Synthesis and Characterization of Polyisobutylene-Polybutadiene Diblocks

Characterization of Polyisobutylene-Polybutadiene Diblocks by HMQC and HMBC

“…Recently, the preparation of PIB-6-PBD has been reported. 5 The polyisobutylene portion was obtained by living cationic polymerization, and the polybutadiene portion, by living anionic polymerization: the starting material, tertiary chloride terminated PIB (PIB-CH2C(CH3)2C1, PIB-C1), undergoes dehydrochlorination-metalation by the n-BuLi/t-ROK system (R = fert-butyl, tert-amyl) to yield the PIB-CH2C(=CH2)CH2+ (PIB+) anion which induces butadiene polymerization. However, before a detailed investigation into controlling the block lengths can be undertaken, a means of measuring the relative block lengths must be available.…”

“…Figure5. Expansions from the 500 MHz HMQC (A) and HMBC (B) spectra showing correlations between aliphatic protons and aliphatic carbons.…”

Block Copolymers by Transformation of “Living” Carbocationic into “Living” Radical Polymerization

“…Polymers with a variety of terminal functionalities can be obtained by “living” cationic polymerization, and some of the end functions may be useful for initiating another polymerization to give block copolymers. Several papers report well-defined block copolymers by the transformation of initiating sites from “living” cationic to anionic polymerization. − Another approach for block copolymers is the coupling reaction of two “living” homopolymers having antagonistic functions, such as carbocationic with group transfer, , or anionic polymerizations . Commonly, these techniques include many steps and the number of monomers is limited to those which can be polymerized by cationic or anionic methods.…”

Synthesis of Linear and Star-Shaped Block Copolymers of Isobutylene and Methacrylates by Combination of Living Cationic and Anionic Polymerizations

“…Metalated PIB, obtained by one-pot dehydrochlorination−metalation of tert -chlorine-ended PIB by potassium tert -amylate/nBuLi and tBuOK/nBuLi mixtures, was used to initiate the anionic polymerization of butadiene resulting PIB−polybutadiene block copolymers …”

“…Metalated PIB, obtained by one-pot dehydrochlorination-metalation of tert-chlorine-ended PIB by potassium tert-amylate/nBuLi and tBuOK/nBuLi mixtures, was used to initiate the anionic polymerization of butadiene resulting PIB-polybutadiene block copolymers. 17 All these methods have several disadvantages: multistep endgroup derivatizations are required for the synthesis of the telechelic PIB initiator precursor, and lithiation and, thus, subsequent initiation of anionic polymerization is not quantitative or requires extreme conditions. As a consequence of less than 100% initiating efficiency, these methods yielded mixtures of homopolymers and block copolymers.…”