Jason A. Massey

Rhodium‐katalysierte Bildung von Phosphor‐Bor‐Bindungen: Synthese des ersten Poly(phosphanylborans) mit hoher Molekülmasse

EinanorganischesAnalogondesPolystyrols ist Poly(phenylphosphanylboran), und es ist das erste gut charakterisierte Polymer mit hoher Molekulmasse, das ein Ruckgrat aus alternierenden Phosphor- und Boratomen enthalt. Es ist uber die metallkatalysierte „Dehydrokupplung” eines primaren Phosphan-Boran-Addukts zuganglich (siehe Schema).

Supramolecular Organometallic Polymer Chemistry: Multiple Morphologies and Superstructures from the Solution Self‐Assembly of Polyferrocene‐block‐Polysiloxane‐block‐Polyferrocene Triblock Copolymers

The solution self-assembly of an organometallic-inorganic triblock copolymer, poly(ferrocenyldimethylsilane)-block-poly(dimethylsiloxane)-block-poly-(ferrocenyldimethylsilane) (PFDMS-b-PDMS-b-PFDMS, 3b; block ratio 1:13:1; Mn = 2.88 x 10(4) gmol(-1), polydispersity (PDI) 1.43 (gel permeation chromatography, GPC)) was studied in n-hexane, a PDMS block selective solvent. Transmission electron microscopy (TEM), atomic force microscopy (AFM), and TEM with negative staining analysis of these micellar solutions after solvent evaporation revealed the presence of multiple micellar morphologies including spheres, cylinders, and novel flower-like supramolecular aggregates. TEM analysis of samples fractionated by ultracentrifugation and preparative size-exclusion chromatography suggest that the formation of multiple morphologies is a consequence of compositional variations. When micellar solutions were prepared at 50 degrees C (above the glass transition of the PFDMS core-forming block) flower-like micellar aggregates similar to those present in micellar solutions prepared at room temperature also formed. However, after solvent evaporation, TEM analysis of micellar solutions prepared in decane at about 150 degrees C, above the melt temperature of the PFDMS core (ca. 120-145 degrees C), revealed the presence of spherical micelles (when decane solutions at 150 degrees C were rapidly cooled to room temperature) and rod-like cylindrical micelles (when decane solutions at 150 degrees C were slowly cooled to room temperature). In contrast, poly(ferrocenylmethylethylsilane)block-poly(dimethylsiloxane)-block-poly(ferrocenylmethylethylsilane) (PFMES-b-PDMS-b-PFMES, 4; block ratio 1:16:1; Mn=2.90x10(4)g mol(-1), PDI= 1.42 (GPC)) and poly(ferrocenylmethylphenylsilane)-block-poly(dimethylsiloxane)-block-poly(ferrocenylmethylphenylsilane) (PFMPS-b-PDMS-b-PFMPS, 5; block ratio 1:15:1; Mn=3.00 x 10(4) gmol(-1), PDI = 1.38 (GPC)), which possess completely amorphous organometallic core-forming blocks, formed only spherical micelles in hexane at room temperature. These observations indicate that crystallinity of the insoluble polyferrocenylsilane block is a critical factor in the formation of the nonspherical micelle morphologies.

Solution characterization of the novel organometallic polymer poly(ferrocenyldimethylsilane)

A series of four well-defined poly(ferrocenyldimethylsilane) (PFS) samples spanning a molecular weight range of approximately 10,000–100,000 g mol−1 was synthesized by the living anionic polymerization of dimethyl[1]silaferrocenophane initiated with n-BuLi. The polymers possessed narrow polydispersities and were used to characterize the solution behavior of PFS in tetrahydrofuran (THF). The weight-average molecular weights (Mw ) of the polymers were determined by low-angle laser light scattering (LALLS), conventional gel permeation chromatography (GPC), and GPC equipped with a triple detector (refractive index, light scattering, and viscosity). The molecular weight calculated by conventional GPC, with polystyrene standards, underestimated the true value in comparison with LALLS and GPC with the triple detection system. The Mark–Houwink parameter a for PFS in THF was 0.62 (k = 2.5 × 10−4), which is indicative of fairly marginal polymer–solvent interactions. The scaling exponent between the radius of gyration and Mw was 0.54, also consistent with marginal polymer–solvent interactions for PFS in THF.

Supramolecular Organometallic Polymer Chemistry: Self-Assembly of a Novel Poly(ferrocene)-b-polysiloxane-b-poly(ferrocene) Triblock Copolymer in Solution.

Micelles with unprecedented flowerlike arrangements of the poly(ferrocene) cores (shown in the TEM image) are among the supramolecular architectures generated in the self-assembly of a novel organometallic triblock copolymer from silicon-bridged [1]ferrocenophane monomers and [Me(2)SiO](3) in hexane, a solvent selective for the central polysiloxane block.

Living Anionic Ring-Opening Polymerization of Unsymmetrically Substituted Silicon-Bridged [1]Ferrocenophanes; A Route to Organometallic Block Copolymers with Amorphous Poly(ferrocenylsilane) Blocks

Living anionic ring-opening polymerization methodology for silicon-bridged [1]ferrocenophanes has been extended to unsymmetrically substituted monomers. This permits access to well-defined amorphous poly(ferrocene) homopolymers and organometallic block copolymers, such as polystyrene-b-poly(ferrocenylmethylphenylsilane), with an amorphous poly(ferrocenylsilane) block. This allows phase separation to occur at lower temperatures, which should facilitate applications in which organometallic nanodomains are desirable.

Supramolekulare metallorganische Polymerchemie: Selbstorganisation des neuartigen Dreiblockcopolymers Poly(ferrocen)‐b‐polysiloxan‐b‐poly(ferrocen) in Lösung

Micellen mit blutenformigen Anordnungen der Poly(ferrocen)-Kerne (siehe TEM-Aufnahme) sind nur eines der supramolekularen Gebilde, die bei der Selbstorganisation der Titelverbindung in Hexan, einem fur den zentralen Polysiloxanblock selektiven Losungsmittel, entstehen. Das metallorganische Dreiblockcopolymer wurde aus siliciumverbruckten [1]Ferrocenophanmonomeren und [Me2SiO]3 erhalten.

Living anionic polymerization of phosphorus-bridged, [1]ferrocenophanes: synthesis and characterization of poly(ferrocenylphosphine) homopolymers and block copolymers

The phosphorus-bridged [1]ferrocenophane Fe(η-C5H4)2-PPh undergoes living anionic ring-opening polymerization at 25 °C in THF using BunLi as initiator to yield monodisperse poly(ferrocenylphosphines) of controlled molecular mass and novel block copolymers with potentially coordinating phosphorus atoms in one segment.

Synthesis and Ring-Opening Polymerization (ROP) of Strained Phosphorus-Containing Rings

Studies of inorganic and organometallic rings containing phosphorus are described. Novel skeletal substitution reactions are reported for B-N-P heterocycles and cyclic thionylphosphazenes are found to undergo ambient temperature ROP in the presence of GaCl3. The phosphorus-bridged [1]ferrocenophane Fe(η-C5H4)2PPh undergoes living anionic polymerization. This provides access to block copolymers such as poly(ferrocenylphosphine)-poly(dimethylsiloxane) which dissolve in hexanes to yield interesting micellar aggregates with organometallic cores.