Compositions: ceramic – Ceramic compositions – Carbide or oxycarbide containing
Reexamination Certificate
1995-10-06
2001-02-13
Group, Karl (Department: 1755)
Compositions: ceramic
Ceramic compositions
Carbide or oxycarbide containing
C501S092000, C501S096300, C501S096200
Reexamination Certificate
active
06187703
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a new class of novel inorganic-organic hybrid polymers that are formed from linear inorganic-organic hybrid polymers of varying molecular weight. These new high temperature oxidatively stable thermosetting polymers are formed from linear polymeric materials having repeat units that contain at least one alkynyl group for cross-linking purposes and at least one bis(silyl or siloxanyl)carboranyl group and wherein the carborane content of the thermosets can be varied. These novel thermosetting polymers can be further converted into ceramics at elevated temperatures.
2. Description of the Related Art
The cross linking of acetylenic polymers has been demonstrated by Neenan et al. in Hypercross-Linked Organic Solids: Preparation from Poly(aromatic diacetylenes) and Preliminary Measurements of Their Young's Modulus, Hardness, and Thermal Stability published in 21 M
ACROMOLECULES
3525-28 (1988), incorporated herein by reference. Other similar cross linking reactions are demonstrated by Callstrom et al. in Poly[ethynlyene(3-n-butyl-2,5-thiophenediyl)-ethynylene]: A Soluble Polymer Containing Diacetylene Units and Its Conversion to a Highly Cross-Linked Organic Solid published in 21 M
ACROMOLoCULES
3528-30 (1988), incorporated herein by reference. The recent literature reflects continuing major research efforts to advance fundamental knowledge in high temperature material design. See K J. Wynne and R. W. Rice, Ceramics Via Polymer Pyrolysis 14 A
NN
. R
EV
. M
AT
. S
CI
. 297 (1984) incorporated herein by reference in its entirety and for all purposes. In the search for high temperature oxidatively stable materials considerable attention has been given to polymers containing boron within the polymer. It has been known that the addition of a carborane within a siloxane polymer significantly increases the thermal stability of such siloxane polymers.
The thermal properties of various siloxane polymers are given by P
ETAR
D
VORNIC ET AL
. in H
IGH
T
EMPERATURE
S
ILOXANE
E
LASTOMERS
published by Huthig & Wepf Verlag Basel, New York (1990) on pp. 277 in FIG. 5.7 and on pp.282 in FIG. 5.12 and by Edward N. Peters in Poly(dodecacarborane-siloxanes) published in J. M
ACROMOL
S
CI
.-R
EV
. M
ACROMOL
. C
HEM
., C17(2) on pp. 190-199 in FIGS. 3,4,5,6,7,10 and 12, each reference being incorporated herein by reference in its entirety and for all purposes. See also Maghsoodi et al. in
Synthesis and Study of Silylene
-
Diacetylene Polymers
published in 23 M
ACROMOLECULES
pp. 4486 (1990), incorporated herein by reference in its entirety and for all purposes.
Many of the carborane polymers manufactured are cited in various U.S. patents. See, for instance, the following U.S. Pat. Nos.: 5,348,917; 5,292,779; 5,272,237; 4,946,919; 4,269,757; 4,235,987; 4,208,492; 4,145,504; 3,661,847; 3,542,730; 3,457,222; and 3,234,288, each patent being incorporated herein by reference in its entirety and for all purposes.
There is a need for oxidatively stable ceramic materials suitable for making rigid components therefrom (e.g. by combining with fiberglass or carbon matrix or other matrix fibers, respectively), such as engine parts, turbine blades and matrices. These components must withstand high temperatures and be oxidatively stable and have sufficient strength to withstand the stress put on such components.
There is a need for carborane-silane and/or carborane-siloxane ceramic materials wherein the carborane content of the ceramics can be varied by varying the carborane content of the precursor thermosetting polymers. Weight percentage loss of the ceramic materials is limited to 50% or less from the original total weight or where the weight percentage loss is limited to 40% or less after formation of the precursor thermoset when heated in excess of 400 to 700° C. in an oxidative environment.
There is a need for carborane-silane and/or carborane-siloxane ceramic materials wherein the carborane content of the ceramics can be varied by varying the carborane content of the precursor thermosetting polymers. Weight percentage loss of the ceramic materials is limited to 30% or less from the original total weight or where the weight percentage loss is limited to 15% or less after formation of the precursor thermoset when heated in excess of 400 to 700° C. in an oxidative environment.
There is a need for carborane-silane and/or carborane-siloxane ceramic materials wherein the carborane content of the ceramics can be varied by varying the carborane content of the precursor thermosetting polymers. Weight percentage loss of the ceramic materials is limited to 20% or less from the original total weight or where the weight percentage loss is limited to 10% or less after formation of the precursor thermoset when heated in excess of 400 to 700° C. in an oxidative environment.
In addition, there is a need for carborane-silane and/or carborane-siloxane ceramic materials that behave more as rigid materials and less as elastomeric materials and wherein the carborane content of the ceramics can be varied.
There is a further need to provide carborane-silane and/or carborane-siloxane ceramic materials wherein the carborane content within the ceramics can be varied to provide maximum thermal stability and minimum cost.
In addition, a majority of the carborane-siloxane and/or carborane-silane polymers made by others show elastomeric properties rather than properties of more rigid products like ceramics. Thus, in addition to thermal stability, there is also a need for materials that behave more as ceramics, upon further polymerization, and less like elastomeric polymers.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide carborane-silane-alkenyl and/or carborane-siloxane-alkenyl containing ceramic materials that show high temperature stability where weight percentage loss is limited to 50% or less from the original total weight or where the weight percentage loss is limited to 40% or less after formation of the precursor thermoset when heated in excess of 400 to 700° C. in an oxidative environment and wherein the content of carborane within the ceramic (and the precursor thermoset) can be varied.
It is therefore an object of the present invention to provide carborane-silane-alkenyl and/or carborane-siloxane-alkenyl containing ceramic materials that show high temperature stability where weight percentage loss is limited to 30% or less from the original total weight or where the weight percentage loss is limited to 15% or less after formation of the precursor thermoset when heated in excess of 400 to 700° C. in an oxidative environment and wherein the content of carborane within the ceramic (and the precursor thermoset) can be varied.
It is therefore an object of the present invention to provide carborane-silane-alkenyl and/or carborane-siloxane-alkenyl containing ceramic materials that show high temperature stability where weight percentage loss is limited to 20% or less from the original total weight or where the weight percentage loss is limited to 10% or less after formation of the precursor thermoset when heated in excess of 400 to 700° C. in an oxidative environment and wherein the content of carborane within the ceramic (and the precursor thermoset) can be varied.
It is therefore yet another object of the present invention to provide carborane-silane-alkenyl and/or carborane-siloxane-alkenyl containing ceramic materials wherein the carborane content within the ceramic materials can be varied to provide maximum thermal stability and minimum cost.
These and other objects are accomplished by forming linear polymers having the composition:
wherein n, n′, u, u′, x, x′, y, y′ and y″ are integers, wherein the ratio y′/y≠0, wherein A is selected from the group consisting of O, an aliphatic bridge, an aryl bridge or mixtures thereof and E is selected from the group consisting of O, an aliphatic bridge, an aryl bridge or mixtures thereof. In addition, E and/or A may f
Keller Teddy M.
Son David Y.
Edelberg Barry A.
Group Karl
Karasek John J.
The United States of America as represented by the Secretary of
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