New Physical Properties

Since the environment of the cavity presented by 2 is spatially and electronically confined, physical properties of encapsulated molecules are expected to change to some extent, or even dramatically. In this section, the variable properties of guests in the cavity of cage 2 are discussed. 

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In this demonstration, chemical changes occur. With the addition of heat, reactants change into products. New substances are formed with new physical properties. Chemistry is the study of chemical change. 

When carbon dioxide is heated beyond its critical point, with a critical temperature of tc = 31.0 °C, a critical pressure of pc = 7.38 MPa, and a critical density of Pc = 0.47 g cm , the gaseous and the liquid phase merge into a single supercritical phase (SC-CO2) with particular new physical properties very low surface tension, low viscosity, high diffusion rates, pressure-dependent adjustable density and solvation capability ( solvation power ), and miscibility with many reaction gases (H2, O2, etc.). It can dissolve solids and liquids. The relative permittivity of an sc-fluid varies linearly with density, e.g. for SC-CO2 at 40 °C, r = 1.4 1.6 on going from 108 to 300 bar. This... 

The preparation of the silylated amines, hydrazines, and hydroxylamines follows conventional synthetic methods established previously for species with fully or partially alkylated silyl groups. The low moleeular masses and the absence of substituent branching lead to new physical properties, however, which make the simple hydrogen-rich molecules attractive for vapour phase technology. 

Polymer of hi molecular weight are in the main inccmq>atible, but it is often advantageous to compound two polymers in order to obtain a combination of new physical properties which either polymer alone cannot have. For example, EPDM rubber is inconq>atible with diene rubbers such as polyisrprene, polybutadiene,... 

In solvent extraction, use is made of weak intermolecular forces selectively attracting some molecules more than others. This concept of selective attraction can be extended to the point of using an extractant capable of forming a chemical bond with the molecules to be extracted, but not with other molecules. In this case, the extractant can be said to react with the partner molecules. In so doing, a new species is formed which will have different physical properties, and in a favorable case these new physical properties will be conducive to facilitating the separation intended. 

Polyelectrolyte brushes constitute a new class of material with very interesting physicochemical properties. The strong stretching of the polymer chains due to segment-segment interactions and electrostatic forces introduce completely new physical properties into monolayers consisting of polyelectrolyte brushes and also into cylindrical brush systems. With the develop-... 

Now, it becomes clear that it is possible to obtain the new physical properties owing to its specific multi-layer structure. 

In 1975 P.G. de Gennes recognized that the interplay between liquid crystalline order and the macromolecular network stmcture generates new physical properties that also resemble those of biological systems and muscles [3]. In the following years Otto Lehmann s early ideas were actually demonstrated with liquid crystalline elastomers although at that time the basic concepts of macromolecular chemistry were still unknown. 

One of the most relevant examples of new physical properties appearing at the interface of two materials is related to the interfiice reconstruction of transition metal perovskites. This is the case of LaAlOs/SrTiOs (LAO/STO) interface [9], where two-dimensional (2D) conductivity is observed at the interface between two insulating materials. The different properties are explained in terms of not only electronic reconstruction but also ion displacement, that is, polar deformations across the interface [10]. 

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