Characterization of Ultralarge Polymers by GelCharacterization of Ultralarge Polymers by Gel Permeation Chromatography: Challenges and Limitations

David M. Meunier and Yongfu LiDow Chemical CompanyCore Research and DevelopmentAnalytical Sciences

Ultralarge versus ultrahigh molar mass key distinctions

Ultralarge polymers defined as those having Rg > ~ 150 nm

Extremely Ultralarge polymers defined as those having Rg > 300 nm

S f 300 2 000 000 / ( ) Linear PS in THF Rg of 300 nm corresponds to 24,000,000 g/mol (est.)

Linear PS in THF of 15,000,000 g/mol* corresponds to Rg of 230 nm

Crosslinked PS nanoparticle having VSF of 2 and molecular weight of Crosslinked PS nanoparticle having VSF of 2 and molecular weight of 24,000,000 g/mol has Rg of ~ 50 nm

For linear chains….Size, not molecular weight, governs the GPC separationSynthetic polymers typically have broad size distributionsSynthetic polymers typically have broad size distributionsFinding ideal (or near ideal) GPC separation conditions is challenging for samples containing material having Rg > 300 nm

2

*Typically the highest MW PS standard available commercially

Key considerations for Ultralarge Polymers*Shear degradation and/or deformationInterchain association and/or aggregationNon-equilibrium transport between mobile phase and stationary phaseo equ b u t a spo t bet ee ob e p ase a d stat o a y p aseConcentration polarization effect – lack of flow suppression in poresHydrodynamically induced diffusionStress-induced diffusionStress-induced diffusionMulti-path effectInstrument limitationsNon-ideal GPC separation is manifested by late elution of ultralarge chains

A laser light scattering detector (e. g., MALLS or LALLS) is essential for detecting late elution

*Giddings, J.G., Adv.Chromatogr. 20 (1982) 217; Porsch, B., et al., J. Chromatogr. A2005, 1068,

3

g , , g ( ) ; , , , g , ,249-260;

Evaluation of GPC conditions with LS and narrow stds

Compare log M versus elution volume from light scattering (continuous points) to log M

l ti l fversus elution volume for narrow standards (discrete data points)Ideal or near ideal GPC elution

log M vs. elution volume plots arelog M vs. elution volume plots are superimposable

Ultralarge polymer sampleLate elution is clearly evident

4

Experimental

Sample preparation• Solutions were prepared in mobile phase solvent (0.05 wt% NaN3), and were

filtered through a 0.45-μm nylon syringe filter prior to injection. Sample concentration was about 0 25C* to ensure that polymer chain entanglementsconcentration was about 0.25C to ensure that polymer chain entanglements were minimized.

Instruments• Waters 2690 set at the optimum flow rate (0.2 – 1.0 ml/minute)p ( )• Wyatt DAWN DSP MALLS + Wyatt Optilab rEX DRI detectors both operating

at a wavelength of 632.8 nm at room temperature, or a Viscotek (Malvern) TDA 301 with LALLS and DRI detection.

Column set• 2 Tosoh TSK-Gel GMPW. 7.5 mm i.d. x 300 mm, 17 µm particles at 25 °C

.

5

Defining a “standard” when none exist (1 of 2)MW

(kg/mol)Rg/nm

MC 15 47.5 20.3

MC 400 146 36 5Blue traceRed traceMC 400 146 36.5

MC 4000 277 52.3

Red traceGreen trace

Retention Volume/ml

6

Log MW versus elution volume plots are completely superimposable

Defining a “standard” when none exist (2 of 2)rms radius vs. volume

MC- 4000 HPMC-1 4000 HPMC-2 4000 HPMC-3 4000

LS dRI

Molar Mass vs. volume

MC- 4000 HPMC-1 4000 HPMC-2 4000 HPMC-3 4000

6

71.0x10LS dRIMW Rg

dius

(nm

)

100.0

ass

(g/m

ol)

1000.0

41.0x10

51.0x10

61.0x10g

rms

rad

10.0

Mol

ar M

a

0.1

1.0

10.0

100.0

All samples have Rg ~ 55 nm and MW ~ 300,000 g/mol; compositions vary slightlyvolume (mL)

10.0 12.0 14.0volume (mL)

10.0 12.0 14.0

0.0

Fractionation appears to be ideal (or near ideal). No late elution observed.

The 4000 series samples were chosen to define optimal separation conditions

7

Evidence of non-ideal elution of ultralarge chains

Molar Mass vs. volume

HPMC-2 4000 HPMC-2 220000

LS dRI

rms radius vs. volume

HPMC-2 4000 HPMC-2 220000

Flowrate is 1.0 ml/minute

g/m

ol)

71.0x10

LS dRIMW

nm)

100.0

LS dRIRg

Mol

ar M

ass

(g

51 0x10

61.0x10

rms

radi

us (

n

10.0

volume (mL)9.0 10.0 11.0 12.0 13.0 14.0 15.0

1.0x10

volume (mL)9.0 10.0 11.0 12.0 13.0 14.0 15.0

10.0

MW (kg/mol) Rg (nm)

HPMC 2 4000 337 58.4

HPMC 2 220000 996 112Red traceBlue trace

8

HPMC 2 220000 996 112 Blue trace

Flow rate dependence of “standard” elution profilesMolar Mass vs. volume

MC- 4000 MC 4000 FR 0.5 MC 4000 FR0.2

91 0x10 LS dRI

mol

)

51 0 10

61.0x10

71.0x10

81.0x10

1.0x10

1.0 ml/min0.5 ml/min

Mol

ar M

ass

(g/m

100.0

1000.0

41.0x10

51.0x10 0.5 ml/min0.2 ml/min

M

0.0

0.1

1.0

10.0

volume (mL)9.0 10.0 11.0 12.0 13.0 14.0

log M versus elution profiles are superimposable at all flow ratesBaseline shifts S/N variation flow rate accuracy produce slight differences

9

Baseline shifts, S/N variation, flow rate accuracy produce slight differences in the chromatograms

Flow rate dependence of ultralarge HPMC elutionMolar Mass vs. volume

HPMC-2 4000 HPMC-2 220000 HPMC-2 220000 FR0.5HPMC-2 220000 FR0.2

LS dRI

g/m

ol) 71.0x10

LS dRI

1.0 ml/min0.5 ml/min0 2 ml/min

Mol

ar M

ass

(g

51.0x10

61.0x10

0.2 ml/minSTANDARD

volume (mL)10.0 12.0 14.0

1.0x10

volume (mL)

Bulk MW measured by at each flow rate was the same – no shear degradationElution profile and log M versus elution volume is flow rate dependentIdeal or near-ideal GPC elution observed for HPMC-2 220,000 at 0.2 ml/minute

10

,

Pay Attention to Deborah (Number)1.0 mL/min

De < 0.5: Random coilDe > 0 5: Coil to stretch transition

w ra

te

Rg,c when De ~ 0.5De > 0.5: Coil to stretch transition

duce

d flo

wR

e

0.025 mL/min

*Schoenmakers/ J. Chromatogr. A 1218 (2011) 6930–6942 J Ch t A 1218 (2011) 1509 1518

*Pasch, Macromolecules, Vol. 38, No. 17, 2005, pp. 7476-748411

6942; J. Chromatogr. A 1218 (2011) 1509–1518

Pay Attention to Deborah (Number) and critical Rg

Rg,c is the radius of gyration where De = 0.5

Flow rate (mL/min) Rg,c (nm)

g gy ein GPC conditions used for cellulose ethers

( ) g, ( )

1.0 169

0.5 2130.5 213

0.2 290

12

Molecular weight averages from GPC-MALLSl / %Flow RatemL/min

MN(kg/mol)

MW(kg/mol)

MW/MN Wt%<Rg,c

HPMC 3 100,000

1 0 220 837 3 80 951.0 220 837 3.80 95

0.5 165 835 5.05 ~100

HPMC 3 250,000

1.0 360 1,140 3.17 88

0.5 220 1,120 5.10 97

0.2 136 1,060 7.83 ~100

HPMC 2 220,000

1.0 292 1,060 3.64 90

0.5 181 1,050 5.82 97

0.2 145 996 6.88 ~100

Conditions highlighted in green yielded log M vs. volume plots that were superimposable with lower MW “standard”, and Wt% < Rg,c was ~100%

13

superimposable with lower MW standard , and Wt% Rg,c was 100%

Ultralarge polyethylene oxide samples

MW (kg/mol) Rg,w (nm)* Wt% > 300 nm

PEO 1 1 000 0PEO -1 1,000 67.7 0

PEO-2 1,750 93.8 0

PEO-3 2,500 115 NA

PEO-4 3,400 138 ~2

PEO-5 5,700 187 2-8 estimate

PEO-6 7 000 210 ~8PEO 6 7,000 210 ~8

*Estimated from published conformation plot Rg = 2.15*MW0.583

Macromolecules 1991, 24, 5943-5947

14

Flow rate dependence of elution – two different samples

358.49

357.00

358.00

ALS

GPC

Mod

e-00

00.v

cm

357.85

357.00

S FI

PA M

ode-

0001

.vcm

Overlay Plot: Refractive Index (mV) Vs. Retention Volume (mL)Method: LALS GPC Mode-0000.vcm

5.6

5 5

.69

2008-01-29_05;24;02_310-3247-1-23-08-0_45u_01.vdt : LALS GPC Mode-0000.vcm 2008-01-29_06;53;16_309-1-23-08-0_45u_01.vdt : LALS FIPA Mode-0001.vcm

1.0ml/min

MWkg/mol

Wt% > 300nm

PEO 6 ~7,000 ~8

354.00

355.00

356.00

_310

-324

7-1-

23-0

8-0_

45u_

01.v

dt /

Met

hod:

L

354.00

355.00

356.00

;16_

309-

1-23

-08-

0_45

u_01

.vdt

/ M

etho

d: L

AL

PEO 6 M ~ 7 000 kg/mol (LALLS)

PEO 5 ~5,800 2-8

300.83 300.21

Overlay Plot: Refractive Index (mV) Vs. Retention Volume (mL)Method: GPC LALS-0002.vcm

2008-02-20_12;20;04_310-3247-1-23-0_45_01.vdt : GPC LALS-0002.vcm351.74 351.47

Overlay Plot: Refractive Index (mV) Vs. Retention Volume (mL)Method: FIPA LALS-0000.vcm

2008-01-30 18;45;18 310-3247-1-23-08-0 45u 02.vdt : FIPA LALS-0000.vcm

351.62

352.00

353.00

2008

-01-

29_0

5;24

;02_

351.77

353.00

2008

-01-

29_0

6;53

;

4.9 8.3Retention Volume (mL)

5.0 6.0 7.0 8.0

PEO 6 MW ~ 7,000 kg/mol (LALLS)PEO 5 MW ~ 5,800 kg/mol (LALLS)

298.00

299.00

300.00

_45_

01.v

dt /

Met

hod:

GPC

LAL

S-0

002.

vcm

297.00

298.00

299.00

5_01

.vdt

/ M

etho

d: G

PC

LAL

S-00

02.v

cm

5.6

0

5.4

6

2008-02-20_13;22;18_309-1-23-0_45_01.vdt : GPC LALS-0002.vcm

349.00

350.00

351.00

_45u

_02.

vdt /

Met

hod:

FIP

A LA

LS-0

000.

vcm

349.00

350.00

351.00

u_02

.vdt

/ M

etho

d: G

PC L

ALA

-000

1.vc

m

5.6

0

5.4

8

_ ; ; _ _ _ 2008-01-30_21;34;31_309-1-23-08-0_45u_02.vdt : GPC LALA-0001.vcm

0.3ml/min0.5ml/min

293 61

294.00

295.00

296.00

297.00

2008

-02-

20_1

2;20

;04_

310-

3247

-1-2

3-0_

293 22

294.00

295.00

296.00

2008

-02-

20_1

3;22

;18_

309-

1-23

-0_4

5

346.00

347.00

348.00

2008

-01-

30_1

8;45

;18_

310-

3247

-1-2

3-08

-0_

345.00

346.00

347.00

348.00

2008

-01-

30_2

1;34

;31_

309-

1-23

-08-

0_45

u

15

293.61 293.22

4.7 8.1Retention Volume (mL)

5.0 6.0 7.0 8.0344.99 344.59

4.8 8.1Retention Volume (mL)

5.0 6.0 7.0

Late elution of ultralarge polyethylene oxide6 different samples all anal ed at a flo rate of 0 3 mL/min R c 253 nm

 7.81

7.60

m

Overlay Plot: Log Molecular Weight Vs. Retention Volume (mL)Method: GPC LALS-0002.vcm

2008-02-21_16;25;40_205-1-23-0_45u_02.vdt : GPC LALS-0002.vcm 2008-02-21_17;38;57_2000k-1-23-0_45_01.vdt : GPC LALS-0002.vcm 2008-02-21_09;09;27_n-60knf-1-23-0_45u_01.vdt : GPC LALS-0002.vcm 2008-02-21_05;00;28_coag-1-23-0_45u_01.vdt : GPC LALS-0002.vcm

6 different samples all analyzed at a flow rate of 0.3 mL/min – Rg,c = 253 nmTSK-Gel GMPW column, 17 µm particle sizeSamples vary in MW (Rg) – significantly larger Rg compared to HPMC

6 60

6.80

7.00

7.20

7.40

etho

d: G

PC

LA

LS-0

002.

vcm

2008-02-20_12;20;04_310-3247-1-23-0_45_01.vdt : GPC LALS-0002.vcm 2008-02-20_13;22;18_309-1-23-0_45_01.vdt : GPC LALS-0002.vcm

W

5.80

6.00

6.20

6.40

6.60

205-

1-23

-0_4

5u_0

2.vd

t / M

log

MW

PEO-6

PEO-5PEO 4PEO-1

5.00

5.20

5.40

5.60

2008

-02-

21_1

6;25

;40_

2 PEO-5PEO-4PEO-3

PEO 24.71

4.7 8.8Retention Volume (mL)

5.0 6.0 7.0 8.0

Late elution worsens as fraction of chains exceeding Rg,c increases

PEO-2

16

Summary and ConclusionsS t ti t l f l ti GPC diti f lt l l h Systematic protocol for evaluating GPC conditions for ultralarge polymers has been developed

Application of the protocol to commercial cellulose ether materials revealed that ideal (or near ideal) GPC conditions could be identified for all commercialthat ideal (or near ideal) GPC conditions could be identified for all commercial grades

Conditions corresponding to De < 0.5 for all chains were necessary for best GPC elutionGPC elution

Ideal (or near ideal) conditions have not yet been identified for ultralargepolyethylene oxide having 1% or more of material exceeding 300 nm Rg

Further increases in R c would appear to be necessary Further increases in Rg,c would appear to be necessary Further flow rate reduction Explore solvent viscosity – limited choices Larger particle size (and pore size) mixed-bed packings – maintain flow suppression g p ( p ) p g pp

in pores Larger radius columns

Exploration of alternative separation mechanisms may be provide additional insight

17

Acknowledgments

Joe Kiefer

Danielle Dodge

Hongwei Shen

18

Later elution of polyethylene oxide

Molar Mass vs. volume

205 151966(001)[2014-11-26-1] 301 159844(001)[2014-11-26-1]205 151966(001)[2014-12-8] 301 159844(002)[2014-12-8]Light scattering (90o) and DRI chromatograms at 0.5 and 0.2 ml/min

mol

)

781.0x10

91.0x10

101.0x10

111.0x10LS dRI

PEO-1PEO-4 MW

Decreasing flow rate0.5 ml/min0.2 ml/min

olar

Mas

s (g

/m

1000.0

41.0x10

51.0x10

61.0x10

71.0x10

PEO-4

PEO-1 MW

0.5 ml/min0 2 ml/min

Mo

0.00.11.0

10.0100.0

PEO 1 MW

Decreasing flow rate

0.2 ml/min

volume (mL)8.0 10.0 12.0 14.0 16.0 18.0

Log M vs. elution volume for PEO-1 superimposable with PEO narrow standardsLate elution of higher molar mass material was still observed for PEO-4 at the

19

lowest practical flow rate of 0.2mL/min

Deborah Number and Deformation

Deborah number (De), which is the product of the longest relaxation time of the polymer, τ, and the strain rate of the flow, έ

De < 0.5: Random coilDe > 0 5: Coil to stretch transition

De=0.80.3<De<1.0 De >1.0

De > 0.5: Coil to stretch transition

Hoagland, Macromolecules, Vol. 41, No. 13, 2008g , , , ,

20