Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
1999-02-23
2001-09-18
Lipman, Bernard (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S033000, C528S043000, C528S087000, C528S096000, C528S377000, C528S380000
Reexamination Certificate
active
06291621
ABSTRACT:
RIGHTS OF THE GOVERNMENT
The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty.
BACKGROUND OF THE INVENTION
The present invention relates to conducting polymers and their use as electrodes in various devices, and, in particular, to certain bithienyinaphthalene-based monomers and polymers.
It is known that conjugated polymeric systems derived from regio-selective synthetic processes that preclude or minimize structural defects have shown, among other properties, much higher conductivity. A version of this approach is illustrated by the design and preparation of symmetrical conjugated monomers like bis(heterocycle-arylene) monomers, which upon electropolymerization, have led to polymers with minimal side reactions. Since these monomers and derived polymers are highly conjugated, they exhibit interesting and potentially useful luminescence characteristics. Most of the literature in poly(bis-heterocycle-arylenes) has focused on benzene as the arylene system. We have found that naphthalene as the arylene part provides more sites to modify the molecular structures of the monomers, and in turn, more control of the electronic properties of the derived polymers to satisfy the bulk property requirements.
It is an object of the present invention to provide novel monomers for the production of thin films and coatings useful in electrochromic applications.
It is another object of the present invention to provide polymers prepared by polymerization of these monomers.
Other objects, aspects and advantages of the present invention will be apparent to those skilled in the art from a reading of the following detailed disclosure of the invention.
SUMMARY OF THE INVENTION
In accordance with the present invention there are provided novel, electropolymerizable monomers of the formulae:
wherein R
1
, R
2
and R
3
are selected from the group consisting of —H, —O(CH
2
)
n
CH
3
,
wherein n has a value of 0 to 11 and m has a value of 1 to 4, and wherein no more than one of R
2
and R
3
is —H.
These monomers are synthesized by the palladium-catalyzed coupling reaction of 2-(tributylstannyl)thiophene with a naphthyl ditriflate or naphthyl dibromide as shown in the examples which follow. The coupling reaction works well in dioxane or toluene at reflux with tetrakis-(triphenylphosphine)palladium(0), Pd(PPh
3
)
4
.
These monomers are preferably electrochemically polymerized. Electrochemical polymerization of the above-described monomers can be carried out according to the methods generally employed for electrochemical polymerization of thiophene, pyrrole, and the like. The electrochemical copolymerization is carried out by cyclic voltammetry, by subjecting a mixture of monomer, solvent and electrolyte to one of the following conditions: (a) setting the potentiostat at a constant electrical potential where the monomer is optimally oxidized; (b) setting the potentiostat at a constant current value; or (c) repeated scanning between the redox potentials of the monomers. Typically, all three conditions are tested for a new monomer in order to select one as the optimal condition for achieving electropolymerized polymer films with the required stability and thickness. If the oxidation-reduction cycle can be repeated several times and the polymer film deposited on the electrode exhibits reproducible cyclic voltammetric (current-voltage) characteristics, it is then deemed to be electrochemically stable and well-behaved.
The solvents which can be used in the present invention may be either aqueous or nonaqueous, although a solution of the aforesaid electrolyte in a nonaqueous organic solvent is preferred. The organic solvents used herein are preferably aprotic and have high dielectric constants. For example, ethers, ketones, nitrites, amines, amides, sulfur compounds, phosphoric ester compounds, phosphorus ester compounds, boric ester compounds, chlorinated hydrocarbons, esters, carbonates, nitro compounds and the like can be employed. Of these, ethers, ketones, nitrites, phosphoric ester compounds, phosphorus ester compounds, boric ester compounds, chlorinated hydrocarbons and carbonates are preferred. Specific examples of suitable solvents include etrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, acetonitrile, proprionitrile, 4-methyl-2-pentanone, butyronitrile, valeronitrile, benzonitrile, 1,2-dichloroethane, .gamma.-butyrolactone, valerolactone, dimethoxyethane, methylformate, propylene carbonate, ethylene carbonate, dimethylformamide, dimethyl sulfoxide, ethyl phosphate, methyl phosphate, ethyl phosphite, methyl phosphite, 3-methylsulfolane, etc. Among these, nitrites and carbonates are especially preferred in order to increase the response speed. These organic solvents may be used alone or in combination.
Specific examples of electrolyte which can be used in the present invention include tetraphenylarsonium chloride, tetraphenylphosphonium chloride, tetra(n-butyl)ammonium bromide, lithium bromide, tetra(n-butyl)ammonium hexafluorophosphate, and tetra(n-butyl)ammonium perchlorate (TBAP). These examples are merely illustrative and not limiting.
Within the context of the implementation of the process in accordance with the invention, the electrochemical reactions are advantageously carried out at the surface of an electrode. By measuring the current delivered during the reaction, the electrode effectively makes it possible to monitor the progress of the polymerization reaction (for example the thickness of the polymer formed) or the progress of subsequent reactions carried out on the copolymer.
The resulting polymers have the structures
wherein R
1
, R
2
and R
3
are as previously defined and n is an integer indicating the degree of polymerization and having a value of at least 1.
REFERENCES:
Chemical Abstract 1991:113317, Jpn. Kokai JP 02218716, Tan et al, Feb. 1989.*
B. Sankaran, J.L. Burkett, B.A. Reinhardt, L-S Tan, Absorption, Emission and Redox Properties of Bithienylnaphthalene Systems, Polymer Preprints, vol. 39, No. 1, Mar. 5, 1998, pp. 157-158.
J.P. Ruiz, J.R. Dharia, J.R. Reynolds, Repeat Unit Symmetry Effects on the Physical and Electronic Properties of Processable, Electrically Conducting, Substituted Poly(1,4-bis(2-thienyl)phenylenes), Macromolecules, vol. 25, No. 2, 1992 (no month given), pp. 849-860.
D.M. Haynes, A.R. Hepburn, D.M. Goldie, J.M. Marshall, A. Pelter, The Physical, Electrical and Electrochromic Properties of Poly(1,4 dithienylbenzene), Synthetic Metals, 55-57 (1993) (no month given), pp. 839-844.
A.D. Child, B. Sankaran, F. Larmat, J.R. Reynolds, Charge-Carrier Evolution in Electrically Conducting Substituted Polymers Containing Biheterocycle/p-Phenylene Repeat Units, Macromolecules, vol. 28, No. 19, 1995, (no month given), pp. 6571-6578.
S. Tanaka, K. Kaeriyama, Electrochemical preparation of poly(dithienylnaphthalene)s and their properties, Polymr Communications, 1990, vol. 31, May (no month given), pp. 172-175.
Sankaran Balasubramanian
Tan Loon-Seng
Bricker Charles E.
Kundert Thomas L.
Lipman Bernard
The United States of America as represented by the Secretary of
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