Controlled hydrophobic/hydrophilicity of chitosan for spheres without specific processing technique.

Chitosan is functionalized with phthalic anhydride at the amino group and poly(ethylene glycol) methyl ether at the hydroxyl group via homogeneous reaction. The product regenerated forms particles in either aqueous solution or organic solvents. The particles are spheres with the size of few micrometers as observed from scanning electronmicroscopy. The present work demonstrates that by simply adjusting the hydrophilicity and hydrophobicity, we can directly obtain spheres without a specific processing technique.