A crosslinked organosilicon polymer or crosslinkable organosilicon prepolymer comprising alternating (a) polycyclic polyene residues and (b) polysiloxane/siloxysilane residues linked through carbon to silicon bonds, wherein the polycyclic polyene residues are derived from polycyclic polyenes having at least two non-aromatic carbon-carbon double bonds in their rings and the polysiloxane/siloxysilane residues are derived from (i) cyclic polysiloxanes or tetrahedral siloxysilanes and (ii) linear, .tbd.SiH terminated polysiloxanes.

This invention relates to new and novel organosilicon polymers and 
prepolymers. 
BACKGROUND OF THE INVENTION 
A new class of high molecular weight organosilicon polymers and prepolymers 
which have excellent physical, thermal and electrical properties and 
outstanding resistance to water, and that can be used to prepare shaped 
articles is described by the instant inventor in U.S. patent application 
Ser. Nos. 07/079,740 (now U.S. Pat. No. 4,900,779) and 07/232,826 (now 
U.S. Pat. No. 4,902,731). They are thermoset or thermoplastic 
organosilicon polymers comprising alternating polycyclic hydrocarbon 
residues and cyclic polysiloxanes or tetrahedral siloxysilane residues 
linked through carbon to silicon bonds. This application is directed to 
novel organosilicon polymers and prepolymers, such as those described in 
U.S. patent application Ser. Nos. 07/079,740 now U.S. Pat. No. 4,900,779 
and 07/232,826 now U.S. Pat. No. 4,902,731, further comprising linear, 
short chain .tbd.SiH terminated polysiloxanes. 
SUMMARY OF THE INVENTION 
A crosslinked organosilicon polymer or crosslinkable organosilicon 
prepolymer comprising alternating (a) polycyclic polyene residues and (b) 
polysiloxane/siloxysilane residues linked through carbon to silicon bonds, 
wherein the polycyclic polyene residues are derived from polycyclic 
polyenes having at least two non-aromatic carbon-carbon double bonds in 
their rings and the polysiloxane/siloxysilane residues are derived from 
(i) cyclic polysiloxanes or tetrehedral siloxysilanes and (ii) linear, 
short chain .tbd.SiH terminated polysiloxanes. 
DETAILED DESCRIPTION OF THE INVENTION 
Preferred linear, short chain .tbd.SiH terminated polysiloxanes have the 
general formula: 
##STR1## 
wherein n is 0 to 1000 and R is alkyl or aryl, preferably methyl or 
phenyl. 
Polycyclic polyenes which can be employed are polycyclic hydrocarbon 
compounds having at least two non-aromatic carbon-carbon double bonds in 
their rings. Illustrative are compounds selected from the group consisting 
of cyclopentadiene oligomers (e.g., dicyclopentadiene, tricyclopentadiene 
and tetracyclopentadiene), bicycloheptadiene and its diels-alder oligomers 
with cyclopentadiene (e.g., dimethanohexahydronaphthalene), and 
substituted derivatives of any of these, e.g., methyl dicyclopentadiene. 
Preferred are bicycloheptadiene, dimethanohexahydronaphthalene, 
dicyclopentadiene and tricyclopentadiene, with the most preferred being 
bicycloheptadiene. Two or more polycyclic polyenes can be used in 
combination. 
Any cyclic polysiloxane or tetrahedral siloxysilane with two or more 
hydrogen atoms bound to silicon will enter into the reaction. Cyclic 
polysiloxanes useful in forming the products of this invention have the 
general formula: 
##STR2## 
wherein R is hydrogen or a substituted or unsubstituted alkyl, alkoxy, 
aromatic or aryloxy radical, n is an integer from 3 to about 20, and R is 
hydrogen on at least two of the silicon atoms in the molecule. 
Examples of reactants of Formula (II) include, e.g., 
tetramethylcyclotetrasiloxane, pentamethylcyclopentasiloxane, 
hexamethylcyclohexasiloxane, tetraethylcyclotetrasiloxane, 
cyclotetrasiloxane, tetraphenylcyclotetrasiloxane, 
tetraoctylcyclotetrasiloxane and hexamethylcyclotetrasiloxane. 
The most commonly occurring members of this group are 
tetramethylcyclotetrasiloxane, pentamethylcyclopentasiloxane, and tetra-, 
penta- and hexamethylcyclohexasiloxanes, with 
tetramethyltetracyclosiloxane being a preferred member. In most cases, 
however, the material is a mixture of a number of species wherein n can 
vary widely. Generally, commercial mixtures contain up to about 20% (in 
purer forms as low as 2%) low molecular weight linear siloxanes, such as 
heptamethyltrisiloxane, octamethyltetrasiloxane, hexamethyl disiloxane, 
etc. 
The tetrahedral siloxysilanes are represented by the general structural 
formula: 
##STR3## 
wherein R is as defined above and is hydrogen on at least two of the 
silicon atoms in the molecule. 
Examples of reactants of Formula (III) include, e.g., 
tetrakisdimethylsiloxysilane, tetrakisdiphenylsiloxysilane, and 
tetrakisdiethylsiloxysilane. The tetrakisdimethylsiloxysilane is the best 
known and preferred species in this group. 
The reactions for forming the organosilicon prepolymers and crosslinked 
polymers can be promoted thermally or by the addition of a hydrosilation 
catalyst or radical generators such as peroxides and azo compounds. 
Hydrosilation catalysts include metal salts and complexes of Group VIII 
elements. The preferred hydrosilation catalysts contain platinum. 
The reactions for forming the organosilicon prepolymer compositions and 
crosslinked polymer proceed readily in the presence of a 
platinum-containing catalyst. The preferred catalyst, in terms of both 
reactivity and cost, is chloroplatinic acid (H.sub.2 PtCl.sub.6 
.cndot.6H.sub.2 O). Catalyst concentrations of 0.0005 to about 0.05% by 
weight, based on weight of the reactants, will effect smooth and 
substantially complete polymerization. Other platinum compounds can also 
be used to advantage in some instances, such as PtCl.sub.2 and 
dibenzonitrile platinum dichloride. Platinum on carbon is also effective 
for carrying out high temperature polymerizations. Other useful platinum 
catalysts are disclosed in, e.g., U.S. Pat. Nos. 3,220,972, 3,715,334 and 
3,159,662. An exhaustive discussion of the catalysis of hydrosilation can 
be found in Advances in Organometallic Chemistry, Vol. 17, beginning on 
page 407. 
It is possible, by selection of reactants, reactant concentrations and 
reaction conditions, to prepare prepolymers and polymers exhibiting a 
broad range of properties and physical forms. Thus, it has been found 
possible to prepare prepolymer liquids, elastomeric materials and hard, 
glassy polymers. 
According to one embodiment, crosslinked polymers per this invention are 
prepared by mixing the reactants and the hydrosilation catalyst and 
bringing the mixture to a temperature at which the reaction is initiated 
and proper temperature conditions are thereafter maintained to drive the 
reaction to substantial completion. 
According to a second embodiment for preparing crosslinked polymers per 
this invention, prepolymers are formed by partially reacting the 
components, until about 30 to about 70% of the SiH groups have reacted. 
Such prepolymers are generally in the form of a flowable liquid, which is 
stable at room temperature. Crosslinked polymers are formed by further 
reacting the prepolymers in the presence of a hydrosilation catalyst. 
In the prepolymers of the second embodiment and the crosslinked polymers, 
the total ratio of carbon-carbon double bonds in the rings of the 
polycyclic polyenes used to form the polycyclic polyene residues (a) to 
.tbd.SiH groups in the polysiloxanes and siloxysilanes used to form the 
polysiloxane/siloxysilane residues (b) is in the range of 0.4:1 to 1.7:1, 
preferably 0.8:1 to 1.3:1. The linear, short chain .tbd.SiH terminated 
polysiloxanes are generally used in an amount up to 70%, preferably 10 to 
50%, by weight of the total polysiloxane and siloxysilane monomers used to 
form the polymer or prepolymer. The short chain, linear .tbd.SiH 
terminated polysiloxanes impart flexibility to the cured polymers and can 
be used to prepare flexible, tough thermosets and elastomers. 
According to a preferred method for preparing crosslinked polymers per this 
invention, prepolymers are formed from polycyclic polyenes and cyclic 
polysiloxanes or tetrahedral siloxysilanes. Then, linear, short chain 
.tbd.SiH terminated polysiloxanes and, optionally, additional amounts of 
cyclic polysiloxanes or tetrahedral siloxysilanes are mixed with the 
prepolymer and the mixture is cured in the presence of a hydrosilation 
catalyst. In this embodiment, the linear, short chain .tbd.SiH terminated 
polysiloxanes are preferably used in an amount 10 to 50%, by weight of the 
polysiloxanes and siloxysilanes added to the preformed olefin reaction 
product. These polysiloxanes impart flexibility to the cured polymers and 
can be used to produce elastomers. 
According to the preferred process, organosilicon prepolymers are made with 
a large excess of carbon-carbon double bonds available for reaction with 
.tbd.SiH groups. That is, the ratio of carbon-carbon double bonds in the 
rings of the polycyclic polyenes used to form the polycyclic polyene 
residues (a) to .tbd.SiH groups in the polysiloxanes and siloxysilanes 
used to form the polysiloxane/siloxysilane residues (b) (i) is greater 
than 1.8:1, preferably greater than 1.8:1 and up to 5:1, and most 
preferably greater than 1.8:1 and up to 2.2:1. 
The organosilicon prepolymers of this embodiment may be prepared by mixing 
the reactants and the platinum catalyst and bringing the mixture to a 
temperature at which the reaction is initiated and proper temperature 
conditions are thereafter maintained to drive the reaction to substantial 
completion (typically, due to the large ratio of double bonds to .tbd.SiH 
groups available for reaction, greater than 90% of the .tbd.SiH groups are 
consumed). 
The prepolymers of this embodiment are generally in the form of flowable 
liquids, which are stable at room temperature. The most stable prepolymers 
are formed at a double bond to .tbd.SiH ratio of about 2:1 since virtually 
all polyene is reacted and excess polycyclic polyene need not be removed. 
(Due to their odor, the presence of unreacted polycyclic polyenes is 
undesirable. Unreacted polycyclic polyenes can be stripped, e.g., using a 
rotoevaporator, to form odorless compositions.) 
The basic reaction is fast. However, it is exothermic, and without using 
heat removal equipment (cooling coils or reflux condenser) the formation 
of the prepolymer is generally carried out for up to twenty-four hours or 
longer, depending on the reaction mass. In a continuous process with 
adequate heat removal, the earliest stages of the reaction can be carried 
out quickly. When 90% or more of the .tbd.SiH groups are reacted the 
prepolymers of the preferred embodiment are stable indefinitely at room 
temperature. 
The crosslinked polymers are formed according to this embodiment by mixing 
the prepolymers with the linear, short chain .tbd.SiH terminated 
polysiloxanes and, optionally, additional cyclic polysiloxanes or 
additional tetrahedral siloxysilanes such that the total ratio of 
non-aromatic, non-conjugated carbon-carbon double bonds in the rings of 
the polycyclic polyenes used to form the polycyclic polyene residues (a) 
to .tbd.SiH groups in the polysiloxanes and siloxysilanes used to form the 
polysiloxane/siloxysilane residues (b) (i) and (ii) is in the ratio of 
0.4:1 to 1.7:1; preferably 0.8:1 to 1.3:1, most preferably about 1:1, to 
form a low viscosity solution, and curing the mixture in the presence of a 
hydrosilation catalyst. 
Preferably, according to this embodiment, the organosilicon prepolymers are 
reacted with the polysiloxanes and/or tetrahedral siloxysilanes to form a 
crosslinked polymer in a mold. The prepolymers and 
polysiloxanes/siloxysilanes are stored separately and are blended in an 
in-line mixer directly before entering the mold. The hydrosilation 
catalyst may be present in either or both stream(s) or injected directly 
into the mixer. The reaction is exothermic and proceeds rapidly so that 
the polymer gels and the product can be removed from the mold in minutes. 
The components of the blends are completely stable until they are mixed. 
This permits indefinite ambient storage of the materials. If the reaction 
upon mixing is too fast and viscosity increases rapidly preventing proper 
mold filling, a cure rate retardant (e.g. tetramethylethylenediamine) can 
be added. 
Alternately, the blend components can be premixed and stirred in a tank. 
These blends have low viscosity and are pumpable. Addition of catalyst 
and/or application of heat can be used to cure the prepolymer composition. 
The reaction may be carried out in an extruder, mold or oven, or the blend 
may be applied directly on a substrate or part. For the more reactive 
compositions, mild complexing agents, such as tetramethylethylenediamine, 
can be added to control the room temperature reaction. The complex 
disassociates at temperatures greater than 100.degree. C. to let curing 
proceed. With stronger complexing agents, such as phosphorus compounds, 
curing temperatures above 150.degree. C. are required. 
In a fourth embodiment, the reaction is carried out in the same manner as 
the preferred embodiment, except the linear, short chain .tbd.SiH 
terminated polysiloxanes are used in forming the prepolymers instead of 
some of the cyclic polysiloxanes or tetrahydral siloxysilanes. Optionally, 
cyclic polysiloxanes or tetrahedral siloxysilanes may completely replace 
the linear, short chain .tbd.SiH terminated polysiloxanes when forming a 
polymer from such a prepolymer. 
Although a hydrosilation reaction via the carbon-carbon unsaturation of the 
polycyclic polyene rings and the .tbd.SiH group is the primary 
polymerization and crosslinking mechanism in all of the methods described, 
other types of polymerization and crosslinking may also take place as the 
curing temperature is increased. These may include, e.g., oxidative 
crosslinking, free radical polymerization (olefin addition reactions) and 
condensation of .tbd.SiH with silanols to form siloxane bonds. 
Additives such as fillers and pigments are readily incorporated. Carbon 
black, vermiculite, mica, wollastonite, calcium carbonate, sand, glass 
spheres, glass beads, ground glass and waste glass are examples of fillers 
which can be incorporated. Fillers can serve either as reinforcement or as 
fillers and extenders to reduce the cost of the molded product. Glass 
spheres are especially useful for preparing low density composites. When 
used, fillers can be present in amounts up to about 80%. Stabilizers and 
antioxidants are useful to maintain storage stability of the formulations 
and thermal oxidative stability of the final product. Coupling agents such 
as vinyl silane and related compounds may be used to wet the glass and 
promote adhesion of the resin to the glass. 
For instance, chopped glass fibers can be slurried in a stabilized liquid 
blend (prepolymer and added polysiloxane or siloxysilane) in compounding 
equipment having a blade stirrer(s) or screw mixer(s). It is best to 
deaerate such a slurry under vacuum before injecting it into a mold. 
Glass or carbon, e.g., graphite, fibers are wetted very well by the liquid 
blends, making the blends excellent matrix materials for high strength 
composite structures. Thus, the prepolymer composition can be mixed with 
cyclic polysiloxanes, tetrahedral siloxysilanes and/or linear, short chain 
.tbd.SiH terminated polysiloxanes to form a blend, a mold containing the 
requisite staple or continuous filament can be charged with the blend, and 
the blend can be cured to form the desired composite structure. Fiber in 
fabric form can also be employed. Fiber reinforced composites of the 
polymers of this invention can contain as much as 80%, preferably 30 to 
60%, by weight, of fibrous reinforcement, and, when fully cured, typically 
exhibit extremely high tensile and flexural properties and also excellent 
impact strength. Other types of fibers, e.g., metallic, ceramic and 
synthetic polymer fibers, also work well. 
The low-viscosity fluid blends are well suited for use in reaction molding 
systems, where rapid mixing and flow into a mold is important. The low 
viscosity and affinity for glass permits filling of molds containing glass 
reinforcement. The high reactivity of the blends gives a fast gel time at 
reasonable temperatures so that molded parts can be quickly taken out of 
the mold and cured further outside the mold. 
The thermoset polymers fabricated from the prepolymer compositions and 
blends described herein are useful in molded electronic parts, electrical 
connectors, electronic and electrical part encapsulation, and various 
aerospace applications. They can be molded into highly reinforced, 
intricate shapes and their inherent high thermal stability, low moisture 
absorbance and fire resistance (high char yield at 1000.degree. C. in air) 
make them uniquely suitable for such uses. 
The thermoset polymers are also useful as structural adhesives, curable in 
situ, to form strong bonds due to a high affinity of .tbd.SiH derived 
silanol groups for polar metal surfaces, especially oxidized metal 
surfaces. The elastomeric embodiments make excellent potting compounds for 
electronic applications since they can be cured in situ and have a low 
equilibrium water content (0.01-0.1%) after humid aging (100% relative 
humidity (RH), 1 week). 
The glass filled, thermoset products which have been polymerized to the 
glassy state are characterized by high physical properties, i.e., high 
modulus and high tensile strength and good flex properties. They are fire 
resistant, burn very slowly when subjected to a flame, and self-extinguish 
when the flame is removed. 
Thermal properties of the thermoset polymers are outstanding. The glass 
transition temperature (Tg) of a fully cured thermoset polymer is about 
200.degree. C. or higher. Thermal stability is excellent with usually less 
than 10% weight loss at 500.degree. C. during Thermogravimetric analysis. 
At 1000.degree. C. in air, they leave about 50% of a ceramic residue. This 
high temperature resistance makes them useful as refractory materials, 
fire resistant materials and ablative materials. 
The thermoset polymers are also resistant to oxidation at ordinary 
temperatures. Above 200.degree. C., oxidative crosslinking of silicon 
portions of the molecule appears to take place, resulting in the formation 
of a dark siliceous outer layer. This oxidized outer layer appears to 
impede the oxidative degradation of the bulk polymer. 
The following examples are presented to demonstrate this invention. They 
are not intended to be limiting. Therein, all percentages, parts, etc., 
are by weight, unless otherwise indicated.

EXAMPLE 1 
This example shows preparation of an organosilicon prepolymer useful in 
preparing crosslinked polymers according to this invention. 
With continuous mixing, 0.031 parts bisbenzonitrile platinum dichloride, 
120.4 parts (2.0 mole, 4.0 equivalents (eq)) bicycloheptadiene, and 120.4 
parts (0.05 mole, 2.0 eq) methylhydrocyclosiloxanes (a mixture of 
tetramethylcyclotetrasiloxane, pentamethylcyclopentasiloxane, 
hexamethylcyclohexasiloxane, available from Huls/Petrarch, Bristol, Pa.) 
were added to a reaction chamber and heated gradually to 100.degree. C. 
over a period of seven hours and held at 100.degree. C. for ten hours. A 
yield of 298.5 parts (98%) of prepolymer was obtained. 
IR analysis was conducted and the product was found not to have a peak at 
2140 cm.sup.-1 (SiH peak), indicating that the hydrosilation reaction was 
complete. 
Proton NMR analysis showed that SiH and bicycloheptadiene double bonds had 
reacted and the expected Si--C bonds had formed (5.8-6.0 ppm) giving 
bicycloheptene substituted methylhydrocyclosiloxane as a pourable fluid 
prepolymer. 
EXAMPLE 2 
This example shows preparation of an organosilicon polymer using the 
organosilicon prepolymer composition of Example 1. 
The bicycloheptadiene/methylhydrocyclosiloxanes prepolymer of Example 1 
(5.1 parts) was stirred with hexamethyltrisiloxane (.tbd.SiH terminated) 
(3.5 parts). Then, platinum catalyst (0.01 parts) was added with stirring. 
The mixture was deaerated under vacuum and poured into a slotted mold 
(3.times.1/2.times.1/8 inches), and cured at 120.degree. C. for 2 hours 
and 150.degree. C. for six hours. The cured polymer had a glass transition 
at 39.degree. C. determined by differential scanning calorimetry. 
Thermogravimetric analysis was carried out in a Du Pont Thermal Analyzer 
(E. I. du Pont de Nemours & Company, Inc., Wilmington, Del.) at 20.degree. 
C./minute, indicating a 10% loss in weight at 500.degree. C. in air and 
nitrogen, demonstrating the excellent stability of the polymer at high 
temperatures. 
EXAMPLE 3 
This example shows preparation of an organosilicon polymer. 
The bicycloheptadiene/methylhydrocyclosiloxanes prepolymer (5.1 parts) of 
Example 1 was stirred with .tbd.SiH terminated polydimethylsiloxane 
(Huls/Petrarch PS-537) (12.0 parts). Then, platinum catalyst (0.01 parts) 
was added with stirring. The compatible mixture was deaerated and poured 
into a slotted mold (3.times.1/2.times.1/8 inches) and cured at 
120.degree. C. for 2 hours and 150.degree. C. for six hours. The cured 
polymer had a glass transition at -34.degree. C. determined by 
differential scanning calorimetry. Thermogravimetric analysis indicated a 
10% loss in the cured polymer at 500.degree. C. in nitrogen and 
490.degree. C. in air, demonstrating the excellent stability of the 
polymer at high temperatures. 
EXAMPLE 4 
This example shows preparation of an organosilicon polymer from the 
prepolymer composition of Example 1. 
The bicycloheptadiene/methylhydrocyclosiloxanes prepolymer composition of 
Example 1 (15.00 parts) was stirred with tetramethyldisiloxane (6.61 
parts). The compatible mixture was a fluid which was degassed under 
aspirator vacuum and poured into a slotted mold (3.times.1/2.times.1/8 
inches) and cured at 50.degree. C. for 2 hours, 120.degree. C. for 2 hours 
and 150.degree. C. for 6 hours. The cured polymer had 10% weight loss at 
480.degree. C. in nitrogen and 475.degree. C. in air, showing excellent 
thermal and thermal oxidative stability. The polymer was cured further at 
200.degree. C. for 2 hours and 250.degree. C. for 2 hours. The glass 
transition temperature of the cured polymer was 79.degree. C. determined 
by thermal mechanical analysis (Du Pont Thermomechanical Analyzer with a 
100 mg load, and expansion probe at 10.degree. C./minute). This 
corresponded closely with the temperature where the complex modulus (G') 
decreased at the glass transition (80.degree. C.) determined by dynamic 
mechanical analysis. The complex modulus of the polymer was 116,000 psi at 
25.degree. C. and 87,000 psi at 75.degree. C. 
EXAMPLE 5 
A catalyst comprising 0.0033 parts platinum (0.1M chloroplatinic acid in 
isopropanol) was added to 30.23 parts dicyclopenntadiene and heated to 
55.degree. C. for 1 hour to form a catalyst complex. Then 6 parts toluene 
was added to the solution. 
The above solution was added gradually to a stirred mixture of 17.48 parts 
1,1,3,3,5,5-hexamethyltrisiloxane (Huls/Petrarch, H7322), 18.40 parts 
methylhydrocyclosiloxanes (Huls/Petrarch, M8830) and 9.25 parts of 
toluene. The addition took 72 minutes and cooling was applied to keep the 
temperature of the reaction in the 49.degree.-61.degree. C. range. The 
reaction was allowed to cool and was stirred at room temperature for two 
days. The toluene was stripped from the prepolymer at 40.degree. C. and 
0.5 mmHg. The prepolymer was a low viscosity, clear fluid (525 centistokes 
at room temperature). All the norbornene double bonds of DCPD were found 
to be reacted by proton NMR. 
The prepolymer was poured into a mold (3.times.1/2.times.1/8 inches) and 
cured at 100.degree. C. for 1 hour and 150.degree. C. for 4 hours. A clear 
polymer, which was slightly flexible and appeared to be tough resulted. 
While the invention has been described with respect to specific 
embodiments, it should be understood that they are not intended to be 
limiting and that many variations and modifications are possible without 
departing from the scope and spirit of the invention.