THE MOLECULAR-STRUCTURE OF BLOCK COPOLYUR ETHANES AS RELATED TO THE SYNTHETIC PROCEDURE USED FOR THEIR PREPARATION

C-13 NMR was used to investigate how the order of adding the monomers during the synthesis of polyurethane block copolymers affects their st ructure. It was found that the order of introducing the reagents into the reaction system is the factor that decisively controls the assembl age of macromolecules and the structure of flexible-chain and rigid-ch ain blocks. It was found that regardless of the synthetic procedure us ed the content of rigid-chain blocks may not exceed 50%. In each synth etic procedure the molecular mass of rigid-chain blocks was found to b e limited.