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Key Centre for Polymer Colloids Plymer - Chemistry Glossary
Category: Sciences > Polymer
Date & country: 11/09/2007, AUS
Words: 192

From the greek words for water (something like hydro) and fear (something like phobos). A compound is hydrophobic if it is 'hates' water and will not dissolve in it. Having little hydrogen bonding capacity and no charge makes a molecule hydrophobic. Most organic molecules, such as hexane, triolein, and styrene are hydrophobic. Opposite of hydrophilic. Nothing to do with rabies (hydrophobia).

Hydroxy group
An hydroxy group is an -OH group hanging off an organic molecule.

A compound required to start a chain reaction, such as free-radical polymerisation. Unlike a catalyst, it is consumed in the reaction, but only a small quantity is normally required since one molecule of initiator can initiate the reaction of many other molecules.

Any chemical compound that is primarily of interest as one of the steps between the starting material and the final product. It is usually best to design chemical processes so that intermediates do not need to be transported from place or stored in large quantities. Methyl isocyanate, an intermediate in the manufacture of certain pesticides, is a good example. For the horrific consequences of inappropriate and entirely unnecessary storage of this highly toxic intermediate, have a look at:…

Generally, any two chemicals with the same chemical formula but a different structure. For example, hexane (C6H14) could be n-hexane, 2-methylpentane, 3-methylpentane, 2,3-dimethylbutane, 2,2-dimethylbutane:

Monomer sometimes used in chain polymerisation. Natural rubber is poly(isoprene), although it generated in nature from the somewhat more complicated building block mevalonic acid phosphate.

The International Union of Pure and Applied Chemists. IUPAC is involved in setting consistent nomenclature, symbols and names of elements, mathematical variables.... Some people think IUPAC is a bunch of funny old men with nothing better to do than meddle with the perfectly good ways of spelling things chemists have used since Paracelsus was a boy, but we polymer scientists know better. Take a wander to the IUPAC website.

Karl Ziegler
Nobel prize winning chemist (1898-1973) who did a vast quantity of work on the catalysts allowing high density poly(ethene) and poly(propene) to be produced. Most of his work was done at the Max Planck Institute for Coal Research in Müllheim, Germany, and had nothing to do with coal, showing the economic benefits of pure research. Like Giulio Natta, he was a keen mountain climber. A quote: 'My only motivation has always been just to do what was fun.' (quoted in 'The Chain Straighteners,' by F. M…

An alkanone or ketone is any carbon compound containing the C-C(O)-C group. Acetone is the simplest ketone and is a common solvent found, for example, in fingernail polish remover.

The word 'kinetic' comes from the greek word for 'motion'. In chemistry, kinetics is the study of how fast reactions occur. In many chemical reactions where there are a number of possible products, the first one formed may be the one that is formed most quickly, not necessarily the one that is most stable; if you leave the reaction going, you should eventually form the product that involves the greatest change in bond energy - the thermodynamic product. Try this dodgy example.

A latex (plural latices, or latexes for the Americans!) is a dispersion of water-insoluble polymer in water. The dispersion is usually of particles (not single molecules) that are around 100 nm (10-4 mm) in size. The particles are keep suspended in the water by thermal convection (which keeps them from settling out) and surfactants (which keep them from sticking together to form bigger and bigger lumps). Another word for latex is polymer colloid.

In a crystal, some arrangement of atoms is repeated in a regular way. If we put an imaginary point at the centre of each repeating unit and mentally throw the rest away, the positions of these points will define a crystal lattice. For example, if the points define the corners of a cube, the crystal is a primitive cubic lattice; if they define the corners and a point in the centre of each face (like a die with a one on every side), the crystal is a face-centred cubic lattice, etc. There are 14 ba…

The cross-linked polymer of linked benzene rings that makes hardwood hard. It is an important structural material for most land plants, and is usually found mixed in with cellulose. Partial digestion of lignin by enzymes (completely different from the ones that break down cellulose) gives complex materials called humic and fulvic acids. These are the substances that give Adelaide water its unique colour and flavour!

A great website that has a lot of information about polymer chemistry. Or, as they describe themselves 'A cyberwonderland of polymer fun': University of Southern Mississippi, Macrogalleria

Once was had the word 'microscopic', it was only a matter of time before we needed 'macroscopic'; anything big enough to be seen with the naked eye is macroscopic in size.

Mechanical Properties
Things you can measure while you push, twist, bend, tear, fold, spindle, or mutilate something - the simplest example is probably putting a known force (stress) on a piece of something and measuring how far it stretches (strain). Millions of pages have been written about stress-strain curves.

Melting Point
The temperature at which a solid turns into a liquid. As temperature is a measure of the kinetic energy of molecules (how much they are moving around), this means that the molecules are moving too much to stay in one place anymore.

Methyl Methacrylate
Monomer commonly used in chain-addition polymerisations.

Organised blob of surfactant molecules with all the hydrophobic tails pointing inwards to create a tiny hydrophobic phase. If you try to dissolve surfactant molecules in water, you will succeed up to a point as more surfactant is added, and then any additional surfactant you add will form micelles. Under the same conditions, a particular surfactant will always form micelles of the same size and containing almost the same number of surfactant molecule.

A non-metric unit of length which can be divided into 8 furlongs, 80 chains, 360 rods, 1760 yards, 5280 feet, 8000 links or 63360 inches. It is equal to 1609.344 metres, more or less.

The adjective derived from 'mole'. The total heat released when a mole of something burns is its molar heat of combustion; the concentration of a substance expressed in moles/litre is its molar concentration, usw.

The mole is defined as the amount of a substance that contains as many atoms or molecules as atoms are contained in 0.012 kg of carbon-12. The easiest way to think of it is that a mole of a substance of a particular weight will weigh that many gramm. There are about 6.02 × 1023 particles in a mole.

Molecular Weight
Molecules are too small to put on a scale, but if you put 6.022 × 1023 of them (60 220 000 000 000 000 000 000, Avogadro's Number) of them on a scale, they will weigh about 2 g (if they are Hydrogen molecules, H2), 128 g (if they are butyl acrylate molecules, C7O2H12) or 10 tonnes (if they are typical molecules of poly(acrylamide)). This number is their 'molecular weight'.

While the farms of antiquity grew many sorts of plant and animal on the same location, modern factory farming involves the cultivation of a single species, to the exclusion of all other forms of life. This is called monoculture.

Any small molecule that can undergo a reaction in which it is incorporated into a large molecule containing many similar units. Common monomers are vinyl acetate, styrene, butadiene and vinyl chloride. (Yes, it is appropriate to consider hydrocarbons as polymers of methylene!)

Short for 'megapascal', that is, one million pascals. A pascal is the pressure generated by a mass of approximately 100g on a square metre under the earth's gravitational field. Atmospheric pressure is about 100,000 pascal (100 kPa, or as weather forecasters like to say, 1000 hPa [hectopascal]), so 7 MPa is about 70 times atmospheric pressure. You may come across values in 'psi', or 'pound force per square inch': 1 MPa is about 145 psi.

The trivial name for poly(2-chlorobutadiene). This polymer is used in the manufacture of fan belts and wetsuits. The monomer, 2-chlorobutadiene (aka chloroprene), looks something like this:

Adding base to an acidic solution until it is no longer acidic, or acid to a basic solution until it is no longer basic. pH 7, where equal amounts of H+ and OH- ions will be present in any aqueous solution, is the pH of a truly neutral solution.

Why atomic weights are complicated. Each element has a certain number of protons in its nucleus, which defins what element it is (e.g,, 92 for Uranium, 2 for Helium, 109 for Meitnerium). To keep the positively charged protons from flying apart through electrostatic repulsion, they are bound together by the 'strong force' which is a veyr powerful force operating over very short distances between protons and neutrons. A certain number of neutrons gives optimal stability to a nucleus - too many or …

A carbon compound containing a carbon-nitrogen triple bond. An example is acetonitrile, a common organic solvent:

The -NO2 functional group. You may have heard of trinitrotoluene (TNT).

Naming things.

Any chemical species that has neither a positive or negative charge is nonionic.

Nuclear Magnetic Resonance
NMR is an analytical technique for working out what an organic compound actually is. It works by placing the sample inside a very strong magnetic field (typically around 100,000 times stronger than the earth's magnetic field, though it can be carried out with weaker and weaker fields as research continues) and playing FM radio waves at it. The strong magnetic field and the absorption and emission of the radio signals allows the operator to work out how the individual atoms are connected within s…

A class of polymers that is widely use in the clothing industry (amongst others). Their common feature is the presence of a -C(O)-NH- link between monomer units. This is also called a peptide bond. See Nylon 66 and Nylon 6.

Nylon 6
Another form of nylon that uses only one monomer unit (not two). This monomer is difunctional with a carboxylic acid group at one end and an amine group at the other. The condensation reaction between two such molecules produces an amide bond in the same way as the synthesis of Nylon 66. The monomer used is (I think) 7-amine-1-heptanoic acid.

Nylon 66
A polymer widely used in a fibrous form in fabrics as well as solid lumps of plastic (e.g. in chopping boards and bearings). Nylon 66 may be formed from the condensation polymerisation of 1,2-hexadiamine and 1,8-octadioic acid, although modern industrial processes have improved upon these reactions by ionising the reagents to the hexadiammonium and 1,8-octadioate ions before the reaction is undertaken.

A steroid hormone responsible for the development of female characteristics in mammals. The proper name for it is 'estradiol'.

Oleate Ion
The oleate ion is one of the most common soaps, being derived from triolein, a component of olive oil.

An oligomer is a molecule which is formed from a few smaller (identical) molecules joined together. Just as a monomer is one (mono) unit (mer) and a dimer is two (di) units, an oligomer is a few units.

Ore flotation
A common way for extracting particles of metal from an ore is to crush the ore into a fine powder, add water and surfactant, and bubble air through. Particles of many useful minerals, which are more hydrophobic than the rock that surrounds them, will stick to the surfactant bubbles and collect at the surface.

When referring to chemical compounds, anything that contains carbon. The original definition was more like 'any chemical found in or derived from a living organism' and most chemists still feel funny calling carbon monoxide or the carbonate ion (CO32-) organic compoinds.

Osmotic Pressure
Where two solutions of different concentration are separated by a membrane which the solvent molecules can move through, but the dissolved particles (solute) can't, the solvent will move from the less concentrated to the more concentrated solution to attempt to equalise the concentrations. The pressure that must be exerted on the solution to stop this influx of solvent is called the Osmotic Pressure, which is given by a simple equation for dilute solutions: Pressure = 8.314 × (Temperature) × (di…

Periodic table
A logical way of writing down all the 111 elements so that the connections between their properties and their electronic structure is 'obvious'. I think 111 is the right number this week.... There are many fantastic periodic tables on the web, such as WebElements.

Flowing into the pores and gaps of a substance; why you can pour water into a cup that is already full of sand, and pour a lot of water into a cup that is already full of popcorn.

Short for poly(ethylene terephthalate), a condensation polymer that is commonly used in soft-drink bottles. It can be prepared by the reaction between ethylene glycol and terephthalic acid to give polymer and water:

Value-added products made from crude oil or natural gas. Most all of the chemicals we use to keep civilisation rolling along.

A sticky, oily, flammable liquid that is a complex mixture of organic compounds (mostly hydrocarbons) and other may vary in colour from nearly colourless to black. Basically, it is another word for crude oil. 'Petr' means something like 'rock' and 'oleum' means something like 'oil'.

If you call a 'system' anything that is in a bucket, that a 'phase' is a part of the system that can be (at least in theory) separated mechanically without any chemical reaction, and is of uniform composition. You could have ice and water mixed in a bucket (two phases) ice and soda water (three phases, if you count the bubbles) or ice and salad dressing (three phases - ice, oil, and vinegar - yuck).

Phosphoric acid, H3PO4, is a weak acid found in many soft drinks.

A nifty reaction carried out inside green plants, and by a number of different kinds of bacteria, which basically uses energy from the sun to run the combustion reaction backwards.

A chemical bond formed by the indirect overlap of two atomic orbitals. I don't think I actually want to get into this, but the two bonds in a double bond are not the same; one is a sigma bond, formed by the direct Head-to-Head' overlap of two atomic orbitals, and this is considerably stronger than the second one, which is a pi-bond.'...

What most people think of when they think of polymers. Strictly speaking, a plastic is a polymeric material that can be molded into different shapes when heated (a thermoplastic) - this is true for most of the materials mentioned on this website, including poly(styrene), nylon66, PVC, and PET. Some misguided people say nasty things about plastic, but it wouldn't be everywhere if it wasn't (a) incredibly useful and (b) incredibly cheap.

'A compound added to a polymer to make it softer and more flexible. These are usually small molecules with dangling bits that can disrupt the packing of polymer chains. A common plasticiser used to soften PVC is dioctyl phthalate:

Polyesters are a class of polymer which use ester linkages (-C-O-C(O)-) to join the monomer units. Polyesters are condensation polymers.

A large molecule (molecular weight ~10 000 or greater) composed of many smaller molecules (monomer) covalentl…'

Side groups
All the carbon based polymers you will find mentioned on this site have the structure -C-C-C-C-C-C- etc. Anything hanging off that centre chain that is not a hydrogen atom is a side group.

A chemical bond formed by the direct 'Head-to-Head' overlap of two atomic orbitals. I don't think I actually want to get into this , but the two bonds in a double bond are not the same; one is a sigma bond and is considerably stronger than the second one, which is a pi-bond formed by the indirect overlap of two atomic orbitals....

Significant figures
If you measure one side of a cube with a ruler marked in cm and find it is 26 cm long, then its volume should be 17576 cm3, right? Wrong! You have only put two meaningful digits into your calculation - the cube could be anywhere from about 25.50001 to 26.49999 cm long on a side, and if you say it has a volume of 17576 cm3 you are claiming accuracy that you don't really have. The correct answer is 1.8 × 104, keeping the same number of meaningful digits in the answer as you started with. The prope…

A soap is a type of surfactant that is derived from the saponification reaction (hydrolysis) of a vegetable oil. A soap has a carboxylate group on the end which can form a complex with calcium ions in hard water. (This causes soaps to form precipiates giving rise to a 'soap scum'.) Soaps are often called fatty acid salts. Common soaps are:sodium oleate (from olive oil) and sodium palmitate (from palm oil).

Sodium dodecyl sulfate
Sodium dodecyl sulfate is one of the most common surfactants. It can also called be called sodium lauryl sulfate, depending on whether it is made from petrochemicals (dodecyl) or plants (lauryl). But they're the same molecule:

Specific heat
The amount of heat required to raise one kilogram of a substance 1 degree in temperature.

Starch is the main source of food energy for most of the world's human population. It can be considered to be a condensation polymer of glucose, like cellulose, although the ether linkages in starch are different to those in cellulose. Starch may be highly branched (amylopectin) or relatively unbranched (amylose).

The geometry of molecules, and the arrangement of their constituent atoms in space, is the subject matter of stereochemistry. What does that actually mean? In the nomenclature section, you will have encountered isomers with the same chemical formula but with the atoms arranged in a different order - such as the various forms of pentane. You will also have met cis and trans isomers of alkenes - these are compounds with the atoms in the same order, but with a different geometry and are simple exam…

Any effect that is caused simply by a chemical group physically getting in the way, rather than by any particular properties of that group, is called a steric effect. A good definition to keep in mind (Organic Chemistry, John McMurry , 1988) is that steric strain is the result of trying to force two objects to occupy the same space. Here is an interesting example of a steric effect.

If you can spell this word, you're a real chemist. To paraphrase the IUPAC definition, stoichiometry is the relationship between the amounts of reactants reacted and the amounts of products produced. An equation that says that 'Two moles of X reacts with one mole of Y to make three moles of Z' is a stoichiometric equation. We have rarely known anyone to use this word when they were not showing off.

In the science called rheology (the study of how materials flow and deform), stress is the force applied to a material and strain is the resulting movement of the material. A simple practical exercise is to measure the length of a rubber band 'at rest', then suspend an object of known weight from it (stress) and measure the change in its length (strain). Try adding bigger and bigger weights, and you may discover something originally discovered by Sir Isaac Newton.

One of the most common monomers used to make chain-growth polymers. It also seems to be the one that everyone studies lots: 'If it works for styrene it must be true for all monomers...' (famous trap).

Sulfuric Acid
H2SO4 A strong acid - in water, it decomposes completely to H+ and HSO4- ions; with a little more prompting, HSO4- can be persuaded to give H+ and SO42-. When I was young, I had quite a bitter disagreement with a friend of mine about whether the element from which its name arises ought to be spelled 'sulfur' or 'sulphur' (IUPAC comes down firmly on the side of 'sulfur'). We eventually reached a compromise, and for many years I stuck to a spelling of 'sulfhur' which miraculously passed uncorrecte…

From SURFace ACTive AgeNT. A substance which prefers to exist at the boundary between two other substances - for example, detergents have one end highly soluble in greasy, non-polar susbtances and one end soluble in water. Sodium dodecyl sulfate is a common surfactant. See also emulsifier.

A mixture of two substances where small pieces of a solid are suspended in a liquid - for example, milk (blobs of fat and protein floating in water) and orange juice (chunks of plant floating in water).

Synthetic Rubber
Any synthetic polymer that mimics the properties of natural rubber. One of the earliest was ABS (Acrylonitrile-Butadiene-Styrene) rubber, a copolymer containing long segments of each of those three monomers.

According to some kind of system. It does not have to be particularly logical- for example, consistently naming chemicals you don't like after people you don't like would be an example of systematic, but irrational, nomenclature.

This is a word that is frequently misunderstood. Let us say we have a collection of observations ('facts') about something - it preferentially absorbs certain wavelengths of light, is composed largely of oxygen, hydrogen, carbon, calcium and phosphorus in certain proportions, and absorbs oxygen from the environment while releasing carbon dioxide. A theory is a way of explaining at these observations that allows us to make additional predictions about the behaviour of the system. If these predict…

Thermal Cracking
A form of cracking that simply uses heat to break up the molecules. The crude oil is heated to 750 to 900 °C in the absence of oxygen and the molecules break up to give free-radicals, which start falling apart and rearranging themselves. Catalytic cracking can be done at much lower temperatures, but generates different products from the decomposition of the crude oil.

The word 'thermodynamic' comes from roots that mean 'heat' and 'motion'. In a chemical reaction where chemical bonds rearrange to give more stable products, the energy that was stored in the bonds will be released as heat. In many chemical reactions where there are a number of possible products, one will be the most stable (give the greatest release of heat) - this will be the thermodynamic product. This might not be the product that is actually formed, since another possible product might be fo…

A polymer that, when heated ('thermo') becomes soft and deformable ('plastic'). Examples are poly(styrene) and poly(ethylene)...

A polymer that, when heated ('thermo') does not become soft and deformable. This is usually because it is crosslinked, and the molecules compriising it cannot move past one another unless chemical bonds are actually broken - which leads to the decomposition of the polymer. Phenol-formaldehyde resin is an example.

Also called a mercaptan. A carbon compound containing the -SH functional group. Mercaptans are responsible for the distinctive odour of cat urine.

The non-systematic name for methylbenzene, like so:

Triolein is the principal component of olive oil. Triolein is a triglyceride -- it consists of glycerol with three ester linkages. It may be hydrolysed (breaking the ester linkages) to form oleate ions in a saponification reaction.

An amino acid with the useful property of aborbing ultraviolet light, helping to make proteins visible to detectors in chromatographs. Some vitamin suppliers call it 'the natural alternative to Prozac'. Tryptophan's biochemical symbol is T and it looks like this:

Tungstic acid comes in two forms - ortho tungstic acid, which is H2WO4, and meta tungstic acid, which is H2W4O13·9H2O. The tungstate anion is WO42-.

Van der Waals Forces
Attractive forces acting between uncharged molecules. There are three kinds: (1) Dipole-dipole forces (2) Dipole-induced dipole forces (3) Dispersion Forces. Named after Johannes Diderik van der Waals (1837-1923).

Vinyl Acetate
A common monomer used to make chain-growth polymers.

Vinyl Chloride
One of the most common monomers used to make chain-growth polymers.

Any fatty substance that is a relatively hard, brittle, and non-greasy at room temperature. Most waxes, whether derived from mineral, vegerable, or animal sources, are a mixture of relatively high molecular weight (more than thirty carbons) hydrocarbons, esters, alcohols, and carboxylic acids.

The non-systematic name for dimethylbenzene.

Any of a number of species of single-celled fungus. Most important are the Saccharomyces spp., which are used in bread making and beer brewing...

A class of minerals that are 'hydrated aluminosilicates'. An aluminosilicate is where some of the Si atoms in silica (which has the perfectly reasonable chemical formula SiO4) are replaced with aluminium, giving an excess negative charge. 'hydrated' means that water is strongly associated with these materials by hydrogen bonding. Lastly, a positively charged 'counter-ion' is needed to balance the negative charge on the zeolite. Zeolites are extremely porous materials, with a regular internal str…

Ziegler-Natta catalyst
A compound containing a metal-carbon bond that can be used to make highly ordered, high density polymers by a chain-growth mechanism. A typical Ziegler-Natta catalyst is the compound formed in situ between titanium trichloride and diethylaluminium chloride.

'Zwitter' is german for 'hybrid', and zwitterions are chemical species that manage to be both cations and anions at the same time. How can this come about? Consider ammonium acetate (NH4CH3COO). It is a perfectly ordinary salt, and when dissolved in water splits into its two constituent ions, NH4+ and CH3COO-. These ions will be able to approach quite close to each other in solution, but there will be no transfer of charge from one to another because of the 'shell' of water around each one. In f…