Nitroxide-Mediated Controlled Free Radical Polymerization of the Chelate Monomer 4-Styryl-tris(2-pyridyl)borate (StTpyb) and Supramolecular Assembly via Metal Complexation

Abstract

The reaction of 4-(dibromoboryl)styrene with 2pyridylmagnesium chloride resulted in the formation of 4-styryltris(2-pyridyl)borate free acid (StTypb), a new polymerizable nonpyrazolyl "scorpionate" ligand. StTypb did not undergo selfinitiated polymerization under ambient conditions and proved to slowly polymerize through standard radical polymerization at 90 °C. Nitroxide-mediated polymerization (NMP) of StTypb at 135 °C proceeded with good control, resulting in a polymer of M n = 27400 and PDI = 1.21. The TEMPO-terminated homopolymer successfully initiated the polymerization of styrene, generating an amphiphilic block copolymer with DP n of 1200 and 78 for the PS and the StTypb block, respectively. A similar block copolymer with DP n of 29 and 20 for the PS and the StTypb block respectively was obtained in a reverse polymerization procedure from a PS macroinitiator. The self-assembly of these block copolymers was examined in selective solvents and preliminary metal complexation studies were performed.

Temperature‐induced self‐assembly and metal‐ion stabilization of histidine functional block copolymers

“…Liu et al have made ruthenium core crosslinked metal‐ion micelles, as well as some magnetic metal‐containing micelles . Jäkle has done nice supramolecular self‐assembly work using metal‐ion coordination of polymer‐supported tris(2‐pyridyl)borates; however, it is not demonstrated to be reversible and the structures are micrometer‐sized . Zhuo et al stabilized micelles using metal‐ion coordination of PEI with both copper and ruthenium and used these to synthesized Pt nanoparticles .…”

“…39,40 Jäkle has done nice supramolecular self-assembly work using metal-ion coordination of polymersupported tris(2-pyridyl)borates; however, it is not demonstrated to be reversible and the structures are micrometer-sized. 41 Zhuo et al stabilized micelles using metal-ion coordination of PEI with both copper and ruthenium and used these to synthesized Pt nanoparticles. 42,43 The incorporation of histidine as an important natural ligand for metal-ion coordination into a block copolymer self-assembly is an exciting way to add some dynamic chemistry to the reversible locking of selfassemblies in the corona.…”

Recent Advances in the Synthesis and Applications of Organoborane Polymers

“…The NMP method was utilized in the block copolymerization of tris(2-pyridyl)borate ligand-functionalized styrene (see Sect. 3.4) [54]. Alternative approaches include Ziegler-Natta [55,56] and ring-opening metathesis polymerization (ROMP) of borane monomers [57].…”

“…Tpyb ligands are more robust than the Tp ligands, allowing for direct polymerization of the styryl derivative 66 by NMP (Fig. 21b) [54]. The block copolymer 67 was generated by sequential polymerization and its nanostructures and metal complexation were studied.…”

“…22a) are isoelectronic to ammonium functionalities. They were introduced by simple "click"-like reaction of the corresponding bromoboranea b [54]. Copyright 2013 American Chemical Society functionalized polymers with 2,2 0 -bipyridine.…”