A Facile Two‐Step Route to Branched Polyisoprenes via AB_n‐Macromonomers

Abstract

A facile two‐step synthesis for branched poly(isoprene)s (PI) based on polyaddition of ABn‐type macromonomers is described. The synthesis of the macromonomers was achieved by anionic polymerization of isoprene and subsequent end‐capping of the polymers by addition of chlorodimethylsilane to the living carbanions. This led to PI‐based macromonomers with narrow polydispersity ($\overline M _{\rm w}$/$\overline M _{\rm n}$ < 1.15) and molecular weights in the range of 1 700 – 22 100 g · mol−1. Synthesis of the branched polymers was carried out by a hydrosilylation‐based polymerization of the macromonomers. Characterization via SEC, SEC‐MALLS, coupled SEC‐viscosimetry and 1H‐NMR‐spectroscopy supported the formation of branched structures. Interestingly, these branched polymers exhibited α‐values that were similar to those reported for hyperbranched polymers based on AB2‐monomers.

Chain Architecture as an Orthogonal Parameter To Influence Block Copolymer Morphology. Synthesis and Characterization of Hyperbranched Block Copolymers: HyperBlocks

“…group. However, in previous similar studies carried out both in our labs and others 81 , residual, unreacted macromonomer is always observed. The coupling reaction of P(S-I-S)65_31 was carried out at 40°C instead of 60°C in order to slow down the rate of reaction.…”

Long‐Chain Hyperbranched Polymers: Synthesis, Properties, and Applications

“…[21, In contrast, the AB x macromonomer in the other method is composed of one A group at either end of the poly mer chain and varying amount of B pendant groups. [50][51][52][53][54][55][56][57][58][59][60][61][62] The amount of B pendant groups is usually corresponding to the degree of polymerization (n) of the polymer chain, so herein AB n is used for distinguishing it from the aforementioned AB x method with a defined number of B end groups (x value).…”

“…Besides the abovementioned AB 2 method, the AB n macromonomer method is designed and regarded as a particular approach to obtain LCHBPs. [50][51][52][53][54][55][56][57][58][59][60][61][62] In this system, the AB n macromonomer is a polymer chain with one A terminal group and the whole or a part repeating units carrying B pendent groups, where the group A can react with B group. This type of macromonomer can be prepared through polymerization of a functionalized monomer carrying a second active B side group.…”

“…[59] Frey's group also described a facile two-step synthesis of poly(isoprene) LCHBPs, which was achieved by anionic polymerization of isoprene to afford AB n macromonomers and then through subsequent hydrosilylation-based polyaddition to form LCHBPs. [60] By using the same method, a series of polybutadiene LCHBPs were then synthesized, and moreover, the high fraction of 1,2-vinyl groups of polybutadiene with enough reactivity was to be easily modified through incorporating a variety of functional moieties. [61] In our group, LCHBPs were constructed through a supramole cular approach based on this AB n -type macromonomers.…”

Synthesis and temperature gradient interaction chromatography of model asymmetric star polymers by the “macromonomer” approach

“…Even the most careful use of anionic polymerisation results in some batch to batch variation in molecular weight. The 'macromonomer' approach, first reported by our group for the synthesis of complex dendritically branched polymers such as DendriMacs [33,38], HyperMacs [54][55][56] and more recently HyperBlocks [57], has become widely adopted as a useful route to make a variety of complex dendritic branched architectures with polymer segments between branch points [58][59][60][61][62][63][64][65][66][67]. In essence the 'macromonomer' approach involves the synthesis of the linear segments of a branched polymer by a living/controlled polymerisation mechanism such that the linear segments contain chain-end functionalities which allow the subsequent construction of branched polymers via coupling reactions between macromonomers.…”