Surface modification using hydridosilanes to prepare monolayers

Details Surface modification using hydridosilanes to prepare monolayers Surface modification using hydridosilanes to prepare monolayers

2003-01-03

2004-01-06

Nakarani, D. S. (Department: 1773)

Stock material or miscellaneous articles

Composite

Of silicon containing

C428S447000

Reexamination Certificate

active

06673459

ABSTRACT:

FIELD OF THE INVENTION
The field of the invention is silane chemistry and modification of metal surfaces.
BACKGROUND OF THE INVENTION
Metal oxides and metals with oxide coatings are used to make various materials and components, including separation substrates for liquid and gas chromatography, substrates for capillary zone electrophoresis, biosensors, microelectronic devices, catalysts, fillers, and pigments. For many of these applications, it is desirable to modify the metal oxide surface, for example, by altering the adsorption, adhesion, wettability, or catalytic properties of the surface.
One way to modify a metal oxide surface is to attach to hydroxyl groups on the surface silane compounds having desired functional groups. Chlorosilanes and alkoxysilanes have been used for such surface modification. The use of these silane compounds can be problematic, however, because chlorosilanes and alkoxysilanes are moisture sensitive and sometimes act as corrosive agents. In addition, the reaction of chlorosilanes with metal oxide surfaces generates hydrochloric acid as a by-product, and the hydrochloric acid may corrode the modified metal oxide surfaces. Furthermore, some chlorosilanes and alkoxysilanes do not react with metal oxide surfaces.
SUMMARY OF THE INVENTION
In one aspect, the invention features a method of modifying a surface. The method includes contacting the surface with a hydridosilane under conditions and for a time sufficient to form a covalent bond between the silicon atom of the hydridosilane and the oxygen atom of a hydroxyl group on the surface. The hydridosilane has the formula:
where each of R
a
, R
b
, R
c
, and R
d
is, independently, H, linear C
1-30
alkyl, branched C
1-30
alkyl, cyclic C
3-30
alkyl, linear C
2-30
alkenyl, branched C
2-30
alkenyl, linear C
2-30
alkynyl, branched C
2-30
alkynyl, C
6-20
aralkyl, C
6-10
aryl, or a polymeric moiety having a molecular weight of about 1000 to about 100,000. The polymeric moiety is selected from the group consisting of hydrocarbon polymers, polyesters, polyamides, polyethers, polyacrylates, polyurethanes, epoxies, and polymethacrylates. Each of R
a
, R
b
, R
c
, and R
d
is optionally substituted with one or more substituents selected from the group consisting of —F, —Cl, —Br, —CN, —NO
2
, ═O, —N═C═O, —N═C═S,
—N
3
, —NR
e
R
f
, —SR
g
, —OR
h
, —CO
2
R
i
, —PR
j
R
k
R
l
, —P(OR
m
)(OR
n
)(OR
p
), —P (═O)(OR
q
)(OR
s
), —P (═O)
2
OR
t
, —OP(═O)
2
OR
u
, —S(═O)
2
R
v
, —S(═O)R
w
, —S(═O)
2
OR
x
, —C(═O)NR
y
R
z
, and —OSiR
aa
R
bb
R
cc
. Each of R
e
, R
f
, R
g
, R
h
, R
i
, R
j
, R
k
, R
l
, R
m
, R
n
, R
p
, R
q
, R
s
, R
t
, R
u
, R
v
, R
w
, R
x
, R
y
, and R
z
, is, independently, H, linear C
1-10
alkyl, branched C
1-10
alkyl, cyclic C
3-8
alkyl, linear C
2-10
alkenyl, branched C
2-10
alkenyl, linear C
2-10
alkynyl, branched C
2-10
alkynyl, C
6-12
aralkyl, or C
6-10
aryl, and is optionally substituted with one or more substituents selected from the group consisting of —F, —Cl, and —Br. Each of R
aa
, R
bb
, and R
cc
is, independently, linear C
1-10
alkyl, branched C
1-10
alkyl, cyclic C
3-8
alkyl, linear C
2-10
alkenyl, branched C
2-10
alkenyl, linear C
2-10
alkynyl, branched C
2-10
alkynyl, C
6-12
aralkyl, C
6-10
aryl, —F, —Cl, —Br, or OR
dd
, where R
dd
is linear C
1-10
alkyl or branched C
1-10
alkyl. At least one of R
a
, R
b
, R
c
, and R
d
is H and at least one of R
a
, R
b
, R
c
, and R
d
is not H. Preferably, two or three of R
a
, R
b
, R
c
, and R
d
are H.
The surface is preferably a metal surface. The metal surface can be selected from the group consisting of a titanium surface, a tin surface, an aluminum surface, an iron surface, a nickel surface, a chromium surface, a manganese surface,-a zirconium surface, a niobium surface, a molybdenum surface, or a tungsten surface. The surface can also be a metal oxide surface or a metallate surface. Alternatively, the surface can contain a metal alloy. A preferred embodiment includes forming a monolayer-modified metal surface.
In another preferred embodiment, each of R
a
, R
b
, R
c
, and R
d
is, independently, H, linear C
1-30
alkyl, branched C
1-30
alkyl, cyclic C
3-30
alkyl, linear C
2-30
alkenyl, branched C
2-30
alkenyl, linear C
2-30
alkynyl, branched C
2-30
alkynyl, C
6-20
aralkyl, or C
6-10
aryl. Preferably, at least one of R
a
, R
b
, R
c
, and R
d
is linear C
1-20
alkyl, or branched C
1-20
alkyl, or phenyl. More preferably, at least one of R
a
, R
b
, R
c
, and R
d
is unsubstituted linear C
1-20
alkyl, unsubstituted branched C
1-20
alkyl, or unsubstituted phenyl.
The invention also features a method of forming a monolayer-modified metal surface that includes contacting a metal surface with a hydridosiloxane-containing polymer under conditions and for a time sufficient to form a covalent bond between at least one silicon atom of the polymer and an oxygen atom of a hydroxyl group on the metal surface. The polymer has the formula R
dd
[—O—Si (R
ee
)(R
ff
)]
n
—. R
gg
, where each of R
dd
and R
gg
is, independently, C
1-6
alkoxy or C
1-6
alkyl, each of R
ee
and R
ff
is, independently H or C
1-6
alkyl, and n is 10 to 1000.
In preferred embodiments, the polymer is a copolymer of hydridomethylsiloxane and dimethylsiloxane. Preferably, the copolymer is at least 50 mol % hydridomethylsiloxane, about 25 mol % to about 30 mol % hydridomethylsiloxane, or about 1 mol % to about 5 mol % hydridomethylsiloxane.
The invention also features a surface that includes a plurality of M—O—Si—(R
a
)(R
b
)(R
c
) moieties. M is Ti, Sn, Al, Fe, or Ni. One or two of R
a
, R
b
, and R
c
are H, and the remaining one or two of R
a
, R
b
, and R
c
are, independently, H, linear C
1-30
alkyl, branched C
1-30
alkyl, cyclic C
3-30
alkyl, linear C
2-30
alkenyl, branched C
2-30
alkenyl, linear C
2-30
alkynyl, branched C
2-30
alkynyl, C
6-20
aralkyl, or C
6-10
aryl, or a polymeric moiety having a molecular weight of about 1000 to about 100,000. The polymeric moiety is selected from the group consisting of hydrocarbon polymers, polyesters, polyamides, polyethers, polyacrylates, polyurethanes, epoxies, and polymethacrylates. Each of R
a
, R
b
, R
c
, and R
d
is optionally substituted with one or more substituents selected from the group consisting of —F, —Cl, —Br, —CN, —NO
2
, ═O, —N═C═O, —N═C═S,
—N
3
, —NR
e
R
f
, —SR
g
, —OR
h
, —CO
2
R
i
, —PR
j
R
k
R
l
, —P(OR
m
)(OR
n
)(OR
p
), —P(═O)(OR
q
)(OR
s
), —P(═O)
2
OR
t
, —OP(═O)
2
OR
u
, —S(═O)
2
R
v
, —S(═O)R
w
, —S(═O)
2
OR
x
, —C(═O)NR
y
R
z
, and —OSiR
aa
R
bb
R
cc
. Each of R
e
, R
f
, R
g
, R
h
, R
i
, R
j
, R
k
, R
l
, R
m
, R
n
, R
p
, R
q
, R
s
, R
t
, R
u
, R
v
, R
w
, R
x
, R
y
, and R
z
, is, independently, H, linear C
1-10
alkyl, branched C
1-10
alkyl, cyclic C
3-8
alkyl, linear C
2-10
alkenyl, branched C
2-10
alkenyl, linear C
2-10
alkynyl, branched C
2-10
alkynyl, C
6-12
aralkyl, or C
6-10
aryl, and is optionally substituted with one or more substituents selected from the group consisting of —F, —Cl, and —Br. Each of R
aa
, R
bb
, and R
cc
is, independently, linear C
1-10
alkyl, branched C
1-10
alkyl, cyclic C
3-8
alkyl, linear C
2-10
alkenyl, branched C
2-10
alkenyl, linear C
2-10
alkynyl, branched C
2-10
alkynyl, C
6-12
aralkyl, C
6-10
aryl, —F, —Cl, —Br, or OR
dd
, where R
dd
is linear C
1-10
alkyl or branched C
1-10
alkyl. Preferably, two of R
a
, R
b
, and R
c
are H. A preferred surface is a monolayer-modified metal surface.
As used herein, “monolayer-modified metal surface” means a surface including a plurality of silane moieties, substantially all of which are covalently bonded to oxygen atoms, which are covalently bonded to metal atoms.
DETAILED DESCRIPTION
The methods of the invention can be used to modify surfaces that react with the hydridosilane compounds, yielding modified surfaces containing covalently attached organosilane moieties. Functional groups on the organosilane moieties can be chosen

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