Polymer Separations by Chemical Composition Using SEC-Gradients

Transcription

1 Polymer Separations by Chemical Composition Using SEC-Gradients Wolfgang Radke PSS Polymer Standards Service GmbH International Symposium on GPC/SEC and Related Techniques Sept. 30 th.-oct. 2 nd 2014 Frankfurt/Main 0 0

2 Agenda Polymer Chromatography: Who is my neighbour? Gradient Chromatography/ Breakthrough Peaks/ Barrier Methods Concept of SEC-Gradients Proof of Concept (PMMA/PS) Separation of Polyamides Application of SEC-Gradients to Copolymer Separations Poly(methyl methacrylate stat methacrylic acid) Poly(n-butyl acrylate stat acrylic acid) Conclusions Seite 1 1

3 Polymer Chromatography Who is my neighbor? 2

4 Ideal Gradient Chromatography Polymer dissolved in initial eluent Flow direction sample Injected solvent 3

5 Breakthrough Peaks Polymers are soluble in only some solvents Solvent differs from initial eluent Flow direction sample breakthrough 4

6 Barrier Methods LC LCA Solvent differs from initial eluent n.b. injection at strong eluent (SEC) conditions sample velocity eluent velocity Sample component 1 Sample component 2 5

7 SEC Gradients The concept v P > v E v P = v E v P < v E Adsorption threshold Flow direction 6

8 SEC Gradients The concept v P > v E v P = v E v P < v E Adsorption threshold Flow direction 7

9 Comparing conventional vs. SEC gradients Conventional gradient Sample dissolved in weak eluent Sample injected at start of gradient Sample experiences LAC conditions when injected Desorption threshold approaches sample Sample fully adsorbed upon injection SEC gradient Sample dissolved in strong eluent Sample injected at end of gradient Sample experiences SEC conditions when injected Sample approaches adsorption threshold Sample only at verge of adsorption 8

10 Old Stuff 9

11 Proof of Concept PMMA standards THF (SEC) SEC gradient ELSD-signal/V ELSD-signal/V 3,0 2,5 2,0 1,5 1,0 0,5 0, ,5 3,0 2,5 2,0 1,5 1,0 0, g/mol g/mol g/mol g/mol g/mol g/mol 1800 g/mol Note inverse volume axis! 0, V R [ml] % THF PSS Proteema column, SEC gradient THF CHCl 3 Polymer view!! 10

12 Proof of Concept PMMA standards M [g/mol] pure THF SEC-gradient 100% THF CHCl 3 SEC-gradient 70% THF CHCl 3 SEC-gradient 40% THF CHCl V/mL PSS Proteema column, SEC gradient THF CHCl 3 11

13 Proof of Concept Separation of PS/PMMA blend Normalized ELSD-signal ELSD-Signal / V 1,0 0,8 0,6 0,4 0,2 0,0 2,5 2,0 1,5 1,0 0,5 THF (SEC) PMMA 54K PS 60K PMMA 54K PS 60K 0,0 0 8,0 7,5 7,0 6,5 6,0 5,5 5,0 V/mL % THF PSS Proteema column, SEC gradient 100 THF CHCl 3 12

14 Separation of Polyamides Normaized ELSD-Signal PA 12 PA 11 PACM 12 PA 612 PA 63T PA 66 PA 6?? Elution Volume /ml PSS Proteema column, SEC gradient 75/25 55/45 Toluene/TFE Precipitation based system! 13

15 Separation of Polyamides Number of Amide Groups / Carbon V R / ml Amide groups / C PSS Proteema column, SEC gradient 75/25 55/45 Toluene/TFE 14

16 Poly(methyl methacrylatestat-methyacrylic acid) PMMA CH 3 C C H 2 C n O O CH 3 PMAA CH 3 C C H 2 C n O O H Tablet coating Dissolution speed depends on AA content Sample M w /gmol -1 D MAA content/% , , , , ,

17 SEC ELSD-Signal/V 1,2 1,0 0,8 0,6 0,4 DMAc isocratic acid content 9% 25% 31% 42% 48% 0,2 0,0 8,0 7,5 7,0 6,5 6,0 5,5 5,0 elution volume/ ml PSS Proteema column 16

18 SEC Gradient 100%DMAc 100%Chloroform ELSD-Signal/V 1,2 1,0 0,8 0,6 0,4 0,2 0,0 acid content 9% 25% 31% 42 48% isocratic DMAc ELSD-Signal /V CHCl 3 -DMAc SEC-gradient 0 9,0 8,5 8,0 7,5 7,0 6,5 6,0 5,5 5,0 elution volume / V Samples dissolved in DMAc 17

19 Optimization Changing gradient slope 1 Adsorption thresholds Flow direction 18

20 SEC Gradient ELSD-Signal/V ELSD-Signal / V SEC-Gradient 100% -0% DMAc SEC-Gradient 0% -50% DMAc elution volume / ml Samples dissolved in DMAc 19

21 Optimization Changing gradient slope 2 Adsorption thresholds Flow direction 20

22 SEC Gradient ELSD-Signal / V SEC-Gradient 50% - 0% DMAc normalized ELSD-Signal / V 0 1,2 0,9 0,6 0,3 SEC-Gradient 5% - 50% DMAc 0, elution volume /ml Samples dissolved in DMAc 21

23 Chemical Composition Distribution 0,3 w(%) 0,2 0,1 0, content methacrylic acid/ wt% 22

24 SEC Gradient vs. Conventional Gradient normalized ELSD-Signal / V ELSD-Signal / V 1,2 0,9 0,6 0,3 0,0 1,2 0,9 0,6 0,3 0,0 6 min. SEC-Gradient 5% - 50% DMAc min. conventional-gradient 5% - 50% DMAc elution volume /ml Samples dissolved in DMAc / CHCl 3 with 4-10% DMAc 23

25 Poly(butyl acrylatestat-acrylic acid) nba H C C H 2 C n O O C 4 H 9 AA H C C H 2 C n O O H Acrylic acid content 0-100% 24

26 SEC Gradient 6 5 ELSD-Signal [V] Elutionsvolumen [ml] 6 min. SEC gradient 100% to 4% DMAc Samples dissolved in DMAc 25

27 Elution Volume vs. Composition 9 Solvent 1 Solvent 2 Elution volume/ml acrylic acid content / % 26

28 Sample Differences ELSD-Signal [V] 1,50 1,25 1,00 0,75 0,50 47 mol % AA 40 mol % AA 64 mol % AA 61 mol % AA Similar composition Incorrect composition 0,25 0,00 10,0 9,5 9,0 8,5 8,0 7,5 7,0 6,5 Elutionsvolumen [ml] 27

29 Conclusions Proof of concept Polymer can be retarded by gradient introduced bevor the sample injection If retardation by adsorption threshold, molar mass independent elution (above critical molar mass) Separtion of polymer blends (PS/PMMA) possible Separation of Polyamides according to Amide content New separation method for poly(methyl methacrylate-statmethyacrylic acid) Similar selectivity as conventional gradient, but no breaktrough peaks New separation method for poly(butyl acrylate-stat-acrylic acid) Differences in CCD or composition can be easily detected Easier adjustement to 2D-chromatography (same column larger pore size) Seite 28

30 Acknowledgements Martin Schollenberger Proof of concept Separation of PS/PMMA, PMMA/PtBA, PMMA/PnBA blends Helena Maier Separation of poly(methyl methacrylate-stat-methyacrylic acid) Separation of poly(butyl acrylate-stat-acrylic acid) Nico Apel Separation of Polyamides TESA SE Samples poly(butyl acrylate-stat-acrylic acid) Seite 29