Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Particulate matter
Reexamination Certificate
2001-10-05
2003-09-30
Kiliman, Leszek (Department: 1773)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Particulate matter
C428S405000, C428S407000, C526S111000, C526S135000, C526S145000, C526S146000, C526S147000, C528S010000, C528S041000
Reexamination Certificate
active
06627314
ABSTRACT:
FIELD OF INVENTION
The invention is directed towards the preparation of nanocomposite particles and structures. A nanocomposite particle and structure may comprise a core and a grafted or tethered polymer. The nanocomposites may be formed by polymerizing monomers onto a functional inorganic colloid comprising a polymerization initiation site. The polymerization process is preferably a controlled/living polymerization process, including but not limited to, atom transfer radical polymerization and stable free radical polymerization. The nanocomposite particles can self-organize in solution, on surfaces or in films forming nanocomposite structures. Tethered AB block nanocomposite particles bring size control, solubility control and control over micro- and macro-functionality to the particles.
BACKGROUND OF THE INVENTION
There is a continuing effort in polymer chemistry to develop new polymer processes and new polymers. A relatively recent development in polymer chemistry has been the development of controlled or living polymerization processes. A controlled or living polymerization process is one in which chain transfer and termination reaction are essentially nonexistent relative to the polymer propagation reaction. These developments have led to the production of polymers that exhibit macro functionality and to the development of functional polymers that possess specific chemical reactivity. The new polymers extend the level of control available to materials engineers in processing polymers and using polymers as building blocks in, or components for, subsequent material forming reactions, such as copolymerizations, chain extensions and crosslinking reactions, and interaction with substrates, including dispersed solids.
A significant economic hurdle which continually needs to be overcome in this effort is to provide the benefits of controlled polymerization from available low cost monomers in available commercial process equipment. These long term objectives have provided the backdrop, or driving force, for the continuing advances in controlled polymerization of radically (co)polymerizable monomers, disclosed in earlier patent applications, and provide the incentive to extend, simplify and make more robust the process known as atom transfer radical polymerization (ATRP).
The recently developed and polymers developed from the classic ATRP reaction are described in U.S. patent applications Ser. Nos. 09/018,554 now U.S. Pat. No. 6,538,051 and 09/534,827 now abandoned, the entire contents of which are hereby incorporated herein by reference. Methods for exercising control over many parameters in a catalytic process for the controlled polymerization of a wide range of free radically (co)polymerizable monomers have been described in publications authored or co-authored by Krzysztof Matyjaszewski and others. See for example, Wang, J. S. and Matyjaszewsk, K.,
J. Am. Chem. Soc.,
vol. 117, p.5614 (1995); Wang, J. S. and Matyjaszewsk, K.,
Macromolecules,
vol. 28, p. 7901 (1995); K. Matyjaszewski et al.,
Science,
vol. 272, p.866 (1996); K. Matyjaszewski et al., “Zerovalent Metals in Controlled/“living” Radical Polymerization,”
Macromolecules,
vol. 30, pp. 7348-7350 (1997); J. Xia and K. Matyjaszewski, “Controlled/“Living” Radical Polymerization. Homogenous Reverse Atom Transfer Radical Polymerization Using AIBN as the Initiator,”
Macromolecules,
vol. 30, pp. 7692-7696 (1997); U.S. patent application Ser. No. 09/126,768, now U.S. Pat. No. 6,121,371 the entire contents of which are hereby incorporated by reference; U.S. Pat. Nos. 5,807,937, 5,789,487, 5,910,549, 5,763,548, and 5,789,489, the entire contents of each are hereby incorporated herein by reference. The subtle interactions between the parameters have been further explored and implementation of the teachings disclosed in these publications has allowed the preparation of many inherently useful novel materials displaying control over functionality and topology, and production of novel tele-functional building blocks for further material forming reactions, resulting from application of the site specific functional and topological control attainable through this robust controlled polymerization process for free radically (co)polymerizable monomers.
The system or process employed to gain control over the polymerization of free radically (co)polymerizable monomers has been described in earlier applications as comprising the use of four components: (i) an initiator molecule; (ii) a transition metal compound having (iii) an added or associated counterion and the transition metal compound complexed with (iv) a ligand(s). The initiator molecule, or polymerization originator molecule may be any molecule comprising one or more radically transferable atom(s) or group(s) capable of participating in a reversible redox reaction with the transition metal compound. The transition metal compound may include an added or associated counterion and comprise a transition metal salt. So that all reactive oxidation states are soluble to some extent in the reaction medium, the transition metal may be complexed with the ligand(s). The components of the system may be optimized to provide more precise control for the (co)polymerization of the free radically polymerizable monomers. See U.S. Pat. No. 5,763,548, the entire contents of which are hereby incorporated herein by reference.
In an embodiment known as “reverse” ATRP, the initiator molecule described above can be formed in-situ by reaction of a free radical with the redox conjugate of the transition metal compound. Other components of the polymerization system such as the choice of the radically transferable atom or group, counterion initially present on the transition metal, and optional solvent may influence the process. U.S. Pat. No. 5,807,937 provides as an example of a single molecule containing a combination of functions, a complex in which the counterion and ligand components are in one molecule. The role of a deactivator, the “persistent radical,” or for ATRP, the transition metal redox conjugate, is also described in U.S. Pat. No. 5,807,937.
While not to be limited to the following description, the theory behind ATRP disclosed in the previous work is that polymerization proceeds essentially by cleavage (and preferably essentially homolytic cleavage) of the radically transferable atom or group from the initiator molecule or, during the polymerization process the dormant polymer chain end, by a reversible redox reaction with a complexed transition metal catalyst, without any strong carbon-transition (C—M
t
) bond formation between the active growing polymer chain end and the transition metal complex. Within this theory as the transition metal complex, in a lower active oxidation state, or in its activator state, activates the initiator or dormant polymer chain end by homolytically removing the radically transferable atom or group from the initiating molecule, or growing polymer chain end, in a reversible redox reaction, an active species is formed that allows other chemistry, essentially free radical based chemistry to be conducted. The transition metal complex in the higher oxidation state, the redox conjugate state or deactivator state, transfers a radically transferable atom or group to the active initiator molecule or growing chain end, thereby reforming the lower oxidation state transition metal complex. When free radical based chemistry occurs, a new molecule comprising a radically transferable atom or group is also formed. In prior publications, the catalytically active transition metal compound, which can be formed in situ or added as a preformed complex, has been described as containing a range of counterions. The counterion(s) may be the same as the radically transferable atom or group present on the initiator, for example a halide such as chlorine or bromine, or may be different radically transferable atoms or groups. An example of the latter counterion is a chloride counterion on the transition metal compound when the initiator first contains a bromine. Such a combination allows
Matyjaszewski Krzysztof
Pyun Jeffrey
Carnegie Mellon University
Kiliman Leszek
Kirkpatrick & Lockhart LLP
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