Chemistry

What is a Polymer



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Polymers are substances that are made up of molecules with a large mass, connected by covalent chemical bonds. They are used throughout society for a variety of different functions. Contrary to popular belief, the polymer material is not limited to plastic. Polymers are used for many different functions including plastic, such as for clothing, or lighter alternatives to common metals.

Polymers are made up of much smaller particles, called monomers that have become chemically bonded together. Chemists are able to make a seemingly endless amount of different types of polymers by simply changing which sorts of monomers are mixed together. Many polymers have very practical uses, such as the physical property that allows them to not decay. In most cases, polymers are used as solids, and very often as a lighter substitute for metals, for example wheel alloys, in which case a polymer substitute can be used to decrease the weight by up to one third, while maintaining the same strength.

Polymers are an extremely important material to us at this point in human history. Our lives are wrapped up in plastic; look around you, chances are many of the things near you are made of some form of polymer. They are used widely in the world today; so widely that it is likely our lives would be very different without them. Plastic would be non-existent, which means that just about everything that we use on a regular basis would be made of wood, metal, or some other expensive and inconvenient material.

The physical properties of polymers vary due to their composition. For example, most polymers will not boil. This is due to the fact that energy required to boil the polymer is greater than the amount that keeps the material's structure together (Charles E. Carraher Jr, 2007). The chemical properties are largely influenced by the attractive forces between the monomer chains. These forces are part of what gives polymers their strength. Often polymers will form ionic or hydrogen bonds between the monomer chains. In these cases, a much greater tensile strength results with the polymer as a whole.

Plastics not only make our daily lives easier, and more cost-effective, but also provide a very interesting area of study and invention for chemists to experiment with. Polymer electrolyte membrane fuel cells are just one of these new, groundbreaking discoveries. Fuel cells are an exciting way of reducing pollutant emissions from many sources, most notably from motor vehicles. Hydrogen fuel cells, for example, once fully developed, should provide us with a huge, un-tapped energy supply with very small pollution.

Polymer fuel cells are one type of proton exchange cells. Proton exchange fuel cells operate in a similar fashion to batteries. They consist of two separate electrodes, connected by an electrolyte in between them. Hydrogen is pumped through the anode, while Oxygen from outside the fuel cell enters through the cathode. With the assistance of a catalyst, the Hydrogen atoms split into a single proton and electron, with the proton travelling to the cathode through the electrolyte, and the electron travelling via the circuit. This process generates electricity from Hydrogen, one of our most readily available elements, and mixes it with Oxygen after the reaction to create only two products; electricity and water! What results is a clean, effective way of producing electricity (Fuel Cells 2000). However, while these fuel cells are a great way of producing clean energy, they have several drawbacks.

One of the major problems with fuel cells has been that they operate at far too high a temperature, for example ceramic fuel cells only work at 800 Celsius. Obviously, at this temperature, most appliances will not be able to function at all; imagine your mobile phone at 800 degrees! There has been a lot of research into solving this problem, and many different materials have been looked into as possible replacements to the original types of fuel cells.

The answer to the issue is simple: Polymer Electrolyte Membrane Fuel Cells. The latest polymer fuel cells allow efficient energy usage, with a moderate temperature. They have the potential to replace many of our current fuel cells with a more efficient, cost-effective and quality alternative; polymer fuel cells are revolutionising fuel cell technology around the world! With the most recent developments alone, we are going to see polymer fuel cells in things like cars, laptops and mobile phones.

Until recently, we have been unable to use polymer fuel cells in mainstream fuel cell production because of several limiting factors. While other fuel cell operating temperatures are extremely high, polymer fuel cell operating temperatures are extremely low, so low in fact that even very small quantities of carbon monoxide within the hydrogen fuel will ruin the platinum catalyst which is vital to the cell. In order to maintain the purity of the fuel cell, it must go through a complex process which causes these fuel cells to become quite expensive in comparison to other, more readily available cells. They must also be kept below 100 Celsius so that the membranes can keep enough moisture within them to conduct protons through the cell.

However, with the latest research and investigations into improving polymer fuel cells, these problems have been eliminated. With a new chemical known as Triazole, polymer fuel cells can now operate at much higher temperatures, which causes the price of these fuel cells to drop dramatically, but creates a much more effective and efficient way of producing energy in a fuel cell.

As good as it seems, a complete takeover of the fuel cell market by polymers may not necessarily be the best thing for us at this point in time. In 1998, in the USA alone, 586.3 billion litres of fuel was consumed (AllCountries.org). This includes petrol, natural gas, jet fuel etc. With those figures as high as they are, we will run out of our major non-renewable fuel sources at some point in the perhaps not-so-distant future. Unfortunately, it is from oil that many of the reactants for the polymer creation reaction are derived from. This essentially means that once the non-renewable energy source oil runs out, we will be stretched for the necessary materials to create not only them, but all plastics, which are turning into one of the most widely used materials in our daily lives. So while polymer fuel cells would not take up a particularly large fraction of the world's polymer market, relying on them in the future may not be a good idea.

Polymers are vital to society as we know it in this day and age. Fuel cells made with polymers can and likely will take over the fuel cell market because of their more user-friendly operating temperature, their low price and efficiency. So in the next few years, when you buy a new laptop, mobile phone or other similar appliance, remember what is powering it; plastic!

References

"Synthetic Polymers" - Charles E. Carraher Jr, 2007 - Advameg Inc. http://www.chemistryexplained.com/Pl-Pr/Polymers-Synthetic.html
"Domestic Motor Fuel Consumption" in the USA http://www.allcountries.org/uscensus/1049_domestic_motor_fuel_consumption_by_type.html
"What is a Fuel Cell?" Fuel Cells 2000, http://www.fuelcells.org/basics/how.htm
"A Future Without Plastic" Mike C, http://www.quazen.com/Science/Environment/A-Future-without-Plastic.7430
"Polymer Exchange Fuel Cells" HowStuffWorks 2000, http://auto.howstuffworks.com/fuel-cell2.htm
"Polymer Electrolyte Fuel Cells" US Department of Energy, 08/03/2007 http://www1.eere.energy.gov/hydrogenandfuelcells/fuelcells/fc_types.html
"Polymer Fuel Cell Breakthrough" Georgia Tech, Science Agogo, http://www.scienceagogo.com/news/20050724233250data_trunc_sys.shtml
"Polymers" Encarta Encyclopaedia 2000, Page 1
"Polymers" Wikipedia, http://en.wikipedia.org/wiki/Polymer

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