Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-05-01
2003-07-15
Egwim, Kelechi (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S430000, C524S458000, C524S612000, C524S803000, C525S348000, C525S375000, C525S385000, C525S411000, C525S412000, C525S415000, C526S073000, C526S075000, C526S256000, C526S258000, C526S265000, C526S270000
Reexamination Certificate
active
06593399
ABSTRACT:
The present invention relates to a method for preparing intrinsically conductive copolymers (ICPs) from polymerizing at least one cyclic heteroatom-containing monomer such as aniline, thiophene, pyrrole, furan, and the derivatives or substituted forms of the respective monomers and an emulsion latex which remains substantially stable in the presence of the cyclic heteroatom-containing monomers and during the course of the polymerization. This invention further relates to the compositions of the intrinsically conductive copolymers prepared in accordance with the method. In addition, the invention also relates to a method of preparing blends of ICPs with carbonaceous materials, metal oxide powders and polar polymers.
ICPs are known to be useful for a number of applications. For instance, ICPs maybe used as part of a coating formulation for inhibiting corrosions of metals, particularly iron or iron based metals such as carbon steel and different types of stainless steel, aluminum, aluminum alloys, nickel and others.
It is known that a number of cyclic heteroatom (O, S, and N)-containing monomers such as aniline, furan, pyrrole, thiophene and their derivatives can be polymerized to yield ICPs. Most of such polymer products are known to be intractable. Typical ICPs do not have very high solubilities in commonly used solvents, and they are usually thermally unstable, infusible and brittle. As a result, most ICPs cannot be processed easily by conventional methods used for processing other polymers. Attempts to solve the processing problems over the past several years produced only limited success. As a result, many predictions that these conductive polymers would usher in novel products such as polymer batteries, electrical wires, or capacitors have largely not been realized.
Polyaniline is an example. It is commonly prepared by an oxidative polymerization of aniline in the presence of a protonic acid. The polymer product is an insoluble green solid precipitate, mostly amorphous and generally insoluble in common organic solvents (see Annis et al.,
Synthetic Metals,
22:191, 1986). U.S. Pat. No. 5,232,631 describes a number of polyaniline salts prepared by reacting polyaniline in the presence of an acid such as dodecylbenzene sulfonic acid, 1,5-naphthalenedisulfonic acid and p-toluene sulfonic acid. These polyaniline salts are only sparingly soluble in nonpolar solvents. U.S. Pat. No.5,232,631 and U.S. Pat. No. 5,324,453 describe the synthesis of polyaniline from a mixture which consists of an aniline monomer, a protonic acid, an oxidant, a polar liquid such as water and a nonpolar or weakly polar liquid chosen from chloroform, xylene, toluene, decahydronaphthalene and 1,2,4-trichlorobenzene. In such a process, post-polymerization removal of residual organic solvents in the polymer products to an acceptable level may pose a substantial challenge to a prospective manufacturer.
The present invention relates to a (co)polymerization method which overcomes many of the difficulties encountered in the prior art and/or provides improvements to the chemical, physical, or mechanical properties of the resultant ICPs which are prepared from at least one cyclic heteroatom-containing monomer.
The present invention also relates to a method for preparing an intrinsically conductive copolymer comprising: preparing an emulsion latex in a medium; forming a mixture by adding at least one cyclic heteroatom-containing monomer to the emulsion latex in the medium under first condition effective to maintain the emulsion latex in a first stabilized emulsion state; causing the monomer(s) in the mixture to polymerize under a second condition effective to produce the conductive copolymer in a second stabilized emulsion state; and optionally, recovering the intrinsically conductive copolymer.
The present invention further relates to a method, wherein the cyclic heteroatom-containing monomer is selected from the group consisting of aniline, substituted anilines, thiophene, substituted thiophenes, furan, substituted furans, pyrrole, substituted pyrroles, and mixtures thereof.
Another embodiment of the present invention relates to an intrinsically conductive copolymer composition prepared by the invented method. The present invention further relates to different methods of using the ICPs in coating formulations with an option of providing a top-coating over the layer containing the ICPs. More specifically, the present invention relates to a method of using the intrinsically conductive copolymer prepared according to claim 1 or 9, the method comprises preparing a coating composition which comprises the intrinsically conductive copolymer; and applying the coating composition on a surface of a metal to form a first layer, optionally applying a top coat layer over the first layer.
It has been discovered unexpectedly that ICPs can be prepared chemically, electrolytically or electrochemically by emulsion polymerization and/or copolymerization and/or graft copolymerization of at least one cyclic heteroatom-containing monomer in the presence of a stable latex emulsion under conditions effective to maintain such stabilized emulsion conditions in one, two- or multi-stages. Examples of a suitable heteroatom include O, N, and S. More than one heteroatoms may be present in the same cyclic heteroatom-containing monomer or in the ICP itself from different monomers incorporated into the ICP. For the present invention, the resultant ICP product should have an intrinsic conductivity equal to or greater than 5×10
−4
Siemens per centimeter, preferably greater than 5×10
−2
Siemens per centimeter, more preferably greater than 1 Siemens per centimeter. It is also within the scope of the present invention that the conductivity is increased by doping with a suitable dopant.
Cyclic heteroatom-containing monomers suitable for use to be (co)polymerized in the present invention include, but are not necessarily limited to aniline, thiophene, pyrrole, furan, substituted anilines, substituted thiophenes, substituted pyrroles, substituted furans, and mixtures thereof. They are of the following generalized structures.
wherein q, r, s, t, w, x, y, and z are independently selected from positive integers and 0(zero); y+z=5; q+r=4; s+t=4; and w+x=4; R
1
and R
5
, are independently selected from the group consisting of H and C
1
to C
18
linear or branched alkyl groups, H and CH
3
are preferred; R
2
, R
3
, R
4
, and R
6
are independently selected from H, C
1
to C
18
linear or branched alkyl groups, aryl groups such as phenyl or substituted phenyls, a benzo group (occupying two adjacent sites on the ring), C(═O)OH, C(═O)H, CH
2
OH, CH
2
OC(═O)R
7
where R
7
is selected from C
1
to C
6
linear or branched alkyl groups, CH
2
CH
2
OH, CH
2
SH, CN, CH
2
NH
2
, C(═O)NH
2
, CH
2
CN, O—R
8
where R
8
is selected from C
1
to C
6
linear or branched alkyl groups, C(═O)R
9
where R
9
is selected from C
1
to C
6
linear alkyl groups, and mixtures thereof. To the extent that it discloses such polymerizable heteroatom-containing cyclic monomers, U.S. Pat. No.5,648,416 is incorporated herein by reference. Many of these compounds can be purchased from Aldrich Chemical Company, ICN Biomedicals, Inc., and other chemical suppliers.
Examples of substituted monomers include, but are not necessarily limited to, alkyl or aryl substituted monomers such as 2-methylaniline, 2-ethylaniline, 3-ethylaniline, 2-methylthiophene, 3-methylthiophene, 3-hexylthiophene, benzo[b]thiophene, 2-methylpyrrole, 2-methylfuran, and mixtures thereof. Many of these cyclic heteroatom-containing monomers may be considered as “aromatic” in nature. In general, these cyclic monomers are characterized by being insoluble or substantially insoluble in, or immiscible or substantially immiscible with water (less than about 1 g per 100 g of water).
An aqueous emulsion latex is a preferred emulsion latex for the present invention. Examples of such an emulsion latex, also referred to as a b
La Fleur Edward Ewart
Way Jiun-Chen
Clikeman Richard R.
Egwim Kelechi
Rohm and Haas Company
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