Synthesis of Isotactic-block-Syndiotactic Poly(methyl Methacrylate) via Stereospecific Living Anionic Polymerizations in Combination with Metal-Halogen Exchange, Halogenation, and Click Reactions

Abstract

Isotactic (it-) and syndiotactic (st-) poly(methyl methacrylate)s (PMMAs) form unique crystalline stereocomplexes, which are attractive from both fundamental and application viewpoints. This study is directed at the efficient synthesis of it-and st-stereoblock (it-b-st-) PMMAs via stereospecific living anionic polymerizations in combination with metal-halogen exchange, halogenation, and click reactions. The azide-capped it-PMMA was prepared by living anionic polymerization of MMA, which was initiated with t-BuMgBr in toluene at -78 • C, and was followed by termination using CCl 4 as the halogenating agent in the presence of a strong Lewis base and subsequent azidation with NaN 3 . The alkyne-capped st-PMMA was obtained by living anionic polymerization of MMA, which was initiated via an in situ metal-halogen exchange reaction between 1,1-diphenylhexyl lithium and an α-bromoester bearing a pendent silyl-protected alkyne group. Finally, copper-catalyzed azide-alkyne cycloaddition (CuAAC) between these complimentary pairs of polymers resulted in a high yield of it-b-st-PMMAs, with controlled molecular weights and narrow molecular weight distributions. The stereocomplexation was evaluated in CH 3 CN and was affected by the block lengths and ratios.

Multiscale Simulation of Temperature- and Pressure-dependent Nonlinear Dynamics of PMMA/CNT Composite Plates

“…1(b). The PMMA polymer developed in our previous study is used here, where thirty-one i-PMMA chains are packed into a periodic box with an initial density of 1.08 g•cm -3 , which is close to the experimental range of 1.15~1.19 g•cm -3 [25,[35][36][37][38][39]. For the nanocomposite, the configuration is constructed that only a small number of SWCNT segments are embedded into the matrix [32].…”

“…1(a), which has been extensively adopted as the reinforcing filler in polymer/SWCNT nanocomposites [32,34]. For the PMMA polymer, isotactic PMMA (i-PMMA) is investigated here, which is widely used in various engineering application due to the excellent mechanical properties [35,36]. The molecular model of i-PMMA polymer chain with fifty repeating units is shown in Fig.…”

Polystyrene-b-Poly(2-(Methoxyethoxy)ethyl Methacrylate) Polymerization by Different Controlled Polymerization Mechanisms

“…The SAP is well known as a suitable mechanism for the synthesis of the block-copolymers with defined structures and the lengths of the different blocks. It is widely used for the polymerizations of the monomers that contain electron accepting substituents (methacrylates among the other monomers) [18]. Obtained polymers typically have narrow molecular weight distribution, with typical values for dispersity of 1.15-1.2.…”

Synthesis and stereocomplexation of PMMA‐based star polymers prepared by a combination of stereospecific anionic polymerization and crosslinking radical polymerization

“…Thus, the mechanistic transformation of an active species can be easily achieved through the halogenation from a living anionic polymerization to a living radical polymerization to form block copolymers. Therefore, a polymer with a higher stereoregularity due to anionic polymerization instead of radical polymerization could be used as a macroinitiator for a radical polymerization, resulting in the synthesis of novel stereoregular macromolecular architectures . In this study, the synthesis of novel core‐crosslinked star polymers with various stereoregular arm polymers was examined by introducing a halogen atom into the end of syndiotactic and isotactic PMMAs via an anionic polymerization and adapting the linking reaction via a radical polymerization of a divinyl compound using a transition metal catalyst (Scheme ).…”