Mechanistic investigations of the addition polymerization of phosphaalkenes
Final Report Abstract
This project lead to the first isolable phosphorus-analogues of butadiene rubber and natural Latex. The isolation of poly(phosphabutadiene) with a mixture of the three expected polymerization-patterns (1,2-, 1,4- and 3,4-polymerization) was possible directly from the reaction mixture, due to the high polymerization potential of the monomer. Molecular weights up to Mn = 6,000 g∙mol^–1 and narrow Polydispersities have been observed. Lacking the potential for controllable polymerization also the isolable phosphaisoprene was prepared in a similar manner. Although presumably anionic initiated polymerization occurs with this precursor, leading to polymers with moderate molecular weights (Mn = 8,600 g∙mol^–1), it is possible to prepare the monomer in satisfactory yields with shorter reaction times. The controlled anionic polymerization of phosphaisoprene with BuLi results in the isolation of macromolecules identical to the one isolated from the reaction mixture. This polymer shows a predominant reaction pattern via the C=C double bond, whereas the presence of different microstructures cannot be ruled out completely. With the retention of the P=C double bond this is a rare example of macrostructures containing a phosphaalkene moiety. Importantly, the molecular weight can be controlled by the monomer to initiator ratio (10:1: Mn = 2,400 g∙mol^–1; 20:1: Mn = 4,200 g∙mol^–1). Further investigations of the reactivity of poly(phosphaisoprene) highlight their big potential as building blocks for gold nanoparticles. Complexation of an Au-core with the polymer via the phosphorus atom has been conducted resulting in high molecular weight macromolecules (Mn = 23,300 g∙mol^–1). This behavior could also be observed with the monomer unit. In conclusion these remarkable results paved the way for further investigations of these unique polymers with regard to crosslinking and preparation of active materials. Especially the present P=C moiety bares a high potential for ground-breaking macromolecules and materials.
Publications
- (2017) Polymerization of 1-Phosphaisoprene: Synthesis and Characterization of a Chemically Functional Phosphorus Version of Natural Rubber. Angewandte Chemie (International ed. in English) 56 (32) 9507–9511
Dück, Klaus; Rawe, Benjamin W.; Scott, Michael R.; Gates, Derek P.
(See online at https://doi.org/10.1002/anie.201703590) - Main-Chain, Phosphorus-Based Polymers. In: Baumgartner, Thomas; Jäkle, Frieder (Hg.) (2017): Main Group Strategies towards Functional Hybrid Materials. Chichester, UK: John Wiley & Sons, Ltd., 2017. S. 329–355
K. Dück, D. P. Gates
(See online at https://doi.org/10.1002/9781119235941.ch13)
