Performance Polymers

Single Wall Carbon Nanotubes

Single Wall Carbon Nanotubes (SWNTs), having a diameter of 1-3 nm and a length of 1-2 ìm, are easily dispersed in an aqueous solution of the surfactant sodiumsodecylsulphate after a gentle ultrasonication treatment. This stable dispersion of predominantly individual SWNTs is subsequently mixed with a latex of a high molar mass polystyrene (PS).

After freeze-drying a powder mixture of PS and 0.3 wt% SWNT is compression molded into a thin film, which is submitted to a four-point electrical resistivity measurement. Whereas an unfilled PS film exhibits an electrical resistivity of 1014 S/cm, the nanocomposite containing merely 0.3 wt% SWNT has an electrical resistivity of 102 - 103 S/cm. For obtaining an antistatic character an electrical resistivity of 106 - 107 S/cm is already sufficient. With a resistivity of only102 - 103 S/cm, applications in plastic transistors come within reach. This simple concept is widely applicable. For a polymethylmethacrylate and a polyethylene matrix very promising results were obtained as well.

MALDI-experiment

Living anionic polymerization is used to make well-defined polymers, meaning they have a predictable chain length and a narrow molecular weight distribution. After consumption of the complete amount of monomer present in the polymerization system, all polymer chains remain active because they still bear a negative charge at the chain end. These anions are very reactive towards a variety of electrophiles, but most of these reactions suffer from unwanted side reactions. Our objective is to attach a certain functionality to the chain ends in a controlled and quantitative fashion.

Characterization of the products of these reactions is not easy, since only a minor change at the chain end is being made, while the entire long polymer chain remains unchanged. So, the product differs only slightly from the starting material. Using MALDI-ToF-MS (Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry) we are able to determine the molecular weight and the molecular weight distribution of the polymers very precisely. Comparison of these results with the theoretical masses of starting materials and products, gives us insight in the endgroups of the polymer chains, leading to a better understanding of the experiments we do.