Grafting reaction of living polymer cations with amino groups on chitosan powder

Abstract

ABSTRACT:The grafting of polymers having controlled molecular weight and narrow molecular weight distribution onto chitosan powder by the termination of living polymer cation with amino groups on chitosan powder was investigated in heterogeneous system. The amino groups of chitosan powder successfully reacted with living poly(isobutyl vinyl ether) [poly(IBVE)] and poly(2-methyl-2-oxazoline) [poly(MeOZO)] cation with controlled molecular weight and narrow molecular weight distribution to give the corresponding polymer-grafted chitosan powders. The percentage of poly(MeOZO) grafting gradually increased and reached 24.5% after 4 days. The solubility of poly(MeOZO)-grafted chitosan in water increased with an increase in the amount of grafted polymer. It was suggested that grafting reaction of living polymer cation with chitosan powder proceeds from surface amino groups to inner amino groups of the powder with progress of the reaction. The mole number of grafted polymer chain on chitosan powder decreased with an increase in the molecular weight of the living polymer cation because the steric hindrance of functional groups of chitosan powder increased with the increasing molecular weight of living polymer.

Chitosan derivatives obtained by chemical modifications for biomedical and environmental applications

“…Some years ago, Yoshikawa et al showed that grafting reactions onto chitosan can also be performed by using living cationic polymerization [49]. These authors grafted chitosan with living poly(isobutylvinyl ether) and poly(2-methyl-2-oxazoline) cation with controlled molecular weight distribution.…”

PEGylation of Chitosan Via Nitroxide‐Mediated Polymerization in Aqueous Media

“…TGA measurements also confirmed that grafting poly(PEGMA‐ co ‐S) to CTS via grafting from improved the thermal stability compared to CTS ‐g‐ GMA‐poly(PEGMA‐ co ‐S) obtained via a grafting to approach. This unexpected improvement in the thermal stability may be attributed to the higher graft density achieved with the grafting from approach, or some termination of the growing chains leading to cross‐linking, as it has been previously observed …”

“…Short reaction times were used as the polymerization of methacrylate monomers is considerably faster than styrenic or acrylic monomers. It has been established that in grafting from polymerizations, low initiation efficiency is a common issue, and, therefore, it was decided to use a large excess of monomers to promote the grafting reaction …”

“…In this paper, we report the PEGylation of CTS by the introduction of PEGMA‐based copolymers via NMP and the grafting to and from approaches in aqueous media. For the PEGylation of CTS via grafting to and NMP, firstly CTS was functionalized with GMA yielding CTS ‐g‐ GMA following previous reports, then poly(PEGMA ‐co‐ S), synthesized via NMP, was grafted to CTS ‐g‐ GMA using the double bond of the GMA unit as anchor group. In the grafting from approach, CTS ‐g‐ GMA was converted SG1‐based macroalkoxyamine, CTS ‐g‐ GMA‐NBB, which enabled grafting copolymerizations of PEGMA and S in aqueous media.…”

Approaches for Functional Modification or Cross‐Linking of Chitosan

“…Grafting of chitosan with living poly(isobutylvinyl ether) and poly(2-methyl-2-oxazoline) cations with controlled molecular weight distribution has been reported [124]. In this study, researchers have analyzed the effect of the molecular weight of living polymer cations on the number of grafted polymers; it was found that the number of grafted polymer chains decreased with the increasing molecular weight of living polymer cations.…”