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Molecular Weight Characterization of Polymers

Keywords: 
Chromatography, Polymers, Molecular Weight, Molar mass
Research Area: 
Physical Sciences
Engineering & Technology
Location: 

Centro Joxe Mari Korta
Avenida Tolosa 72
20018 Donostia-San Sebastián

Website: 
Contact: 

Dr. Amaia Agirre
amaia.agirre@ehu.eus
943018476

Available for external users?: 
Yes
Description: 

The molecular weight (Mw) and molecular weight distribution (MWD) have a strong relation in the final properties and industrial applications of polymer. Most of the times, in order to understand the performance of a polymer its characterization is crucial. Nowadays, rapid and powerful techniques are available for determining Mw and MWD.

Size Exclusion Chromatography (SEC)
SEC has become the most popular method for determination of molar mass distribution and molar mass moments, and, in combination with light scattering and viscosimetric detectors, for determination of the distribution of root mean square (RMS) radius and intrinsic viscosity, detections of aggregation, and characterization of the molecular conformation and branching.

Aqueous solutions and THF can be used as the carrier fluid and triple detection is possible using Multi Angle Light Scattering (MALS), Viscosimeter and Refractive Index (RI) detectors.

Asymmetric Flow Field Flow Fractionation (AF4)
FFF is also a fractionation technique in which molecular weights and particle sizes can be measured. The separation is achieved with no stationary phase, solely by flow in an open channel where a perpendicular field is applied.

The main advantage of the AF4 compared to a conventional SEC is the lack of stationary phase. The limitations and problems present in the SEC, such as characterization of branched/cross-linked polymers or the enthalpic interaction between the stationary phase and the polymer chains are avoided.

Aqueous solutions and THF can be used as the carrier fluid. Multi Angle Light Scattering (MALS) and Refractive Index (RI) detectors are used with this separation method.

Services: 

- Molecular weight and molecular weight distribution measurements with differente separation techniques: SEC and AF4.
- Ultrahigh molecular weight characterization
- dn/dc measurements

Equipment

SEC or AF4 separation techniques for THF soluble polymers

HPLC system
- LC-20AD pump
- SIL-20AHT Autosampler
- CBM-20A module
Multi Angle Light Scattering Detectors (MALS): Dawn HELEOS
- Molar mass range: 200 Da to 10 GDa
- Molecular size range (rg): 10 – 500 nm, up to 1000 nm with shape-specific models
- Molecular Size Range (Rh, with DLS): Flow: 1 – 300 nm
Batch: 0.5 nm – 1 µm
- Static Scattering detectors: 18 angles
- DLS Scattering Angle (optional WyattQELS: any one of 18 static scattering angles

SEC or AF4 separation techniques for water soluble polymers

HPLC system
- LC-20AD pump
- SIL-20AHT Autosampler
- CBM-20A module
Multi Angle Light Scattering Detectors (MALS): Mini Dawn TREOS
- Molar mass range: 200 Da to 10 MDa
- Molecular size range (rg): 10 – 50 nm, up to 150 nm with shape-specific models
- Molecular Size Range (Rh, with DLS): Flow: 1 – 40 nm
Batch: 0.5 nm – 1 µm
- Static Scattering detectors: 3 angles
- DLS Scattering Anlge (optional WyattQELS): 90º