Water-soluble building blocks for terpyridine-containing supramolecular polymers : synthesis, complexation, and pH stability studies of poly(ethylene oxide) moieties

Poly(ethylene oxide) of various molecular weights ([bar M ]n = 3 000, 5 200, 10 000, 16 500 g · mol-1) has been modified with terpyridine end groups as building blocks for water-soluble metallo-supramolecular polymers. Metallo-supramolecular A-A homopolymers have been prepared and characterized by complexing the terpyridine units of one selected poly(ethylene oxide) ([bar M ]n = 3 000 g · mol-1) with the following transition metal ions in their 2+ oxidation state: Fe, Ru, Co, Ni, Cu, Zn, and Cd. In addition, the stability of the supramolecular connection with respect to pH variations has been investigated

From supramolecular block copolymers to advanced nano-objects

The formation of asymmetric bis-complexes, based on terpyridine ligands and ruthenium ions, is described as a powerful tool for the self-assembly of polymer blocks end-functionalized with terpyridine units. This is illustrated in this contribution for the synthesis of amphiphilic metallo-supramolecular block copolymers, which are further used to produce aqueous micelles. Finally, the reversibility of the supramolecular bond opens new avenues for the preparation and manipulation of these nano-objects

Reversible metallo-supramolecular block copolymer micelles containing a soft core

An amphiphilic metallo-supramol. poly(ethylene-co-butylene)-block-poly(ethylene oxide) diblock copolymer contg. a bis(2,2':6',2''-terpyridine)ruthenium(II) complex as a supramol. connection between the two constituting blocks was used to prep. stable aq. micelles. The micelles were characterized by dynamic light scattering and at. force microscopy. Individual micelles were obsd. together with aggregates of micelles. Only the addn. of a large excess of competitive ligand caused the cleavage of the very stable ruthenium comple

Analytical ultracentrifugation studies on terpyridine-end-functionalized poly(ethylene oxide) and polystyrene systems complexed via Ru(II) ions

In this paper we study the solution properties of several metallo-supramolecular assemblies containing polystyrene (PS) and poly(ethylene oxide) (PEO) blocks linked via Ru2+ ions: PS20–[Ru2+]–PEO70, PS20–[Ru2+]–PS20, and PEO225–[Ru2+]–PEO225. Sedimentation equilibrium measurements were performed to determine the molar mass distribution and state of association, and the sedimentation velocity measurements were used to obtain the molar mass distribution, sedimentation coefficient distribution, their average values, and average diffusion coefficient. The results obtained from the two types of experiments are compared and discussed. Association - Analytical ultracentrifugation - Assemblies - Metallo-supramolecular - Molar mass - Sedimentatio

Application of (automated) atomic force microscopy to combinatorial polymer materials research

Scanning probe microscopy was combined with combinatorial techniques to study of the morphol. of polymer blends and metallo-supramol. block copolymer libraries. Morphol. and cond. measurements of carbon black / poly(dimethylsiloxane) composites demonstrated the relation between sample prepn., morphol., and material properties. Phase sepn. was studied of a metallo-supramol. block copolymer library based on terpyridine-functionalized polystyrene - Ru terpyridine - poly(ethylene oxide) block copolymer. By varying the block length of the polyoxyalkylene blocks and their vol. ratio, the whole range of thin film morphologies were obsd., from lamellar to spherical phase sepn

Melt morphology of polystyrene-poly(ethylene oxide) metallo-supramolecular diblock copolymer

Using SAXS, the melt morphol. of a polystyrene-poly(ethylene oxide) metallo-supramol. diblock copolymer, which is prepd. by coupling terpyridine-terminated polyethylene oxide and terpyridine-terminated polystyrene with RuCl3, is studied, and the presence of the the metal-ligand complex (MLC) in the mol. chain leads to a different morphol. and drives the mol. to form spherical aggregates. The aggregate has a core radius of 1.5 nm surrounded by a polymer shell with an out radius of approx. 2.4 nm, and the size of the aggregate decreases with temp. and affects by the crystn. of the polyethylene oxide block. [on SciFinder (R)

Structure-property study of diblock copolymer micelles: Core and corona radius with varying composition and degree of polymerization

The synthesis and characterization of well-defined poly((styrene-alt-diphenylethylene)-bisoprene) diblock copolymers via sequential anionic polymerization are discussed. Indeed, modified 1,1-diphenylethylene commodity elastomers have appeared recently as an alternative to the well-known elastomers for high-temperature applications. The obtained materials were used for the preparation of block copolymer micelles. The hydrodynamic radius of the micelles in solution was determined by dynamic light scattering and the size of the core by atomic force microscopy at dry conditions. It was found that the observed characteristics of the studied micelles correlate to theoretical scaling predictions. Moreover, the average size of the unimers could be determined with high precision from the obtained experimental data and theoretical knowledge

Dynamic light scattering and cryogenic transmission electron microscopy investigations on metallo-supramolecular aqueous micelles: evidence of secondary aggregation

Metallo-supramolecular diblock copolymers consisting of a polystyrene (PS) block connected to a poly(ethylene oxide) (PEO) block by a bis(terpyridine)ruthenium complex (PS20-[Ru]-PEOy) were used to prepare aqueous micelles. The length of the PS block was kept constant, while two PEOs of different molecular weight were used. The resulting hydrated micelles and aggregates were characterized by a combination of cryogenic transmission electron microscopy (cryo-TEM) and dynamic light scattering measurements. The results were compared to those obtained for a covalent counterpart (PS22-b-PEO70). Cryogenic transmission electron microscopy allowed visualization of the PS core of the micelles. Moreover, the aggregates result from clustering of individual micelles

Iridium(III) complexes with PEO and PS polymer macroligands and light-emitting properties : synthesis and characterization

On the basis of terpyridine functionalized poly(ethylene oxide) (PEO) and poly(styrene) (PS), a series of light-emitting iridium(III) compounds was effectively synthesized. The respective iridium(III) target compounds were prepared by grafting chloro-bridged precursor complexes [Ir(ppy)2--Cl]2 (ppy = phenylpyridine) and [Ir(ppy-CHO)2--Cl]2 (ppy-CHO = 4-(2-pyridyl)benzaldehyde) onto terpyridine functionalized PEO and PS tails. 1D and 2D NMR characterization was performed revealing the expected resonances. Gel permeation chromatography (GPC) proved the stability and purity of the targeted materials. Preliminary investigations of the light-emitting properties were carried out by standard methods such as UV-vis and steady-state luminescence spectroscopy. The morphology and the quality of films of these iridium(III) compounds were furthermore investigated using AFM. Improved stability on the electrode surface was illustrated using cyclic voltammetry. One of the polymer materials was compared to the neat complex, which showed quick degradation