Investigations of novel phases and states produced by means of high pressure.
Composites based on nanotubes and polymers
In this project, we investigate the possibilities to make new improved materials by high pressure treatment, e.g. using nanotubes. Nanotubes, which consist of carbon that forms a tubular structure with a diameter of only a few nanometer, have excellent mechanical, electrical and thermal properties. Nanotubes are stronger than steel, can conduct current better than copper and are better heat conductor than diamond. In one study, we investigate if high pressure produced composites based on nanotubes and polymers can obtain similar properties.
In this project we use high pressure methods to produce and study new and interesting states of matter. High pressure induces structural changes that cannot be obtained at ambient pressure conditions, and properties may change orders of magnitude. This provides many possibilities for both applied and basic science, and a few are described here. Common to all of these is the use of high pressure to alter the state of a substance. Simultaneously, we use unique high-pressure, in-situ, methods, which allow us to directly follow the changes as well as to characterize the new states. In particular, we use thermal, optical and dielectric methods which are specially designed for high-pressure studies. We describe a high-pressure method to chemically bond nanotubes and a polymer to make a strong flexible polymer composite with potentially interesting mechanical, electrical and thermal properties. We have made a preliminary successful study where we crosslink liquid poly(isoprene), with and without nanotubes, by using only high pressure. That is, we can do this without adding vulcanization chemicals. We now plan to synthesize a composite using functionalized nanotubes, which can form bonds with the polymer. We expect that this high-pressure produced polymer nanotube composite can have significantly better mechanical and thermal properties than those found previously for composites produced at ambient conditions. We will address a fundamentally very important question that concerns water and its glassy states, which are produced at high pressures. In this case, we will explore the possibility of two liquid states of water, which provide a key for understanding its numerous anomalous properties. We suggest dielectric spectroscopy investigations at low-temperatures of both bulk and confined water, which will yield vital information about the molecular mobility. This information is essential for advancing the understanding of the states and, thus, the properties of water. We have recently used the method and studied the transformation of one glassy water state to its liquid state. The glassy water states are obtained via pressure-induced amorphization (PIA), which is a quite new way of producing glasses that gives a glassy state with extraordinary crystal-like properties. We propose experiments on doped water to gain further information about PIA and the PIA produced states as well as to alter the conditions for PIA. We also explore the potential to change and improve pharmaceuticals and hydrogen storage materials by means of high pressure. During the last year, we have made several investigations which concern these subjects and which are aimed at producing new improved high pressure phases as well as gaining further knowledge about the atmospheric pressure phases. Here we suggest several studies where we apply pressure to induce changes in the state of matter. The specific aims are to: * Produce and study the mechanical, electrical and thermal properties of carbon nanotube composites in which the carbon nanotubes are chemically bonded to the polymer matrix. This will be accomplished using high pressure on a solution of a polymer and functionalized nanotubes, which should yield a high-density composite with strong intermolecular bonds. The high-pressure conditions for such a potential reaction have already been established in a preliminary study. * Certify whether or not the glassy states of water transforms to a liquid on heating by dielectric studies of PIA produced glassy water states. This will help us ascertain if these have a thermodynamic continuity with liquid water and, consequently, if there are several liquid water states. We have already provided such results for one of the glassy states. * Use PIA or another high pressure route to produce new states, e.g. amorphous or new polymorphic forms of pharmaceuticals, with improved properties such as increased bioavailability. Similarly, potential materials for hydrogen-storage will be studied under pressure. * Provide a detailed understanding of PIA and to find means to change the pressure-temperature co-ordinates of PIA, e.g. by using dopants, to promote further experimental studies, which are hampered by the normally very high pressures of PIA. * Provide results that are of fundamental importance in evaluation of basic relations such as the Stoke-Debye-Einstein relation and gain a more profound understanding of properties, e.g. conductivity governed by percolation, which depends strongly on density.