© Fraunhofer LBF

Graphit – ungeahnte Perspektiven in der HPLC von Polymeren

Robert Brüll (robert.bruell@lbf.fraunhofer.de)Fraunhofer-Institute for Structural Durability and System Reliability LBFwww.lbf.fraunhofer.de

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The Fraunhofer-Gesellschaft Main locations in Germany

� 67 institutes

� More than 23,000 employees

Main locations

Other locations

The Fraunhofer LBF

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Fraunhofer LBF in Darmstadt

ZSZ-e

Main building

LOEWE-CenterAdRIA

Transfer Center for Adaptronics

Darmstadt- Kranichstein site

Darmstadt City site –Division Plastics

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Basic TechnologyResearch

Research toProve Feasibility

TechnologyDevelopment

Technology Demonstration

System / Subsystem Development

System Test& Operations

Contract research

Services for industry

Cooperation with Fraunhofer LBFFrom fundamental research to marketable products

� Publicly funded projects

� EU, BMWi, BMBF,…

Initial research

� Application of proven methods and procedures

� Structural and system analyses

� Consultation

� Qualification of skilled staff …

� Applied research

� Bilateral R&D cooperation

� Feasibility studies

� …

TRL 1

TRL 2

TRL 3

TRL 4

TRL 5

TRL 6

TRL 7

TRL 8

TRL 9

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� Molecular Characterization

� HT HPLC

� Non-polar/polar

� Non polar

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Challenges in Polymer Analysis

HPLC (LAC) SEC

� Multidimensional techniques are required to analyze the chemical heterogeneity

� Classical: fractionations

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� Potential Benefits

� faster than fractionation

� can be tuned more selective

� also amorphous samples can be analyzed

� The Scientific Challenge

� Must withstand 160 °C!!!!

Liquid Chromatography

n

n n

n

n n

Stereo-sequences

Monomer-Sequences

Monomer/Stereo-sequences

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Separation Modes

SEC

LAC

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LCCC

LCCC

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Screening of Mobile Phases: Solvents for Polyethylene

decalin/cyclohexane, 1/3vol.decalin/methylcyclohexane, 1/3vol.

2-chlorotoluenedecalin

TCBphenylcyclohexane

decalin/phenylcyclohexane,1/3vol.1,1,2,2-ethane

decalin/cyclohexylacetate,1/3vol.decalin/2-ethyl-1-hexanol, 4/5vol.

decalin/cyclohexanone, 1/3 vol.-dodecane

-dodecane/2-ethyl-1-hexanol, 4/5vol.2,2,4,4,6,8,8-heptamethylnonane

cyclohexylacetatehexylacetate

cyclohexanone-nonylalcohol

2-ethyl-1-hexanol

70 80 90 100 110 120 130 140 150 160Temperature (oC), at which precipitation starts

Polyethylene

nn

n

Cloud Point Temperature

Polyethylene 260,000 g/mol

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Stationary phase: Polygosil 1000; mobile phase: gradient decalin - cyclohexanone (dotted line); temperature: 140 °C; detector: ELSD; sample solvent: decalin (TCB for the PVAc standards)

Ethylene-Vinylacetate Copolymers High-Temperature Gradient HPLC

0 2 4 6 8 10 12 14 16 18

0

2

4

6

8

10

12

0

20

40

60

80

100

PVAc

19 %

Res

pons

e E

LSD

(V

)

E lu tion V o lum e (m L)

PE126 kg/m ol

5%

12%

14%

28%

45 %

60 %

70%

% V

ol. C

yclo

hexa

none

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3500 3000 2500 2000 1500 1000

60

80

100

Tra

nsm

issi

on (

%)

Wavenumber (cm-1)

High-Temperature HPLC Coupled with FTIR for EMA Copolymers

4 8 12 16 20 24 28 32

0

10

20

30

40

50

60

70

80 1225 1124 1218 1209 MA 1225 MA 1224 MA 1218 MA 1209

Elution Volume (mL)

Gra

m S

chm

idt

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

relative content of MA

4 6 8 10 12 14 16 18 20 22 24 26 28 30

0

20

40

60

80

100

120

MA content EMA 18 EMA 28 EMA 14 EMA 9

Gram Schmidt EMA 18 EMA 28 EMA 14 EMA 9

Elution Volume (mL)G

ram

Sch

mid

t

0,0

0,5

1,0

1,5

2,0

2,5

3,0

relative content of MA

Producer 2Producer 1

Broad chemical distribution Narrow chemical distribution

PE

A. Albrecht, R. Brüll, T. Macko, H. Pasch, Macromolecules 40 (2007) 5545 – 5551

A. Albrecht, R. Brüll, T. Macko, P. Sinha, H. Pasch Macromol. Chem. Phys. 209 (18) (2008) 1909

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Hyphenation of HPLC and SEC: 2D-LC

2D-Liquid Chromatography

Vr

1

2

1

2

HPLC

SEC PMMA

PBMolar Mass

Co

mp

osi

tio

n

The ultimate characterization of a polymer sample, which chromatography may deliver!

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2D-LC HPLC valves, HPLC column oven

HT 2D-LC: Developing the Hardware

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Quantitative Detection

� Scheme of the instrument

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HT 2D-LC-IR of Grafted PolyolefinsPP-g-MA (1 mol %) PP-g-MA (1.7 mol %)

� Two spots

� Before the gradient – iPP (elutes in SEC mode)

� In the gradient – iPP-g-MA (symmetric profile)

�PP-g-MA exhibits higher average molar mass compared to iPP

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New Stationary Phases

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Graphite – Structure Selective Stationary Phase

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The Breakthrough

0 5 10 15 20 25

0.0

0.2

0.4

0.6

0.8

1.0

isotactic PP

PE

syndio-tactic PP

resp

on

se o

f E

LS

D [

Vo

lts]

elution time [minutes]

atactic PP

Start of gradient

T. Macko, H. Pasch, Macromolecules, 2009 42 (16), 6063R. Chitta, T. Macko, R. Brüll, G. Kalies, J. Chrom. A, 2010, 1217(49) 7717 – 7722T. Macko, R. Brüll, Y. Wang, Y. Thomann, Column – an electronic journal, September, 2009, 15R. Brüll, A. Albrecht, Nachrichten aus der Chemie, 2009, 57, 152 – 154R. Chitta, T. Macko, R. Brülll, R. Cong, M. Miller, A de Groot, J. Sep. Sci. 2013, 36(13) 2063

Stationary Phase: Hypercarb™ Mobile Phase: Decanol→TCB

� Separation according to composition and microstructure is possible

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EP-Copolymers

7 8 9 10 11 120,00

0,05

0,10

0,15

0,20

0,25

C2-73.7%

C2-63.4%

C2-60.5%C2-52.8%

C2-50.1%

C2-42.5%

C2-33.2%

EL

SD

sig

nal

[V

]

Elution Volume [mL]

C2-18.6%

100 90 80 70 60 50 40 30 20 10 00

2

4

6

8

10

12

14

Elu

tio

n v

olu

me

[mL

]

C2 [wt.%]

Random EP copolymers with different average chemical composition

Hypercarb™ & 1-decanol→TCB

Linear dependence

R. Brüll, T. Macko, A. Ginzburg, Y. Wang, Macromol. Rapid Comm. 2010, 31(2) F53-54T. Macko, F. Cutillo, V. Busico, R. Brüll, Macromol. Symp. 2010, 298, 182-190T. Macko, R. Brüll, R.G. Alamo, Y. Thomann, V. Grumel, Polymer 2009, 50, 5443 - 5448

� Separation according to ethylene content is possible

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EPDM: Influence of Diene

8,7 9,0 9,3 9,6 9,9 10,2 10,50,0

0,1

0,2

0,3

0,4

0,5

ENB-7.2%, C2-49 wt.%

ELS

D s

igna

l [V

]

Elution Volume [mL]

ENB-3.8%, C2-49 wt.%

nm

Hypercarb™ & 1-decanol→TCB

variation in ENB content

R. Chitta, T. Macko, R. Brüll, G. van Doremaele, L.-C. Heinz, J. Polym. Sci. Polym. Chem., 2011, 49(8), 1840 – 1846R. Chitta, A. Ginzburg, G. van Doremaele, T. Macko, R. Brüll, Polymer, 2011, 52(26), 5953 – 5960

� Diene adds to retention

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HT 2D-LC

HPLC: Hypercarb™, 1-decanol → TCB, 0.1 mL/min, 140 °C

SEC: PL Rapide™ H, TCB, 2.5 mL/min, 160 °C

A. Ginzburg, T. Macko, V. Dolle, R. Brüll, J. Chromatog. A 2010, 1217, 6867A. Ginzburg, T. Macko, V. Dolle, R. Brüll, Eur. Polym. J., 2011, 47, 319

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Unique and Identical Segments of Copolymers

� Mathematical Operations can be performed on matrices

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Improving Signal to Noise in HT 2D-LC

� Multiple injections increase signal intensity

� No shift in spot position

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� Oligomers are present in many polyolefins

� Migrants in food packaging

� Component of Oil

� Analysis by GC-techniques limited

Separation of Oligomers in PE

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Oligomer Separation – Peak Assignment

� Oligomers from C54 to C114 identified in PE 1 kg/mol. HypercarbTM/Decane→ODCB/ 130 °C

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TG-NMR of Ethylene/1-Octene

� Concentration decreases at 120 °C (E/O, 37 % Octene)

� Fully reversible, without hysteresis

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Portable automatic fraction collector, PAFC, for HT-LC

Designed by TiborTiborTiborTibor

Heater

Side viewValve and Temperature display

The CoreSoftware to control the switching valve

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Preparative GPC of a high molar mass Polyethylene with varying Number of Fractions

15 16 17 18 19 20 21 22 230.0

0.2

0.4

0.6

0.8

1.0

8 % overlap

32

EL

SD

res

po

nse

[V

](A

rea

no

rmal

ized

)

SEC elution volume [mL]

1

7 % overlap

a) 14 15 16 17 18 19 20 21 22 230.0

0.2

0.4

0.6

0.8

1.0

1.2

13 % overlap

16 % overlap

12 % overlap

2 543EL

SD

res

po

nse

[V

](A

rea

no

rmal

ized

)

SEC elution volume [mL]

1

15 % overlap

b)

3 fractions 5 fractions

8 fractions

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Conclusions

� Graphite provides a platform for HPLC of Polyolefins

� Oligomers can be identified in PE

� TG-NMR and Solution DSC prove that the mechanism in TGIC is based on adsorption

� Multiple injections combined with a fraction collector allow preparative isolation of specific components

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THE REAL HEROES

TiborJan

Dib

Sampat

AbhishekPrabhuSubin

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THE REAL HEROES

Gordian

Nico

Guru

Tobias