BINDING OF CARBOXYLATED STARBURST DENDRIMERS TO POLY(DIALLYDIMETHYLAMMONIUM CHLORIDE)

The interaction between poly(diallydimethylammonium chloride) (PDADMAC ) and carboxylated starburst dendrimers (generations 0.5, 3.5, 5.5 and 7.5) was investigated over a range of ionic strength from 0.01 to 0.5 0 M NaCl using pH titration, turbidimetry and quasi-elastic light scat tering methods. Complex formation occurs most readily with generation 7.5, which may be attributed to its high charge density relative to th e smaller dendrimers. The effects of ionic strength confirmed the elec trostatic nature of the interaction, while pH titrations revealed that complex formation is stoichiometric. Analysis of pH titrations via th e effect of binding on the pK(a) of the dendrimer carboxylic acid grou ps lead to estimates of the free energy of complex formation.