Block polymer preparation via both anionic and free radical polymerization

Abstract

A new method of block polymer preparation using combined anionic and free radical polymerization was investigated. In the method the first monomer was polymerized anionically. The resulting polymeric anions were then reacted with an episulfide to form a polymer with mercaptan end‐groups. This mercapto—polymer was mixed with a second monomer(s) in an inert solvent for the free radical polymerization. Conventional free radical initiation methods were used to initiate the polymerization of the second monomer but because of the high chain transfer constant of the mercaptan groups, a large number of the free radical chains would grow from the first polymer to form a block polymer. Block polymers difficult or impossible to make by direct anionic polymerization can thus be prepared. Several block polymers, including the new thermoplastic elastomers, poly[(styrene‐co‐acrylonitrile)‐b‐butadiene‐b‐(styrene‐co‐acrylonitrile)] and poly(bromostyrene‐b‐butadiene‐b‐bromostyrene) were prepared by this method.

Synthesis of New Thermoplastic Elastomers by Silver Nanoparticles as Cross-Linker

“…This route is similar to a described synthesis of α,ω-dimercapto-poly( cis -butadiene). However, the degree of functionalization has not been determined, and we assume it to be low due to gelation problems we describe here for poly( cis -isoprene) …”

Preparation of PMMA-PS-PMMA via combination of anionic and photoinduced charge-transfer polymerization

“…1 Essentially, two kinds of methods can be used to synthesize block copolymers: One is living polymerization systems, including the well-known anionic polymerization, cationic polymerization, 2 group-transfer polymerization, 3 and "living" controlled radical polymerization. 4,5 The other is to combine different polymerization techniques together, such as anionic polymerization with cationic, 6 anionic with Ziegler-Natta 7 coordinate polymerization, and anionic with radical 8 polymerization. By means of the latter method, some special block copolymers which are impossible to prepare by a single polymerization method can be obtained.…”

Influence of (1,3‐phenylene)bis(3‐methyl‐1‐phenyl pentylidene)dilithium initiator concentration on the modality of polybutadiene

“…The first published 1,3‐bis(1‐phenylethenyl) benzene (PEB)‐based dilithium initiators were prepared by the reaction of sec ‐butyllithium ( s ‐BuLi) with PEB or 1,3‐bis[1‐(methylphenyl) ethenyl] benzene (MPEB) 17, 18. These initiators were used to prepare α,ω‐dilithium polybutadienes19 and triblock copolymers 20. The addition reaction of s ‐BuLi onto PEB was found to be clean and rapid.…”