Polysilazane thermosetting polymers for use in chromatographic systems and applications
View Patent ↗This invention relates to an amorphous non-glassy ceramic composition that may be prepared by curing, calcining and/or pyrolyzing a precursor material comprising silicon, a Group III metal, a Group IVA metal, and/or a Group IVB metal.
1. A pipette comprising a barrel and a tip, said tip containing a fluid-permeable mass comprising a particulate adsorbent material dispersed in a matrix comprising a polysilazane polymer and a polysiloxane polymer.
2. A pipette as set forth in claim 1 wherein the fluid-permeable mass has a permeability of about 5 to about 20 μL/second.
3. A pipette as set forth in claim 1 wherein said matrix is substantially not irreversibly adsorptive of an analyte or other target compound that is adsorbed by said particulate adsorptive material.
4. A pipette as set forth in claim 1 containing at least about 40% by weight of said particulate adsorptive material.
5. A pipette as set forth in claim 1 wherein the B.E.T. surface area of said particulate adsorptive material is at least about 1 m 2 /g.
6. A pipette as set forth in claim 1 wherein the concentration of said adsorptive material is such that the surface area thereof is at least about 0.1 m 2 /cc of said fluid permeable mass.
7. A pipette as set forth in claim 1 wherein said tip is tapered.
8. A pipette as set forth in claim 1 wherein the aspect ratio of said permeable mass is at least about 11.
9. A pipette as set forth in claim 1 wherein said polysiloxane polymer contains repeating Si—H groups at from about 1% to about 10% intervals.
10. A pipette as set forth in claim 1 wherein said polysiloxane polymer comprises siloxane repeating units of the formula:
wherein
R 3 is hydrogen, substituted or unsubstituted hydrocarbyl, alkoxy, aryloxy, nitro, cyano, amino, hydroxy, or an —O—Si≡ moiety; and
R 4 is hydrogen, methacryl, C 1-20 alkyl, C 2-20 alkenyl, fluoroalkyl, carbonyl, carbinol, glycidyl, straight, branched or cyclic —(CH 2 —O—CH 2 ) n , and aryl optionally substituted with C 1-6 alkyl, fluoro, chloro, cyano or aryl.
11. A pipette as set forth in claim 1 wherein said polysilazane polymer comprises silazane repeating units having the formula:
wherein:
R 1 is selected from the group consisting of hydrogen, vinyl, alkyl, hydroxy, alkoxy, amino, alkylamino, mercapto, acetoxy, halo, hydroxyalkyl, dimethylamino, oxime, isocyanate, CH 2 Q-(OCH 2 CH 2 ) n OH,
R 2 is selected from the group consisting of methacryl, C 1-20 alkyl, C 2-20 alkenyl, fluoroalkyl, carbonyl, carbinol, glycidyl, straight, branched or cyclic —(CH 2 —O—CH 2 ) n , and aryl optionally substituted with C 1-6 alkyl, fluoro, chloro, cyano or aryl;
Q is C 1-8 alkyl; and
n is 1 to about 20.
12. A pipette comprising a barrel and a tip, said tip containing a fluid-permeable mass comprising a particulate adsorbent material dispersed in a matrix comprising a polysilazane polymer and a polysiloxane polymer wherein said polysilazane polymer has the formula:
wherein R is H or —CH═CH 2 and n is 1 to 20.
13. A pipette as set forth in claim 1 wherein said particulate adsorptive material is selected from the group consisting of carbon, organic polymers, silicas, zeolites, aluminas, metal or ceramic powders.
14. A pipette as set forth in claim 1 wherein at least 85% of the pore volume of said particulate adsorptive material is constituted of pores having a pore size between about 2.5 Å and about 10,000 Å.
15. A pipette as set forth in claim 14 wherein at least 85% of the pore volume of said adsorptive material is constituted of pores having a pore size between about 100 Å and about 300 Å.
16. A pipette as set forth in claim 1 wherein the ratio of polysiloxane polymer to polysilazane polymer is about 1.0 to 0.5 to about 1.0 to 10.0.
17. A pipette tip as set forth in claim 1 , wherein the fluid permeable mass comprises an absorptive bed.
18. A pipette tip as set forth in claim 1 , wherein the fluid permeable mass forms an adsorptive plug.