Thursday, 24 January 2013

Polymer Carpets

Hannah Bruce Macdonald

It seems as though every new development nowadays is on the nano-scale, and this is no exception. Professors from the University of Munich and the University of Dresden have improved a method for the synthesis of polymer carpets.

A Polymer Carpet
Polymer carpets are made by grafting styrene polymers onto copper supported graphene and these scientists have discovered that the carpet density and thickness depends on the hydrogenation of the graphene. Graphene is an incredible material, due to its versatility, but what makes it so useful as a support for making polymer carpets is how stable it is to mechanical and chemical influences. The team working on these carpets say that the ‘Polymer carpets exhibit remarkable and unprecedented properties combining extreme thinness, mechanical and chemical stability, robustness, flexibility, and (chemical) sensitivity’. The chemical sensitivity mentioned by the team may sound like a flaw, but this actually means that the nature of the carpet (effectively its thickness, fluffiness or tangled-ness) can be fine-tuned with changes in conditions like the solvent quality, wetting and pH.

Natural (left) and artificial (right) nacre
Polymer carpets are one of those materials that seem to be good at everything. They are similar to biological membranes, such as the outside layer of cells, but have the significant advantage of stability and the ability to withstand considerable pressure. This feature means they have been applied to use in water purification and desalination. Any developments in these fields are of huge importance globally and more research and discoveries in this field could make these polymer carpets a viable solution to the cleanliness of drinking water.

Another unsuspected use of these is in the synthesis of artificial nacre. If, like me, you don’t know what nacre is, it is mother of pearl, the shiny inside coating of some seashells and the outer surface of pearls. Pearls have had many uses over the years, but these tend to be mostly decorative, in jewellery or furniture, but are beginning to be applied in more areas. The pearl is originally made as a surface to protect the molluscs’ soft material from damage through bombardment and protection from parasites. Nacre is now being used as a novel material in medical surgery, as it has been shown to stimulate the growth of cartilage when injected into bones. The ability to make a Nacre alternative in the labs could prove to be advantageous, over having to source it from the sea.

Any improvements in the understanding of the mechanism or the synthesis of polymer carpets is useful, and allows a large step to be taken towards applications such as these, however the greatest use of these diverse materials could yet to be discovered.