Ultrasound-assisted synthesis of block copolymers of chitosan and D,L-lactide: Structure and properties

The block copolymers of chitosan with D,L-lactide are synthesized under UV irradiation of the homogeneous solution of the corresponding homopolymers with the yield of the main product being 96 wt %. The polyblock structure of copolymer chains, in which the size of polylactide blocks is varied in the range of (2.9-22.0) x 10(3) depending on the synthesis conditions, is demonstrated. The incorporation of polylactide blocks into the structure of chitosan leads to development of the material structure close to the structure of polylactide. The films of the block copolymers containing 16 wt % polylactide and having a molecular mass of its blocks of 22.0 x 10(3) have increased values of breaking stress (47 MPa) and ultimate strain (20%) compared to chitosan (24 MPa and 1.9%, respectively). The obtained block copolymers possess bactericidal properties.