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Module 1: Overview of Nanotechnology

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Video 1: Chemical Nature of Nanomaterials
So now from here what we will do we’ll move on to the second level of classification whichis your chemical nature of classification.Chemical nature of classification, they could be classified into 3 categories, one is theirorganic origin, second one is inorganic origin, third one is carbon waste.So there are 3 different classes in terms of their chemical classification, in termsof organic nanomaterial that could be dendrimer, micelle, liposomes, and ferritin are commonlyknown as organic nanoparticles or nanomaterials.So organic one concludes, dendrimer, micelle, liposomes, ferritin.These are commonly known organic nanoparticles and these nanoparticles are biodegradable,mostly non toxic and such particles such as micelle and liposomes has a hollow core, soif you see a micelle it will be something like this, these are the lipid moieties orhydrophobic moieties which are making the micelle, if you look at the centre the centralcavity is all hollow, hollow centre cavity or the hollow core.And also known as nano capsule and are sensitive to thermal and electromagnetic radiation suchas heat and light and they are also known as nano capsules and these are very importantfrom agricultural perspective in terms of release of say insecticide, herbicides, pesticide,those all could be encapsulated inside and they could be used for slow release.These are also called nano capsules and are sensitive to thermal and electromagnetic radiations.In terms of heat and electromagnetic radiation also light.So these are some of the very unique characteristics made in ideal choice for any kind of deliverysystems and this delivery system has a carrying capacity, stability could be tuned accordingto our needs and requirements.Then comes your inorganic rather in that community which includes your inorganic nanoparticlesor nanomaterials includes metal-based, you have metal oxide based, so metal-based andmetal oxide based includes mostly inorganic nanoparticles or nanoparticles that are synthesisedfrom metals to nanometric sizes either by destructive or constructive method are metalbased nanoparticle almost all the metals can be synthesise into nanoparticles and the mostcommonly metals for nanoparticle synthesis are aluminium, cadmium, cobalt, copper, gold,iron, lead, silver, zinc.And in terms of metal oxide based, metal oxide based nanoparticles are synthesised to modifythe properties of the respective metal-based nanoparticles and for example if you see ironhere Fe2O3, you have Al2O3 aluminium, you have different other such metal based systemswhich are there.This also includes a series of metal sulfide based which will be dealing pretty frequentlythen you have rare earth base.So these are all different kind of nanomaterial which are either metal based or metal oxidebased or metals sulfide, metal sulfide could be say if we talk about iron FeS2, if we talkabout rare earth, we are talking about CeCO2 cerium oxide, FeS2 iron sulfide, we will talkabout say molybdenum sulphide, MoS2, which is a material very very similar to grapheneoxide, similarly we will be talking about some of the other sulfides where metal isrepresented M here.And sulfide is written as S, so there are different kind of sulphide compounds we willbe dealing in the inorganic section and then we will be talking about now the carbon basedwhich is a huge group as an artifact or carbon based and this is where lot of these journeyshave started.So the carbon based nanomaterials are classified under fullerenes, graphenes, then you havecarbon nano tubes (CNT), then you have carbon nano fiber, then you have carbon blackand then you have activated carbon in nano sizeand in nano dimension.So these are the different categories, when you talk about fullerenes, we are talkingabout buckminsterfullerene it’s kind of a cage of carbon, it is something like geodesicdome it is a kind of cage wire you can entrap different kind of moieties like this whereas if we talk about the graphene.We are talking about a 2 dimensional sheet of carbon ring something like this, we talkabout carbon nano tubes, we are talking about a hallow tube of carbon something like this,so when we talk about carbon fibres these are just like nano fibers we talked about,this will be the fibrous like this and then carbon blacks are nothing but particles, anactivated carbon is also similar to the particle.Now most of this carbons could be further functionalized or could be derived by a functionalizingthem with OH group, so increase their interaction with water, their properties of hydrophilicitycould be modulated by having functionalizing them with OH and they could be derivatizedas nitrogen doped, the different techniques which have been developed deriving them withnitrogen doped technique.And much of this carbon which are arise in nature, normally has a rose through geologicalera where most of the biomass through the ages, through millions of years under highpressure and high temperature underneath the earth crust that transform into things likecoal, things like diamond, graphite, and if you take this material and follow the techniquesof pulling out nanomaterials you will see all these materials are filled with nanomaterials.In nature we have graphite or graphene kind of the stuff present in the coal.This all is happening through ages of exposing these biomass which are rich in carbon, andpartly nitrogen little bit of 16% nitrogen and other compounds increase amount and thishigh temperature, low oxygen and high pressure through the ages have led to conversion ofthe biomass into some form of nanomaterial.The reason why I am highlighting this part is while we will be talking about synthesisyou will appreciate that much of the synthesis which we will be talking about in terms ofthe physical mode of transformation where we have to give mechanical pressure, heat,light is nothing new because nature has already made nanomaterials by exposing the raw materialto high pressure, high temperature, lack of oxygen and (12:47) other combinations of this.Only thing is that in the natures laboratory these are happen but time was never a constraint,time always remain in almost in finite order but in our lifetime time is the already constrain.So when we talk about synthesis we had to emulate nature and at time we have to becomemore smarter than nature in terms of compressing time in order to achieve it and of coursesuch things to get a large scale would not be that easy because nature has produced themthrough many, many, many 1000 of years.So talking about carbon, carbon nanomaterial are one of the very promising candidate fordecorating them with different kind of moieties what we wanted to tell you, say for examplerather talk about the nano ribbons I told you that these are the different ways youcan really modulate the nano fibres.Similarly when we talked about nano composites I told, so say for example your core compositesis carbon and on top of carbon you are doing all these kind of decorations, say nitrogen,phosphorus and all this kind of thing, it is possible, but of course one has to ensurewhen we are functionalizing the carbon like this we have to ensure these, this functionalizationof carbon leads to when exposed to the area of delivery or site of delivery it shouldbe able to deliver easily without much problem, so that is very very critical.

Video 2: Summarizing the Classification of Nanomaterials
So to summarise the different kind of classification nanomaterials what we have talked as of nowso they could be classified under 2 heading either based on shape and geometric or basedon their chemical nature.In terms of the shape and geometry we talked about nano cages, a hollow interior coarsematerial of 10 to 150 nanometres, we talked about nano crystals, we talked about a nanocrystal could be even a sphere hallow sphere, we talked about nano belts, we talked aboutnano fibers, we talked about nanoparticles, we talked about nano tubes, we talked aboutnano wires, talked about quantum dots, we talked about nano composite and I mentionedabout nano diamond and all other different forms of nanomaterials.In terms of their chemical classification they are either organic base or they willbe inorganic base or they will be carbon based.In terms of organic base they could be that dendrimers, something like this, likea dendritic tree neuron if you look at a neuron it is something like this, it is axon (16:41)if you look at the dendritic tree it is a well spread out something like this is sothis is what dendrimer are then micelle I have already shown you the pictures of themicelle, and liposomes which is pretty similar, and ferritin iron binding clusters and theseare mostly bio degradable as I mentioned and these are non toxic and they have a hollowcore and they are also sometimes called nano capsule in terms of when we talk about micelleor the liposome and their properties of the degradation their opening it could be regulatedby thermal or electromagnetic radiation you can expose them to light then they may openup partially if you increase the intensity of light they will open up more.So there are several modifications what you can do with these kind of nanomaterials, thenwe talked about the metal based nanomaterials or the inorganic nanomaterial and within inorganicwe talk about metal based where we talk about aluminium, cadmium, Cobalt, copper, silver,iron, zinc, silver, zinc, lead, similarly in terms of the metal oxide base Fe2O3, Al2O3,then you have zinc oxide ZnO, copper oxide CuO, these are the different nanomaterialswhich will be discussing in our in terms of applications in agriculture then silver oxideor several of them and in terms of the third category is the metal sulphide we will betalking we talk about them in terms of iron pyrite FeS2, molybdenum sulphide And any othermetal sulphide, zinc sulphide likewise ZnS then we will talk about rare earth, ceriumoxide (18:56) lanthanide series La, rare earth oxides, lanthanide series.So then the third category what we discussed is the carbon based system and within thecarbon based system as we talked about fullerenes, graphene, which is fullerene is about fullereneC60 and all those kind of very complex, cage compounds of carbon 3 dimensional cage compoundsof carbon which is the nearest one which could be achieved was with the molybdenum whereyou could have the strong cage of molybdenum, then you have graphene, then you have carbonnano tubes, these are the hallow tubes and you have carbon fibers, and you have carbonblack and you have activated carbon in nano dimension.And these could be functionalized with OH group.These could be functionalized with carboxyl group depending on your requirements, whatyou wanted them to be functionalized with OH group for their solubility in water, theycould be derivatised as nitrogen doped carbon material for different applications.So this is the overall classification.Now from here what we will do we will move on to the synthesis of nanomaterials wherewe will be talking about 3 different synthesis techniques, physical, chemical and biologicalorigin.So next we will move on to the synthesisThank you.