Nanocomposites of dendritic polymers

Details Nanocomposites of dendritic polymers Nanocomposites of dendritic polymers

2001-02-10

2003-12-16

Yoon, Tae H. (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C523S205000, C524S504000, C528S480000

Reexamination Certificate

active

06664315

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to the formation of novel nanocomposites between dendritic polymers and a variety of materials.
BACKGROUND OF THE INVENTION
The literature describes the formation of nanoparticles in various classical polymers, such as organization and immobilization of metal compounds in linear, branched and crosslinked polymers. In particular, the literature describes immobilization of metals, metal ions, and metal sulfides using ionomers, and block copolymers.
Rules of complex formation are well known in physical chemistry as a consequence of more than fifty years of extensive research. Formation of such complexes may occur on the surface of dendritic polymers or in their interior. These phenomena have been described in many publications.
Preparation and analysis, physics and chemistry of nanosized materials is described for instance in the series of books of Kluver Academics On The Physics and Chemistry Of Materials With Low-Dimension Structures, such as “Physics and Chemistry Of Metal Cluster Compounds” edited by L. J. De Jongh, Kluver Academic, Dordrecht/Boston/London, 1994, and references thereof. A general drawback of the presently used methods of preparing nanosized materials is that they either require sophisticated and expensive instrumentation or tedious and extensive preparation and purification processes. Simple preparation of transiently stabilized nanosized materials in solution is possible by employing a combination of small organic ligands and amphophilic molecules. However, these clusters lack long-term stability. Also, a general disadvantage with known methods of preparing nanosized materials is that the size and size distribution of the resulting nanoparticles obey statistical rules. As a result, preparation of nanoparticles with a narrow size distribution requires tedious purification procedures.
J. U. Yue et al. have reported, in
J. Am. Chem. Soc.
1993, 115, 4409-4410, a technique for preparing nanosized materials involving synthesis of zinc fluoride in poly(2,3-trans-bis-tert-butylanildimethyl-norborn-5-ene) domains within polymethyltetracyclododecene matrices, and interconversion of the zinc fluoride clusters to zinc sulfide. Yue et al. concluded that the disclosed method demonstrated a general approach for carrying out a chemical reaction within a nanoscale region of a block copolymer, and speculated that different kinds of clusters can be synthesized from a given starting material. Yue et al. hypothesized that lead sulfide and cadmium sulfide clusters can be prepared using the general approach disclosed, and reported that this same approach has been used to generate zinc sulfide quantum clusters which are superior in quality to zinc sulfide clusters generated using other techniques.
Martin Moller reported in
Synthetic Metals,
1991, 41-43, 1159-1162, the synthesis of nanosized inorganic crystallites or clusters of cadmium sulfide, cobalt sulfide, nickel sulfide and zinc sulfide prepared from functionalized diblock copolymers of polystyrene and poly-2-vinylpyridine. The diblock copolymers were prepared with narrow molecular weight distributions by sequential anionic polymerization. Films were prepared by solvent evaporation with metal salts of copper, cadmium, cobalt, nickel, zinc and silver. The films were subsequently treated with gaseous hydrogen sulfide to form the corresponding metal sulfides.
W. Mahler, in
Inorganic Chemistry,
1988, 27(3), 435-436, reported the preparation of polymer-trapped semiconductor particles by milling an ethylene-methacrylic acid copolymer with a metal acetate or acetylacetonate at an elevated temperature (160° C.) to form a neutralized ionomer.
T. Douglas et al. have reported in
Science
, Jul. 7, 1995 Vol. 269, 54-57, the synthesis of amorphous iron sulfide minerals containing either 500 or 3000 iron atoms in each cluster. The synthesis was achieved within the nanodimensional cavity of horse spleen ferritin. The report indicates that the reaction of acidic (pH 5.4) sulfide solutions within ferritin results in the in situ nanoscale synthesis of protein encapsulated iron sulfides. Douglas et al. speculated that such bioinorganic nanoparticles might be useful as biological sensors and markers, drug carriers, and diagnostic and radioactive agents. More specifically, magnetoferritin has shown potential as a contrast agent for magnetic resonance imaging of tissue and uranium oxide-loaded ferritin could have use in neutron-capture therapy. Douglas et al. have also suggested that nanodimensional metal sulfides could be useful in the preparation of semiconductors which could be of technological, and perhaps biological importance.
Y. Wang et al have reported in
J. Chem. Phys.,
1987 87(12), 7315-7322, December 15, the preparation of nanodimensional lead sulfide clusters in ethylene-methacrylic acid copolymers by exchanging Pb
2+
into the polymer film and then reacting the resulting lead-resin complex with hydrogen sulfide.
J. P. Kuczynski et al. have reported in
J. Phys. Chem.,
1984, 88, 980-984, the synthesis of cadmium sulfide in a Nafion polymer film. Small cadmium sulfide crystalline particles were reported to exhibit properties similar to those of cadmium sulfide single crystals.
M. Krishnan et al. have reported in
J. Am. Chem. Soc.,
1983, 105, No. 23, 7002-7003, a method of incorporating a dispersed semiconductor (CdS) throughout an ionically conductive polymer membrane (Nafion), in which a suitable redox couple and catalyst can be added to promote photocatalytic reactions on the membranes. The pre-treated membrane was immersed in a solution of Cd
2+
(pH=1) to incorporate Cd
2+
in the membrane by ion exchange. Subsequent exposure of the membrane to hydrogen sulfide produced spherical cadmium sulfide particles of a diameter of one micrometer or smaller. A cationic redox agent, such as methylviologen (MV
2+
), can be incorporated into the membrane. Kishnan et al. also reported that platinum can be incorporated into the CdS/MV
2+
membrane system, and have speculated that by employing an analogous technique, incorporation of other semiconductors, such as titanium oxide and zinc sulfide, should be possible.
Albert W-H Mau et al. have reported in
J. Am. Chem. Soc.,
1984, 106, No. 22, 6335-6542, that hydrogen-production efficiencies from water in photocatalytic reactions at cadmium sulfide crystallites embedded in a polymer (Nafion) matrix containing a hydrogen evolution catalyst (Pt) were greater than those observed with unsupported colloidal or powdered semiconductors under similar conditions.
Y. Ng Cheong Chan et al have reported, in
Chem. Mater.
1992, 4, 885-894, methods for forming metal clusters that are less than 100 Angstroms in diameter, that have a narrow size distribution, and that are dispersed evenly throughout a nonconductive polymer matrix. These methods involve reduction of metal complexes and aggregation of metal atoms in the solid state, either in an organometallic homopolymer or in an organometallic block of a microphase-separated diblock copolymer. Chan et al. suggest that such compositions might exhibit discernable catalytic properties.
In
J. Am. Chem Soc.
1992, 114, 7295-7296, Chan et al. reported the synthesis of single silver nanoclusters evenly dispersed within spherical microdomains of block copolymer films.
Sung Soon Im et al. reported, in
J. Appl. Polym. Sci.,
1992, 45, 827-836, the preparation of metallic sulfide and polyacrylonitril (PAN) film composites which exhibit improved electrical conductivity. The composites were prepared by a chelating method in which PAN films were treated with ammonium hydroxide solution to induce amidoxime groups which were coordinated with Cu
2+
and Cd
2+
absorbed to the amidoximated PAN films and subsequently treated with hydrogen sulfide gas to form CuS-PAN and CdS-PAN composite films.
M. Francesca Ottaviani et al. reported in
J. Am. Chem. Soc.
1994, 116, 661-671, the preparation and characterization of Cu
2+
complexes formed with anionic polyamidoamine (PAMAM) Starb

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