Note: Descriptions are shown in the official language in which they were submitted.
W093/04094 2 0 9 3 91~ PCT/US92/07001
REACTED COMPOSITES, ORG~IC-INO~GANIC COMPOSITES, A~D
METHODS FOR PRODUCI~G COMPOSITES
~ACKGROUND OF THE INVENTION
The present invention pertains to organic-
inorganic composites and to methods for producing
composites. This invention more particularly pertains
to ~1) reacted composites formed by the reaction of
reactive sites of particular organic-inorganic
composites or star polymers, and a method for preparing
those reacted composites; and (~) pa-ticular organic-
inorganic composites ~hereinafter referred to as
"TPSi(oR)3 composites") which are non-net~!or~ in nature
- and have an inorganic core co :-.ich organic arms are
lS attached by Si-O-metal bonds and have reactive si~es
and a method for preparing those composites.
This invention relates to the following
patent and applications. U.S. Patent No. ~,933,391 to
Timothy E. Long and Sam R. Turner, which is
20 incorporated herein by reference, teaches the use of
end-capped polymers. U.S. Patent No. 4,933,391
discloses polymers which have the general formula T-P-
Ea-(CH2)n-Si(OR)3, in which T is selected from an
initiator fragment, each P~ is independently selected
S from hydrogen and straight chain alk~1 radicals having
up to about 8 carbon atoms, E is a benzyl group or
substituted benzyl group having up to about 12 carbon
atoms, a is a whole number having a value of 0 or 1, n
is a whole number having a value of 0 to 4, and P is a
30 poly(vinylaromatic) or poly(diene) chain. U.S. Patent
; No. 5,096,942, issued March 17, 1992 to Timothy E. Long
and Larry W. Kelts, which is incorporated herein by
reference, teaches particular organic-inorganic
s composites (hereinafter referred to as ~TPESi(oR)3
s 3s composites~) using those polymers. In U.S. Patent No
5,096,942, the organic-inorganic composites are
'
:
....
,,
' '~
.
W093/04094 2 0 9 3 9 1 ~ PCT/US92/07001
--2--
disclosed as having sites reactive with small molecules
and linear polymers. U.S. patent application No.
555,505 for Timothy E. Long and Sam R. Turner
(hereinafter referred to as "star polymer application n
s which is incorporated herein by reference, teaches
polymers (hereinafter referred to as ~star polymers~')
produced using the end-capped polymers of U.S. Patent
- No. 4,933,391. (TPSi(OR)3 composites, TPESi(OR)3
composites, star polymers and other similar organic-
inorganic composites are also referred to collectively
herein as "TP-organo-silanes".) Timothy E. Long and
Larry W. Kelts are co-inventors herein. This invention
and the invencions disclosed in the above-identified
patent and appiication are commonly assigned.
Is The following ar~ also relates to the
application.
Antonen, U.S. 3,655,598 discloses use of
trialkoxysilyl difunctional polybutadiene oligomers
which are co-condensed with Si-OH functional resins to
form a network which is insoluble.
Taylor, U.S. 3,817,911 makes composites by a
simultaneous synthesis of an organic polymer and a
metal oxide precursor. The system is a physical blend.
H. Schmidt, Journal of Non-crystalline
2S Solids, 73 ~1985) 681-691, furthers the concept of use
of the sol-gel process to prepare compositions having
inorganic and organic components. The organic part of
the composite is contributed by the organic group in a
trialkoxysilane, RSi(OR')3. Schmidt does not employ a
telechelic, trialkoxysilyl functionalized polymer, nor
use such a polymeric chain as a solubilizing agent for
the composite.
Huang et al. and Glaser et al., Polymer
Bulletin 14, 557-564 (1985) and Polymer Bulletin 19,
51-57 (1988) prepare insoluble network structures using
; low molecular weight monomers such as tetraalkoxysilane
,:
.. ... .. .. ~ . . _ , .. . , ., . ~ . . . . . . . . .. . . . . . . ... . . . . . .
.
,. '
.
W093/04094 2 0 9 3 9 1 ~ PCT/US92/07001
and titanium isopropoxide in combination with
oligomeric and polymeric materials.
Mark, ChemTech April 1989, pp. 230-233,
discloses a process for making a network which
5 comprises reacting surface hydroxyls on silica filler
particles with difunctionalized triethoxysilyl
terminated poly(dimethylsiloxane). The networks are
insoluble.
Laible et al., Advances in Colloid and
Interface Science, 13 (1980), pps. 65-99, is similar to
~ark. I~ teaches attaching a trialkoxysilyl
monofunctionalized polymer to a silica particle.
It is therefore highly desirable to provide
improved organic-inorganic composites, improved reacted
1~ composites and improved methods for producing
composites.
SUM~RY OF T~E INVENTION
In the broader aspects of the invention,
there is provided a reacted composite having primary
and secondary subunits having the respective general
formulas
(10-POLYCOND)m1 ~Z2)m6
T--P--Ea--(CH2)n--Sli--(Z )m2 (R2)m7 ~t(Z )m4
~OR )m3 (OR )m5
and
and another composite having the general structure T-P-
Si(OR)3 and methods for producing those composites. In
these formulas, T is an initiator fragment, P is
poly(diene) or poly(vinylaromatic), E is benzyl having
up to about 12 carbons, a is 0 or l, n is an integer
from 0 to 4, POLYCOND is a partially condensed metal
polycondensate having metal atoms selected from
3b silicon, zirconium, titar.ium, aluminum, lead, boron,
and tin, zl is an ether link to another subunit, z2 is
an ether link to the polycondensate, Rl is selected
.
.-
.
. , . _ .. . ,, . .. . , ~ . ~ . . ... . .. . .. . . . .... .. . . . ..... . . ....
. .
W093/04094 2 o 9 3 912 PCT/US92/07001
--4--from -H ar.d alkyls having from l to 4 carbons, M is a
metal selected from silicon, zirconium, titanium,
aluminum, lead, boron and tin or is carbon, R2 is alkyl
or arylalkyl having a molecular weight less than
l,000,000, each ml, m2, and m3 is selected from
integers from 0 to 3, ml + m2 is an integer from l to
3, ml + m2 + m3 = 3, m4 + m6 is an integer from l to
the valence of M - l, and m4 + m5 + m6 + m7 = the
valence of M. The term ~ether link" used herein refers
to -O- lin~ages to carbons or to metal atoms. It is an
advantageous effect of some embodiments of the
invention to provide improved organic-inorganic
composites, improved reacted composites and improved
methods for producing composites which can provide
~5 varied Tl, T2, and T3 reactivities.
DESCRIPTION OF A SPECIFIC EMBODIMENT
The reacted composite of the invention is a
macromolecule in which two different sets of Uarmsu are
joined to a metal condensate ~coreU. One of the sets
of arms is a polymer. The other set can be another
polymer or a small molecule. Surprisingly, both sets
of arms are present in large numbers and are not
present on a random basis or on the basis of a
competition between components in a single reaction.
-The reacted composite of the invention
incorporates primary and secondary subunits. The total
number of subunits in a macromolecule of the reacted
` 30 composite of the invention is from 3 to 50. The
~- primary subunits have the general formula
- POLYCOND ) m 1
T--P--Ea--(CH2)n--Sli--(Z )m2
( OR ) m3
.
,
:
... -:-, :, '' .
,,,
.
W093/04094 2 0 9 3 ~ 1 2 PCT/US92/07001
-5-
The secondary subunits have the general formula
(Z2 )m6
(R2)m7 1l~ (Z )m4
(Rl )m5
T is an initiator fragment. P is a
poly~vinylaromatic) or po y(diene) chain. E is a
benzyl group or a substituted benzyl group having up to
about 12 carbon atoms. a is 0 or 1. n is an integer
having a value from 0 to 4. The moiety T-P-Ea-(CH2)n-
of the primary subunit represents a "primary arm" of
the reacted composite. Each primary arm is directly
bonded to a silicon atom, referred to herein
collectively as primary arm silicon atoms or primary
arm metal atoms.
POLYCOND is a partially condensed metal
polycondensate having metal atoms selected from the
group consisting of silicon, zirconium, titanium,
aluminum, lead, boron, and tin. The partial
condensation of the metal polycondensate means that in
addition to metal condensation bonds having the general
formula M-OM, in which each M is a metal, the
polycondensate also includes metal non-condensation
bonds having the general formula, M-OR, in which M is a
metal and R is selected ~rom hydrogen and lower alkyl
groups of up to about four carbon atoms.
Rl is selected from the group consisting of -
.,.'
H and alkyls having from 1 to 4 carbon atoms.
.~zl is an ether link to a primary subunit or
an ether link to a secondary subunit. z2 is an ether
link to the partially condensed metal polycondensate.
- - ~ M is a metal seIected from the g-oup
'30 consisting of silicon, zirconil~m, titanium, aluminum,
lead, boron and tin or is carbon.
R2 is alkyl or arylalkyl and has a total
.
~ '; ,. ~ ' ' '' , -
. .
.: . , ~ ' .
W093t04094 2 o 9 3 9 ~ 2 PCTIUS92/07001
--6--
molecular weight less than l,000,000. R2 is not the
same as the T-P-Ea-(CH2)n- of the primary subunit. R2
represents the "secondary arm" of the reacted
composite. Each R2 is directly bonded to a metal atom,
referred to collectively herein as secondary arm metal
atoms.
Each ml, m2, and m3 is selected from integers
from 0 to 3. ml + m2 is an integer from l to 3. ml +
m2 + m3 is equal to 3. m4 + m6 is an integer from l to
the valence of M - l. m4 + m5 + m6 + m7 is equal to
the valence of M.
The "core" of the reacted composite (and the
TPSi(oRj3 composites discussed below) represents the
"inorganic" portions, that is, all portions except the
; 15 arms: the silicon and other metal atoms and their
ether linkages and hydroxyl and alkoxy substituents.
The primary subunits of the reacted
composites of the invention are contributed by TP-
organo-silane reactants which have primary moieties
represented by the general formula
(f -POLYCOND)m1
T--P--Es~--(CHz ) n--Sli--(Z)m2
(OR1 )m3
Z represents another primary moiety and all other
designations have the same meanings as presented above
~ in discussion of the reacted composites. Like the
- 25 reacted composites of the invention, the TP-organo-
silane reactants have arms and a core. The arms have
the general formula T-P-Ea-(CH2)n- and correspond to
the primary arms of the reacted composites. The core,
like the core of the reacted composites, represents the
remaining portions of the macromolecule: the silicon
; atoms and their ether linkages and hydroxyl and alkoxy
substituents. The core of a TP-organo-silane reactant
:
.
.,. .- -- - - :
,... . - . ,
':
-
~
.
. .
W093~094 2 ~ 9 3 9 1 2 PCT/US92/07001
--7--differs from the core of a reacted composite of the
invention in that the TP-organo-silane reactant lacks
secondary arm metal atoms.
In the TP-organo-silane reactants, if ml is
0, then the reactant corresponds to the ~star polymers"
of U.S. patent application No. 555,505. If ml is not
0, then the reactant is described herein as a "organic-
inorganic compositen. In a particular embodiment of
the invention, the reacted composites are prepared
using novel organic-inorganic composites identified
herein as "TPSi(OR)3 composites".
The TPSi(OR)3 composites of the invention are
represented by the TP-organo-silane reactant formula
above when a = 0 and n = 0. In the TPSi(OR)3
composites of the invention the arms have the general
formula T-P-, in which T is an initiator fragment and P
is a poly(vinylaromatic) or poly(diene) chain. Each
polymer arm has a molecular weight of from about l000
- to about l00,000, and the average number of arms bonded
to the core is from about 3 to about 50 or more. The
i, core has a ratio of metal condensation bonds to the
total number of possible metal condensation bonds
within the range of from about 0.5 to about 0.9. The
s core has a metal content in which the ratio of moles o
silicon contributed by the primary arms, that is,
primary arm silicon atoms, to the total moles o metal
in the core is within the range of~from about 0.25 to l
; to about 4 to l. The core is about 5 to about 30
weight percent of the TPSi(OR)3 composite.
The method of the invention for producing
TPSi(OR)3 composites has the following two steps:
~. reacting an end-capped polymer with acidic water to
-, prepare a prehydrolyzed intermediate in which about 50
to about l00 percent of -OR groups are converted to -OH
and reacting the intermediate with a hydrolyzable metal
compound.
.
.. .... . . . . . . . . .. ...
.
- . .
.
W093/~094 PCT/US92/07001
2093 ~ ~2 -8-
The endcapped polymers of the first step have
the general formula T-P-Si(OR)3, in which the same
designations have the same meanings as in previous
structure formulas. These polymers are made by bonding
an endcapping group to a polymeric chain previously
formed by an anionic living polymerization. The living
polymerization is conducted using an olefinic
unsaturated monomer and a univalent anionic initiator.
Preferably an alkyllithium, alkylsodium, or
alkylpotassium initiator is used.
Many unsaturated monomers containing carbon-
to-carbon dQuble bGnds can be polymerized using anionic
initiators to yield living polymers. These include
conjugated and non-conjugated dienes and vinyl-
substituted aromatic compounds. Some illustrative, butnon-limiting examples of useful dienes include the
conjugated dienes having up to about 18 carbons, such
as l,3-butadiene, isoprene, l,3-pentadiene, 2-phenyl-
l,3-butadiene, l,3-octadecene, and the like.
Illustrative, but non-limiting examples of vinyl
^ substituted aryl monomers include styrene, alpha-
. ~
methyl-styrene, 4-methylstyrene, 4-tert-butylstyrene,
4-decyclstyrene, alpha-methylstyrene, 2-
vinylnaphthalene, 2-vinylpyridine, and other vinyl
~; 's substituted aromatics having up to about 18 carbon
atoms. It will be understood by a skilled practitioner
that the living polymers used as intermediates in this
invention can be homopolymers, copolymers, or block
copolymers.
The living polymerization is conveniently
carried out at a temperature of from about -85C to
about 120C. The polymerization is also conveniently
carried out in a liquid ether or an aliphatic
hydrocarbon which does not react with the catalyst.
3s Tetrahydrofuran, cyclohexane, petroleum ether, and the
like can be used. When a reaction medium, such as
,
.
,. . . I
. - : , ;
. - . .
W093/04094 2 ~ 9 ~ 9 1 2 PCT/US92/07001
tetrahydrofuran has a tendency to react with
material(s) used in the process, such an undesirable
side reaction can be minimized in some instances by
conducting the process at a low temperature. Hence, one
5 may use a reaction temperature as low as about -78C or
lower when tetrahydrofuran is employed as the reaction
, medium.
Further details concerning the preparation of
living polymers of the type used in this invention are
available in the art, e.g., U. S. Patents 4,933,391;
3,956,419; 4,371,670; 4,379,891; 4,408,017; and
4,618,650. The descriptions of living polymers and
methods for their formation within those patents are
incorporated by reference herein as if fully set forth.
~urning now to the endcapping process, it can
be applied to anionic living polymers having any
!' molecular weight. Hence, the molecular weight is not a
critical variable in the end-capping process. For
` convenience, it is preferred that the metal terminated
polymer have a polymeric chain with a molecular weight
in the range of from about 500 to about 1,000,000, more
i~ preferably from about 1,000 to about 100,000 and that
, the ~etal used be a univalent metal such as lithium,
sodium, or potassium.
~5 Several criteria must be m~t for the
selection of a suitable functionalization (endcapping)
reagent. First, an electrophilic site for direct
deactivation of the polymeric carbanion must be present
in the molecule. Also, the reaction should be
quantitative or nearly quantitative, in order to
maximize the efficiency of subsequent formation of
condensed products. In addition, the efficiency of the
- functionalization reaction should be characterizable by
. a variety of complimentary techniques, e.g.
spectroscopic and chemical.
; For this invention endcapping agents are
~.
.. ,... .... ,... , .................. , . ~... . ...... ........... ....... . ........... .
.
W093/04094 PCT/US92/07001
2O93s~æ ~
--10--
selected from those having the formula:
Ra-Si(ORb)3 .
Ra is a reactive center for nucleophilic att~ck by the
univalent metal carbanion. Ra can be a halogen radical
selected from fluoride, chloride, bromide, and iodide.
Ra can also be a halo(lower alkyl)- moiety. Rb is an
alkyl radical of up to 8 carbon atoms.
Examples of endcapping agents useful in this
invention are halotrialkoxysilanes including fluoro,
chloro, and bromo substituted tri~methoxy, ethoxy,
butoxy)silanes. The endcapping reaction can be carried
out in the reaction medium in which the metal
terminated polymer is formed. The reaction temperature
is not critical. It has been conducted at -78C in
tetrahydrofuran and at 60C in cyclohexane.
Temperatures above and below those temperatures, e.g.,
from about -85C to about 100C, can be employed if
desired. The reaction can be conducted for a reaction
time within the range of from about 0.25 to about 2.0
hours. Shorter and longer times can be used if desired.
The endcapping reaction is preferably
- conducted using an excess (10-100 mole percent or more)
of the endcapping agent. However, it is not necessary
that an excess be used; an exact stoichiometry can be
'5 employed, if desired. The process is preferentially
conducted at ambient or slightly elevated pressures
e.g. 1 atmosphere to about 1.1 atmosphere. Such
pressures are not critical, and higher pressures or
vacuum can be used if desired.
The end-capped polymers prepared by reacting
the metal terminated polymers and above-described end-
capping agents are soluble in a material such as
tetrahydrofuran, dimethylformamide, dimethylacetamide,
acrylonitriie, N-methylpyrollidone, sulfolane,
dimethylsulfoxide, and the like.
The end-capped polymers, produced as
.:
.. ,, . " , . . . . . . . . . .. .. . ..
- . .
., . . .. , . : , -
' . .
..
,,
.
~' ' '. ' ~
W093/04094 2 ~ 9 3 ~ ~ 2 PCT/US92/07001
--11-
described above, are bonded to a metal polycondensate
that is formed in situ from a hydrolyzable reactant
MXn M is selected from Si, Zr, Ti, Al, Pb, B, or Sn;
X is a hydrolyzable group selected from halogen and
5 alkoxy groups of one to about eight carbon atoms; and n
is the metal valence. X and the R groups of the living
polymers can be the same or can differ. Generally
speaking, the alkoxy groups on the end-capped polymers
react in a sol-gel hydrolysis/condensation reaction at
a slower rate than the hydrolyzable groups in MXn. In
order to make the rate of reaction more balanced, the
end-capped polymer is subjected to a prehydrolysis,
which forms Si-OH groups available for condensation.
- The prehydrolyzed intermediate produced is then reacted
with the hydrolyzable reactant, one or more materials
having the formula MXn.
The conditions utilized to conduct the
~i prehydrolysis favor hydrolysis over condensation. The
differences between hydrolysis and condensation are
. 20 well known to a skilled practitioner. For example the
equation:
R'Si(OR)3 + 3H20 ` R'Si(OH)3 + 3ROH
illustrates complete hydrolysis of a trialkoxysilane
such as a trimethoxysilane or triethyoxysilane. As
. 25 shown, for each mole equivalent of trialkoxysilane
- employed, three moles of water are required for
complete hydrolysis (ignoring any water produced by
condensation). For the purposes of this application,
certain terminology is employed to describe features of
this invention. Thus, Si-OR and Si-oH bonds
illustrated by equation (1) are termed ~non-
`~ condensation bonds." In such bonds, silicon is not
linked through an oxy~en bridge to another metal atom.
On the other hand, bonds in which metal atoms are
3s linked through an oxygen bridge to form M-O-M groups,
, ~, ...... ... . - -
~ W093/04094 ; 2 0 9 3 ~ 12 PCTtUS92/07001
-12-
wherein each metal atom M is alike or different and is
selected from the metals represented by M as stated
above, are called ~metal condensation bonds.~ An
illustrative M-O-M group is an Si-O-Si group. An M-O-M
s group contains two metal condensation bonds.
The products and intermediates in the process
of this invention can be characterized by the following
ratio:
actual number of metal condensation bonds
IO p = --____________________
total number of possible condensation bonds
The reaction can be followed using 29Si NMR analysis to
determine the actual number of metal condensation bonds
formed. The total possible condensation bonds that can
be formed can be calculated from the moles of
- hydrolyzable metal compound times the number of
replaceable groups in the molecule that can condense.
For the polymeric silicon-containing reactant
~o T-P-Si(OR)3, the total possible metal condensation
bonds is (number of moles) x 3.
The reaction conditions emp~oyed to conduct
the prehydrolysis step in the process of this invention
are not critical. One generally uses reaction
~` '5 conditions that favor hydrolysis over condensation and
conducts the reaction under the selected set of
reaction conditions to achieve the desired rate of
hydrolysis. In general, one adds enough water to the
reaction and conducts the process so that on a
theoretical basis, all -OR groups could hydrolyze.
Thus for prehydrolysis of all three alkoxy groups on
the T-P-Si(OR)3 endcapping reactant, one generally uses
: at least three moles of water per each mole of the
polymeric reactant.- It is to be understood that less
- 35 than three moles of water can be employed especially if
it is desired to hydrolyze less than all of the alkoxy
. : . : . , ,
, ' . ~ '' .- ' ' . ~
- .:
- . . .
, ~ .
W093/04094 2 ~ ~ 3 9 1 2 PCTtUS92/07001
groups present in the polymeric reactant. It is
convenient to use about 4 moles of water for each mole
of endcapping reactant, however, there is no real upper
limit on the amount of water to be employed. It is
s preferred that the amount of water not exceed about 20
moles per mole of T-P-Si(OR)3 reactant. Thus, per each
mole portion of the polymeric reactant, it is generally
preferred to use from about 2.0 to about 6.0 moles of
water in the prehydrolysis and thus provide a
-1 ~0 prehydrolyzed intermediate having, theoretically, about
50 to about l00 percent of the OR groups converted to
OH. It is to be recognized, however, that the amount
of water employed can be somewhat outside this range.
Although the prehydrolysis is preferably
conducted in an acidic medium for the preparation of
other TP-organo-silanes, such as TPESi(OR)3 composites,
. the prehydrolysis for the preparation of TPSi(OR)3
composites is slow in an acidic medium. This is
surprising since, as is known in the sol-gel art,
hydrolysis is fast under acidic conditions (low pH).
The acidic medium also provides acid as catalyst for
~ the condensation reaction, however, in the case of
; TPESi(OR)3 composites the acid undesirably drives the
reaction toward condensation. If there is an
appreciable amount of condensation, then an appreciable
amount of starting polymeric reactant will be
~ transformed into a material with limited available
; sites for reaction with the MXn reactant, and the yield
of desired product will be reduced.
For prehydrolysis, a reaction temperature is
selected which gives a suitable reaction rate, and
- i which does not cause an undesirable amount of
condensation (of hydrolyzed functionalized polymer).
. In general, one employs a reaction temperature within
3s the range of from about -35C to about 75C.
Temperatures somewhat outside this range can also be
~ .
W093/0409~ 9 ~'~ PCT/US92/07001
-14-
employed. Preferably, one employs a reaction
temperature within the range of from about -20C to
about 60C.
Generally speaking, faster rates of
hydrolysis are obtained with higher reaction
temperatures. Also, condensation is usually faster
with higher reaction temperatures. As indicated above,
for the purpose of this invention condensation of the
prehydrolyzed intermediate can be objectionable, since
it diminishes the ability of this intermediate to react
with the MXn reactant employed in the second step of
the process of this invention. Therefore, when
selecting a reaction temperature, or a regime of
reaction temperatures, one keeps in mind not only the
desire to achieve a suitable hydrolysis reaction rate,
but also the desire to refrain from producing an
unacceptable amount, for example, greater than 50
percent, of undesired condensation product. Thus, one
chooses a reaction temperature (or temperatures) which
-~ 20 'Ibalances" ~a) the rate of the desired prehydrolysis,
with ~b) the rate of the undesired condensation of the
prehydrolyzed intermediate, so that hydrolysis is
heavily favored, and any condensation is maintained
;within an acceptable amount.
` ~5The reaction time is not a truly independent
variable, but it is dependent at least to some extent
on the other reaction conditions employed; for example,
the reaction temperature, the inherent reactivity of
the reactant, the efficiency of the catalyst employed,
etc. In general, one employs a reaction time that
strikes a favorable balance between the hydrolysis that
is desired, and (undesired) condensation of the
prehydrolyzed intermediate. Such a reaction time can
be selected with a limited amount of preliminary
experimentation, especially if the reaction results are
;followed using 29Si NMR as an experimental tool. As
~.
, ~ .
., .
~ . .
:. :
:
W093/04094 2 0 9 3 9 1 2 PCT/US92107001
-15-
shown by the examples, a suitable prehydrolysis
reaction time can be about one hour. Greater or lesser
reaction times can be employed. Thus, reaction times
for the prehydrolysis are generally in the range from
- 5 about five minutes to about five hours. Reaction times
-, somewhat outside this range can be used.
The reaction pressure is not critical. In
general, the prehydrolysis is conducted at ambient
pressure; however, greater and lesser pressures can be
used if desired. For example, one may wish to run the
prehydrolysis at a reduced pressure to facilitate
hydrolysis, e.g. when the hydrolysis by-product is a
volatile species such as isobutylene, methanol or n-
~ butanol. Thus for example, one may use a reaction
- 15 pressure of from about O.l to about l.0 atmospheres.
Pressures above and below this range can also be used.
After the prehydrolysis, the prehydrolyzed
intermediate is condensed with the MXn reactan~. The
mole ratio of MXn to intermediate is from about 0.25 to
l to about 4 to l. This step can involve a partial
hydrolysis of the MXn reactant prior to its
condensation; however, it is to be understood that the
condensation can at least to some extent occur via an
alcohol producing condensation or similar reaction such
as illustrated using a silicon tetraalkoxide by the
equation:
T-P-Si(OR)20H + RO-Si(OR)3 ~ T-P-Si(OR)2-O-Si(OR)3 + R-OH.
In general, water producing condensations are faster
; than alcohol producing condensations, especially in
silicon systems. With other metal alkoxides, alcohol
producing condensation reactions ~ecome more important.
Titanium and zirconium alkoxides hydrolyze and condense
much faster than silicon alkoxides. When mixed with
silicon hydroxides, they can catalyze silicon
condensation, or condense rapidly with silicon
,. .. . , ... ~ .. . .. " . , .. .. , ,. ,.~ ,, ,, .,. , =
,
- .,
- ': :'
. ~ :
W093/04094 3 9 ~ 2 -l6- PCT/US92/07001
alkoxides themselves.
It is to be understood that the water
necessary for the composite forming step can come from
three sources: (l) water present in the acid/water
mixture at the end of the prehydrolysis step, (2) water
that evolves from the water producing condensation
reaction, and (3) water added at the beginning or
during the composite forming step. It is often
favorable to limit the amount of water present when the
MXn reactant or reactants are added. It may be
convenient to conduct the composite forming step in the
presence of the acid/water mixture which remains after
the prehydrolysis step and which contains the
prehydrolyzed intermediate. The MXn compound can be
added all at once or in increments.
The composite forming reaction is generally
conducted at a temperature in the range of from about
-35C to about 130C and preferably is conducted at a
: temperature of from about -10C to about 75C.
Reaction at room temperature or thereabouts is highly
preferred in many instances.
The time employed for the composite forming
step is not a truly independent variable, but is
dependent at least in part on the inherent reactivity
of the reacting materials, the quantity employed, the
catalyst used, and the reaction temperature(s)
selected. Generally speaking, this time is from 30
minutes to 250 hours. The reaction pressure can be
selected from those pressures discussed above when the
prehydrolysis step was described.
The TPSi(OR)3 composites of the inve~tion
have M-OH groups contributed by both the MXn reactant
and the endcapped polymer. A surprisingly large
percentage of these M-OH groups, also referred to
3s herein as a reactive sites a, can be reacted to provide
additional M-OM bridges. This reaction is utilized in
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20939~ 2
W093/04094 PCT/US92/07001
-17-
the method of the invention for the preparation of
- reacted composite to produce one of the embodiments of
the reacted composites of the invention.
~ Alternative embodiments of the reacted
-- 5 composites of the invention can be produced from
organic-inorganic composites disclosed in U.S. Patent
No. 5,096,942. Disclosed therein are organic-inorganic
composites prepared by the reaction of endcapped
polymers having the general structure TPESi(OR)3 and
j 10 MXn reactants, in which T and P and other designations
are the same as elsewhere herein. Other alternative
` embodiments of the reacted composites of the invention
- can be prepared from the star polymers disclosed in
U.S. patent application No. 555,505.
In the method of the invention for preparing
reacted composites, TP-organo-silane, such as a
TPSi(OR)3 composite or star polymer, is reacted with a
n secondary condensation reactant", that is, a small
molecule or linear polymer bearing a group which is
capable of reacting with the H- of a silanol or other
metal hydroxy and forming an M-O-M bridge. Exemplary
silanol group reactions are tabulated in Iler, Ralph
K., "The Chemistry o~ Silica", John Wiley & Sons, New
York, 1979. Suitable secondary condensation reactants
2S are chlorosilanes, carboxylic acids, alkoxysilanes, and
alcohols. Specific examples of useful secondary
hydrolysis-condensation reactants are:
trimethylchlorosilane, methacryloxypropyldimethyl-
chlorosilane, n-decyldimethyl-chlorosilane, 3-
cyanopropyldimethylchlorosilane, 2-(4-
chlorosulfonylphenyl)ethyldimethylchlorosilane, 3-
chloropropyldimethylchlorosiloane, n-butyldimethyl-
chorosilane, l,6-bis(chlorodimethylsilyl)hexane, and 3-
aminopropyldiisopylethoxysilane. Useful linear
polymers include the above-disclosed endcapped polymers
having the general structure TPSi(OR)3 and endcapped
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W093/04094 PCTtUS92/07001
20939~ -18-
polymers disclosed in U.S. Patent No. 4,933,391. Other
suitable linear polymers are disclosed in the other
` references listed above for endcapped polymers.
Because of this capacity to incorporate a variety of
- s moieties, the reacted composites of the invention can
have a wide variety of uses. For example, the reactive
sites can carry and, in effect, disperse in a film or
the like specific groups which provide a desired
function, such as dye moieties for photography.
Reaction of the organic-inorganic composite
or s~ar polymer and the secondary condensation reactant
is performed in solution or as a melt without solvent
or with a non-solvent. If solvent is used, selection
of that solvent is not critical. Suitable solvents
include cyclohexane, toluene, chloroform, and other
similar materials. A convenient solution concentration
, is 15-20 percent solids. The reaction temperature is
not critical, however, a temperature of 25C or higher
` is desirable to increase the rate and extent of
- 20 reaction. Any reaction pressure can be employed,
however, atmospheric pressure is convenient.
The secondary condensation reactant can be
added in an amount in stoichiometric excess of the
number of reactive sites or a less amount may be used
` 25 if incomplete reaction is desired. A convenient amount
i of secondary condensation reactant for high levels of
conversion is a tenfold excess of reactant to residual
reactive silanols. The reaction can be allowed to
proceed until the level of conversion has reached a
constant value by 29si NMR analysis. Convenient times
are generally 0.2 to 48 hours.
The reacted composite produced can be
isolated from solution by solvent evaporation or
precipitation into nonsolvent. The latter procedure
- 35 provides the added benefit of removing any unreacted
silane.
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W093t04094 2 0 9 3 912 PCT/US92/07001
-19-
Reacted composites can be differentiated from
their precursors on the basis of the presence of
secondary subunits and also on the basis of relative
~ percentages of metal atoms bearing different numbers of
- 5 -OM groups, that is metal atoms bonded by l, 2, 3, or
more oxygen bridges to other metal atoms. The
following nomenclature is used herein to designate
those metal atoms. The terms ~T~ T2~, and so on,
each refer to a silic~n atom contributed by endcapped
polymer bearing the superscripted number of -OM groups.
Thus, for example, a Tl silicon is bonded to one other
metal atom through an oxygen bridge. Each silicon in
the moiety Si-O-Si is a Tl silicon. The terms "Q3~ and
the like refer to metal atoms of the inorganic core,
contributed by the MXn reactant, bearing the
: superscripted number of oxygen-metal bridges. Star
polymers and reacted composites of star polymers lack
Q3 and Q4 metal atoms. In the following, ~T" and ~Q"
metal atoms are described as percentages of total metal
atoms. Percent condensation is equal to the number of
condensed metal atoms, that is, ~T~ and ~Q" metal
atoms, divided by the total number of metal atoms, both
condensed and uncondensed.
In the reacted composites of the invention,
'5 the percentage of T2 metal atoms decreased and the
percentage of T3 metal atoms increased in comparison to
star polymer precursors. For organic-inorganic
composite precursors, the percentages of both T2 and Q3
metal atoms decreased and the percentages of T3 and Q4
metal atoms increased. Overall, the conversion of star
polymer or organic-inorganic composite to reacted
composite resulted in an increase in the condensation
of metal atoms o about 50 to about-90 percent. This
- extent of incorporation of additional moieties into the
3s star polymers and organic-inorganic composites was
surprising. This is particularly true in view of the
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WO93/0409093g ~ PCT/US92/07001
-20-
anomalous behavior Of Tl metal atoms. In Example l, a
star polymer was 66 percent condensed and the reacted
composite was 74 percent condensed. The star polymer
was 16 percent Tl. In the reacted composite no Tl
s metal atoms were observed. In Example 4, a TPSl(OR)3
composite showed 8 percent Tl groups. The reacted
composite showed 7 percent Tl groups. This difference
in the reactions of Tl metal atoms in the methods of
the invention for preparing reacted composites is very
surprising and cannot be fully explained, other than
noting that sterically hindered sites are evidenced by
limited cluster growth and thus the Examples evidence
unexpected differences in the accessibility of reactive
sites.
~ 15
PreDaration of C4~-Dolystyrene-CH2-para-phenvl-
~i(OCH~L3 endca~ed nolvmer
All glassware was rigorously cleaned and
dried in an oven at 120C for 24 hours. The reactor
was a 250 mL, 1 neck, round-bottom flask equipped with
a magnetic stirrer and a rubber septum. The septum was
secured in place with copper wire in order that a
positive pressure of ultra pure nitrogen could be
maintained. The reactor was assembled while hot, and
subsequently flamed under a nitrogen purge. After the
flask had cooled, the polymerization solvent
(tetrahydrofuran) was added to the reactor via a
double-ended needle (cannula). The reactor was
submerged into a -78C bath and allowed to reach
thermal equilibrium. Purified styrene monomer was
charged into the reactor with a syringe. The
calculated amount of initiator was quickly syringed
into the reactor and immediately one could see the
formation of the orange polystyrl lithium anion. The
- 35 polymerization was allowed to proceed for 20 minutes to
ensure complete conversion.
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W093/~094 2 0 9 3 9 1 2 PCT/US92/07001
-21-
Upon completion of the polymerization, the
endcapping reagent t50% molar excess compared to
lithium) was added quickly via a syringe. The complete
disappearance of the orange color was indicative of
; s complete deactivation of the polymeric carbanion.
After functionalization, the polymers
(molecular weights greater than 3000 g/mole) were
precipitated in HPLC grade methanol which contained
~0.05% water (determined by titration). The
l0 precipitation and vacuum filtration were conducted
under a nitrogen blanket to minimize hydrolysis of the
trialkoxysilyl end-groups. Residual solvent was
removed in vacuo at 80C for 12 to 18 hours.
.
15 Pre~aration of the star ~olvmer:
C4Hg-polystyrene-CH2-para-phenyl-Si(OCH3)3 endcapped
polymer was dissolved in tetrahydrofuran to provide an
approximately 15-18 percent (weight/weight) solution.
20 A 4:1 molar ratio of water to silicon (based on polymer
repeat unit molecular weight) was added as a 0.15 N
solution of HCl. The solvent was allowed to evaporate
slowly at room temperature for 4 days. The reaction
product was then heated at 120C for ~8 hours.
Pre~aration of (T-P-E-Si~OR)3 composite
^~ Approximately 1.0 grams of C4Hg-polystyrene-
CH2-para-phenyl-Si(OCH3)3 endcapped polymer was
dissolved in tetrahydrofuran (approximately 0.075 M).
30 The endcapped polymer was then prehydrolyzed. For the
prehydrolysis, a 1.0 M HCl solution was added to the
~ tetrahydrofuran solution of the polymer in an amount
p such that the water:silicon ratio was 4:1. The
- resultant mixture was maintained at 30C for 1.0-1.5
- 35 hours at atmospheric pressure. The resulting solutions
were characterized by 29si NMR at the end of the
.
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W093/04094 ~ PCT/US9~/07001
20939 ~ ~ -22-
hydrolysis period to ascertain that hydrolysis was
complete and an acceptably low amount of condensation
had taken place.
After prehydrolysis, the MXn reactant:
tetramethoxysilane (also referred to herein as ~TMOSr)
sufficient to provide approximately 10 weight percent
TMOS was added to the THF/aqueous mixture of the
prehydrolyzed polymer. The reaction mixture was then
maintained at 30C and ambient pressure for
approximately 36 hours. Liquid was then evaporated
from the resultant mixture.
The following examples are presented for a
further understanding of the invention:
~E~AM~LE_1
Star polymer was prepared as disclosed above
using C4Hg-polystyrene-CH2-para-phenyl-Si(OCH3):3 end-
capped polymer having a molecular weight of 2,900
; 20 determined by Size Exclusion Chromatography (SEC) in
tetrahydrofuran at 30C using a viscometry detector and
universal calibration with polystyrene standards. 29Si
Nuclear magnetic resonance characterization was per-
formed using a Bruker AM-500 spectrometer at 99.32 MHz.
All samples were referenced to tetramethylsilane (TMS).
Chromium acetylacetonate ~Cr(acac)3] was added at
approximately 0.015 M to reduce the longitudinal relax-
ation time for the 29si NMR spectra. The spectra were
obtained using inverse-gated decoupling (decoupler on
during acquisition and off during relaxation delay) to
~- suppress any negative nuclear Overhauser effect. The
relaxation agent and decoupling sequence facilitated
~^ quantitative measurements. The 29si NMR indicated that
.,
- silicon atoms were condensed 66% percent to Si-O-Si and
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W093/04~94 2 0 9 3 9 1 2 PCT/US92/07001
-23-
that the distribution was 16~ T1, 70% T , and 14% T3.
The star polymer was readily dissolved in
tetrahydrofuran at 25C to provide a 15-20 percent
(weight/volume). An excess of trimethylchlorosilane
was added. The reaction was allowed to proceed for
~i several hours and then the reacted composite was
; isolated by precipitation in a nonsolvent: methanol
followed by evaporation of the nonsolvent. 29Si NMR
analyses, conducced as above-described gave a final
distribution of 0% T1, 52% T2, and 48% T3.
EX~PLE 2
The star polymer was prepared as described in
Example 1. The star polymer was then dissolved in
; tetrahydrofuran at 25C to provide a 15-20 percent
(weight/volume) solution. Endcapped polymer
trimethoxy(silylphenylmethyl) terminated polystyrene,
which has the general formula T-P-E-Si(OCH3)3, and
having the molecular weight of 10,100 was added to the
star polymer solution. The reac~ion mixture was
maintained at 25C for 24 hours. The reacted composite
produced was isolated by drying and precipitation.
Molecular weight analysis of the reacted composite
produced was conducted as described in Example 1 and
indicated an increase in molecular weight equivalent to
the addition of 2.4 endcapped polymer moieties to each
star polymer macromolecule.
EX.~MPLE 3
~ The procedures of Example 2 were followed
; with the following exceptions. The endcapped polymer
used was the same as in Example 2 except the molecular
weight was 45,800. The reaction mixture was allowed to
`- react for 24 hours. Molecular weight analysis of the
reacted composite produced was conducted as described
,~ in Example 1 and indicated an increase in molecular
weight equivalent to the addition of 1.1 endcapped
polymer moieties to each star polymer macromolecule.
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EX.~M~LE 4
- The TPSi(OR)3 composite was prepared as
follows. Approximately 1.0 grams of C4Hg-polystyrene-
benzyl-Si(OCH2CH3)3 endcapped polymer was dissolved in
tetrahydrofuran (approximately 0.075 M). The endcapped
~; polymer was then prehydrolyzed; For the prehydrolysis,
a 1.0 M HCl solution was added to the tetrahydrofuran
solution of the polymer in an amount such that the
water:silicon ratio was 4:1. The resultant mixture was
maintained at 30C for 22.0 hours at atmospheric
pressure, at which time an additional 16 equivalents of
1 M HCl was added-. Since hydrolysis and condensation
: we~e especially slow in this system, the reaction was
allowed to continue at that temperature and pressure
IS for an additional 47 hours. The resulting solutions
were then characterized by 29si NMR to ascertain that
hydrolysis was complete and an acceptably low amount of
i condensation had taken place.
Two equivalents of tetraethyl orthosilicate (Si-
'0 (OCH2CH3)4) were then added. After reacting for 12
days the reaction mixture was heated above its Tg, (to
110C), to push the condensation reaction to an
acceptable level.
; The TPSi(OR)3 composite was analyzed as
'5 follows: 295i Nuclear magnetic resonance
characterization was performed as in Example 1 and
indicated that silicon atoms were condensed as follows:
; T 63~ and Q 85%. The distribution was 13% T1, 31% T2,
; 7% T3, 30% Q3 and 19% Q4. The organic-inorganic
composite was readily dissolved in tetrahydrofuran at
`~ 25C. Trimethylchorosilane was added in a ten-fold
excess and the reaction mixture was reacted for about 5
hours at 25C. Analyses, conducted as described above,
~i gave a final distribution of 10% T1, 20% T2, 20% T3,
15% Q3 and 35% Q4. The final values for condensation
were T 73% and Q 93%.
,
.
W093/04094 2 0 9 3 912 PCT/US92/07001
-25-
EX.~MPLE S
TPESi(OR)3 composite was prepared as
-described above, having a molecular weight of
.approximately 100,000 determined by the same
s procedures used in Example 1. 29Si Nuclear magnetic
resonance characterization was performed as in Example
1 and indicated that silicon atoms were condensed as
:follows: T 82% and Q 85~. The distribution was 15%
T2, 12% T3, 5% Q2, 34% Q3 and 34% Q4. The organic-
;i,10 inorganic composite was readily dissolved in
tetrahydrofuran at 25C. Trimethylchorosilane in ten-
fold excess was added and the reaction mixture was
reacted for 48 hours at 25C. Analyses, conducted as
described above, gave a final distribution of 8% T2,
20% T3, 16% Q3 and 56~ Q4. The MMR integrals indicated
that the T type silicons were 91% condensed and the Q
type silicons were 95% condensed.
While specific embodiments of the invention
have been shown and described herein for purposes of
illustration, the protection afforded by any patent
which may issue upon this application is not strictly
limited to a disclosed embodiment; but rather extends
to all modifications and arrangements which fall fairly
within the scope of the claims which are appended
) 25 hereto:
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