Kinetics of atom transfer radical polymerization.

摘要

Atom transfer radical polymerization (ATRP) is a powerful controlled radical polymerization (CRP) technique that provides control over topology, composition, microstructure, and functionality of polymeric materials. Kinetic study has become very important to understand the nature of ATRP and to develop new catalysts and predict catalytic activity. Investigation of structure-reactivity relationship for various catalysts and initiators is of particular interest through the determination of the equilibrium constant (K ATRP), activation rate constant (kact) and deactivation rate constant (kdeact). Some simulations have also been used to analyze specific ATRP systems (Chapter 1).; Previously, most literature data on kinetic and thermodynamic parameters were determined under various conditions. There was even no precise way to determine equilibrium constants. Simulations of ATRP have been only applied to the ideal normal ATRP case but not those developed in recent years (Chapter 1).; The main goal of the research presented here is to solve some basic kinetic problems for ATRP. In Chapter 2, new equations for determination of the ATRP equilibrium constants are described. These equations enabled the precise measurements of KATRP with values ranging from 10-11 to 10-3. With the newly determined K ATRP, values, comparison and prediction of catalyst activities becomes possible. The values of kdeact were also calculated based on the kact from Chapter 3.; Values of KATRP determine the position of equilibrium, but how fast the equilibrium is established. Determination of the activation rate constant (kact) would elucidate this question. In Chapter 3, several methods are presented to determine values of kact. Their values were also examined for various ligands, initiators, solvents, temperatures, counterions and other conditions.; Values for KATRP, k act, kdeact obtained from Chapters 2 and 3 establish the basis for the kinetic simulations of any ATRP systems. In Chapter 4, simulations are carried out for various ATRP systems. Kinetic modeling was also applied to the nitroxide mediated polymerization (NMP) chain extension from macroinitiator via activator regenerated by electron transfer (ARGET) ATRP. Detailed kinetic analysis was also carried out for the Cu(0) initiated ATRP through modeling (Chapter 5).; Mechanistic and kinetic study helps to find the optimal conditions for new ATRP reactions. Two detailed examples are given in Chapter 6. The first example illustrates the identification the right conditions to prepare high molecular weight polyacrylonitrile via ARGET ATRP. The second example gives the analysis the mechanism and also seeks the appropriate conditions for synthesis of polyacrylamides using Cu(I) or Cu(0).