AB Block Research Articles

Anionic polymerization of a fluorinated butadiene

Abstract1,1‐Bis(trifluoromethyl)‐1,3‐butadiene (I) is cleanly prepared in three steps. I produces an amorphous polymer by free‐radical catalysis. Crystalline poly‐I is produced by butyllithium catalysis in tetrahydrofuran at −78°C. Qualitative kinetic experiments indicate that the anionic polymerization proceeds by a “living polymer” process. An AB block copolymer may be formed by adding I to anionically propagating butadiene; however, the reverse does not occur.

Application of GPC in the Study of Stereospecific Block Copolymers

Abstract Three different techniques involved in the preparation of Stereospecific block copolymers were studied using gel permeation chromatography (GPC). These techniques involved the use of a monofunctional organo-lithium catalyst, a difunctional organolithium catalyst, and a combination of a monofunctional organolithium catalyst and a coupling technique. GPC curves were obtained on the block copolymers using two different column sequences and solvents. The ABA block copolymers studied contained styrene, vinyl toluene, or α-methyl styrene as thermoplastic monomers and butadiene as the elastomeric monomer. The results obtained showed that block copolymers prepared using monomers and catalyst systems free of impurities generally exhibited single peaked GPC curves. In systems where impurities were found to be present, small amounts of A block homopolymer and AB block copolymer were formed. In such cases, the GPC curves were observed to have two or three peaks.