Living carbocationic polymerization

Star and Hyperbranched Polyisobutylenes via Terminally Reactive Polyisobutylene‐Polystyrene Block Copolymers

“…The low glass transition temperature (T g ) of PIB makes it useful as a component of thermoplastic elastomers in linear as well as in branched forms 11–19. Due to these special properties, several attempts have been reported on the synthesis of highly branched polyisobutylenes so far 12–16, 20–33. Previously, it was found that intra‐ and intermolecular Friedel‐Crafts alkylation of the benzene rings of styrene (St) units in polystyrene (PSt) segments might occur by carbocationic chain ends 13, 16–23, 34, 35.…”

“…Due to these special properties, several attempts have been reported on the synthesis of highly branched polyisobutylenes so far 12–16, 20–33. Previously, it was found that intra‐ and intermolecular Friedel‐Crafts alkylation of the benzene rings of styrene (St) units in polystyrene (PSt) segments might occur by carbocationic chain ends 13, 16–23, 34, 35. This undesired side reaction was observed not only during the cationic polymerization of pure St,35 but in the case of the preparation of thermoplastic elastomer block copolymers composed of PIB and PSt13–19 as well.…”

A New Synthetic Method for the Preparation of Star‐Shaped Polyisobutylene with Hyperbranched Polystyrene Core

“…There is significant interest in three‐dimensional, branched polymer structures like dendrimers, hyperbranched, star, and graft polymers. Dendrimers possess perfect branched structures 1–31. The hyperbranched polymer structure is similar to that of dendrimers, but it is usually composed of random branch‐on‐branches 4–6.…”

“…The hyperbranched polymer structure is similar to that of dendrimers, but it is usually composed of random branch‐on‐branches 4–6. The simplest branched structures are star‐shaped polymers consisting of a central core and many polymer arms radiating out from this core 4, 7–46. These types of branched polymers have some special properties, such as their low viscosity and the large number of chain ends in a macromolecule where functional groups can be placed.…”

“…The second possibility is the “ arm first ” strategy, where the polymer arms are synthesized first with reactive end groups, and then these arms are connected to a core or coupled by a core forming multi cross‐linking reaction. The synthesis of star polymers and star block copolymers are performed usually by living polymerization methods, like cationic,9–27, 35, 38, 39, 46 anionic,40, 41 radical,42–44 group transfer,29, 31, 32, 45 and other living polymerizations 4…”