Elizabeth Henao, Germán Quintana and Ezequiel Delgado
Universidad Pontificia Bolivariana, Medellín, Colombia
This research is about the preparation of hydrogels by complexation of carboxymethylcellulose (CMC), carboxymethylated starch (CMS) and alginic acid (AA) with chitosan (CS), evaluating the effect of anionic/cationic ratio (CMC/CS from 2.5 to 200, CMS/CS from 40 to 320, AA/CS from 4 to 50) on hydrogel morphology. The CMC/CS and CMS/CS gels are viscous at high ratios, agglomerate at middle ratio, and at low ratios, the CMC does not show any precipitate. CMC gels formed agregates with electric potential values around -372 mV to -51 mV. CMS hydrogels also agglomerated at a potential of 526 mV and that appearance remained until a potential of -158mV.
After the equilibrium time (12 hours), zeta potentials for CMC were between 656and -962 mV for the CMC, 526 and -664 mVs for the CMS and -22 and -762 mVs for the AA. Those values corresponded to pHs of 2.5 and 3.8 (CMC), 3 and 3.6 (CMS) and 2.7 and 3.1 (AA), respectively.
Reaction between polymers was stopped after 30 minutes of agitation, without allowing the sample to reach equilibrium. CMC/CS and CMS/CS hydrogels showed more agglomeration at low zeta potential, while AA/CS did not show a great difference in terms of potential.