Ionic gels - Physical Gels from Biological and Synthetic Polymers - page 148

Step I
( R < 0.25)

Step I
( R < 0.25)

Ca ++ Ca ++

Monocomplex Monocomplex

Step II
(0.25 < R < 0.55)

Step II
(0.25 < R < 0.55)

Egg-box dimer

Egg-box dimer

Step III
( R > 0.55)

Step III
( R > 0.55)

inter-cluster associated multimer

inter-cluster associated multimer

(a) Short-chain alginate (b) Long-chain alginate

Schematic illustration of the multiple-step binding of Ca 2+ to alginate: (a) short-chain alginate; (b)
long-chain alginate. The zigzag lines, smooth lines and dots stand for G-blocks, M-blocks and
calcium ions, respectively. R is the feed ratio of Ca 2+ to G residue. Reprinted with permission from
Fang et al.( 2007 ) © 2007 American Chemical Society.

Figure 5.18