What is Seeding?

Copolymer resin beads are typically produced in three ways:

1. Classic batch suspension polymerization: robust proven technology resulting in a relatively broad particle distribution that has to be adjusted by sieving with a Uniformity Coefficient of <1.6 (UC). Typical particle sizes range from 100-1200

2. Jetting: process where monomer phase is pushed thanks to pulse or vibration through a special steel membrane or cane into aqueous phase thus forming suspension with a narrow size distribution (UC <1.3); high yield economical process, it provides products with unique performance characteristics. Typical particle sizes range from 50 to 250 µm

3. Seeding: uniform particle size beads with a very narrow particle size distribution (UC <1.1) are created by first producing small 'seeds', which are subsequently grown (seeded) through repeated additional polymerization until the required particle size is achieved. Typical particle sizes range from 3 to 50
µm. The great advantage is seeding in especially in HPLC applications:

  • Consistent packing characteristics
  • Better kinetics
  • Improved resolution
  • Lower column backpressure

Seeded polymerisation: mono-size, ultra-fine beads for chromatography

Polystyrene 'seeds' are first produced through dispersion polymerization of styrene in alcohols.  These initial seeds are in the range from 1 to 5 µm.

'Seeds' can be grown in two ways depending on the physical properties required.

  • Non-porous  - typical sizes from 5 to 50 µm (swelling with monomers)
  • Macroporous - typical sizes from 5 to 30 µm (swelling with monomers and porogen)
  • Sizes currently offered: 5, 10 ,15, 20 & 30 micron
  • Narrow range of particle size, UC < 1.1 (almost monobeads)
  • Production batch: 10Kg
  • Application: Chromatography [Preparative (HPLC), processing/purification of biomolecules] and Calibration
  • Chromatography performance:
    1. Resolution (efficiency & selectivity)
    2. Loading capacity

    3. Back pressure/speed (size, porosity)
    4. Recovery

Seeding technique is used for a range of our products including Chromalite® GN (Calibration), Chromalite® AD and Chromalite® MN (Chromatography).