The first synthesis of chitin derivatives with well-defined block copolymer side chains, i. e., chitin-graft-[poly(2-methyl-2-oxazoline)-block-poly(2-phenyl-2-oxazoline)] (5), chitin-graft-[poly(2-methyl-2-oxazoline)-block-poly(2-butyl-2-oxazoline)] (6), and chitin-graft-[poly(2-methyl-2-oxazoline)-block-poly(2-tert-butyl-2-oxazoline)] (7), was achieved by the reaction of partially deacetylated chitin (1) with living polyoxazoline block copolymers 2–4. The graft copolymers 5–7 are associated into micelles above the critical micelle concentration (CMC). CMCs of 5 (0.01–0.02 wt.-%) are smaller than those (0.32–0.50 wt.-%) of ω-hydroxyl-terminated poly(2-phenyl-2-oxazoline)-block-poly(2-methyl-2-oxazoline) (2-OH), which is a model block copolymer of the side chain segment of 5. The self-aggregates of 5–7 are capable of forming a complex with hydrophobic low molecular weight substances such as pyrene and magnesium 1-anilinonaphthalene-8-sulfonate (ANS). Cryo-transmission electron microscopy showed that the graft copolymer 5 forms globular particles (diameter: 40 nm) and larger cylindrical aggregates (diameter: 40 nm, length: 80–200 nm). The average radius of gyration of the particles of 5 from the SANS analysis is 36 nm.
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Aoi et al. (1999) studied this question.