Comprehensive Characterization of Natural Rubber Samples using … Event/201… · Thermal Field-Flow-Fractionation coupled with MALS and Triple Detection Dr. Gerhard Heinzmann, Postnova

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Comprehensive Characterization of

Natural Rubber Samples using

Thermal Field-Flow-Fractionation

coupled with MALS and Triple Detection

Dr. Gerhard Heinzmann, Postnova Analytics GmbH, Germany

International Symposium on GPC/SEC and Related Techniques,

Amsterdam, The Netherlands, September 26th-29th, 2016

http://www.postnova.com/

www.postnova.com . www.postnova.com .

• FFF Separation Platform

• Thermal FFF (TF3)

• TF3-MALS and TF3-Triple/Tetra/Penta Detection

• Application Examples

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Separation and Detection Platform

3

TF2000 Thermal FFF

AF2000 Flow FFF

Light Scattering

Detector

PN3621 MALS

RI detector PN3150

Concentration

Malvern

Zetasizer

Agilent 7900 ICP-MS

CF2000 Centri FFF

Size Separation

UV detector PN3211

DAD detector PN3241

Fluori detector PN3411

ELS detector PN3510

…

SC2000 GPC

Viscometer detector

PN3310

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FFF Separation Principle

Separation Mechanism

• Separation in a narrow ribbon-like channel

• Laminar flow inside the channel

• External field perpendicular to the solvent flow

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Thermal FFF – Principle

TF2000: Separation

VE ~ DTΔT/D

Thermal Diffusion

Coeffcient

-> Depends on

chemical composition Applications

• Rubbers Polymers

• Gels / Latexes

• Cross-linked

Polymers

• Thermal gradient up to Δ120°C

• Separation kDa up to several MDa

• Analysis time, 10 – 120min (no upper limit)

• Separation depends on Size and Chemical Composition (“2 Dimensional”?)

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Advantages of Thermal FFF

compared to GPC/SEC:

Excellent separation for

high MW extended

´Exclusion Limit´

No filtration of gel

material, no clogging of

columns No shear degradation in

porous columns / frits

No interaction

with stationary

phase

Thermal FFF vs. GPC/SEC

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FFF – Triple Detection

- MALS

- Viscometer

- Concentration Detector(s)

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Thermal FFF

8

Setup of TF2000 Thermal FFF with Triple Detection (Penta Detection)

MALS / Viscometer / 3x Concentration Detector

Detector Setup: UV => MALS => Visc => RI => ELSD

Conditions: Solvent = THF, Flow rate = 0.3 mL/min

Alternative Setup: UV => MALS => Split: Visc => Waste and RI => ELSD => Waste

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RI signal = KRI * (dn/dc) * Conc

LS signal = KLS * (dn/dc)2 * Conc * Mw

• MW from MALS + RI

• Rg from MALS

• IV from Viscometer + RI

• Rh from Viscometer + RI + MALS

• Mark-Houwink plot (log IV vs. log Mw) shows structure and degree of branching

Determination of Mw, Rg, IV and Structure

Visco signal = KVisco * [ƞ] * Conc

UV signal = KUV * Ɛ * Conc

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Results

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TFFF Applications – PS

System • TF2000 FFF System

• PN3150 RI Detector

Conditions • Injection Volume: 20 µL

• Concentration: 2 mg/mL

• Temp. grad. T = 90°K to 0°K

Separation of PS standards

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TFFF Applications – PS with Pentadetection


• PN3621 MALS

• PN3310 Viscometer

• PN3211 UV

• PN3150 RI

• PN3510 ELSD




DOW PS 1683 / MW = 250 kDa, PD = 2.5

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TFFF Applications – PS with Pentadetection

System

• TF2000 FFF System

• PN3621 MALS


• PN3211 UV

• PN3150 RI

• PN3510 ELSD

Conditions

• Injection Volume: 50 µL



DOW PS 1683 / MW = 250 kDa, PD = 2.5

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TFFF - Separation by Chemical Composition

Separation of PS and PMMA-Standards with same Rh

SEC vs. Thermal FFF (TF3)

TF3 enables separation of molecules with the same hydrodynamic

volume according to their chemical composition!

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TFFF Applications – SBR Rubber with Pentadetection

RI

ELSD

MALS

Viscometer

UV

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Application Example:

Natural Rubber

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Radius of Gyration Molar Mass

• Nanoscale impurities with same size separated according to different

chemical composition

TFFF Applications - Natural Rubber

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TFFF Applications – Natural Rubber with Pentadetection


• PN3621 MALS


• PN3211 UV

• PN3150 RI

• PN3510 ELSD




Natural Rubber Sample (Polyisoprene)

a = 0.98

Stiff chain structure in low MW area

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• PN3621 MALS


• PN3211 UV

• PN3150 RI

• PN3510 ELSD




Natural Rubber Sample

a = 0.49

More compact structure in high MW area (branching?)

a = 0.98

TFFF Applications – Natural Rubber with Pentadetection

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0.025

0.125

0.225

0.202

0.206

0.21

0 10 20 30 40 50 60 70

ELS

D D

ete

cto

r Sig

nal [V

]

LS

Dete

cto

r S

ignal [V

]

Time [min]

__ LS 92° __ ELSD

Raw Data Fractogram of TF3 - MALS and ELSD

System • PN5300 Auto Injector

• TF2000 Thermal FFF

• ELSD

• PN3621 MALS (92° SLS)


• Concentration: 2.0 mg/mL

• LS 92°(red trace)

• ELSD (blue trace)

• The fractogram shows a system start peak at 11 min.

• The 1st peak – the main peak - was detected between 15

- 50 min by light scattering and ELSD detection.

• A 2nd peak was detected at 54 min predominantly by light

scattering.


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0.000

0.002

0.004

0.006

0.008

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

1.E+10

1.E+11

1.E+12

11 21 31 41 51

Dete

cto

r Sig

nal [V

]

Mola

r M

ass [g/m

oL]

Time [min]

Molar Mass / LS 92°

Overlay: Molar Mass and LS Signal • The molar mass was calculated from MALS and ELSD data • Literature value for dn/dc = 0.124 mL/g • In the 1st peak the sample contains rubber material with a molar mass of appr. 4.7 x 105 g/mol (w-

average) and in the 2nd peak of 3.6 x 108 g/mol.

Conditions • Molar Mass (red dots)

• LS Signal (blue trace)

• Fitting by Random Coil Model

Mw[g/mol]

1. Peak

13.0 – 48.5

min

n-Average 2.7 x 105

w-Average 4.7 x 105

z-Average 8.1 x 105

2. Peak

48.5 – 56.0

min

n-Average 8.1 x 106

w-Average 3.6 x 108

z-Average 1.5 x 109

1 2


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0.000

0.002

0.004

0.006

0.008

10

100

1,000

11 21 31 41 51

Dete

cto

r Sig

nal [V

]

Radiu

s [nm

]

Time [min]

Radius / LS 92°

Overlay: Radius of Gyration and LS Signal • The Radius of Gyration was calculated from MALS angular data

• The main/1st peak shows a Radius of Gyration of 42 nm (z-average) and the 2nd peak a Radius of

Gyration of 218 nm.

Conditions • Radius of Gyration (red dots)

• LS Signal (blue trace)

• Fitting by Random Coil Model

Rg [nm]

1. Peak

13.0 – 48.5

min

n-Average 23

w-Average 31

z-Average 42

2. Peak

48.5 – 56.0

min

n-Average 65

w-Average 107

z-Average 218

1 2


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Molar Mass

Molar Mass [g/mol]

1e+4 1e+5 1e+6 1e+7 1e+8 1e+9 1e+10

Diffe

rential

0.1

0.09

0.08

0.07

0.06

0.05

0.04

0.03

0.02

0.01

0.0

Cum

ula

tive

1.0

0.0

Molar Mass

Molar Mass [g/mol]

1e+4 1e+5 1e+6 1e+7 1e+8 1e+9 1e+10

Diffe

ren

tial

1.0

0.0C

um

ula

tive

1.0

0.0

Molar Mass Distribution

Zoom in Molar Mass Distribution

Differential Molar Mass Distribution (blue trace), Cumulative Molar Mass Distribution (red trace)

The sample shows a multimodal distribution. For the 1st fraction (13 – 48.5 min) the

distribution is in the range of 9.2 x 104 – 2.8 x 106 g/mol and for the 2nd fraction (48.5 – 56

min) in the range of 2.7 x 106 – 2.3 x 109 g/mol). The sample contains 1.3 % of high

molar mass material (gel). Calculation based on concentration detector signal.


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System • PN5300 Auto Injector

• AF2000 FFF System

• PN3621 MALS Detector

• PN3150 RI Detector

• PN3510 ELSD



Fractal Dimension

log r

2

log

M

1.0E+01

9.0E+00

8.0E+00

7.0E+00

6.0E+00

5.0E+00

4.0E+00


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Fractal Dimension 51.6 – 54.8 min

The Fractal Dimension was evaluated for 2 different regions.

For the 1st region of the fractogram (17.5 – 44.6 min) the Fractal Dimension is 1.78 and

for the 2nd region (51.6 – 54.8 min) 2.92.

The Fractal Dimension change indicates that in the 2nd part of the fractogram there is

material with a higher density, indicating cross linking or branches.

Fractal Dimension 17.5 - 44.6 min

Fractal Dimension=1.78

log r

1.81.751.71.651.61.551.51.451.41.351.31.251.2

log M

7.0E+00

6.0E+00

5.0E+00

Fractal Dimension=2.92

log r

2.42.352.32.252.22.152.12.0521.95

log M

1.0E+01

9.0E+00

8.0E+00


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Summary

Thermal FFF is a Powerful Method for

Polymer and Biopolymer Characterization

• Increased resolution for high molar mass species • Huge flexibility in choice of fractionation power (gradient)

• No interaction with stationary phase / no artifacts

• No degradation due to shear stress during the separation

• No filtration by stationary phase or frits

• Separation according to molecular weight and size as well as according to

chemical composition offers new horizons for further applications

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Thank you for your

Attention

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Documents

Comprehensive Characterization of Natural Rubber Samples using … Event/201… · Thermal Field-Flow-Fractionation coupled with MALS and Triple Detection Dr. Gerhard Heinzmann, Postnova