Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
The copolymer compositions of the instant invention
comprise the polymerization product of the polysiloxane
monomers and monomer or monomers containing an activated
vinyl group. These polymers are employed to make biomed-cal
devices and optical products, e.g. contact lenses, intraocular
implants, etc.
25 BACKGROUND OF THE INV-NTION
Field of the Invention
This invention relates to novel polymeric compositions
and more particularly to biomedical devices made therefrom. These
~" '.
, ., ., _ . .. . . .. . ... , . _ . .
. ~ .
,
,
.
-
)7433
'
1 devices comprise ~illerless, oxygen txansporting, hydrolytically
stable, biologically inert, transparent, biomedical devices
prepared from the polymerization of monomers which are poly(or-
- ganosiloxanes~ a,~ terminally ~onded through divalent hydro-
: 5 carbon groups to polymerized, free radical polymerizably activated
unsaturated groups. The invention further particularly relates
^ to polymers and~or copolymers which comprise poly(organosiloxanes)
terminally bonded through divalent hydrocarbon groups to activated
unsaturated groups copolymerized with monomers containing
i::
activated vinyl groups. The copolymers are optically clear,
and colorless. The polymers and copolymers described herein
can be usefully employed for, as stated, making "hard" or
"soft" contact lenses, intraocular implants, as well as other
' ~
prostheses, more particularly "soft" contact lenses.
,,,: i ~
i~,,
~ 15 PRIOR ART STATEMENT
~' ~
The use of siloxane polymers for the fabrication of optical
contact lenses and biomedical devices is desirable. The desira-
bility is due to the high oxygen transportability and generally
the relative softness of polysiloxanes. The tear strength and
~ ~ 20 tensile strength of polysiloxane elastomers, however, are gen-
!~"'.;' erally poor and as a result fillers are employed to increase the
..;
~ strength of the elastomers. In U.S. Patent Nos. 3,996,187,
1~; 3,996,189, 3,341,490 and 3,228,741 there are described contact
lenses fabricated from poly(organosiloxanes) containing fillers.
The tear strength and tensile strength of the contact lenses made
' from the instant polymer are of sufficient strength so that no
:
~ .
-2-
. .
' '":
. ,~
:'
17~33
1 fillers are required.
U.S. Patents 3,996,187 and 3,996,189, as mentioned above,
disclose contact lenses made from rein~orced polysiloxanes.
The lenses contain various polysiloxanes with index of refrac-
tions similar to the silica filler so that an optically cIear
silica filled silicone elastomer can be formed ~rom aryl and
alkyl siloxanes. The material contains from 5 to 20 percent
silica. The silica is used, as mentioned, for strength. The
~instant invention contains no fillers for strength since the
instant material has sufficient strength without fillers.
U.S. Patent 3,341,490 discloses contact lenses made from
blends of siloxane copolymers containing reinforcing silica
fillers. As mentioned, the contact lenses or biomedical devices
of the instant invention contain no fillers.
U.S. 3,228,741 discloses contact lenses made from silicone
rubber particularly hydrocarbon substituted polysiloxane rubber.
This silicone material contains fillers such as pure silica to
control flexibility, pliability and resiliency of the lenses.
The instant polymers require no fillersO
U.S. Patent 3,808,178 discloses a polymeric material con-
taining a polymethacrylate backbone with relatively short poly
(organosiloxane) ester side chains on the backbone ~olymer~
There is no cross-linking involved in '178 since the monomers
disclosed in '178 are monofunctional i.e. have only one functional
; 25 group on each monomer. In order to get cross-linking in '178 it is
; taught at column 5 of '178 that different monomers must be added
for cross-linking which have more than one functionality. However,
- in the instant invention cross-linking is obtained since each
~, .
.: ' .
'7433
:, .
...... .
1 siloxane monomer is difunctional i.e. each monomer contains
. . - -
two functional groups, most preferably two methacrylate groups
` which results in cross-linking. Furthermore, contact lenses
- made from the polymers disclosed in '178 would not transport --
,
oxygen sufficiently whereas contact lenses made from the instant
` polymers would transport oxygen sufficiently to meet the require-
,:, ~ , . , _, .
ments of the human cornea. - ,l
U. S. Patent 3,518,324 teaches vulcanizing to make silicone
rubber whereas the instant invention is concerned with contact
lenses made from polymerizing specific monomers.
`~ U. S. Patent 3,878,263 teaches one configuration which
may be
15 . (R = C - C - OR" - SlO ~ Si~ Rc
... . .
Rs may be monovalent hydrocarbons.
R' may be a monovalent hydrocarbon. ~ ~
20 ~ 1 c may equal zero but when c equals zero then~rZ must be OR"".
;~ Z is an important ingredient since this is used to cross-
, ,~
link the chains. Therefore, the monomers of the instant invention
` are not taught in '263.
U. S. Patent 2,770,633 discloses 1,3-bis(4-methacryloxybutyl)
., :.,
tetramethyl disiloxane, one of the preferred monomers used in the
~-;- instant invention. This is taught at column 1, line 63 of '633
. , .
when R equals vinyl. However, '633 teaches only the monomer whereas
the instant invention teaches not only the monomer but the polymer.
In fact '633 would not want the monomer to polymerize since it would
not perform its function as a lubricant if polymerized.
--4--
~1~7~33
~"
1 U.S. Patent 2,906,735 teaches a reaction between an
alkyl siloxane and acrylic acid or a methacrylic acid resulting
in a disiloxane terminated by acrylate groups. '735 does not
teach the polymers of the instant invention.
U.S. Patent 2,922,807 discloses disiloxanes having acryloxy
or methacryioxy groups attached to the silicone through a divalent
alkylene radical of from 2 to 4 carbon atoms.
None of the above patents teach the instant invention much
less the preferred reactions of the instant invention which is
1,3-bis(4-methacryloxybutyl) tetramethyl disiloxane reacted with
preferably octamethyl cyclotetrasiloxane to form the preferred
monomer. This preferred monomer is then polymerized to the
preferred cross-linked polymer of the instant invention. Further-
more, and most importantly, none of the prior art teaches novel
contact lenses or biomedical devices of the instant invention
made from the instant polymers.
U.S. 3,763,081 discloses, in pertinent part, the polymeriza-
,
tion of an unsaturated siloxane which is somewhat difficult to
,:
polymerize since a double bond in this type of monomer generally
is not very active. One must use both high temperatures and a
; peroxide catalysis or a platinum catalysis in order to complete
this type of reaction. See, for example, '081 at column 4 lines
55-46. In the instant reaction the monomeric materials are
referred to specifically as having activated unsaturated groups
bonded through a divalent hydrocarbon group to the siloxa~e whereas
'081 has no activated unsaturated groups bonded to the siloxane.
U.S. Patent 2,865,885 in pertinent part teaches a vinyl
group which is not activated as shown in column 1 lines 25-30 of
... .
--5--
11~7~3~
~: .
~ 1 '885. The reason '885's double bond is not "active" in the sense
.
as defined in the instant application is that the double Oond is
` bonded to either sulfur or oxygen. In the instant invention this
same position would have a (-P-) carbonyl group. This would make
,~ .
the double bond active as defined in the instant application.
- Therefore, in '885 since the reactivity ratios are so different
: i.e. the double bond is not active in '885 as defined in the in-
stant invention, it would be very difficult to get an acceptable
copolymerization reaction using the formulae of '885 as compared
to the active double bond in the instant in~ention which easily
copolymerizes. In the instant invention the vinyl group is
"activated~' to facilitate free radical polymeri-zation. The
;- formula given at column 1, lines 25-30 of ~885 does not lend it-
self to free radical polymerization due to the lack of resonance
,
but rather it lends itself to ionic polymerization due to the
polar nature of the substituents. Therefore, it would be extremely
difficult, if at all possible, for '885 to form the compounds
of the instant invention. Also t.he compounds formed in '885 are
~ot hydrolytically stable becaùse of the presence of the silicone-
nitrogen bond in the formula. The instant invention cannot use
a hydrolytically unstable compound. Furthermore, the products
of this hydrolysis in '885 could be injurious to the human eye
particularly the amines. ~lso at column 3 of '885 the linkage
is an amine linkage to the double bond and in the instant invention
this linkage is always an alkyl. Therefore, '885 does not teach
the instant monomers.
U. S. patent 2,793,223 in pertinent part at Example 5 at
-5a-
433
1 column 3, lines 30-41 teaches that a phenyl group is attached
to the siloxane. Therefore, that material would be very hard
and opaque. This would be unsuitable ~or contac~ lens which
must be transparent. Furthermore, contact lenses made from
the polymers made from the monomers disclosed in '223, because
of the presence of the phenyl group on the siloxane as shown in
Example 5 of '223, would not transport oxygen sufficientiy
whereas contact lenses made from the instant polymers would trans-
port oxygen sufficiently to meet the requirements of the human
cornea.
Katz and Zewi, "Correlations Between Molecular Structure
and Some Bulk Properties of Highly Crosslinked Polysiloxanes",
J. Polymer Sci., Vol. 46, Pages 139-148 (1974) teaches,
in pertinent part, that divinyl monomers can be prepared
. ~ .
by esterification of the carboxyl-terminated compounds with
two molecules of a monoester of ethylene glycol and acrylic
acid. Polymerization can be effected by ultraviolet radiation
at room temperature. Also taught is the structure as shown
on page 146 of the Katz et al article. If this formula was
, .
broken down as it relates to the ma~erial taught in the
instant application, the formula would be as follows
. . .
~ .
.
:
.
5b
~7~33
. . .
~ -1 CH2-CH---
(A) C - 0
~ '
CH2
CH2
(R) 0
:~ C = O
~. I
- I 2
(CH 3 - Si - CH 3)
~'' O
: CH3~ cH3
CH2
~ 7 2
; 15 (R) C = 0
.. ~, ' - ' O
.~'- . I
CH2
~ (A) C = 0
In the above formula the R group has an ester linkage
whereas in the instant material the R is a hydrocarbon group.
Therefore, the R linkage in the Katz et al paper is
not as hydrolytically stable as the hydrocarbon linkage in the
instant polymer. The ester group in Katz et al can be
hydrolyzed. This stability is important if this material
is to be used in soft contact lenses since soft contact lenses
are usually heated in order to disinfect them. As mentioned,
- , .
, .
1~7~33
1 if the lens loses its shape, then it loses its optics. It
should be understood that the instant material does have an
ester linkage. However, this linkage is between the-A and
the R groups. It is actually located in the A group as
illustrated below by a formula of one of the most preferred
embodiments of the instant invention.
=.
,
I CH
-
(A) C = 0
, . I . . .
; ' 10 o
C H 2
: (R) ~
.,,. . ~ .
- CH3-1i-CH3
` ` 15 ~
... I
CH3_Si_CH
,., . ~
; 20 (R) ~
CH 2
O
) C = O
~--~CH 2- C----
CH
' .
.. ' .
. .
-5d-
~1~7433
1 This Katz et al reference, in addition to teaching
the specific formula on page 146, merely teaches that
phase differences are detectable as the siloxane chain
length is decreased. As the siloxane chain increases in
length, Katz et al teaches that the phase differences are
lost and these differences merge into one conti~uous
transition.
In addition to the above, it is important to note
that Katz et al does not suggest any usage for this material.
Katz and Zewi l'Some Rheological Properties of Highly
.,
Crosslinked Polysiloxanes" J. Polymer Sci. Vol. 13, Pages
: 645-658 (1975) teaches, in pertinent part, the same materials as taught in the above cited (1974) article by Katz et al.
This article teaches in more detail the steps necessary in
order to make the starting materials for the polymer as taught
in the '74 article. Katz et al is teaching in this article,
in pertinent part, how to synthesize the carboxyl terminated
siloxane. This is illustrated on pages 646-647. Katz et al
then cross-links this using a different chemical reaction
than in the instant application in order to make the polymer
as shown on page 649. This polymer is not related in any way
to the instant materials. In addition to the above, it is
important to note that this Katz et al reference also makes
no mention of any uses of the material.
Katz and Zewi "Microheterogeneity in Crosslinked Polysiloxane"
J. Polymer_Sci. Polymer Chemistry Addition, volume 16, pages 597-
614 (March, 1978) teaches, in pertinent part, the same materials
as taught in the above cited (1974) and (1975) articles by Katz
et al. The only new material mentioned appears on pa~e 598,
- 30 line 8 i. e. cross-linked polyesters. However, these cross-linked
polyesters are not pertinent to the instant 2ppl' cation.: Katz
,,
.
11~37433
et al is teaching in this article, in pertinent part, how to
prepare the monomers which are also disclosed in the instant
application. Katz et al is merely suggesting the same cross-
linked material as he suggested in his earlier (1974) and
(1975) articles. Katz et al then discusses the physical
- properties and the microheterogeneity of these cross-linked
.... .
polymers. He discusses the difference in the phase separation
- on the submicroscopic scale. As tc the physical properties
~ which Katz et al mentions in his article, on page 597 he dis-
,; 10 cusses the physical properties in general of polysiloxanes.
Katz et al talks about specific properties of his polymers
at page 609 where he presents modulus-temperature data. Then
he discusses cross-linking efficiency on page 607. He is
measuring properties which will give him an idea of his
15 efficiency of cross-linking. Again, it should be stated that
Katz et al in this (1978) article teaches no more material than
he taught in his earlier articles except for the disclosure
of the cross-linked polyesters on page 598. However, these
materials are not relevant to the instant application. In
20 addition to the above, it is important to note that this
Katz reference also makes no mention of any uses of this material
except as possible sealants.
,~:
~:'
,~ .
:,
:
-5f-
'''
33
- 1 SUMMARY OF THE INVENTION
.
., .
The present invention provides materials which can
- be use~ully employed for the fabrication of prostheses
such as heart valves and intraocular lenses, as optical
contact lenses or as films. - - -
In one embodiment of this invention is providedfillerless, oxygen transporting, hydrolytically stable,
biologically inert, transparent shaped article for use ir1
biomedical applications except as contact lenses comprising
a crosslinked polymer made from a poly(organosiloxane) ,~
terminally bonded through a divalent hydrocarbon group to
polymerized, ~ree radical polymerizably activated, unsaturated
groups.
When the terms "activated" or "free radical polymerizably
activated" are used with the term "unsaturated groups" herein,
lt is meant that an unsaturated group which is activated is one
which has a substituent which facilitates free radical poly-
merization. These activated-unsaturated groups are polymerized
to form the polymers o~ the instant invention. Pre~erably, the
activating groups used herein lend themselves to polymerization
under mild conditions, such as, ambient temperatures.
When the statement is made "a poly(diorganosiloxane)
monomer ~,~ terminally bonded through divalent hydrocarbon
~ groups to polymerized free radical polymerizably activated
- 25 unsaturated groups" it is meant that the poly(organosiloxane)
- compound as described herein has been attached to a compound
having a divalent hydrocarbon group, such as, methylene or
propylene etc. and then at each end o~ this compound is attached
~t~ 33
.
1 an activated unsaturated group such as methacryloxy etc. and
this then is the most preferred monomer. Then when the
monomers are polymerized (i.e. cross-linked) the activated
unsaturated groups are polymerizated (free radical polymeriza- --
tion) then the monomers form three dimensional-homopolymers
or copolymers which are the materials of which the contact
ienses or biomedical devices are made.
The monomers employed in accordance with this invention,
as a result of the presence of the act.ivated unsaturated groups,
are readily polymerized to form three dimensional polymeric net-
works which permit the transport of oxygen and are optically clear,
strong and can be made, as desired, soft or hard.
When the term monomer is used herein we mean to include
polysiloxanes end-capped with polymerizable unsaturated groups.
The process of lengthening the siloxane portion of the monomer
is referred to herein as siloxane ring insertion. The chain
length of the polysiloxane center unit of the monomers may
be as high as 800 or more.
When the term polymerization is used herein we refer to
the polymerization of the double bonds of the polysiloxanes end-
capped with polymerizable unsaturated groups which results in a
cross-linked three dimensional polymeric network.
The relative hardness (or softness) of the contact
lenses, i.e. polymer, of this invention can be varied by
decreasing or increasing the molecular weight of the mono-
meric poly(organosiloxane) end-capped with the activated
unsaturated groups or by varying the percent of the comono-
mer. As the ratio of organosiloxane units to end cap units
'
.. ..
-7-
,
7~ 3
1 ~ncreases the softness of the material increases~- Converse-
ly, as this ratio decreases the rigidlty and hardness of the
material increases.
More preferably there is provided a fillerless, oxygen
transporting, flexible, hydrolytically stable, biologically
inert, transparent, resilient, soft, polymeric contact lens
or shaped article for use in biomedical applications other
than as contact lenses comprising a poly(organosiloxane)
-terminally bonded through divalent hydrocarbon groups to
polymerized, free radical polymerizably activated~ unsaturated
rrou~s forming a homopolymer in a cross-linked network. This
preferred contact lens may be formed by spin casting, if desired,
such as taught in U.S. patent 3~408g429~
In another embodiment of this invention there are pro-
lS vided polymerizates comprising a poly(organoslloxane) ~,~terminally bonded through divalent hydrocarbon groups to
polymerized, ~ree radical polymerizably activated unsaturated
groups copolymerized with one or more monomers which can be one
of lower esters of acrylic or methacrylic acid, styryls~ allyls
or vinyls forming a copolymer in a cross-linked network. The
copolymers are in the form of three dimensional networks which
are clear, strong and can be usefully employed in providing
films, and shaped bodies such as contact lenses.
The novel copolymers of this invention can comprise 10
to 90 parts by weight of one or more of the monomers of (organo-
siloxanes) described herein and 90 ~o 10 parts by weigh~ of the
polymerizable monomers. The preferred contact lenses or biomedical
device formed from these copolymers are fillerless, oxygen trans-
~ 7~33
.. .
1 porting, flexiblej hydrolytically stable, biologically inert,
transparent, resilient and soft.
Tne three-dimensional network polymer products of this -
nvention are readily prepared by means of conventional free
~ radical polymerization techniques. The monomers of organosiloxane
; alone or in the presence of comonomers together~with about 0.0~
to about 2% by weight of a free radical initiator may be heated
~o a temperature of about 30C to about 100C to initiate and
complete the polymerization. The polymerizable monomers i.e.,
. . ,
the poly(organosiloxane), with or without comonomers can prefer-
ably be sub~ected at room temperature to irradiation by W light
in the presence of suitable activators such as benzoin, acetophe-
; none, benzophenone and the like for a sufficient time so as to
form a three dimensional polymer network.
The polymerization can be carried out directly in contact
lens molds or can be cast into discs, rods or sheets which can
then be fabricated to a desired shape. Preferably the polymeri-
zation is carried out while the material is being spin cast such
as taught in V.S. patent 3,408,429.
As is well established~ the oxygen transportability of
polysiloxanes is substantially greater in comparison to the
; conventional contact lens polymers such as polymethyl methacrylate
- (PM~IA) or polyhydroxyethylmethacrylate (PHEMA). The oxygen
:
; transpor~ability of the materials of this invention can be
:,
2~ varied by altering the percentage oP siloxane l1nits. For
exa~ple, a high percentage of siloxane units results in a
- product more capable of transporting oxygen as compared with
; a lower percentage of siloxane units which results in a
,~aterial with less ability to transport oxygen.
' ' ; :
. ;' . ,
.,' -9-
.' .
1L3;~
1 DESCRIPTION OF PREFERRED ~MBODIMENTS
In accordance with one embodiment of this invention --
optical contact lenses or shaped articles for use in biomedical
ap?lications are provided which are fabricated from three-
5 d~mensional network polymerizates of poly(organosiioxanes)
~,~ terminally bonded through divalent hydrocarbon groups to
polymerized free radical polymerizably activated, unsaturated
croups. Typically, the poly(organosiloxanes) i.e. monomers,
e~.~loyed are of the formula:
~ 3~ ll
A-R-Ii t O-Si t O-Si-R-A
R2 \ R4J R2
~herein A is an activated unsaturated group, R is a divalent
hydrocarbon radical having from 1 to about 22 carbon atoms,
Rl, R2, R3 and R4 can be the same or different and each is one
of a monovalent hydrocarbon radical or a halogen substituted
monovalent hydrocarbon radical each having from 1 to about 12
carbon atoms and m is O or greater.
Desirably m can be in the range of 50 to about 200.
However, the range of m can be greater such as preferably 50 to
800. However, m can be greater than 800. Should one desire to
obtain a harder contact lens m should be less than 25.
~ hen the term "soft" is used herein to describe the
contact lenses or the biomedical devices of the instant invention
it is meant that m, in the above formula, after polymerization,
is more than 25, preferably from about 50 to about 800. When
10~
7433
1 ~he term "hard" is used herein to describe the contact lenses
or the biomedical devices of the instant invention, it is
~e2nt that m, in.the above formula, after polymerization, is
less than 25.
Pre~erably A is one of
2 - cyanoacryloxy
11
CH2 = lC - C - O -
C -- ~ .
. 10 acrylonitryl
CH2 = f -
C - N
acrylamido
., ., O
` 1 '11
. ~ CH2 = CH - ~ - NH -
acryloxy
'' 11
: CH2 = CH - C - o -
~ methacryloxy
:,
20 CH2 = C - C - O -
CH3
- styryl
~ . CH = CH2
:; .
-lOa-
,
~ 7433
1 and
N - vinyl - 2 - pyrrolidinone - x - yl
wherein x may be 3, 4 or 5
CH - CH
/ 2 2
CH = CH - N
Il CH2
10 ~ 3
~ ore preferably A is acryloxy or methacryloxy. Howeverg
other groups containing activated unsaturation can be readily
employed, such groups being ~ell known to those skilled in the
art. Most preferably A is methacryloxy or acrylamido. R may
be preferably an alkylene radical. Therefore, preferably R is
methylene, propylene, butylene, pentamethylene, hexamethylene,
octamethylene, dodecylmethylene, hexadecylmethylene and
octadecylmethylene; arylene radicals such as phenylene, bi-
phenylene and the corresponding alkylene and arylene radicals.
More preferable R is an alkylene radical having about 1, 3 or 4
carbon atoms. Most preferably R is an alkylene radical having
from about 3 to 4 carbon atoms e.g. hutylene. Preferably, Ri, R2,
R3 and R4 are alkyl radicals having frGm 1 to 12 carbon atoms, e.g.,
methyl, ethyl, propyl, butyl, octyl, dodecyl and the like, cycloalkyl
radicals, e.g., cyclopentyl, cyclohexylg cycloheptyl and the like,
mononuclear and binuclear aryl radicals, e.g., phenyl, naphthyl
and the like; aralkyl radicals, e.g., benzyl, phenylethyl,
~7~33
1 - phenylpropyl, phenylbutyl and the like; alkaryi radicals,
e.g., tolyl, xylyl, ethylphenyl and the like; haloaryl
radicals such as chlorophenyl3 tetrachlorophenyl~ difluoro-
phenyl and the like; halo substituted lower alkyl radicals
having up to about four alkyl carbon atoms such as floromethyl
and floropropyl. More preferably Rl, R2, R3-and R4 are methyl
radicals and phenyl radicals, most preferably R~, R2, R3 and R4
are methyl radicals.
The activated unsaturated group end-capped polysiloxanes,
i.e. monomers, employed in this invention can be prepared by
equilibrating the appropriately substituted disiloxane, for
example, 1,3-bis(4-methacryloxybutyl) tetramethyl disiloxane,
- with a suitable amount of a cyclic diorganosiloxane, e.g.,
hexamethyl cyclotrisiloxane, octaphenyl cyclotetrasiloxane,
hexaphenylcyclotrisiloxane, 1,2,3-trimethyl- 1,2,3-triphenyl-
cyclotrisiloxane, 1,2,3,4-tetramethyl- 1,2,3,4-tetraphenyl
.cyclotetrasiloxane and the like in the presence of an acid
,
or base catalyst. The degree of softness, the physical pro-
perties such as tensile strength, modulus and percent elonga-
tion will determine the amount of cyclic diorganosiloxane
equilibrated with the disiloxane. By increasing the amount of
; cyclic siloxane one increases m.
The reaction between a cyclic diorganosiloxane and
di~iloxanes, although not specifically disclosed for the
disiloxanes employed in this invention as to provide the activated
unsaturated groups as the end caps for polysiloxanes, is a
conventional reaction aId described by, for example, Kojima et al.
. , :
-12-
33
1 Preparation of Polysiloxanes Ha~ing Terminal Carboxyl or
:. Hydroxyl Groups, J. Poly~ Sci., Part A-l, Vol. 4, pp 2325-27
; (1966) or U.S. Patent No. 3,878,263 of Martin issued April
15, 1975.
The following reactions represent the most preferred
materials of the instant invention. 1,3-bis~hydroxyalkyl) tetra-
methyl disiloxane dimethacrylates are prepared by the following
reactions: (11 esterification with acryloyl or methacryloyl
,
: chloride or anhydride. For example, the following is with
methacryloyl chloride:
'''
ICH3 fH3
HO tCH2 ~n ~i - O - ~i tCH2tn OH
~ 15 CH3 H3
:~''. +
. ICH3 R n preferably = 1,3 and 4
. ¦ n most preferably = 3 or 4
.~ 2 CH2 = _ I 1 _ Cl
- fH3 ~ ~H3 fH3 ~ f
- - tCH2tn ~i - O - ~i tCH2tn
H2 H3 H3 H2
n preferably = 1,3 or 4
: n most preferably = 3 or 4
. (2) Another most preferred method of preparing 1,3-bis(hy-
. drosyalkyl) tetramethyl disiloxane dimethacrylates is by transesteri- :
-13
., . ~ '.
t7433
. l fication with methyl methacrylate: -
., ,
CH3 1l. CH3 C-H3
3 HO ~CH2~nSi - O - 1i ~CH ~ OH
CH3 3
: 1 3 1 1CH3 ICH3 - ~ 1l fH3
CH = C - C ~ ~CH2~n 1i - O ~ CH2~n 2
CH3 CH3
~'~ 10
, .
.; n preferably = I,3 or 4
. n most preferably = 3 or 4
....
- Then the number of siloxane groups between the two
methacrylate caps can be increased from 2 to 2+4X by a ring
opening insertion reactlon with X moles of octamethyl
cyclotetrasiloxane as follows:
CH O _fH3 fH3 1 fH3
., CH2 = C - C ~ ~CH2~n 1 i - o - si ~CH2~ 0 - C - C = CH
~ CH3 c~3
.. : . .
n preferably = l, 3 or 4
+ n most preferably - 3 or 4
,'', . ,
CH3 1 3
CH - Si - O Si - CH
X moles O O
I I
CH3 - Si - O - Si - CH
1 1 3
CH3 CH3
: , -
' , \ /
-14-
~1~7~33
1 CH3 f CH3 ~1CH3 ~ f 3 I CH3
C C - ~CH2~n Si - --si-o t Si ~CH2~n Il
:~ H2 CH3 ~ 3 Jm 3
n preferably = 1, 3 or 4 - m preferably = 50 to 800
n most preferably = 3 or 4 . . _ .
\ (cross~linking/pnlymeriza~ion)
(three dimensional network)
1 1l fH3 ~1CH3 ~ I 3
H3 ~ CH CH3 3
CH CH2
., ' I H2
~ 0 - C - C - CH CH3 - C - C -
n preferably = 1, 3 or 4
n most preferably = 3 or 4
m preferably = 50 to 800
~'. , ' ,.
.:
11~7433
1 The poly(organosiloxanes) ~,~ termina'ly bonded through
divalent hydrocarbon groups to polymerized, free radical
polymerizably activated unsaturated groups i.e. the-monomers
herein, are generally clear, colorless liquids whose viscosity -~
; 5 depends on the value of m. These monomers can be readily -
~, ~ .. . .
cured to cast shapes by conventional methods su~h as UV poly-
mérization, or through the use of free radical initiators
:~ plus heat. Illustrative of free radical initiators which can
!, ' .
~e employed are bis(isopropyl) peroxy dicarbonate, azobisisobuty-
ronitrile, acetyl peroxide, lauroyl peroxide, decanoyl peroxide,
benzoyl peroxide, tertiarybutyl peroxypivalate and the like.
In order to further control the properties of the
polymers of the instant invention one can polymerize a mixture
of the monomers comprising monomers having a low value of m
and monomers having a high value for m. When m has a low
.. . . .
~ v~lue i.e., below 25, the resulting contact lenses or biomedical
.
; devices i.e. polymers, are relatively hard, oxygen transporting,
. . .
hydrolytically stable, biologically inert, transparent and do
not need fillers to improve the mechanical properties. The
monomers have a relatively low ~.olecular weight and as a result
the viscosity is low enough e.g. about 3 centistokes so that the
lenses may be made easily by spin casting. When m has a relatively
high value i.e., above 25, the resulting contact lenses or
biomedical devices i.e. polymers, become relatively soft, oxygen
transporting, flexible, hydrolytically stable, biologically
inert, transparent, resilient, and do not need fillers to improve
; the mechanical properties. The monomers should have pr-eferably
a molecular weight low enough so that the viscosity is low
; enough to spin cast the monomers e.g. about 175 stokes or below
measured in Gardner viscosity tubes. Preferably m is about 50
to 800.
"~:
,, ' :
-16-
7433
1 In accordance with another embodiment of this invention
there are provided polymers of monomers which are poly(organo-
siloxane) terminally bonded through a divalent hydrocarbon
group to an activated unsaturated group copolymerized with
monomers containing an activated vinyl group.
The comonomer can be any polymerizable monomer ~lhich
readily polymerizes by ~ree radical polymerization an~
preferably is a monomer containing an activated vinyl group.
Through the addition of comonomers one can enhance particular
desirable properties. For example, buttons fabricated from
copolymers of the instant monomers of the poly(siloxanes) and
tetrahydrofurfuryi methacrylate can be more easily lathed into
contact lenses as compared with buttons i.e. polymers, made
from monomeric polysiloxanes alone. Wettability o~ contact
lenses i.e. polymers, fabricated from the polysiloxanes can be
substantially increased by copolymerizing the instant monomers
with N-vinyl pyrrolidone.
Illustrative of comonomers which can be use~ully employed
in accordance with this invention are:
The derivatives o~ methacrylic acid, acrylic acld,
itaconic acid and crotonic acid such as:
methyl, ethyl, propyl, isopropyl, n-butyl,
hexyl, heptyl, aryl, allyl, cyclohexyl, 2-hydroxyethyl, 2 or 3-
hydroxypropyl, butoxyethyl, methaerylates; and pro?yl, iso?ropyl,
butyl, hexyl, 2-ethyl hexyl, heptyl, aryl, acrylates; and propyl,
isopropyl, butyl, hexyl, 2-ethyl hexyl, heptyl, aryl, itaconates,
and propyl, isopropyl, butyl, hexyl, 2-ethyl hexyl, heptyl, aryl,
crotonates.
.,'` .
17-
:' ' ,
1:107433
'`` Mono or di esters of the above mentioned acids with
. ~.
~ polyethers of the below general formula may be used:
,.. ..
~ HO(CnH2nO~qH
. ~ .
~A
wherein n is a number of from 1 to about 12, preferably
~z 5 2 or 3, and q is a number of from 2 to about 6 preferably 2 to
,,.~,
3.
Other comonomers may include:
styryls, such as, tertiary butyl styrene, propyl styrene,
~, styrene, divinyl benzene, vinyl ethyl benzene, vinyl toluene etc.
Allylic monomers, such as, di allyl diglycol dicar- -
bonate, allylcyanide, allyl chloride, diallyl phthalate, allyl
bromide, diallyl fumarate and diallyl carbonate may be used.
; Nitrogen containing monomers can be also used, such as:
n-vinyl pyrrolidone, 3-oxybutyl acryamide, etc.
;~ 15 The lower the value of m in the formula for the instant
- monomers the more compatible are the monomers with the above men-
tioned comonomers.
The advantages of using the contact lenses or biomedical
devices i.e. polymers, of the instant invention which are made
from the monomers disclosed herein are numerous. For example,
(1) the advantages of using activated vinyl terminal groups to
cure the siloxane material are (a) the high reactivity systems
permit rapid cure at room temperature if suitable initiators
~; are used. Room temperatures are preferred. This is desirable
:~ 25 since the preferred method of casting the contact lens is spin
casting. (b~ No fillers are needed to get useful physical
strength as is common with most silicone resins. This is desirable
~ since the use of fillers requires that other possibly undesirable
:''''
.~
-18-
.,
,
~1~7~33
1 materials be added to the composition in order to correct the
refractive index of the contact lenses. (2) Furthermore,
the contact lenses or biomedical devices made from the
polymer of the ihstant invention a~e oxygen transporting. ~
The human cornea requires about 2 x 10-6 cm3/ (sec. cm2
a m.) of oxygen through the contact lens as reported by Hill and
Fatt, American Journal of Optometry and Archives of the ~eri-
can Academy of Optometry, Vol. 47, p. 50, 1970. When m is at
least about 4 the chain of siloxane is long enough in the instant
composition to e~ceed the oxygen transportability requirements
of the cornea and other living tissue. However, in specific
situations m may be as low as 0. Because of the unique proper-
ties of the contact lenses or biomedical devices i.e. polymers,
of the instant invention m may be great enough to allow sufficient
oxygen transportability and at the same time still retain its
desirable properties of elasticity, tear resistance, flexibility,
resilience and softness.
When the term oxygen transportability or oxygen transporting
is used in the instant application it is meant that the material
will allow sufficient transmission of oxygen through itself to
supply the necessary oxygen requirements of the human cornea and
other living tissue. The oxygen requirement for the human cornea
as mentioned, is about 2 x 10 6 cm3/ (sec. cm2 atm.). The oxygen
transportability was determined by a special test procedure
; 2~ described in conjunction with Example 10 herein. (3) These
lenses and biomedical devices are hydrolytically stable meaning
that when the contact lenses or devices are placed into an
aqueous solution~ e.g., in the eye, or during the disinfectin~
step, i.e. water plus heat, the lenses or devices will not change
in chemical composition, i.e. hydrolyze and cause the lenses or
the devices to change shape resulting in an undesirable change in
optics or shape. (4) The more preferred contact lenses or
. ~ :
1~ 33
, ....... .
;; 1 biomedical devices of the instant invention are aiso resilient.
When the term resilient is used herein it is meant that after
the lenses or biomedical devices have been deformed the lenses -
or devices will return quickly to their original shape. (5)
The lenses are preferably made by spin casting, e.g. by the
method as disclosed in U.S. 3,408,429. Monomers which have
:
; too high a viscosity cannot be spin cast. However, generally
the higher the molecular weight of the monomers the longer
the chain length, i.e. the larger the value of m, and as a
consequence the more desirable the properties are for the
~referred contact lenses i.e. polymers, of the instant invention,
made from these monomers. The longer the chain length and the
higher the molecular weight the higher the viscosity of the
monomers. However, if spin casting is to be used the viscosity
of the monomers must be such that these materials can be spin
cast. The monomers of the instant invention can have molecular
weights high enough to give all the desirable properties when
polymerized but low enough to be spin cast while still in the
monomeric form. The preferred weight average molecular weight
is from about 4,000 to 60,000 for the monomers of the instant
.~
invention. (6) The most preferred contact lenses or biomedical
devices of the instant invention should be soft. By the use
of the term "soft" in the instant application it is meant in
the preferred embodiment that the lenses should have a Shore
2~ hardness of about 60 or below on the A scale. (7) The preferred
contact lenses or biomedical devices of the instant invention
should be flexible. When the term "flexible" is used herein, it
is meant that the contact lens or biomedical device is ca~able
of being folded or bent back upon itself without breaking.
-20-
11~743~
1 The most preferred contact lens or biomedical device of
the instant invention is a fillerless~ oxygen transporting,
flexible, hydrolytically stable, biologically inert, trans-
parent, resilient, so~t, polymeric contact lens or shaped
article for use in biomedical applications comprising a
- poly(organosiloxane) monomer ~,~ terminally bonded throu~h
divalent hydrocarbon groups to polymerized free radical
polymerizably activated unsaturated groups. The poly(organo-
siloxane) monomer used to make the polymer from which the
contact lens or biomedical device is made has the formula
in the most preferred embodiment of the instant invention of
A - R - li ~ - Si t - si R - A
R2 ~ R4/m R2
wherein A is selected from the group consisting of methacryloxy
and acryloxy, R is an alkylene radical having from about 3 to
about 4 carbon atoms and m is from about 50 to 800.
The most pre~erred contact lenses or biomedical devices,
,
i.e. polymers, of the instant invention, as mentioned, are
- 20 fillerless, have an oxygen transport rate of at least about
2 x 10 6 cm3/ (sec. cm2 atm.), are hydrolytically stable,
biologically inert, transparent, resilient, and have a softness
preferably of about 60 or below on the Shore hardness A scale.
Most pre~erably the Shore hardness should be 25 to 35 on the A
- 2~ scale.
-21-
1~ 743;3. :
, . .
" 1 To further illustrate the most preferred contact lenses --
, ...................................................................... . .
or biomedical devices of the instant invention's physical
properties, the tensile modulus of elasticity should be about
,400 g/mm/mm2 or less. Both the Shore hardness and modull~s
are related to the comfort of the lenses to the wearer when
used on the human eye.
Another advantage of the preferred soft co-ntact lenses of
the instant invention is that lenses made from the polymers of the
~' instant invention can be made large enough to cover the entire
cornea of the eye resulting in more comfort. Hard contact lenses,
;', such as PMMA lenses, have to be made smaller due to their poor
. ,,
oxygen transportability. Furthermore, the larger the lenses,
-'the easier it is to locate the optical center of the lenses.
: . , .
, The larger the lens the easier it is to maintain the optlcal
''axi's which is required in making special lenses for people
~, wlth particular eye problems, e.g., for those persons with
astigmatism. Another advantage of the preferred soft lenses
of the instant invention is that the instant preferred soft
' lenses have a softness similar to HEMA lenses but in addition,
and most importantly, are more oxygen permeable, i.e. are
, cap,able of transporting more oxygen. HEMA lenses are not
oxygen permeable or capable of transporting oxygen to a degree
necessary to meet all the requirements of the human cornea.
22-
1~t7433
.
1 When the word "oxygen permeable".is used herein it means
that the instant biomedical polysiloxane material will trans- ~
port oxygen at a rate of at least about 2 x 10~6cm3/(sec. cm2
atm. ) .
While the polysiloxane of the instant invention can be
used to prepare contact lenses these polymers and copolymers
can also be employed for other uses, such as, shaped articles
for use in biomedical applications. These polymers and copoly-
mers can be used to make biomedical devices i.e. shaped articles,
:~ 10 such as dialyzer diaphragms, to prepare artificial kidneys and
other biomedical implants, such as disclosed in Wichterle, U.S.
Patent 2,976,576 and Wichterle, U.S. 3,220,g60. The instant
" .
polymers and copolymers can be used in preparing therapeutic
. bandages as disclosed in Shephard, U.S. Patent 3,428,043. The
, .
1~ instant polymers and copolymers can also be used in preparing
- medical surgical devices e.g. heart val~es, vessel substitutes,
intrauterine devices, membranes and other films, dialyzer dia-
, .... .
phragms, catheters, mouth guards, denture liners and other such
- devices as disclosed in Shephard U.S. Patent 3,520,949 and
Shephard U.S. 3,618,231. The instant polymers and co-polymers
can be used to modify collagen to make blood vessels, urinary
.bladders and other such devices as disclosed in Kliment U.S.
Patent 3,563,925. The instant polymers and co-polymers can
. be used to make catheters as disclosed in Shephard U.S. Patent
; 2~ 3,566,874. The instant polymers and co-polymers can be
used as semipermeable sheets for dialysis, artificial dentures
and all of such disclosures as set forth in Stoy U.S. }atent
'
-22a-
7~33
.
1 3,607,848. The instant polymers and co-polymers can be used-
in making breathable leather and other materials as-disclosed
in Shephard, U.S. Patent 3,660,218. The instant polymers and
co-polymers can be used in ophthalmic prostheses and all other
uses disclosed in Wichterle U~s? Patent 3,67~,5Q4. The instant
co-polymers and polymers can be used in making printing plates
and for other similar type uses as disclosed in Takaishi
U.S. Patent 3,733,200.
When the terms "shaped article for use in biomedical appli-
cations" or "biomedical device" are used herein it is meant
that the materials disclosed herein have physiochemical proper-
ties rendering them suitable for prolonged contact with living
; tissue, blood and the mucous membrane such as would be required
for biomedical shaped articles, such as, surgical implants,
blood dialysis devices, blood vessels, artificial ureters,
artificial breasts tissue and membranes intended to come in
contact with body fluid outside of the body, for example,
membranes for kidney dialysis and heart/lung machines, and
the like. It is known that blood, for example, is rapidly
damaged in contact with artificial surfaces. The design of a
synthetic surface which is antithrombogenic and nonhemolytic
to blood is necessary for prosthesis and devices used with blood.
The instant polymers and copolymers are compatible with living
tissue.
The instant polymers and copolymers disclosed herein can
be boiled and/or autoclaved in water without being damaged
whereby sterilization may be achieved. Thus, an article
formed from the instant polymers and copolymers disclosed herein
may be used in surgery where an article compatible with
living tissue or with the mucous membrane may be used.
~ .
-22b-
~1~7433
1 The following examples are illustrative only and should
not be construed as limiting the invention. All parts and
percents referred to herein are on a weight basis and all
viscosities measured at 25C. unless otherwise specified.
. ' '" ,.
A ~ . EXAMPLE 1
': .'~
557 g of 1,3-bis(4-hydroxybutyl) tetramethyl disiloxane,
634 g of dry pyridine and 2 liters of hexane are charged to a 5
liter reaction flask equipped with a mechanical stlrrer and
drying tube. The mixture is chilled to 0C and then 836 g of
methacryloyl chloride is added drop wise. The mixture is
agitated continuously overnight. The reaction solution is ex-
i ....
tracted consecutively with 10% water solutions of HCl and NH3
in order to remove excess reagents and pyridine hydrochloride.
.. ..
The resulting solution of the product in hexane is dried with
;15 anyhdrous MgS04, filtered, and solvent removed at reduced pressure.About 459 g (55% yield) of 1,3-bis(4-methacryloxy butyl) tetra-
methyl disiloxane is collected. The structure is confirmed by
infrared spectra, proton magnetic resonance spectra and elemental
analys~s. IR spectra shows no intense hydroxyl band between
3100 and 3600 cm~l but does show strong methacrylate absorptlons
at 1640 and 1720 cm~l. PMR spectra agreed with the proposed
structure:
-22c--
1~7~33
H\ /CH2 -~CH5 ~ CH6 -Si C
1,3-bis(4-methacryloxy butyl) tetramethyl disiloxane.
,:'. .
; 1 0
Proton ~ Integrated Area Multiplicity
. H1
2 1 singlet
H3 6.50 1 singlet
H 3.00 3 singlet
H 5.15 2 triplet
., ~
H~ 2.7 4 multiplet
H6 1.65 2 triplet
H 1.20 6 singlet
Elemental analysis gave 13.6% Si (calc. 13.5%)~ 58.1% C
~calc. 57.9%, and 9.4%H (calc. 9~2%). The product was a clear,
colorIess, fragrant fluid.
EXAMPLE 2
The fluid product of Example 1 is placed between glass
plates with 0.2% benzoin methyl ether and irradiated with W
light at room temperature. A colorless, optically clear, hard,
.
-23-
~1~7433
1 highly crosslinked film is obtained- The follo~ing is a represen-
tation of the cross-linked polymer.
~ (three dimensional network)
- CH2 CH
3 1_C_o-cH2~cH2~2cH~-si-o-si-cH2~c~2~2cH2-o-8-( ~-CH3
~ CH3 CH3
CH2 2
~H ~ --C~2~H2~2c~2-Sl-o-ll_c~2~c~2~2 2 3
1 2 1 2
1 2 iCH2
3 CH3-C-~_
EXAMPLE 3
489.75 g of octamethylcyclotetrasiloxane and 10.25 g of 1,3-
bis(4-methacryloxybutyl) tetramethyl disiloxane are charged into a
reaction vessel equipped with a mechanical stirrer. About 25 g of
Fuller's Earth and 1.35 ml of conc. H2S04 are mixed and added to
. the vessel with continuous stirring while bubbling dry N2 through
the reaction mixture. The charge is warmed to 60C and stirred
for two days, at which time the viscous fluid is neutralized with
Na2C03, diluted with hexanes, and filtered. The hexanes/monomer
solution is washed with water, dried with MgS04 (anhydrous) and
:
-24- ;
~1~7~3;~ .
1 solvent removed at reduced pressure. Low molecular weight
unreacted cyclic siloxanes are removed by heating the monomer
to 110C at 0.2 mm Hg in a rotary evaporator. The product
~- obtained is an odorless, colorless, clear fluid of 8.5 stokes
viscosity measured in Gardner Vlscosity tubes. The monomer
comprised about 260 repeating Me2tSiO units. ~luid collected
during the devolatilizing of the product shows no methacrylate
absorptions in IR spectra and could not be cured.
IR spectra of the monomer shows a slight methacrylate
absorption and broad siloxane absorptions between 1000 and 1100
. . .
cm~l, indicative of linear poly(dimethyl siloxanes-) with the
following formula~
C CIH3 ICH3 1 3 ICH3
- - 0 - CH2~CH2~2CH2 - Si - 0- Si - C 1 2~ 2~2 2 ~ ~
CH2 CH3 ~ H3 k )o CH3 H2
: . . .
EXAMPLE 4
.. . .
~ilms of the fluid product of Example 4 are cast between
glass plates by adding 0.2% bis(isobutyl) peroxy dicarbonate to the
monomer and heating for 1/2 hour at 40C, 1/2 and 60C and 1/4 hr.
at 80C. The glass plates are separated. The films are then kept
at 80C for 15 minutes. Colorless optically clear, odorless, elas-
tic and strong films are obtained such as represented by the three
dimensional network polymer below. The following phys~cal properties
are measured on an Instron tester ASTM D1708, no conditioning,
using standard "dog bone" samples cut from 0.2 mm thic~. films. The
-~ speed is 0.25 inches per minute. This test is used on all the
3 Examples where tensile strength, modulus and eiongation are measured.
-25-
1~37433
`: 1 (three dimensional network)
¦ IH3 ~C~ ~ CH3 1 2
~ 2 3
i ~ 3 ~ ~260 3 ~ ;
CH3-C-g--CH2~CH2~2CH2-'~1-~i~5i-CX2~CH2~2C~}2-0-8-C-CH
¦ CH3 H CH3
CH2 2
: 15 1H
: 1 2 1 2
_ o_g- -CH3
: 20
Tensile strength 150 g/mm
Tensile modulus 72 g/mm
.. Elongation 177
; EXAMPLE 5
:;. 25 The fluid product of Example 4 together with 0.2~ di(sec-
butyl)-peroxydicarbonate is placed in a suitable contact lens
spin casting mold and spin cast under polymerizable conditions
to a contact lens such as taught in U.S. patent 3,408,429.
Thelens is optically clear, elastic and. strong.
' ~ -2~-
'''
''' X'
,.''
'' '
, . .
1~7~33
1 ~XAMPLE 6
About 97.3 g of octameth~l cyclotetrasiloxane, 2.7 g of
1,3-bis (4-methacryloxybutyl~ tetramethyl disiloxane and 0.6 ml
of trifluoromethyl sulfonic acid are charged to a pressure bottle,
sealed and shaken for 24 hours. The viscous monomer fluid
obtained is neutralized with sodium carbonate and diluted with
hexanes. The monomer/hexanes solution is washed with water, dried
with anhydrous MgSO4 and the solvent removed at reduced pressure.
Volatiles are removed from the monomer at 0.2 mm Hg and 110C
using a wiped film still. High pressure gel permeation chromato-
graphy of the product shows essentially total removal of low mole-
cular weight volatile material. The product is a colorless, clear,
odorless fluid of 4.4 stokes viscosity measuring in Gardner vis-
cosity tubes. The polymer below comprises about 200 repeating
Me2~ib units. IRspectra are similar to those taken in Example 4.
.. I
(three dimenslonal networ~
C~3-C-9-0-C~2~C~2~2CH2-Sl-O~f~Sl-CH2~CH2~2cH2_o_c_c_cH3
~ CH3 H oCH3
, CH2 H2
C}l I g_o-CB ~C~z~2c~2-ll-o~ CH2~ 2 2 2 3
fH2 ~H2
H2 - l H2
0~C~3 ~H3~ O~~-~
~27-
. '
~1~t7433
:.`
1 EXAMPLE 7
Films are made from the viscous fluid product of Example 7
using procedures similar to Example 5. The films are tested,
ASTM D1708, obtaining the following results:
Tensile strength 159 g/mm
Tensile modulus 104 g~mm
Elongation 151%
EXAMPLE 8
The viscous fluid product produced in Example 7 is mixed
with 2.0~ benzoin butyl ether. About 30 ~1 of the mixture is
~;~; placed in a spinning contact lens mold under N2 atmosphere.
After 20 minutes irradiation with UV light, a cured contact
; lens is obtained. The lens formed is optically clear, elastic
and strong.
EXAMPLE 9
Ten (10) parts of allylmethacrylate monomer and four
- tenths (0.4) of a part of t-butyl peroctoate are added to
ninety (90) parts of the fluid product obtained in Example 4.
; The reaction mixture is placed into a casting cell which is
then placed into an 80C oven for half an hour. The temperature
is thereafter raised to 100C and maintained at 100C for one
; hour. An optically clear film is removed from the cell and kept
at 80C for 15 minutes.
The above is repeated by reacting the product of Example
4 with several other monomers as shown in Table I. The percent
shown in Table I is the percent of co-monomer used. The
.,
``''~
., .
,
-28-
' .
, .
-
-
11~7433
.
. . .
l properties of the copolymers are outlined in Table I.
As illustrated in Table I, it is one purpose of the instant
invention to increase the tensile strength and elongation while
retaining sufficient oxygen transportability. One problem with
the prior art silicone polymers is that these polymers are not
very strong and have poor tear strength and- p~r tensile strength.
One of the problems with the PHEMA (control) is that contact lenses
' made from this material do not have the necessary oxygen transport-
- ing properties to meet all the requirements of the human cornea.
--.l0 As mentioned, the oxygen requirement of the human cornea is about
2 x 10-6 cm3/ (sec. cm2 atm). Table I illustrates'the effect the
instant co-monomers have on the strength of the polymers of the
' instant invention. There is an improvement in tensile strength
' with the use of the instant monomers.
15' In the case of modulus, it would be most preferred i~ the
modulus is below 300 in order to obtain a soft contact lens.
Therefore~ generally the lower the modulus the softer the contact
.
' lens.
" As to elongation, it is generally preferred'that elongation
be as high as possible.
As to oxygen transport, it is desirable that this rate be
maximized. This rate should be greater than the rate of oxygen
required by the human cornea.
The tensile strength test, modulus test and elongation test
~5 are measured, as mentioned, on an Instron Tester ASTM D 1708
using standard "dog bone" samples cut from 0.2 mm thick films.
There is no conditioning and the speed is 0.25 inches per minute.
'' .
.
'
, . .
` 11~7-~33
1 The Oxygen Transport Rate was deter~ned by the following
technique. This test is measuring the oxygen permeability of a
material while it is wet with water. This is an attempt to
closely reproduce the same conditions which exist in the human
eye when fitted with a contact lens, Two chambers filled with
water at 32C are connected together by a common passageway over
which is placed the material to be tested. Nitrogen-purged
water is pumped into both chambers until the oxygen concentration
;~ is very lo~ (rO.04 ppml. Then air water (oxygen concentration
~8 ppml is introduced into the lower chamber. There is located in
the upper chamber an oxygen sensing electrode which measures the
diffusion of oxygen from the lower chamber through the membrane
being tested and into the upper chamber. This measures apparent
; oxygen transport rate of the material covering the passageway
between the two chambers.
. . .
,'
.
.'. .
' 1
. .
,:,
.,,
: :,
,~
,,
,, .
~.,
:
::
~ -30-
': ~
. :
1~7~a33
K¦~S¦ h;
:J ¦ o . ~c =r 3 a x
. g a _ _ . _ _ _ _
O ~ O ~D ~ ~ U~ O ~ O ~ ~ ~
hO Q~ IS~ ~O O ~1 (~ I J r-l O ~i In ~-1 Dl~
3 1 ~ ~ ~ ~ ~ ~ ~ ~
_ ~,
. ~ o~
. ~ o ~ ~ ~ ~ o o ~ ~ ~ ~ o o
H ~ ~ 3 ~ t--~D o~ ~ ~ ~ t--c- ~ c~ ~o
~ 11 ~
~ _ _ _ _ _ _
': S ~.,
. h
~ h ~ 3 ~ ~ ,~ o ~ o Ir , ~ o ~ ~r ~:
E~ E~
''~ . - _ _ __ _ _ _ _ _
~ o~ ~ ~ 8~ ~ ~e 1~ ~* ~ ~
O O O O O O O 10 O O O X
~.~ ~1 rl ~ r1 rl rl ~1 r~i ~ ~ ~1 O
., ~d ~ ~
~ ~ . a) td
,. c) a) o) a) c) ~ ~ ~
.: ~ ~1 ~ ~1 ~ ~ ~d ~ ~1 ~1 ~d tl~ a) ~ c:C
., ~ ~ ~ ~ ~ ~ ~ ~ ~ ~C X ~ ~ ~ ~ :1:
.. ~) ~ P ~ P ~c P o P o Q~ Q~ a) h h
. ~ . ~3 h ~ ch~ ~ h E~ ~ h ~ ~ d S
a: ~ ~C al X ~ O ~d ~ h nJ rl ~J ~1 H ~ c~
:~ t~ J~ ~,C ~.C P .C,C ~: .C P ~ ~ ~d ~d
~ ~ ~ q) P~ ~ ~ Q) a~ i~ 1~ l 1
P~ cl: m ~i m
. ~
.
i~ a33
1 ~XAMPLE 10
58,3 g of 1,3-bis~4-methacryloxybuty~ll tetr~methyl
disiloxane, 41.7 y of octamethyl cyclotetrasiloxane, 1 ml
concentrated H2SO4 and 2 gm of Fuller's earth are charged
into a pressure flask. After two days equi`libration the mixture
is neutralized with Na2CO3, filtered, diluted with hexanes,
washed with water, dried, and the solvent removed at reduced
-- pressure. The monomer product as illustrated below was a
colorless, odorless fluid with low viscosity as measured in
Gardner Viscosity tubes.
10 g of monomer product is mixed with 0.-L wt~ ~ benzoin
methyl ether and 0.1 wt % azobis(isobutyronitrile). The
initiator-monomer solution is poured into button molds and
cured for 20 minutes under UV light in a nitrogen atmosphere
and thereafter followed by 30 minutes at 80C in air. The
' buttons are optically clear, colorless, hard and tough. Contact
lenses are lathed from these buttons. The following is the
formula for th~ above monomer:
~ ~ T 3 /f ~ f 3
CH3~~- -o-cH2~cH2t2cH2~ i-O~fi-Ch2~CH2t2CH2-O- -~-CH3
~: H2 3 ~ 3~ 3 H2
EXAMPLE 11
~ 7 g of the monomer product produced in Example 10
'! and 3 g of N-vinylpyrrolidone are mixed with 0.1 wt % benzoin
methyl ether and 0.1 wt. % azobis(isobutyronitrile). The ini-
tiator-monomer-comonomer solution is cured as described in
:
~,.'
. .
-31-
~9.
~1~i7~33
.
l Example lO
; The copolymer buttons obtained are opt~cally clear,
colorless, hard and tough. The lathing of the buttons to
contact lenses is substantially easier than the lathing of
Example lO buttons.
EXAMPLE 12
. .
30% tetrahydrofurfuryl methacrylate (TFM) is copoly-
merized with 70% monomer of Example ll in suitable molds.
The buttons obtained are optically clear, colorless, hard and
tough. The TFM copolymer buttons are lathe cut into contact
lenses.
EXAMPLE_13
99.3 g of octamethyl cyclotetrasiloxane, 0.7 g of 1,3-
bis(4-methacryloxybutyl) tetramethyl disiloxane, and 0.3 ml of
trifluoromethyl sulphonic acid are charged to a pressuxe bottle.
The hottle is sealed and shaken for five days. The monomer
fluid obtained is neutralized with sodium carbonate and diluted
with hexanes and filtered. The monomer/hexanes solution is washed
with water, dried over MgSO4 and the solvent removed at reduced
pressure. ~olatiles are removed from the prepolymer at 0.2 mm Hg
pressure and 110C. High pressure gel permeation chromatography
;-; of the product shows all low molecular weight volatile material
is removed. The product is a colorless, clear, odorless fluid
of very high viscosity with about 800 repeating Me2fiO units.
The following is a formula for the above monomer.
-32-
'~ ,
7 ~3 ~
3-C-8-0-CH2~CH2~2C~2-Sl ~ 1 ~-5i-CH2~CH2~2C~2-0-C-C-CH3
CH2 3 00 3 2
..
XAMPLE 14
Films are made ~rom the viscous rlu1d product of
. Example 14 uslng procedures similar to Example ~. The ~ilms
~- are tested givlng the following results. The following is a
.. representation o~ the cross linked polymer.
(three dimensional network)
.,., ~ ~
; . ,~ s~
;: '~'2 CH
C-C--CH2~CH2~2CH -5~ 5~-CH2~CH2~2CH2-o C_¦_CH3
, ¦ 3 oo 3
2 1 2~ ~2~2CH2-l~ 9L -c~2~cH2~2cH2-o-c-l-cH
CH fH2
7H2 7 2
~--0-Ç-C-CH3 CH -C-g-0
. Tensile strength 34 g/mm
. .
Tensile modulus 38 g/mm
% Elongation 208%
~ -33-
.-' X
':~
1~7433
EXAMPLE 15
Tetramethyl ammonium silanolate is prepared using the
- method of GiIbert and Kantor (J. Poly. Sci., 40, pp 35-58,
(1959), Transient Catalyst for the Polymerization of Organo-
siloxanes). 13 g of octaphenyl cyclotetrasiloxane, 92.4 g of
octamethyl cyclotetrasiloxane, and 2.7 g of i,3-bis(4-methacry-
loxybutyl) tetramethyl disiloxane are charged to a 500 ml 4-neck
round bottom flask fitted with a drying tube, an N2 gas inlet
and a mechanical stirrer. The mixture is heated to 120 C
and 1/2 ml of the base catalyst added. The temperature is
increased to 130C over the next 15 mir.utes and is held there
for 10 minutes followed by cooling to room temperature. The
viscous fluid product is diluted with hexanes, washed wi.th
acidic water (1% HCl), twice with water alone, dried over MgSO4,
and solvent removed at reduced pressure. The product is siloxane
monomer consisting of 5 mole % phenyl substituted silicone and 95
mole % methyl substituted silicone. An infrared spectrum of the
monomer product shows sharp weak absorptions at 700, 1430, 1590
and 3050 cm~l and a shoulder on the broad Si-O-Si absorption at
1125 cm~l. These are characteristic of phenyl and silicone phenyl
groups. The product is colorless, transparent, odorless, and
viscous. The viscosity is 17 stokes as measured in the Gardner
Viscosity tubes. It is cast into elastic, transparent films using
procedures similar to Example 5.
We Claim:
,
-34-
: . .
