Molecular and colloid chemical characterization

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Equipment

• eluents
  aqueous: salt solutions, e.g. with organic coeluents, e.g. 0.2 M Na₂SO₄+1% HAc
  organic: Tetrahydrofuran (THF), Chloroform (TCM), Dichlormethane (DCM), Hexafluorisopropanol (HFIP), Toluene, Dimethylformamide (DMF), Dimethylacetamide (DMAc), Dimethyl sulfoxide (DMSO), e.g. with added salt, e.g. NaNO₃, LiBr, CF₃COONa, more on request
  
• detectors
  RI refractometer, UV detector,
  Evaporative light scattering detector ELSD
  combination with viscometer or multi-angle light scattering (MALS)
  
• special features: column temperature control, fragment collector
  

Target

• determination of molar mass averages (M_n, M_W) and molar mass distribution (Polydispersity index D)
• relatively
  calibration with dextran, pullulan, polyvinylpyridine, polystyrene sulfonic acid, PS, PMMA, PEG, PEO
• universal calibration, combination with viscometry
  
• absolute
  GPC-MALS (combination with multi-angle light scattering)

Application
and Download

• molar mass analysis of synthetic
  polymers and copolymers
• molar mass analysis of natural and bio-based polymers (e.g. starch, cellulose, lignin, proteins, PLA, PHB)
• reaction monitoring of polymer syntheses
• tracking of degradation reactions, recycling processes and aging

Methods of comparison and supplementation

• membrane osmometry (M_n)
• static light scattering (M_W; R_Z; A₂)
• dynamic light scattering (d_H)
• differential refractometry (dn/dc)

Equipment

• GONOTEC OSMOMAT 090 membrane osmometer
• membranes: cellulose triacetate (cut-off 5,000, 10,000 and 20,000 g/mol), regenerated cellulose (cut-off 20,000 g/mol)
• solvents: water and aqueous salt solutions as well as organic solvents like tetrahydrofuran, toluene, chloroform etc.

Target

• measurement of the osmotic pressure p as a function of the polymer concentration and extrapolation of the reduced osmotic pressure to the concentration zero
  • numerical average molar mass M_n and 2^nd virial coefficient A₂

Application
and Download

• molecular characterization of
  reference materials from Poly-DADMAC

Methods of comparison and supplementation

• aqueous size exclusion chromatography (M_n; M_W; D)
• static light scattering (M_W; R_Z; A₂) 
• differential refractometry (dn/dc)
• dynamic light scattering (d_H)
  

Equipment

• multi-angle light scatterer from Wyatt, model DAWN NEON and DAWN Heleos II, computer controlled
• wavelength of the laser: 658 nm

Target

• determination on molecular data of synthetic and natural polymers in dilute solutions
• weight average of molar mass M_W
• numerical average of the radius of gyration R_G
• analysis of the behavior of synthetic and natural polymers in concentrated solutions
• structural analytics of polymers
• determination of relationships between structure and properties
• investigation of association and aggregation processes

Equipment

• Delsa Nano +C (Beckman Coulter)
• Zetasizer Nano (Malvern)
• Mastersizer X (Malvern)
• Particle sizer LS 13320 XR (Beckman Coulter)
• Wyatt DynaPro NanoStar

Target

• determination of diffusion coefficient and hydrodynamic radius by means of dynamic light scattering
• mathematical determination of particle sizes by cumulate, contin, Marquardt and NNLS methods
• determination of intensity, volume and number distribution functions
• particle size distribution of nano- and microparticles

Application and Download

• determination of the hydrodynamic radius of polymers and polyelectrolytes as a function of solvent, electrolyte content and pH value
• derivations concerning the property profile of polymer dispersions (viscosity, sedimentation / flotation etc.)
• investigation of symplex formation between cationic starch and anionic polyelectrolytes

Methods of comparison and supplementation

• electron microscopy