On the Modification of Chitosan Through Grafting

Abstract

The feasibility of grafting poly( methyl acrylate) and poly[ 1-(methoxycarbonyl) ethylene] onto chitosan, poly-P( 1 +4)-2-amino-2-deoxy-D-glucose, was investigated. The grafting reaction was carried out in aqueous solution by using ferrous ammonium sulfate (FAS) in combination with H,O, as redox initiator. The effects of such reaction variables as chitosan, monomer and initiator concentrations, reaction time, and reaction temperature were determined. Through this study the grafting reaction could be optimized. The grafting yield reached its maximum 1037 Copyright 0 1995 by Marcel Dekker, Inc.Downloaded by [Michigan State University] at 23:07 27 December 2014 1038 YAZDANI-PEDRAM ET AL.value of 332% when 0.3 g chitosan was copolymerized with 3 mL monomer at 7OoC for 120 minutes with [FAS] = 6 x lo-' M, [H,O,] = 6 x 10 -3 M, and 8 mL water. The grafted chitosan was found to be insoluble in solvents for chitosan and solvents for poly(methy1 acrylate), but did show swelling in dilute acetic acid, methanol, acetone, and in an ethanol/2% acetic acid 1 : 1 mixture. The thermal stability of chitosan and grafted chitosan were studied by dynamic thermogravimetric analysis. The results show that the graft copolymer is thermally more stable than pure chitosan. The overall activation energy for graft copolymerization was estimated to be 32.8 kcal/mol.

Selective crystallization of calcium salts by poly(acrylate)-grafted chitosan

“…Generally, the biopolymers chitin and chitosan are insoluble and do not form film materials. However, when grafted with poly(acrylic acid) or polyacrylamide, they become insoluble, are able to form flakes with a nearly flat surface, and show functional groups that can influence crystal nucleation and growth [18][19][20][21][22]. To our best knowledge, the spatial distribution of polar functional groups, that is, the local charge density, is of crucial importance for the nucleation and determines the orientation of crystals.…”

Chitosan-organosilane hybrids?Syntheses, characterization, copper adsorption, and enzyme immobilization

“…3 Silylating agents of the general formula (CH 3 O) 3 SiORONH 2 present two reactive functional groups: the amine ONH 2 , and methoxy OOCH 3 groups. Under the influence of specified amounts of water the latter group suffers hydrolysis to undergo polycondensation to finally form polysiloxane OSiOSiO groups through a sol-gel process.…”

Hydrogels based on modified chitosan, 1. Synthesis and swelling behavior of poly(acrylic acid) grafted chitosan

“…We have also used Fenton's reagent (H 2 O 2 /Fe 2+ ) for grafting poly(methyl acrylate) onto chitosan. In both cases the grafted chitosan showed enhanced thermal stability 40) . Recently, by grafting vinyl pyrrolidone, we were able to carry out the reactions in a homogeneous phase 21) .…”

“…As we have previously observed, the extent of grafting vinyl monomers onto cellulose, chitin, chitosan, etc. is very sensitive towards reaction conditions 16,21,39,40) . Therefore, a systematic study of the effect of different reaction variables on grafting of acrylic acid onto chitosan, is presented in this work.…”