Ideal molecular weight distributions of multiblock copolymers prepared via RAFT polymerization

摘要

The ideal equilibrium distribution of blocks within multiblock polymers that form when polyfunctional or cyclic reversible addition-fragmentation chain transfer (RAFT) agents are employed in radical polymerization is deduced theoretically. The theory is compared with the actual process via the experimentally determined mass ratio of the two noninterconvertible block types-middle and end blocks-and via the direct fitting of theoretically derived functions to measured size-exclusion chromatography (SEC) curves. Numerical simulations using a statistical approach confirm the results. It is shown that multiblock copolymers of higher homogeneity are prepared with the theoretically examined RAFT strategy than with the commonly used coupling of functionalized prepolymers.