Selective crystallization of calcium salts by poly(acrylate)-grafted chitosan.
The biopolymer chitosan was chemically modified by grafting polyacrylamide or polyacrylic acid in a homogeneous aqueous phase using potassium persulfate (KPS) as redox initiator system in the presence of N,N-methylene-bis-acrylamide as a crosslinking agent. The influence of the grafted chitosan on calcium salts crystallization in vitro was studied using the sitting-drop method. By using polyacrylamide grafted chitosan as substrate, rosette-like CaSO4 crystals were observed. This was originated by the presence of sulfate coming from the initiator KPS. By comparing crystallization on pure chitosan and on grafted chitosan, a dramatic influence of the grafted polymer on the crystalline habit of both salts was observed. Substrates prepared by combining sulfate with chitosan or sulfate with polyacrylamide did not produce similar CaSO4 morphologies. Moreover, small spheres or donut-shaped CaCO3 crystals on polyacrylic acid grafted chitosan were generated. The particular morphology of CaCO3 crystals depends also on other synthetic parameters such as the molecular weight of the chitosan sample and the KPS concentration.
Neira-Carrillo
Andrónico
A
Faculty of Veterinary and Animal Sciences, University of Chile, Santiago, Chile.
Yazdani-Pedram
Mehrdad
M
Retuert
Jaime
J
Diaz-Dosque
Mario
M
Gallois
Sebastien
S
Arias
José L
JL
D000180:Acrylic Resins / Q000737:chemistry*; D002119:Calcium Carbonate / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D003460:Crystallization; D008855:Microscopy, Electron, Scanning; D017680:Potassium Compounds / Q000737:chemistry; D013431:Sulfates / Q000737:chemistry; D000099166:Polyacrylamides
D000180:Acrylic Resins; D002119:Calcium Carbonate; D048271:Chitosan; D017680:Potassium Compounds; D013431:Sulfates; D000099166:Polyacrylamides; C006903:carbopol 940; C009007:potassium persulfate