Poroushybrid material with organic groups removed from the surface
A material for chromatographic separations, processes for its preparation, and separation devices containing the chromatographic material. In particular, porous inorganic/organic hybrid materials are provided with a decreased concentration of surface organic groups. These materials may be surface modified and have enhanced stability at low pH.
1 . A hybrid material for chromatographic separations, said material having an interior area and an exterior surface, said material having a composition represented by:
[A] y [B] x (Formula I),
wherein x and y are whole number integers and A is
SiO 2 /(R 1 p R 2 q SiO t ) n (Formula II)
and/or SiO 2 /[R 3 (R 1 r SiO t ) m ] n (Formula III);
wherein R 1 and R 2 are independently a substituted or unsubstituted C 1 to C 7 alkyl group, or a substituted or unsubstituted aryl group, R 3 is a substituted or unsubstituted C 1 to C 7 alkylene, alkenylene, alkynylene, or arylene group bridging two or more silicon atoms, p and q are 0, 1, or 2, provided that p+q=1 or 2, and provided that in Formula II, when p+q=1, t=1.5, and when p+q=2, t=1; r is 0 or 1, provided that in Formula III, when r=0, t=1.5, and when r=1, t=1; m is an integer greater than or equal to 2; and n is a number from 0.01 to 100;
B is:
SiO 2 /(R 4 v SiO t ) n (Formula IV)
wherein R 4 is hydroxyl, fluorine, alkoxy, aryloxy, substituted siloxane, protein, peptide, carbohydrate, nucleic acid, or combinations thereof, R 4 is not R 1 , R 2 , or R 3 ; v is 1 or 2, provided that in Formula IV, when v=1, t=1.5, and when v=2, t=1; and n is a number from 0.01 to 100;
said interior of said material having a composition of A; said exterior surface of said material having a composition represented by A and B, and wherein said exterior composition is between about 1 and about 99% of the composition of B and the remainder comprising A.
2 . The material of claim 1 wherein said exterior surface has a composition that is between about 70 and about 90% of composition B, with the remainder comprising composition A.
3 . The material of claim 1 wherein said exterior surface has a composition that is between about 80 and about 90% of composition B, with the remainder comprising composition A.
4 . The material of claim 1 wherein R 4 is hydroxyl.
5 . The material of claim 1 wherein R 4 is fluorine.
6 . The material of claim 1 wherein R 4 is methoxy.
7 . The material of claim 1 wherein R 4 is
—OSi(R 5 ) 2 —R 6 (Formula V)
wherein R 5 is a C 1 to C 6 straight, cyclic, or branched alkyl, aryl, or alkoxy group, a hydroxyl group or a siloxane group, and R 6 is a C 1 to C 36 straight, cyclic, or branched alkyl, aryl, or alkoxy group, wherein R 6 is unsubstituted or substituted with one or more moieties selected from the group consisting of halogen, cyano, amino, diol, nitro, ether, carbonyl, epoxide, sulfonyl, cation exchanger, anion exchanger, carbamate, amide, urea, peptide, protein, carbohydrate, nucleic acid functionalities, and combinations thereof.
8 . The material of claim 7 wherein R 6 is a C 18 group.
9 . The material of claim 7 wherein R 6 is a cyanopropyl group.
10 . (canceled)
11 . (canceled)
12 . The material of claim 1 , having a specific surface area of about 50 to 800 m 2 /g.
13 . The material of claim 1 , having a specific surface area of about 100 to 200 m 2 /g.
14 . The material of claim 1 , having specific pore volumes of about 0.25 to 1.5 cm 3 /g.
15 . The material of claim 1 , having specific pore volumes of about 0.5 to 1.0 cm 3 /g.
16 . The material of claim 1 , having an average pore diameter of about 50 to 500 Å.
17 . The material of claim 1 , having an average pore diameter of about 100 to 300 Å.
18 . The material of claim 1 , having been surface modified by polymer coating.
19 . A method of performing a chromatographic separation comprising running a sample through a column containing the material of claim 1 .
20 . The material of claim 7 , having a surface concentration of R 6 greater than about 2.5 μmol/m 2 .
21 . The material of claim 7 , having a surface concentration of R 6 greater than about 3.0 μmol/m 2 .
22 . The material of claim 7 , having a surface concentration of R 6 greater than about 3.5 μmol/m 2 .
23 . The material of claim 7 , having a surface concentration of R 6 between about 2.5 and 3.7 μmol/m 2 .
24 . (canceled)
25 . (canceled)
26 . The material of claim 20 , having a specific surface area of about 50-800 m 2 /g.
27 . The material of claim 20 , having a specific surface area of about 100-200 m 2 /g.
28 . The material of claim 20 , having specific pore volumes of about 0.25 to 1.5 cm 3 /g.
29 . The material of claim 20 , having specific pore volumes of about 0.5 to 1.0 cm 3 /g.
30 . The material of claim 20 , having an average pore diameter of about 50 to 500 Å.
31 . The material of claim 20 , having an average pore diameter of about 100 to 300 Å.
32 . The material of claim 20 , which have been surface modified by polymer coating.
33 . A method of performing a separation comprising running a sample through a column containing the material of claim 20 .
34 . A separation device comprising the material of claim 1 .
35 . The separation device of claim 34 , said device selected from the group consisting of chromatographic columns, filtration membranes, sample clean up devices, and microtiter plates.
36 . A method of preparing a hybrid chromatographic material, comprising:
a) prepolymerizing a mixture of an organoalkoxysilane and a tetraalkoxysilane in the presence of an acid catalyst to produce a polyalkoxysiloxane.
b) preparing an aqueous suspension of said polyalkoxysiloxane, said suspension further comprising a surfactant, and gelling in the presence of a base catalyst so as to produce a porous material having silicon C 1 to C 7 alkyl groups, substituted or unsubstituted aryl groups, substituted or unsubstituted C 1 to C 7 alkylene, alkenylene, alkynylene, or arylene groups.
c) modifying the pore structure of said porous material by hydrothermal treatment; and
d) replacing one or more surface C 1 to C 7 alkyl groups, substituted or unsubstituted aryl groups, substituted or unsubstituted C 1 to C 7 alkylene, alkenylene, alkynylene, or arylene groups of the material with hydroxyl, fluorine, alkoxy, aryloxy, or substituted siloxane groups.
37 . The method of claim 36 , wherein said replacing involves reacting the hybrid material with aqueous H 2 O 2 , KF, and KHCO 3 in an organic solution.
38 . The method of claim 36 , wherein the molar ratio of said organotrialkoxysilane and tetraalkoxysilane is about 100:1 to 0.01:1.
39 . The method of claim 36 , wherein said surfactant is an alkylphenoxypolyethoxyethanol.
40 . The method of claim 36 , wherein said suspension further comprises a porogen.
41 . The method of claim 36 , wherein said tetraalkoxysilane is tetramethoxysilane or tetraethoxysilane.
42 . The method of claim 36 , wherein said material has a composition represented by:
[A] y [B] x (Formula I),
wherein x and y are whole number integers and A is
SiO 2 /(R 1 p R 2 q SiO t ) n (Formula II)
and/or SiO 2 /[R 3 (R 1 r SiO t ) m ] n (Formula III);
wherein R 1 and R 2 are independently a substituted or unsubstituted C 1 to C 7 alkyl group, or a substituted or unsubstituted aryl group, R 3 is a substituted or unsubstituted C 1 to C 7 alkylene, alkenylene, alkynylene, or arylene group bridging two or more silicon atoms, p and q are 0, 1, or 2, provided that p+q=1 or 2, and that when p+q=1, t=1.5, and when p+q=2, t=1; r is 0 or 1, provided that when r=0, t=1.5, and when r=1, t=1; m is an integer greater than or equal to 2; and n is a number from 0.01 to 100;
B is:
SiO 2 /(R 4 v SiO t ) n (Formula IV)
wherein R 4 is hydroxyl, fluorine, alkoxy, aryloxy, substituted siloxane, protein, peptide, carbohydrate, nucleic acid, or combinations thereof, R 4 is not R 1 , R 2 , or R 3 ; v is 1 or 2, provided that when v=1, t=1.5, and when v=2, t=1; and n is a number from 0.01 to 100;
said interior of said material having a composition of A; said exterior surface of said material having a composition represented by A and B, and wherein said exterior composition is between about 1 and about 99% of the composition of B and the remainder comprising A.
43 . The material formed by the method of claim 36 .
44 . The material of claim 1 , wherein n is 0.2 to 0.5, when p is 0, q is 1 and t is 1.5.