In situ preparation of a compatibilized poly(cis-1,4-butadiene)/poly(ε-caprolactone) blend

The ternary Ziegler-Natta type catalyst system based on neodymium versatate (NdV), diisobutylaluminium hydride (DIBAH) and ethylaluminium sesquichloride (FASC) was used for the in situ preparation of a compatibilized blend consisting of poly(cis-1,4-butadiene) (BR = butadiene rubber) and poly(epsilon-caprolactone) (PCL). Poly(cis-1,4-butadiene)-block-poly(epsilon-caprolactone) which acts as compatibilizer for the two immiscible polymers BR and PCL was obtained by a two step sequential polymerization wit the preparation of a living cis-1,4-BR building block in the first stage and the subsequent polymerization of CL during the second stage. This preparation method resulted in a polymer blend comprising the homopolymers BR and PCL as well as the block copolymer BR-block-PCL. For detailed characterization the block copolymer was separated from the respective homopolymers BR and PCL by means of fractionation with the binary solvent mixture dimethylformamide/methylcyclohexane (DMF/MCH) which mixes well at elevated temperature and exhibits phase separation at ambient temperature, H-1 NMR, IR, SEC and TEM were used for characterization of the block copolymer.