Comprehensive Polymer Analysis Strategies

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1 Comprehensive Polymer Analysis Strategies Mike Woodman, LC Applications Scientist 10 February,

2 Review of GPC/SEC Polymer Analysis Portfolio The Agilent GPC/SEC portfolio is a complete GPC solution for our customers, from a single vendor. Instrumentation Infinity GPC/SEC System w/ Concentration Detector Infinity GPC/SEC w/ Multi Detector Suite - GPC 220 for high temperature work (olefins ) Consumables - Large range of organic columns, PLgel, PlusPore - Large range of aqueous columns, PLaquagel, PolarGel - Large range of standards for both aqueous and organic applications Software - Agilent GPC/SEC, conventional and multi-detector w/ 1260 control - Conventional GPC Cirrus plug-in for OpenLAB CDS or EZChrom 2

3 Agilent 1260 Infinity GPC/SEC System Modular approach to Conventional GPC Versatile system with a wide range of modules that can be tailored to satisfy multiple techniques GPC/SEC minimum requirements include - RID, and/or optional VWD or DAD - Isocratic Pump, degasser recommended - Vial-based Autosampler - Thermostatted Column Compartment - Agilent GPC/SEC Software (full or OpenLab/Cirrus) 1260 system commonly configured for HPLC - Binary or Quaternary Gradient Pump w/ degasser - Vial-based Autosampler - Thermostatted Column Compartment - Detection via VWD, MWD, DAD, RID and/or ELSD - GPC plug-in (Cirrus) for OpenLAB Software 3

4 1260 Infinity GPC/SEC Multi Detector Suite G7800A Advanced Detection for Absolute Accuracy Any combination of: Refractive Index, and Viscometer, and/or Dual Angle Light Scattering detector with Remote PC software-controlled or integrated keypad Signal inputs as well as signal outputs Accurately heated detector modules (ambient to 60 C) High sensitivity, maximum stability 4

5 Agilent GPC/SEC Software A complete package for data collection/analysis Single channel, concentration only data RID, UV/Vis, ELSD Use Agilent GPC/SEC Software, or Available as Cirrus OpenLAB Plug-in MW info relative to standards chosen GPC/SEC Multi-Detector Software Concentration Detector (usually RID) Dual Angle Light Scattering and/or Viscometer Long Chain Branching Calculations Absolute molecular weights* * specific sample and system requirements must be met 5

6 Special Requirements for Best Polymer MWD Results When Using any Variant of MDS with GPC/MDS Software For dual angle light scattering and viscometer-based detectors, a concentration detection is always required Accurate sample concentration must be known A concentration detector response factor (dn/dc) must be known or calculated for operating solvent and temperature 6

7 Special Requirements for Best Polymer MWD Results Ideal polymers are pure homopolymers Ideal molecular weights (Mw) are well above 10,000 Copolymer analysis is possible, however co-monomer ratio must be constant across the entire MW distribution Blended polymer samples are not good candidates for MDS 7

8 Not All Polymer Problems are Solved w/ GPC GPC can give molecular weight distribution information GPC and specific detection may yield absolute molecular weight information, with certain sample-related restrictions Linear or long chain branched homopolymer MW can be accurately measured with MDS variants however 8

9 Not All Polymer Problems are Solved w/ GPC GPC will not give compositional information or identity GPC may not separate polymer blends unless MW is highly disparate between the components GPC may not be ideal for competitive deformulation work Polymers (oligomers, often) below 5000 MW are not good candidates for any MDS approach (limitations of technology, not limitations of our implementation) 9

10 Alternatives to GPC MWD Approach Alternatives to GPC Separation Reversed phase separation, at near room temperature, for low MW polymers (<5000 MW) (can be MS friendly) Cloud Point Chromatography gradient separations, at near room temperature, primarily with medium to high MW organic soluble polymers on ordinary reversed phase columns No Chromatography Thermal methods like DSC, TGA, etc. Classic mechanical testing methods (shear, etc.) Purpose-specific (dissolution, processing behavior, etc.) Spectroscopic Techniques (FTIR, UV/VIS, etc.) 10

11 Reversed Phase Separation of Lower Molecular Weight Polymers 11

12 Reversed Phase Separation of Lower Molecular Weight Polymers, Gradient Slope Optimization PEG

13 Reversed Phase Separation of Low MW Polymers 13

14 Cloud Point Chromatography Principles Over a wide variety of room temperature soluble polymers, a good solvent and a miscible non-solvent are selected The sample, dissolved in a good solvent, is injected into a porous or non-porous column while mobile phase of a nonsolvent is flowing The sample precipitates as a thin film on the particle surface A gradient elution proceeds, from a non-solvent to a solvent condition, and polymers elute primarily based on the critical point the ratio of non-solvent/solvent that dissolves the polymer from the surface film and elutes it to a suitable detector 14

15 One of Many Published References 15

16 Homologous Series -- Methacrylates 16

17 Co-monomer Ratio, Styrene-Butadiene 17

18 Cloud Point Chromatography, aka GAP, GPEC, and many other names 18

19 Cellulose Derivatives 19

20 Cellulose Derivatives, Zoom View 20

21 Cellulose Acetates, Degree of Acetylation Marginal THF sol. Excellent THF sol. 21

22 Summary, Cloud Point Separations Dissolution principles allow resolution by monomer solubility with minimal molecular weight bias Excellent approach for co-polymer and polymer blends Simple gradient setup, with reversed phase column, adaptable to most gradient LC systems The preferred detector is evaporative light scattering though other detectors could work with specific polymer types An adjunct to classical size exclusion separation 22

23 Agilent Polymer Analysis Wide variety of instrument configurations isocratic, gradient binary or quaternary solvent delivery switching valves for online automation UV/VIS, RI, VIS, LLS, ELSD, MS, MS/MS Consumables, Standards and Columns for organic and water soluble polymer analysis Absolute and Relative Molecular Weight Distributions Alternative Separation Techniques for low molecular weight polymers, polymer blends, polymer formulations Additives Extractables and Leachables (EnL) with LC/MS 23