Jak budowa molekularna i warunki termodynamiczne (p-T) wpływają na dynamikę molekularną monoalkoholi oraz dioli?

Abstract

Alcohols are studied from the beginning of the twentieth century in order to find answers to many fundamental questions related to the specific properties of materials containing hydrogen bonds. The unique properties of these compounds is not only the ability to easily supercooling to a glassy state, but above all the fact that in some of them (with single OH group in the structure), the dynamics of the hydrogen bonds can be monitored directly with a broadband dielectric spectroscopy (BDS) in a very wide range of times, from 10-9s to 103s. Therefore, studies on molecular dynamics of monoalcohols are essential for understanding the properties of associative materials. In the case of polyols (diols have in the structure two OH groups) we do not directly observe the relaxation process responsible for the occurrence of supramolecular structures, however, their research provides a lot of additional information about the effect of hydrogen bonds and structures created by them on the properties of associative liquids. Despite intense research, there is still no answer to some of the fundamental questions, including how does the molecular structure affects the molecular dynamics of alcohols under the influence of various thermodynamic conditions, whether the increase in pressure will affect the relaxation dynamics of the alcohol mixture with the non-dissolving solvent?The key task in the course of the conducted research, which form the basis of the presented doctoral dissertation, was to answer the questions that concerned issues related to the molecular dynamics of mono- and polyalcohols: 1) How does the architecture of molecules affect the molecular dynamics of simple alcohols? What is the role of thermodynamic conditions? 2) In the mixture of 2-ethyl-1-hexanol with 2-ethylhexylbromide (2E1H / 2E1Br) with a sufficiently high alcohol concentration there is the possibility of simultaneous testing of Debye's and structural relaxation properties also under high pressure conditions. This in turn gives the opportunity to find an answer to the question, what is the effect of different thermodynamic conditions on the dynamics of 2-ethyl-1-hexanol 2E1H dynamics, and in particular on structural relaxation? 3) How do thermodynamic conditions and differences in the architecture of molecules, including the addition of a second hydroxyl group, affect the properties of diols?