopolymers the repeating unit is not that important for copolymer it is important we will see that also ok so similarly we have cationic polymerization there the intermediate is in cation cationic polymerization ok anionic polymerization intermediate is in anion ok so that mechanism like I said even this is also not important the only thing is if you have any cationic suppose h plus present then this cs2 double bond cs2 will attack like this if I write down here you see cs2 double bond cs2 we have with h plus it forms cs3 cs2 plus now this reacts with again cs2 double bond cs2 and the reaction proceeds ok so that's how the reaction goes in cationic polymerization anionic may will have this if you have suppose a salt like k ns2 so it is k plus ns2 minus and when this reacts with cs2 double bond cs2 so in this what happens this minus attacks on this carbon and this goes here so we will get cs2 ns2 ns2 cs2 and cs2 negative so this is cationic polymerization this is anionic polymerization again this negative charge will attack on to this molecule shift and we get a long chill compound that's how it goes so like I said it is not important ok the mechanism here ok this is the three reaction we have addition and addition polymerization which involves free radical cationic polymerization and anionic polymerization