Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2002-04-15
2003-06-03
Foelak, Morton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C264S041000, C264S042000, C521S150000
Reexamination Certificate
active
06573307
ABSTRACT:
FIELD OF INVENTION
The invention relates to a process for making fluorinated polymer adsorbent particles and to their use as a stationary phase for carrying out chromatographic separations.
BACKGROUND OF THE INVENTION
Support materials for use in high productivity liquid chromatography must be mechanically strong in order to withstand operation at high rates of flow under high pressures. Moreover, they must be stable over the wide range of pH to which such materials are subjected during normal operation and regeneration. The stability of the polymeric particles in its environment allows it to withstand degradation and decomposition. Physical properties of particular importance to chromatographic media are (1) sphericity of the particles; (2) high surface area; (3) high pore volume and availability; (4) wide range of pore diameters; and (5) wide range of particle diameters.
The particles of the invention are an improvement over known particles in respect of many of the above properties. Furthermore, the fluorinated surface of certain of the particles of the invention present unusual and unexpected polarity that is beneficial in performing chromatographic separations such as that used for DNA.
SUMMARY OF THE INVENTION
The invention is therefore directed to the manufacture of improved fluorinated particles having adsorbent properties for superior performance as the stationary phase for use in chromatographic separations.
The invention provides a process for the preparation of porous spherical particles of fluorinated polymer adsorbent comprising the steps of:
(1) forming a water-insoluble solution of organic compounds comprising a monomer selected from C
2-4
alkylene glycol esters of a C
3-6
acrylic acid or divinyl benzene; a polyfluorinated vinyl monomer; a free radical initiator; and a water-insoluble, organic solvent-soluble porogenic material, the weight ratio of the comonomers to porogenic material being from 0.5:1 to 2:1;
(2) forming a dilute solution of a dispersing agent in water from which any oxygen has been purged with inert gas;
(3) with agitation and inert gas purging, rapidly dispersing the water-insoluble solution of organic compounds from step (1) into the dilute aqueous solution from step (2) and, as necessary, adjusting the temperature of the dispersion to 30-90° C. to initiate copolymerization of the monomers, the level of mixing energy being sufficient to disperse the water-insoluble solution of organic compounds in the solution from step (2) in the form of liquid droplets having an average diameter of no more than 10-300 micrometers, at least 90% of the droplets being within 40% above or below the average mean particle diameter;
(4) continuing the agitation and oxygen purging of the dispersion from step (3) for a time sufficient to effect complete copolymerization of the monomers and particulation of the droplets in the form of finely divided polymer particles by precipitation of the copolymer therein;
(5) separating the finely divided copolymer particles from the polymerization reaction medium;
(6) extracting the porogenic material from the separated copolymer particles of step (5) by washing the particles with inert organic solvent, thereby forming pores within the copolymer; and
(7) drying the porous copolymer particles.
The invention further provides a process for the preparation of porous spherical particles of fluorinated polymer adsorbent comprising the steps:
(1) forming a water-insoluble solution of organic compounds comprising (a) a monomer selected from C
2-4
alkylene glycol esters of a C
3-6
acrylic acid and a divinyl benzene; (b) a polyfluorinated vinyl monomer; (c) a monomer selected from acrylic acid, methacrylic acid and esters thereof; (d) a free radical initiator; and (e) a water-insoluble, organic solvent-soluble porogenic material, the weight ratio of comonomers (a) plus (b) plus (c) to the porogenic material being from 0.5:1 to 2:1;
(2) forming a dilute solution of a dispersing agent in water from which any oxygen has been purged with inert gas;
(3) with agitation and inert gas purging rapidly dispersing the water-insoluble solution of organic compounds from step (1) into the dilute aqueous solution from step (2) and, as necessary, adjusting the temperature of the dispersion to 30-90° C. to initiate copolymerization of the monomers, the level of mixing energy being sufficient to disperse the water-insoluble solution of organic compounds in the solution from step (2) in the form of liquid droplets having an average diameter of no more than 10-300 micrometers, at least 90% of the droplets being within 40% above or below the average mean particle diameter;
(4) continuing the agitation and oxygen purging of the dispersion from step (3) for a time sufficient to effect complete copolymerization of the monomers and particulation of the droplets in the form of finely divided polymer particles by precipitation of the copolymer therein;
(5) separating the finely divided copolymer particles from the polymerization reaction medium;
(6) extracting the porogenic material from the separated copolymer particles of step (5) by washing the particles with inert organic solvent, thereby forming pores within the copolymer; and
(7) drying the porous copolymer particles.
The invention further provides adsorbent particles made by the process described above.
The present invention further provides uses for the particles according to the invention as a stationary phase in chromatographic techniques. Certain particles of the invention are particularly suited to use where the sample to be chromatographed is a macromolecule containing nucleotides, nucleosides or polypeptides, such as DNA, RNA or endotoxins.
DETAILED DESCRIPTION OF THE INVENTION
The invention relates to a method for making high quality adsorbent fluoropolymer particles by suspension polymerization with an aqueous solution containing a conventional dispersing agent. The basic components of the process are (1) the water-insoluble polymerization system, which is comprised mainly of a polyfluorinated monomer, two or more ethylenically unsaturated monomers and a free radical-initiating catalyst, and (2) the dispersion medium, which is a dilute aqueous solution containing a conventional dispersing agent. By water-insoluble solution, it is meant a solution sufficiently water-insoluble to permit suspension polymerization to occur. Preferred ethylenically unsaturated monomers are monomers having divinyl functionality. Non-fluorinated monomers having divinyl functionality are more preferred. Poly(vinyl alcohol) and poly(vinyl pyrrolidone) are preferred dispersing agents
A. Dispersing Agents
The polymerization of the polyfluorinated copolymer for use in the invention is conducted in the presence of a dilute aqueous solution containing a dispersing agent, for example poly(vinyl alcohol) or poly(vinyl pyrrolidone). The principal function of the dispersing agent is to adjust the interfacial surface tension between the finely dispersed water-insoluble polymerization components and the continuous aqueous medium phase. By regulating the concentration of dispersing agent dissolved in the aqueous medium, the droplet size of the dispersed polymerization system and thus the size of the resultant polymerized particles can be more finely controlled.
So long as the dispersing agent is essentially completely dissolved in the aqueous medium, a wide range of molecular weights of the dispersing agent may be used successfully in the practice of the invention. One preferred dispersing agent is PVA that is at least 80% hydrolyzed, and more preferably at least 86% hydrolyzed, with a molecular weight of at least about 1,000. The maximum usable molecular weight is a function of the ambient water solubility of the dispersing agent. For example, the molecular weight of the PVA used will ordinarily not exceed 150,000 and preferably is no higher than 100,000.
For the purposes of the invention, the concentration of PVA in the aqueous medium should be within the range of 1 to 50 mL PVA per liter of water. Below 1 mL/L the modifying eff
Lowe Christopher
Smiley Leonard H.
Tucker Julie
Foelak Morton
Prometic Biosciences Inc.
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