WO2012166861A1

WO2012166861A1 - Size exclusion chromatography of polymers

Info

Publication number: WO2012166861A1
Application number: PCT/US2012/040122
Authority: WO
Inventors: Rongjuan Cong; Al PARROTT; Lonnie G. Hazlitt; Wallace W. Yau; Charles Michael CHEATHAM; Alexander W. Degroot
Original assignee: Dow Global Technologies Llc
Priority date: 2011-06-02
Filing date: 2012-05-31
Publication date: 2012-12-06

Abstract

The invention provides a method for a Size Exclusion Chromatography (SEC) of a polymer, said method comprising introducing a solution, comprising the polymer, into a liquid flowing through a first stationary phase, and wherein the first stationary phase comprises a porous graphitic carbon (PGC). The invention also provides an apparatus for Size Exclusion Chromatography (SEC) of a polymer, said apparatus comprising at least one column comprising a first stationary phase, and wherein the first stationary phase comprises a porous graphitic carbon (PGC). The invention also provides an apparatus for Size Exclusion Chromatography (SEC) of a polymer, said apparatus comprising at least one column comprising a first stationary phase, and wherein the first stationary phase comprises a porous graphitic carbon (PGC), and wherein the PGC has a median particle size, D50, less than, or equal to, 30 µm in diameter, and wherein less than 10% of particles have a diameter of D10, where D10 = 0.5 x D50, and at least 90% of the particles have a diameter of D90, where D90 = 1.5 x D50.

Description

SIZE EXCLUSION CHROMATOGRAPHY OF POLYMERS

REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional Application No.

61/492,592, filed on June 2, 2011, and incorporated herein by reference.

BACKGROUND OF THE INVENTION

Size exclusion chromatography (SEC), commonly called Gel Permeation

Chromatography (GPC), was discovered by The Dow Chemical in early 1960s. The technique has been widely used in characterizing molecular weight distribution (MWD) for synthetic and natural polymers. For such polymers, and in particular, for olefin-based polymers, it is important to obtain accurate molecular weight characterization using SEC, including, for example, accurate molecular weight distribution (MWD).

Current SEC (GPC) columns, used in MWD analysis of olefin-based polymers are typically packed with crosslinked polystyrene. However, the column thermal stability, thermal shock, column compositional integrity, and column shredding are key challenges for conventional packing materials. Over extended periods of time, crosslinked polystyrene tends to undergo chain cleavage or degradation, and this chain cleavage and degradation have been attributed as a cause for column failure. Commercial, rigid, silica stationary phase typically generate chromatograms showing poor peak symmetry and peak tailing because of the adsorption with solute in some polar solvents. Many of the problems associated with stationary phase especially impact the high temperature SEC analysis of polymers, such as ethylene-based polymers, propylene-based polymers, and other olefin-based polymers.

Thus, there is a need for new SEC methods that use new packing materials (or stationary phases) that have improved inertness, for example, improved thermal stability.

There is also a need for such methods that have maintained or improved resolution compared to crosslinked polystyrene. There is a further need for such methods with less tailing and good peak symmetry in the generated chromatograms.

U.S. Patent 4,263,268 discloses porous carbon for chromatography, and for a catalyst support. The porous carbon is formed by depositing carbon into the pores of a porous inorganic template, such as silica gel, porous glass or a porous oxide, for example, alumina, and, thereafter, removing the template as by dissolution or evaporation. Carbon is preferably deposited as a polymerizable organic material that is polymerized in situ in the template pores, and then pyrolyzed to carbon. Size exclusion chromatography (SEC) processes are disclosed in the following references: J. C. Moore, J. Polym Sci A, 2, 835-843 (1964); J. C. Moore, J. Polym Sci C, 21, 1-3 (1968); and M. Striegel, W. Yau et al., Modern Size Exclusion Liquid Chromatography, Wiley, the 2^nd edition, 2009). SEC separation mechanism was discussed by Benoit in 1967 (Grubisic, R. Rempp, and H. Benoit, J. Polym. Sci. B, 5, 753 (1967)).

Some high temperature chromatography separations using porous graphitic carbon are disclosed in the following references: Macko et al., Separation of Propene/l-Alkene and Ethylene/1 -Alkene Copolymers by High-Temperature Adsorption Liquid Chromatography, Polymer 50 (2009), 5443-5448; Macko et al., Separation of Linear Polyethylene from Isotactic, Atactic, and Syndiotactic Polypropylene by High-Temperature Adsorption Liquid Chromatography, Macromolecules (2009), 42, 6063-6067; Chitta et al., Elution Behavior of Polyethylene and Polypropylene Standards on Carbon Sorbents, Journal of Chromatography A, 1217 (2010) 7717-7722; Findenegg et al., Adsorption from Solution of Large Alkane and Related Molecules onto Graphitized Carbon, Carbon, Vol 25, No. 1, (1987), 119-128; and Yin et al., Theoretical Study of the Effects of Intermolecular Interactions in Self-Assembled Long-Chain Alkanes Adsorbed on Graphite Surfaces, Surface and Interface Analysis (2001), 32, 248-252. See also U.S. Publication Nos. 2010/0093964 and 2011/0152499.

Other referenced disclosing porous graphitic carbon are the following: Roy et al., Development of Comprehensive Two-Dimensional High Temperature Liquid

Chromatography x Gel Permeation Chromatography for Characterization of Poly olefins, Macromolecules (2010), 43, 3710-3720; and Ginzburg et al., High-Temperature Two- dimensional Liquid Chromatography of Ethylene-Vinylacetate Copolymers, Journal of Chromatography A, 1217 (2010), 6867-6874; Anna Tornkvist, Aspects of Porous Graphitic Carbon as Packing Materials for Capillary Liquid Chromatography, PhD Dissertation, Uppsala University, (2003); and John H. Knox, et al., J. Chromatography, pp 3-25, 352

(1986). In 2010, HYPERCARB was used in a mode of High Temperature Thermal Gradient Interactive Chromatography (HT-TGIC) for quantifying comonomer distribution for polyolefins (Cong, et al., Macromolecules, 2011, 44 (8), 3062-3072).

As discussed above, there remains a need for new SEC methods that have improved inertness, for example, improved thermal stability. There is also a need for such methods that have maintained or improved resolution, with less tailing and good peak symmetry in the generated chromatograms. These and other needs have been met by the following invention. SUMMARY OF THE INVENTION

The invention provides a method for a Size Exclusion Chromatography (SEC) of a polymer, said method comprising introducing a solution, comprising the polymer, into a liquid flowing through a first stationary phase, and wherein the first stationary phase comprises a porous graphitic carbon (PGC).

The invention also provides an apparatus for Size Exclusion Chromatography (SEC) of a polymer, said apparatus comprising at least one column comprising a first stationary phase, and wherein the first stationary phase comprises a porous graphitic carbon (PGC).

The invention also provides an apparatus for Size Exclusion Chromatography (SEC) of a polymer, said apparatus comprising at least one column comprising a first stationary phase, and

wherein the first stationary phase comprises a porous graphitic carbon (PGC), and wherein the PGC has a median particle size, D50, less than, or equal to, 30 μιη in diameter, and wherein less than 10% of particles have a diameter of D10, where D10 = 0.5 x D50, and at least 90% of the particles have a diameter of D90, where D90 = 1.5 x D50.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 depicts the "column temperature versus time" for an inventive SEC method. Figure 2 depicts the chromatogram of polystyrene cocktail #1 (a mixture of polystyrene standards of Mw 3,900,000; 320,000 and 34,500) generated using an inventive SEC method.

Figure 3 depicts the chromatogram of polystyrene cocktail #2 (a mixture of polystyrene standards of Mw 1,980,000; and 120,000; each reported by the manufacturer), generated using an inventive SEC method.

Figure 4 depicts a plot of the "retention volume of the polystyrene standards" versus the "log molecular weight reported by the manufacture" for an inventive SEC method (lower dashed line, one column only), and a comparative SEC method (upper solid line, a series of four columns).

Figure 5 depicts the chromatograms of five polyethylene (PE) standards, generated using an inventive SEC method.

Figure 6 depicts a plot of the "retention volume of the polyethylene standards" versus the "log molecular weight reported by the manufacture" for an inventive SEC method (lower line, one column only), and a comparative SEC method (upper line, a series of four columns). DETAILED DESCRIPTION

It has been discovered that the inventive SEC methods surprisingly generate chromatograms with similar or better resolution, and with less tailing and good peak symmetry, and show extended thermal stability over time, as compared to cross linked polystyrene and silica gels. The inventive SEC methods also unexpectedly show excellent correlations between the "retention volumes" and "molecular weights of the eluted polymer fractions," and these results can be achieved with a minimal number of columns. The inventive methods allow for improved thermal stability, reduced pressure fluctuations, improved chemical resistance, and long column lifetime.

As discussed above, the invention provides a method for a Size Exclusion

Chromatography (SEC) of a polymer, said method comprising introducing a solution comprising the polymer, into a liquid flowing through a first stationary phase, and wherein the first stationary phase comprises a porous graphitic carbon (PGC).

An inventive method may comprise a combination of two or more embodiments as described herein.

In one embodiment, the stationary phase is operated isothermally, the solvent compositions and solvent flow rates do not change, and a SEC analysis of the distribution of concentration of polymer versus elution volume is obtained.

In one embodiment, the first stationary phase is subject to a temperature gradient. In a further embodiment, the temperature gradient (cooling or heating) is greater than, or equal to, 0.1°C per minute, or greater than, or equal to, 1.0°C per minute, or greater than, or equal to, 2.0°C per minute.

A temperature gradient device (for example, a GC oven (Aiglent Technologies), used in a CEF from PolymerChar) is an instrument that is used to thermally treat, or cool, a column (for example, a chromatography column) in a controlled manner. Other examples are Hewlett Packard GC ovens, and ATREF ovens (for example, see Gillespie et al., U.S.

2008/0166817A1).

In one embodiment, the first stationary phase is subject to a solvent gradient.

A solvent gradient device (for example, a dual pump system with a mixer (Agilent Technologies) as available from PolymerChar) is an instrument that is used to mix two or more solvents in a controlled manner, and wherein the solvent mixture is used as an eluent in a column (for example, a chromatography column). Examples include a binary Shimadzu

LC-20 AD pumps (see Roy et al, Development of Comprehensive Two -Dimensional High

Temperature Liquid Chromatography x Gel Permeation Chromatography for Characterization of Poly olefins, Macromolecules 2010, 43, 3710-3720) and binary Agilent pump from HT-LC instrument ( PolymerChar).

In one embodiment, the first stationary phase is subject to both a temperature gradient and a solvent gradient, for example, by using a combination of at least one oven and at least one pump, each as described above. In a further embodiment, the temperature gradient is greater than, or equal to, 0.1°C per minute, or greater than, or equal to, 1.0°C per minute, or greater than, or equal to, 2.0°C per minute.

In one embodiment, the first stationary phase has a mean particle size (D50) less than, or equal to, 30 microns in diameter.

In one embodiment, the first stationary phase has a mean particle size (D50) less than, or equal to, 30 microns in diameter, and wherein less than 10% of the particles have a diameter of D10, wherein D10 = 0.5 x D50.

In one embodiment, the first stationary phase has a mean particle size (D50) less than, or equal to, 30 microns in diameter, and wherein at least 90% of the particles have a diameter of D90, wherein D90 = 1.5 x D50.

In one embodiment, the first stationary phase has a mean particle size (D50) greater than zero, and further greater than one micron in diameter.

In one embodiment, the molecular weight distribution and/or the molecular size distribution of the polymer is/are measured. Examples of devices for such measurements include the PL-GPC 220 Integrated GPC/SEC System (30-220°C) from Agilent

Technologies; TDAmax by Malvern; and a high temperature GPC unit from PolymerChar.

In one embodiment, the method further comprises fractionating the solution comprising the polymer into polymer fractions.

In one embodiment, the method further comprises fractionating the solution comprising the polymer into polymer fractions, and introducing the polymer fractions into a second stationary phase that is different from the first stationary phase. For example, the second stationary phase may differ from the first stationary phase in one or more features, such as chemical composition, mean particle size, particle size distribution, pore size and/or pore size distribution.

In one embodiment, the second stationary phase is subject to a temperature gradient.

In a further embodiment, the temperature gradient is greater than, or equal to, 0.1 °C per minute, or greater than, or equal to, 1.0°C per minute, or greater than, or equal to, 2.0°C per minute. A temperature gradient device (for example, a GC oven (Aiglent Technologies), used in a CEF from PolymerChar) is an instrument that is used to thermally treat, or cool, a column (for example, a chromatography column) in a controlled manner. Examples include Hewlett Packard GC ovens, and ATREF ovens (for example, see Gillespie et al., U.S.

2008/0166817A1).

In one embodiment, the second stationary phase is subject to a solvent gradient. A solvent gradient device (for example, a dual pump system with a mixer (Agilent Technologies) as available from PolymerChar) is an instrument that is used to mix two or more solvents in a controlled manner, and wherein the solvent mixture is used as an eluent in a column (for example, a chromatography column). Examples include a binary Shimadzu LC-20 AD pumps (see Roy et al, Development of Comprehensive Two -Dimensional High Temperature Liquid Chromatography x Gel Permeation Chromatography for

Characterization of Poly olefins, Macromolecules 2010, 43, 3710-3720) and binary Agilent pump from HT-LC instrument ( PolymerChar).

In one embodiment, the second stationary phase is subject to both a temperature gradient and a solvent gradient, for example, by using a combination of at least one oven and at least one pump, each as described above. In a further embodiment, the temperature gradient is greater than, or equal to, 0.1°C per minute, or greater than, or equal to, 1.0°C per minute, or greater than, or equal to, 2°C per minute.

In one embodiment, both the first and second stationary phases are subjected to a temperature gradient. In a further embodiment, the temperature gradient is greater than, or equal to, 0.1°C per minute, or greater than, or equal to, 1.0°C per minute, or greater than, or equal to, 2.0°C per minute.

In one embodiment, both the first and second stationary phases are subjected to a solvent gradient.

In one embodiment, both the first and second stationary phases are subjected to both a temperature gradient and a solvent gradient, for example, by using a combination of at least one oven and at least one pump, each as described above. In a further embodiment, the temperature gradient is greater than, or equal to, 0.1°C per minute, or greater than, or equal to, 1.0°C per minute, or greater than, or equal to, 2.0°C per minute.

In one embodiment, the liquid flowing through the first stationary phase is a nonpolar solvent. Examples of nonpolar solvents include, but are not limited to, orthodichloro- benzene, 1 ,2,4-trichlorobenzene, and hexane. In one embodiment, the liquid flowing through the first stationary phase is a polar solvent. Examples of nonpolar solvents include, but are not limited to, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), and water (H₂0).

In one embodiment, the liquid flowing through the first stationary phase is a nonpolar solvent or a polar solvent.

In one embodiment, the polymer has a concentration in the solution of greater than 0.02 milligrams per milliliter of solution.

In one embodiment, the first stationary phase consists essentially of a porous graphitic carbon.

In one embodiment, the first stationary phase consists essentially of a porous graphitic carbon coated and/or grafted onto silica particles.

In one embodiment, the first stationary phase is contained in only column.

In one embodiment, the "retention volume (y in ml) of a polymer fraction per column versus the molecular weight of the polymer fraction (x in Dalton)" meets the following relationship: y = -m(log x) + b, where b is < 30, or < 25, or < 20 ml, and m is < 3.0 or < 2.5 ml/log(Dalton). In a further embodiment, the dimension of the column is "300 mm X 7.8 mm."

In one embodiment, the "retention volume (y in ml) of a polymer fraction per column versus the molecular weight of the polymer fraction (x in Dalton)" meets the following relationship: y = -m(log x) + b, where b is greater than 10, but less than, or equal to, 30 ml, and m is greater than 0.5, but less than 8.0 ml/log(Dalton). In a further embodiment, the dimension of the column is "300 mm X 7.8 mm."

In one embodiment, the "retention volume (y in ml) of a polymer fraction per column versus the molecular weight of the polymer fraction (x in Dalton)" meets the following relationship: y = -m(log x) + b, where b is greater than 10, but less than, or equal to, 30 ml, and m is greater than 1.0, but less than 8.0 ml/log(Dalton). In a further embodiment, the dimension of the column is "300 mm X 7.8 mm."

In one embodiment, the "retention volume (y in ml) of a polymer fraction per column versus the molecular weight of the polymer fraction (x in Dalton)" meets the following relationship: y = -m(log x) + b, where b is greater than 10, but less than, or equal to, 30 ml, and m is greater than 1.5, but less than 8.0 ml/log(Dalton). In a further embodiment, the dimension of the column is "300 mm X 7.8 mm."

In one embodiment, the "retention volume (y in ml) of a polymer fraction per column versus the molecular weight of the polymer fraction (x in Dalton)" meets the following relationship: y = -m(log x) + b, where b is greater than 10, but less than, or equal to, 30 ml, and m is greater than 2.0, but less than 8.0 ml/log(Dalton). In a further embodiment, the dimension of the column is "300 mm X 7.8 mm."

An inventive SEC method may comprise a combination of two or more embodiments as described herein.

An inventive apparatus may comprise a combination of two or more embodiments as described herein.

The following embodiments apply to each inventive apparatus as described above.

In one embodiment, the first stationary phase has a mean particle size (D50) greater than zero, or greater than one micron in diameter.

In one embodiment, the apparatus further comprises a means to subject the first stationary phase to a temperature gradient. In a further embodiment, the temperature gradient is greater than, or equal to, 0.1°C per minute, or greater than, or equal to, 1.0°C per minute, or greater than, or equal to, 2.0°C per minute.

A temperature gradient device (for example, a GC oven (Aiglent Technologies), used in a CEF from PolymerChar) is an instrument that is used to thermally treat, or cool, a column (for example, a chromatography column) in a controlled manner. Examples include Hewlett Packard GC ovens, and ATREF ovens (for example, see Gillespie et al., U.S.

2008/0166817A1).

In one embodiment, the apparatus further comprises a means to subject the first stationary phase to a solvent gradient.

A solvent gradient device (for example, a dual pump system with a mixer (Agilent Technologies) as available from PolymerChar) is an instrument that is used to mix two or more solvents in a controlled manner, and wherein the solvent mixture is used as an eluent in a column (for example, a chromatography column). Examples include a binary Shimadzu LC-20 AD pumps (see Roy et al, Development of Comprehensive Two -Dimensional High Temperature Liquid Chromatography x Gel Permeation Chromatography for

In one embodiment, the apparatus further comprises a means to subject the first stationary phase to both a temperature gradient and a solvent gradient, for example, by using a combination of at least one oven and at least one pump, each as described above. In a further embodiment, the temperature gradient is greater than, or equal to, 0.1°C per minute, or greater than, or equal to, 1.0°C per minute, or greater than, or equal to, 2.0°C per minute.

In one embodiment, the apparatus further comprises a means to measure molecular weight distribution and/or the molecular size distribution of the polymer. Examples of devices for such measurements include the PL-GPC 220 Integrated GPC/SEC System (30- 220°C) from Agilent Technologies; TDAmax by Malvern; and a high temperature GPC unit from PolymerChar.

In one embodiment, the apparatus further comprises a second stationary phase that is different from than first stationary phase. For example, the second stationary phase may differ from the first stationary phase in one or more features, such as chemical composition, mean particle size, particle size distribution, pore size and/or pore size distribution.

In one embodiment, the apparatus further comprises a second column comprising a second stationary phase that is different from than first stationary phase. For example, the second stationary phase may differ from the first stationary phase in one or more features, such as chemical composition, mean particle size, particle size distribution, pore size and/or pore size distribution.

In one embodiment, the apparatus further comprises a means to subject the second stationary phase to a temperature gradient, for example by a combination of the ovens and pumps in the PolymerChar apparatus described above. In a further embodiment, the temperature gradient is greater than, or equal to, 0.1°C per minute, or greater than, or equal to, 1.0°C per minute, or greater than, or equal to, 2.0°C per minute.

2008/0166817A1). In one embodiment, the apparatus further comprises a means to subject the second stationary phase to a solvent gradient.

In one embodiment, the apparatus further comprises a means to subject the second stationary phase to both a temperature gradient and a solvent gradient, for example, by using a combination of at least one oven and at least one pump, each as described above. In a further embodiment, the temperature gradient is greater than, or equal to, 0.1°C per minute, or greater than, or equal to, 1.0°C per minute, or greater than, or equal to, 2.0°C per minute.

In one embodiment, the liquid flowing through the first stationary phase is a nonpolar solvent. Examples of nonpolar solvents include, but are not limited to, 1 ,2-dichlorobenzene, 1,2,4-trichlorobenzene, and hexane.

In one embodiment, the liquid flowing through the first stationary phase is a polar solvent. Examples of nonpolar solvents include, but are not limited to, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), and water (H₂0).

In one embodiment, the liquid flowing through the first stationary phase is a nonpolar solvent or a polar solvent. In one embodiment, the polymer has a concentration in the solution of greater than 0.02 milligrams per milliliter of solution.

In one embodiment, the first stationary phase is contained in only column.

In one embodiment, the "retention volume (y in ml) of a polymer fraction per column versus the molecular weight of the polymer fraction (x in Dalton)" meets the following relationship: y = -m(log x) + b, where b is < 30, or < 25, or < 20 ml, and m is < 3.0 or < 2.5

ml/log(Dalton). In a further embodiment, the dimension of the column is "300 mm X 7.8 mm."

An inventive SEC apparatus may comprise a combination of two or more

embodiments as described herein. The following embodiments may apply to both the inventive SEC methods and inventive SEC apparatus.

In one embodiment, the first and/or the second stationary phase(s) further comprise(s) at least one inert filler. Inert fillers include, but are not limited to, inorganic materials, such as, but not limited to, glass, stainless steel shots, and copper shots. As used herein, the term "inert" refers to a material that does not chemically react or physically adsorb polymers from the solution or eluent, each used in the chromatographic process.

In one embodiment, the first stationary phase further comprises at least one inert filler. Inert fillers include, but are not limited to, inorganic materials, such as, but not limited to, glass, stainless steel shots, and copper shots.

In one embodiment, the second stationary phase further comprises at least one inert filler. Inert fillers include, but are not limited to, inorganic materials, such as, but not limited to, glass, stainless steel shots, and copper shots.

In one embodiment, the first and the second stationary phases, independently, further comprise at least one inert filler. Inert fillers include, but are not limited to, inorganic materials, such as, but not limited to glass, stainless steel shots, and copper shots.

In one embodiment, the first stationary phase comprises less than, or equal to 50 weight percent inert filler, and further less than, or equal to 30 weight percent inert filler, based on the sum weight of the inert filler and porous graphitic carbon. In one embodiment, inert filler is in the form of spheres. In a further embodiment, the spheres have a diameter from 2 to 250 microns, or from 5 to 125 microns, or from 7 to 50 microns.

In one embodiment, the inert filler is glass.

In one embodiment, the inert filler is stainless steel shot.

In one embodiment, the inert filler is copper shot.

In one embodiment, the first stationary phase comprises less than, or equal to 50 weight percent glass, and further less than, or equal to 30 weight percent glass, based on the sum weight of the glass and porous graphitic carbon. In one embodiment, the glass is in the form of spheres. In a further embodiment, the spheres have a diameter from 2 to 250 microns, or from 5 to 125 microns, or from 7 to 50 microns.

In one embodiment, the second stationary phase comprises greater than, or equal to 50 weight percent inert filler, and further greater than, or equal to 60 weight percent inert filler, based on the weight of the second stationary phase. In one embodiment, the at least one filler is in the form of spheres. In a further embodiment, the spheres have a diameter from 2 to 150 microns, or from 5 to 125 microns, or from 7 to 50 microns. In one embodiment, the inert filler is glass.

In one embodiment, the inert filler is stainless steel shot.

In one embodiment, the inert filler is copper shot.

In one embodiment, the second stationary phase comprises greater than, or equal to 50 weight percent glass, and further greater than, or equal to 60 weight percent glass, based on the weight of the second stationary phase. In one embodiment, the glass is in the form of spheres. In a further embodiment, the spheres have a diameter from 2 to 250 microns, or from 5 to 125 microns, or from 7 to 50 microns.

An inventive SEC method can be coupled, on or off line, with other analytical methods. For example, the effluent from an SEC column containing a copolymer of a selected molecular size can be analyzed by Temperature Rising Elution Fractionation (TREF), Crystallization Elution Fractionation (CEF) or Thermal Gradient Interactive Chromatography (TGIC), to determine the comonomer ratio of the selected molecular size. See also Roy et al., Development of Comprehensive Two-Dimensional High Temperature Liquid Chromatography x Gel Permeation Chromatography for Characterization of

Polyolefins, Macromolecules (2010), 43, 3710-3720; Gillespie et al., "APPARATUS AND METHOD FOR POLYMER CHARACTERIZATION," US2008/0166817A1 ; each incorporated herein by references.

The Crystallization Elution Fractionation (CEF) technique relies mainly upon the ability of polymers to crystallize from a moving carrier (Monrabal, et al., "Crysallization Elution Fractionation. A New Separation Process for Poly olefin Resins, Macromol. Symp. 2007. 257, 71-79). The crystallization substrate is normally spherical glass beads, or stainless steel shot, or a mixed spherical glass beads with stainless steel shot, and is more or less inert with respect to physical interaction with the polymer in solution. Substrates, such as HYPERCARB, carbon nanotubes, or silicon nanotubes, do not rely only upon the crystallizibility of the polymer from solution, but also on adsorption/interactions of the polymer at the surface of the substrate. This new technique is known as Thermal Gradient Interaction Chromatography (TGIC) as well as high temperature liquid chromatorgraphy at thermal gradient mode for polyolefins. Both CEF and TGIC rely upon a thermal gradient to elute polymer.

The method of this disclosure could be scaled up to include large scale fractionations of many grams or many pounds of polymer, by scaling up the size of the apparatus and the column(s). An inventive method may comprise a combination of two or more embodiments as described herein.

The first stationary phase may comprise a combination of two or more embodiments as described herein.

The second stationary phase may comprise a combination of two or more

embodiments as described herein. PGC

The following embodiments may apply to both the inventive SEC methods and the inventive SEC apparatus.

The first stationary phase comprises a porous graphitic carbon (PGC).

In one embodiment, the PGC has a pore size from 30 A to 3000 A, or from 30 A to 2000 A.

In one embodiment, the PGC is composed of flat sheets of hexagonally arranged carbon atoms.

In one embodiment, the PGC is composed of flat sheets of hexagonally arranged carbon atoms with a satisfied valence, as, for example, in a very large polynuclear aromatic molecule.

The term "graphitic carbon" includes a varieties of materials comprising the element carbon in the allotropic form of graphite, irrespective of the presence of structural defects. The three-dimensional hexagonal crystalline, long-range order of graphite can be detected in the material by diffraction methods (such as X-ray diffraction spectroscopy), independent of the volume fraction and the homogeneity of distribution of such crystalline domains. Carbon nanotubes and carbon "buckeyballs" are examples of forms of graphitic carbon that are useful in the SEC of this disclosure.

In one embodiment, the first stationary phase consists of a porous graphitic carbon.

In one embodiment, the first stationary phase consists of a porous graphitic carbon coated and/or grafted onto silica particles. In one embodiment, the first stationary phase consists essentially of a porous graphitic carbon and a porous graphitic carbon coated and/or grafted onto silica particles.

In one embodiment, the first stationary phase consists of a porous graphitic carbon and a porous graphitic carbon coated and/or grafted onto silica particles.

In one embodiment, the porous graphitic carbon is packed into columns and comprises flat sheets of hexagonally arranged carbon atoms at the molecular level.

In one embodiment, the porous graphitic carbon has an average particle size from about 1 to about 30 microns, or an average particle size of about 5 microns, or 7 microns or 13 microns.

In one embodiment, the porous graphitic carbon has an average particle size from about 1 to about 30 microns.

In one embodiment, the porous graphitic carbon has a pore size from about 30 A to about 3000 A, or from about 30 A to about 2000 A.

In one embodiment, the porous graphitic carbon has an average particle size from about 1 to about 30 microns, or an average particle size of about 5 microns, or 7 microns or 13 microns, and a pore size from about 30 A to about 3000 A, or from about 30 A to about 2000 A.

In one embodiment, the porous graphitic carbon has an average particle size from about 1 to about 30 microns, and a pore size from about 30 A to about 3000 A, or from about 30 A to about 2000 A.

In one embodiment, surface of the porous graphitic carbon has an area from about 50 to about 400 square meters/gram, or from about 100 to about 300 square meters/gram, or from about 100 to about 140 square meters/gram.

In one embodiment, the length of a column comprising the first stationary phase is from about 100 mm to about 500 mm, and the diameter of the column is from about 4.6 mm to about 10 mm.

An example of a commercially available stationary phases that consists essentially of porous graphitic carbon includes the HYPERCARB brand HPLC column from Thermo Scientific, Waltham MA; and DISCOVERY ZR-CARBON brand HPLC column from Sigma Aldrich, St. Louis, MO.

The PGC may comprise a combination of two or more embodiments as described herein. Polymers

In one embodiment, the polymer is a nonpolar polymer, for example, polyethylene, polypropylene and polystyrene.

In one embodiment, the polymer is a polar polymer, for example, ethylene vinyl acetate.

In one embodiment, the polymer is an olefin-based polymer. In a further

embodiment, the olefin-based polymer is an ethylene-based polymer or a propylene -based polymer.

In one embodiment, the olefin-based polymer is an ethylene-based polymer.

In one embodiment, the olefin-based polymer is an ethylene/alpha-olefin

interpolymer. In a further embodiment, the alpha-olefin is a C3-C10 alpha-olefin, and preferably selected from propylene, 1-butene, 1-hexene, and 1-octene.

In one embodiment, the olefin-based polymer is an ethylene/alpha-olefin copolymer.

In a further embodiment, the alpha-olefin is a C3-C10 alpha-olefin, and preferably selected from propylene, 1-butene, 1-hexene, and 1-octene.

In one embodiment, the olefin-based polymer is a copolymer of ethylene and an alpha-olefin. In a further embodiment, the alpha-olefin is 1-butene or 1-octene.

In one embodiment, the olefin-based polymer is a polyethylene homopolymer.

In one embodiment, the olefin-based polymer is a propylene -based polymer.

In one embodiment, the olefin-based polymer is a propylene/alpha-olefin

interpolymer. In a further embodiment, the alpha-olefin is ethylene, or C4-C10 alpha-olefin, and preferably selected from ethylene, 1-butene, 1-hexene, and 1-octene.

In one embodiment, the olefin-based polymer is a propylene/alpha-olefin

copolymer. In a further embodiment, the alpha-olefin is a C2, or C4-C10 alpha-olefin, and preferably selected from ethylene, 1-butene, 1-hexene, and 1-octene.

In one embodiment, the olefin-based polymer is a copolymer of propylene and an C4- C10 alpha-olefin, and preferably selected from 1-butene, 1-hexene, and 1-octene.

In one embodiment, the olefin-based polymer is a copolymer of propylene and ethylene.

In one embodiment, the olefin-based polymer is a polypropylene homopolymer. In one embodiment, the olefin-based polymer has a density less than, or equal to, 0.97 g/cc; or less than, or equal to, 0.96 g/cc; or less than, or equal to, 0.95 g/cc (1 cc = 1 cm³). In one embodiment, the olefin-based polymer has a density less than, or equal to, 0.92 g/cc; or less than, or equal to, 0.90 g/cc; or less than, or equal to, 0.88 g/cc (1 cc = 1 cm³).

In one embodiment, the olefin-based polymer has a density less than, or equal to, 0.89 g/cc; or less than, or equal to, 0.88 g/cc; or less than, or equal to, 0.87 g/cc (1 cc = 1 cm³).

In one embodiment, the olefin-based polymer has a density greater than, or equal to,

0.83 g/cc; or greater than, or equal to, 0.84 g/cc; or greater than, or equal to, 0.85 g/cc (1 cc = 1 cm³).

In one embodiment, the olefin-based polymer has a density from 0.83 g/cc to 0.97 g/cc, or from 0.84 g/cc to 0.95 g/cc, or from 0.85 g/cc to 0.93 g/cc (1 cc = 1 cm³).

In one embodiment, the olefin-based polymer comprises from 1 mole percent to 49 mole percent of an alpha-olefin, as determined by ¹³C NMR. Preferred alpha-olefins are discussed above. In a further embodiment, the olefin-based polymer is an ethylene-based polymer or a propylene-based polymer.

In one embodiment, the olefin-based polymer comprises from 2 mole percent to 29 mole percent of an alpha-olefin, as determined by ¹³C NMR. Preferred alpha-olefins are discussed above. In a further embodiment, the olefin-based polymer is an ethylene-based polymer or a propylene-based polymer.

In one embodiment, the olefin-based polymer comprises from 5 mole percent to 9 mole percent of an alpha-olefin, as determined by ¹³C NMR. Preferred alpha-olefins are discussed above. In a further embodiment, the olefin-based polymer is an ethylene-based polymer or a propylene-based polymer.

Olefin-based polymers include, but are not limited to, low density polyethylene (LDPE); high density polyethylene (HDPE); heterogeneously branched linear polymers (include Ziegler-Natta polymerized polymers, such as LLDPE, and include products such as DOWLEX Linear Low Density Polyethylene (LLDPE) available from The Dow Chemical Company); homogeneously branched substantially linear polymer (such as AFFINITY Polyolefin Plastomers and ENGAGE Polyolefin Elastomers, both available from The Dow Chemical Company); homogeneously branched linear polymers (such as EXACT Polymers available from ExxonMobil); and olefin multiblock copolymers (such as INFUSE Olefin Block Copolymers available from The Dow Chemical Company).

Olefin-based polymers also include polypropylene homopolymers, impact propylene based copolymers, and random propylene based copolymers. Other polymers include, but are not limited to, ethylene/acrylic acid copolymers, ethylene/vinyl acetate copolymers and ethylene/styrene interpolymers, halogenated polymers, polymers containing maleic anhydride moieties, and polyelectrolytes.

A polymer may comprise a combination of two or more embodiments as described herein.

An olefin-based polymer may comprise a combination of two or more embodiments as described herein.

An ethylene-based polymer may comprise a combination of two or more

embodiments as described herein.

A propylene-based polymer may comprise a combination of two or more

embodiments as described herein.

DEFINITIONS

The term "polymer," as used herein, refers to a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The generic term polymer thus embraces the term homopolymer (employed to refer to polymers prepared from only one type of monomer, with the understanding that trace amounts of impurities can be

incorporated into the polymer structure), and the term interpolymer as defined hereinafter.

The term "interpolymer," as used herein, refers to polymers prepared by the polymerization of at least two different types of monomers. The generic term interpolymer includes copolymers (employed to refer to polymers prepared from two different types of monomers), and polymers prepared from more than two different types of monomers.

The term "olefin-based polymer," as used herein, refers to a polymer that comprises a majority amount of polymerized olefin monomer, for example ethylene or propylene, based on weight of the polymer, and, optionally, at least one comonomer.

The term "ethylene-based polymer," as used herein, refers to a polymer that comprises a majority amount of polymerized ethylene monomer (based on weight of the polymer) and, optionally, at least one comonomer.

The term "ethylene/a-olefin interpolymer," as used herein, refers to an interpolymer that comprises a majority amount of polymerized ethylene monomer (based on the weight of the interpolymer) and at least one a-olefin.

The term, "ethylene/a-olefin copolymer," as used herein, refers to a copolymer that comprises a majority amount of polymerized ethylene monomer (based on the weight of the copolymer), and an a-olefin, as the only two monomer types. The term "propylene-based polymer," as used herein, refers to a polymer that comprises a majority amount of polymerized propylene monomer (based on weight of the polymer) and, optionally, at least one comonomer.

The term "propylene/a-olefin interpolymer," as used herein, refers to an interpolymer that comprises a majority amount of polymerized propylene monomer (based on the weight of the interpolymer) and at least one a-olefin.

The term, "propylene/a-olefin copolymer," as used herein, refers to a copolymer that comprises a majority amount of polymerized propylene monomer (based on the weight of the copolymer), and an a-olefin, as the only two monomer types.

The term "composition," as used herein, includes a mixture of materials which comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition.

The term "multidimensional chromatography," as used herein, refers to the coupling together of multiple separation mechanisms (for example, see "J.C. Giddings (1990), Use of Multiple Dimensions in Analytical Separations, in Hernan Cortes Editor, Multidimensional Chromatography: Techniques and Applications (1st ed. pp. 1), New York, NY: Marcel Dekker, Inc.)."

The term "stationary phase," as used herein, refers to a material which exists as a solid phase in the fluid stream (liquid) in a chromatographic process.

The terms "comprising," "including," "having," and their derivatives, are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term "comprising" may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term, "consisting essentially of excludes from the scope of any succeeding recitation any other component, step or procedure, excepting those that are not essential to operability. The term "consisting of excludes any component, step or procedure not specifically delineated or listed. TEST METHODS

Polymer density was measured in accordance with ASTM D-792-08.

Melt index (12) of an ethylene-based polymer is measured in accordance with ASTM D-1238-04, condition 190°C/2.16 kg. For propylene -based polymers, the melt flow rate (MFR) is measured in accordance with ASTM D-1238-04, condition 230°C/2.16 kg.

D50 (D10, D90)

The particle size distribution can be measured with ACCUSIZER 780 OPTICAL

PARTICLE SIZER (Particle Size System, Florida, USA), which uses the principle of Single Article Optical Sizing (SPOS) to count and size particles one at a time, thus eliminating missed particles, and providing accurate particle size and count information. The illumination/detection system in the sensor is designed to provide a monotonic increase in pulse height with increasing particle diameter. The standard calibration curve is obtained by measuring a series of standard polystyrene latex samples from NIST Traceable Monodisperse Standards (Duke). The detailed procedure for calibration can be found in the operation menu provided by Particle Size System. A particle size distribution (PSD) is constructed by counting a large amount of particles (at least 55,000 particles). The sample is dissolved in methanol (HPLC grade) at low enough concentration, according to the operation procedure provided by Particle Size System. The D50, D10 and D90 are calculated by the software of ACCUSIZER 780. Other solvents suitable include TCB (HPLC grade) and ODCB (HPLC grade). The D50, is defined as the mean particle size, in diameter, where half of the particle population (number distribution) resides above, or equal to, this D50 value, and half the particle population (number distribution) resides below this D50 value. D10 = 0.5 x D50, and D90 = 1.5 x D50.

EXPERIMENTAL

Solvents

Ortho-dichlorobenzene (ODCB, 99% anhydrous grade) and 2,5-di-tert-butyl-4- methylphenol (BHT, catalogue number B1378-500G, batch number 098K0686) were purchased from Sigma- Aldrich. Eight hundred milligrams (ppm) of BHT (based on the weight of the ODCB) and five grams of silica gel were added to two liters of ODCB. The "ODCB containing BHT and silica gel" is now referred to as "ODCB." This ODCB was sparged with dried nitrogen (N2) for one hour before use. The silica gel was Silica Gel 40 (particle size 0.2-0.5 mm, catalogue number 10181-3), purchased from EMD. The silica gel was dried in a vacuum oven at 160°C, for about two hours before use.

The 1 ,2,4-trichlorobenzene (TCB) was purchased from Fisher Scientific. Two hundred ppm (based on the weight of the TCB) of BHT was added to the TCB. This TCB was

then sparged with dried N2. Polymer Samples

Commercially available polystyrene standards with known molecular weights were purchased from Polymer Laboratories (Current Agilent Technology).

Commercially available polyethylene standards with known molecular weights (Product name: Polyethylene GPC calibration Kit E-WM-10 Lot 4) (PE)) were purchased from Polymer Laboratories (Current Agilent Technology,).

Hexacontane (Mw of 843.61) was purchased from Sigma- Aldrich.

Columns

The comparative columns (20 μιη Mixed A, 300 x 7.5 mm, four columns in series) were purchased form Agilent Technology.

The column packed with a porous graphitic carbon was a "Column Number KS- 0411103Z" for high temperature application, available from Thermo Scientific. The column specification included the following: Media Batch Number PGC 478, column back pressure of 1150 psi, the pore size of 250 A. The reported particle size was 7 μιη.

Comparative SEC Method

The chromatographic system consisted of Polymer Laboratories Model PL-220. The unit was equipped with a differential refractive detector as a concentration detector. The column and carousel compartments were operated at 140°C. Four Polymer Laboratories (Current Agilent Technology), 20 μιη Mixed- A columns were used with the TCB, as solvent sparged with N₂. The samples were prepared at a concentration of 0.5 mg/mL" in TCB for the molecular weight (Mw) above, or equal to, 1,000,000 Dalton; and at "1.0 mg/ml" in TCB for the molecular weight (Mw) less than 1,000,000 Dalton. Each polystyrene standard was prepared by agitating lightly for one hour at 160°C. The injection volume was 200 μL·, and the flow rate was 1.0 ml/min. Retention volume was reported as the volume of solvent passed through stationary phase upon the sample injection.

Inventive SEC Method - Example 1

The inventive SEC method was performed with a commercial Crystallization Elution Fractionation instrument (CEF, Polymer Char) in ODCB. The commercial CEF instrument was equipped with an infrared detector IR-4 (Polymer ChAR, Spain). To perform SEC analysis, using the CEF instrument, each polystyrene sample solution was prepared by the autosampler. The sample concentration in ODCB was "0.4 mg/ml" for polystyrene molecular weight (Mw) over 1,000,000 Dalton, and "0.75 mg/ml" for polystyrene molecular weight from 1,000,000 to 10,000 Dalton.

The sample solution was loaded to the column packed with porous graphitic carbon (reported pore size is 250 Angstroms (A), and the reported particle size is 7 micrometers (μιη)), and maintained at a temperature of 130°C. The sample solution was maintained on the column isothermally at 130°C, for four minutes (cooling temperature being set the same as the stabilization temperature in CEF methodology). After this time, the elution process began using a "1.0 mL/min" pump flow rate, and the data was collected. After 15 minutes, the samples were eluted from the column. Next, the temperature of the column was raised to 145 °C, at 3°C/min, to finish the elution.

The schematic drawing of the "column temperature versus time" for this SEC is shown in Figure 1, and the experimental parameters are shown in Table 1. A guard column (PLgel 10μΜ Guard) of "50 x 7.5 mm" (Polymer Lab, catalogue number PL1110-1120, Varian Inc, currently Agilent Technologies) was installed in the detector oven just before the IR-4 detector.

Table 1 : Experimental Parameters for ³olystyrene

Temperature profile Column loading and vial filling

Stabilization Temperature 130 °C Column Load Volume 0.4 mL

Stabilization Rate 10 °C / Solvent pick up flow rate 25 ml / min min

Stabilization Time (Pre) 5 min Vial filling flow rate 5 ml / min

Stabilization Time (Post) 2 min

Crystallization Temperature 130 °C Loop Loading and filter cleaning

Crystallization Rate 3 °C / min Sample pick up flow rate 2 ml / min

Crystallization Time 2 min Sample pick up volume 2.2 ml

SF Time 15 min Load Loop Flow Rate 1.25 mL/min

Elution Temperature 145 °C Load Loop Volume 1.2 mL

Elution Rate 5 °C / min Clean Line Flow Rate 1.25 mL/min

Cleaning Temperature 145 °C Clean Line Volume 4 mL

Cleaning Rate 40 °C / Clean Filter Flow Rate 4 mL/min min

Cleaning Time 2 min Clean Filter Volume 5 mL

Cleaning Transfer Line 5 mL / min Flow Rate

Temperature Zones Cleaning Transfer Line 2.00 ml

Volume

Top Oven Temperature 150 °C

Transfer Line Temp 150 °C Pump flow

Needle Temp 150 °C Pump Stabilization Time 15 s

Cleaning Column Pump 1 mL / min Flow

Dissolution Crystallization Pump Flow 0 mL / min

Dissolution Temperature 160 C Elution Pump Flow 1 mL / min

Dissolution Stirring 2 Load Column Pump Flow 0.3 mL / min

Figure 2 shows the chromatogram of polystyrene Cocktail #1 (a mixture of polystyrene standards of Mw 3,900,000 Dalton; 320,000 Dalton; and 34,500 Dalton; each reported by the manufacturer) by using the inventive SEC method. As shown in this figure, it has been discovered that the inventive method/apparatus surprisingly separates polystyrene based on molecular weight.

Figure 3 shows the chromatogram of polystyrene Cocktail #2 (a mixture of polystyrene standards of Mw 1,980,000 Dalton; and 120,000 Dalton; each reported by the manufacturer) by using the inventive SEC method. Also, as shown in this figure, the inventive method surprisingly separates polystyrene based on molecular weight.

Figure 4 shows the correlation of the "retention volume of the polystyrene standards" versus the "molecular weight reported by the manufacture" for the inventive SEC

method/apparatus (one column only), and a comparative SEC method (a series of four columns). As shown in this figure, it has been discovered that a surprisingly strong correlation exists between retention volume and the manufacturer reported weight average molecular weight (Mw) over three decade of Mw (log Mw). Also, as seen in Figure 4, surprisingly, the inventive SEC method/apparatus required only one column to achieve sufficient resolution of the polystyrene standards, as compared to the comparative method/apparatus which required four columns.

Inventive SEC Method - Example 2

The second example used narrow polyethylene standards (PE) with the molecular weight reported by the manufacturers from a range of from 843.6 to 192,000 Dalton. Two PE cocktails were used as discussed below.

Cocktail #3 consists of PE with reported molecular weight (Mw) of 192,000, 22,500 and 1,100 Dalton, at 33.3 : 33.3 : 33.3 (wt: wt), respectively.

Cocktail #4 consists of PE with reported molecular weight (Mw) of 59,900 and 843.6

Dalton.

The molecular weight analysis was performed with the same instrument as used for Inventive Example 1, with the following changes: each PE sample was at concentration of "0.75 mg/ml" in ODCB; the stabilization temperature was equal to the crystallization temperature set at 155°C; and the elution temperature was 170°C. The experimental parameters are shown in Table 2.

Table 2: Experimental Conditions for Polyethylene

Figure 5 shows the chromatograms of the PE standards. As shown in this figure, it has been discovered that the inventive method/apparatus surprisingly separates polyethylene based on molecular weight. It has also been surprisingly discovered that a strong correlation exists between retention volume and the "log Mw" reported by the manufacturer, as shown in Figure 6. Also, only one column was needed to achieve sufficient resolution of the polyethylene standards. The slope of the retention volume versus log (Mw) of the inventive method with one column (300 mm X 7.8mm) is "-2.0 mL/log (Mw of polyethylene)." The slope of the four comparative columns, at same column length (300 mm X 7.5mm per column), is "-3.0." The slope of the comparative stationary phase per column is thus "-3.0/4= -0.75 mL/log (Mw of polyethylene)." It has been discovered, as shown by the steeper slope, as discussed above, that the inventive method/apparatus has improved resolution at the same column length. Another unique feature of the invention is that the first stationary phase has an outstanding thermal, chemical and mechanical stability. Its performance does not change significantly upon a rapid temperature change (so called temperature shock, for example at a thermal change rate of 30°C/min), or multiple thermal cycles or solvent composition change, or sudden change in flow rate. This feature is especially critical for high temperature SEC. It is well known in the prior art of SEC technique, with the comparative stationary phase, that extreme cares must be taken when handling comparative SEC stationary phase, which includes slowly cooling or heating, gradually switching between different mobil phases, in order to maintain its performance. The robustness of the inventive method makes it very applicable as a quick tool for industrial QC laboratories.

Although the invention has been described in considerable detail in the preceding examples, this detail is for the purpose of illustration, and is not to be construed as a limitation on the invention, as described in the following claims.

Claims

CLAIMS:

1. A method for a Size Exclusion Chromatography (SEC) of a polymer, said method comprising introducing a solution, comprising the polymer, into a liquid flowing through a first stationary phase, and wherein the first stationary phase comprises a porous graphitic carbon (PGC).

2. The method of Claim 1, wherein the first stationary phase is subject to a temperature gradient.

3. The method of any of the previous claims, wherein the first stationary phase is subject to a solvent gradient.

4. The method of any of the previous claims, wherein the first stationary phase has a mean particle size (D50) less than, or equal to, 30 microns in diameter, and wherein less than 10% of the particles have a diameter of D10, wherein D10 = 0.5 x D50.

5. The method of any of the previous claims, wherein the first stationary phase has a mean particle size (D50) less than, or equal to, 30 microns in diameter, and wherein at least 90% of the particles have a diameter of D90, wherein D90 = 1.5 x D50.

6. The method of any of the previous claims, wherein the molecular weight distribution and/or the molecular size distribution of the polymer is/are measured.

7. The method of any of the previous claims, further comprising fractionating the solution comprising the polymer into polymer fractions, and introducing the polymer fractions into a second stationary phase that is different from the first stationary phase.

8. The method of Claim 7, wherein the second stationary phase is subject to a temperature gradient.

9. The method of Claim 7 or Claim 8, wherein the second stationary phase is subject to a solvent gradient.

10. An apparatus for Size Exclusion Chromatography (SEC) of a polymer, said apparatus comprising at least one column comprising a first stationary phase, and wherein the first stationary phase comprises a porous graphitic carbon (PGC).

11. An apparatus for Size Exclusion Chromatography (SEC) of a polymer, said apparatus comprising at least one column comprising a first stationary phase, and

12. The apparatus of Claim 10 or Claim 11, further comprising a means to subject the first stationary phase to a temperature gradient.

13. The apparatus of any of Claims 10-12, further comprising a means to subject the first stationary phase to a solvent gradient.

14. The apparatus of any of Claims 10-13, further comprising a means to measure molecular weight distribution and/or the molecular size distribution of the polymer.

15. The apparatus of any of Claims 10-14, further comprising a second stationary phase that is different from than first stationary phase.