Telechelic polymers and sequential

New Telechelic Polymers and Sequential Copolymers by Polyfunctional Initiator-Transfer Agents (Inifers) End Reactive Polyisobutylenes by Semicontinuous Polymerization... 

J.P. Kennedy and R.A. Smith, New telechelic polymers and sequential copolymers by polyfunctional initiator-transfer agents (inifers). II. Synthesis and characterization of a, a>-di(ferf-chloro)polyisobutylenes,. Polym. Sci., Part A Polym. Chem., 18(5) 1523-1537,1980. 

Most of the methods for synthesizing block copolymers were described previously. Block copolymers are obtained by step copolymerization of polymers with functional end groups capable of reacting with each other (Sec. 2-13c-2). Sequential polymerization methods by living radical, anionic, cationic, and group transfer propagation were described in Secs. 3-15b-4, 5-4a, and 7-12e. The use of telechelic polymers, coupling and transformations reactions were described in Secs. 5-4b, 5-4c, and 5-4d. A few methods not previously described are considered here. 

Substituted farans have been shown to be effective end-quenchers in both the TiCU- and BCls-initiated polymerization of PIBs resulting in quantitative functionalization as determined by NMR. In addition, the allylic cation formed upon functionalization was found to be an effective initiating species for the polymerization of methyl vinyl ether to form the corresponding PIB-I7-PVE by sequential monomer addition, and the concept was extended to the preparation of three-armed star block polymers. Other bis-furanyl derivatives have also been used as coupling agents for the preparation of telechelic PIBs. °... 

There are numerous reports in the literature describing the synthesis of low polydispersity PNIPAm (co)poly-mers via CRP methods. For example. Binder et al. [54] described the synthesis of telechelic PNIPAm using functional NMP initiators modified via azide-alkyne cycloadditions. Efficient block copolymerization of NIPAm with styrene was achieved via sequential polymerization initiated by a-hydrogen alkoxyamine [55]. A PNIPAm block was first prepared and then chain extended with styrene yielding amphiphilic diblock copolymers. Initial attempts to use ATRP to prepare PNIPAm resulted in polymers with broad polydisperisities [56], but this problem was circumvented by utilizing a more efficient ligand for the initiator complex [57]. 

---