THEORETICAL STUDIES OF POLY(FERROCENYLSILANES): CHAIN CONFIGURATION AND SELF-ASSEMBLY

Abstract

<p> This thesis summarizes theoretical results of two projects on the investigation of a novel organometallic polymer, the polyferrocenylsilanes(PFS). The study is carried out in collaboration with the experimental groups of Prof. Manners and Prof. Winnik at the Department of Chemistry of University of Toronto. </p> <p> In the first project, a rotational isomeric state (RIS) model is applied to study the configurational statistics of an ideal polyferrocenyldimethylsilane (PFDMS) chain: Fc[Fe(C5H4)2SiMe2]nH (Fe= Fe(C5H5)(C5H4)). The necessary conformation energies are derived from the molecular mechanics study of oligomeric (n=1,2) models for PFDMS reported by O'Hare et al.(J. Am. Chem. Soc. 1996, 118, 7578). In particular, pseudoatom and pseudobonds are introduced to describe the RIS chain of PFDMS, consistent with the special molecular geometry of the repeating ferrocene and organosilane units. The mean square unperturbed dimensions ((r^2)0, (R^2g)0), the characteristic ratios Cn(C∞) and the temperature coefficients dln (r^2)0/dT of PFDMS are calculated. The results show that an ideal PFDMS chain has a relatively low value of Coo and fast convergence of Cn to C∞ with increasing n, indicating a high static flexibility of this type of transition metal-containing polymer. The previously unknown Kuhn length of PFDMS is obtained based on the calculated C∞ </p> <p> In the second project, by taking PFS-b-PDMS/alkane as a model system, general phase behaviours of the self-assembled micelles in dilute crystalline-coil copolymer solutions (solvents are selective for the coil blocks) are investigated. Three types of aggregates - lamellar, rodlike and tubular micelles are studied based on the existing experimental observations. The computation results reveal three types of phase diagrams, namely, lamella-tube-rod phase diagrams with or without a triple point and lamella-rod phase diagrams. It is shown that lamella-tube-rod morphological transitions can be induced by changing the coil/crystalline block ratio or the temperature. Possible improvement of the theory and the current challenges of studying PFS-b-PDMS self-assembly in alkane solvents for both theories and experiments are discussed. </p>