Polyelectrolyte adsorption onto cellulose fibres - A review

This review focuses upon the following questions: a) Why are the polyelectrolytes adsorbed onto cellulosic fibres? The easies t way to describe the adsorption is as an interaction between the charges o n the fibres and the charges on the polyelectrolytes. However the entropy g ain upon the release of counterions to the charges on the fibres and the po lyelectrolytes gives a much larger contribution to the adsorption energy th an the charge interaction. There are some investigations which clarify the influence of certain basic parameters on the fibres and the surfaces and th ese investigations will be reviewed. An attempt will also be made to create a link between published adsorption data and the Scheutjens-Fleer theory f or polyelectrolyte adsorption. Another important question is how the polyel ectrolytes are adsorbed on the fibres, i.e. are the segments only found in trains on the surface or will there be some loops and/or tails protruding i nto the solution? Very little is known about this but the topic will be dis cussed in some detail. b) Where are the polyelectrolytes adsorbed - on the external surfaces of th e fibres or within the fibre wall and how is this related to the molecular properties of the polyelectrolytes? There are a lot of definitions in the l iterature about fibre surfaces, external surfaces etc. but it is important to link the adsorption to molecular properties and the work in this area wi ll be reviewed. The influence of fines will also be discussed. c) What controls the kinetics of polyelectrolyte adsorption and are there m odels to describe this adsorption? It is still not entirely known how polym ers that adsorb onto the internal surfaces of the fibres are then transport ed through the fibre wall. The work conducted in this area will be reviewed , It is also important to know the kinetics of the reconformation of the po lymer on the fibre surface and this topic will also be discussed in detail. Finally the kinetics of desorption will be treated.