Metallopolymers for Conductors, Sensors and Nanocomposites
Final Report Abstract
The main topic of both projects was polyferrocenylsilanes, a metallopolymer which possesses iron, a transition-metal in a polymer main chain. This particularly interesting metallopolymer has potential application towards different subjects in nanoscience as a building block for bottom up approach. The first project focused on the synthesis and characterization of the relatively unexplored poly(ferrocenylmethylsilane) (PFMS), which turned out to behave very differently towards ROP compared to the dimethyl-substituted counterpart. Studying the mechanism during the anionic and photocontrolled ROP and the role of the Si-H group in PFMS and corresponding [1]methylsilaferrocenophane led to a better understanding of this system. PFMS prepared using n-BuLi as an initiator was shown to contain cyclic contaminants whose formation indicated the existence of backbiting reactions during polymer chain growth. On the other hand, photolytic ROP of [1]methylsilaferrocenophane using Na[C5H5] as an initiator led only to the formation of linear material but was not a living process due to side reactions between the initiator and the Si-H groups in the monomer [1]methylsilaferrocenophane. High resolution 1H and 13C NMR spectroscopic studies revealed that obtained PFMSs were all atactic, irrespective of the polymerization route utilized. The crystallization of the samples was investigated by wide-angle X-ray scattering (WAXS), which showed a reflection corresponding to a d-spacing of 6.32 Å, differential scanning calorimetry (DSC), which revealed melting endotherms in the range 106 – 139 °C, and by polarizing optical microscopy (POM). The second successfully completed project dealt with synthesis and self-assembly behavior of diblock copolymers containing a poly(ferrocenyldimethylsilane) block. Overcoming the encountered difficulties in the synthesis and purification of block copolymers, interesting self-assembly behavior in solution was observed. The design of branched cylindrical micelles by crystallization-driven selfassembly of poly(ferrocenyldimethylsilane) containing block copolymers was achieved by the growth of thinner-core cylindrical micelles at the termini of the thicker-core cylindrical micelle seeds. Diblock copolymer block lengths and ratios, solvent and temperature played a crucial role and by adjusting the parameters a control over the branched micelles growth could be achieved. The branched cylindrical micelles provide a promising scaffold for the fabrication of a variety of other branched nanomaterials.
Publications
- “Branched Cylindrical Micelles via Crystallization-Driven Self-Assembly”. Journal of the American Chemical Society, 2013, 135 (47), 17739–17742
Huibin Qiu, Van An Du, Mitchell A. Winnik and Ian Manners
- “Poly(ferrocenylmethylsilane): An Unsymmetrically Substituted, Atactic, but Semicrystalline Polymetallocene”. Macromolecules, 2013, 46 (12), 4742–4753
Van An Du and Ian Manners
