Orthogonal C-B Bond Transformation as an Approach for Versatile Synthesis of End-Functionalized Polymers

Conventionally inaccessible end-functionalized vinyl polymers were synthesized via orthogonal side-chain replacement for terminal and repeating units of poly(alkenyl boronate)s. A terminal-defined polymer of isopropenyl boronic acid pinacol ester (IPBpin) was synthesized via RAFT polymerization, and subsequent cobalt (Co)-catalyzed end olefination afforded the polymer carrying the C(sp²)-B bond at the terminal and the C(sp³)-B bond in repeating units. Herein, the terminal C(sp²)-B bond was selectively transformable via palladium (Pd)-catalyzed Suzuki-Miyaura cross coupling, and subsequent transformation of the repeating C(sp³)-B unit gave the poly(α-methyl vinyl alcohol) [poly(MVA)] bearing various functional groups at the terminal. The boron-based stepwise polymer reaction thus overcame the synthetic difficulty of the end-functionalized poly(MVA), which is ascribed to the poor polymerization ability of the corresponding acetate monomer, i.e., isopropenyl acetate.

Conjugate substitution and addition of α-substituted acrylate: a highly efficient, facile, convenient, and versatile approach to fabricate degradable polymers by dynamic covalent chemistry

Degradable poly(conjugated ester)s with various backbones were synthesized via conjugate substitution (S_N2′) polymerization of bis[α-(chloromethyl)acrylate] and nucleophilic monomers under ambient conditions.

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

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 CCl₄ as the halogenating agent in the presence of a strong Lewis base and subsequent azidation with NaN₃. 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 alkyne-azide 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 CH₃CN and was affected by the block lengths and ratios.

Anionic polymerization of ethyl acrylate initiated by tetrabutylammonium azide: direct synthesis of end-clickable polyacrylate

Tetrabutylammonium azide, a weak nucleophile, was found to initiate the living anionic polymerization of ethyl acrylate in the presence of alkylaluminum bisphenoxides as monomer activators to afford clickable azide-end polymers.

Rational design of soluble and clickable polymers prepared by conventional free radical polymerization of acetylene-functionalized acrylate

Soluble and clickable acetylene-functionalized polyacrylates were synthesized via conventional free radical polymerization of a rationally designed tertiary propargylic acrylate.

Addressing the mid-point of polymer chains for multiple functionalization purposes through sequential thiol–epoxy ‘click’ and esterification reactions

A synthetic strategy is devised for the preparation of mid-chain multifunctional polymers.

Polymerization of α-(halomethyl)acrylates through sequential nucleophilic attack of dithiols using a combination of addition–elimination and click reactions

Polycondensation involving sequential nucleophilic attacks of a dithiol on an α-(bromomethyl)acrylate efficiently yielded a polysulfide.

α-(Aminomethyl)acrylate: polymerization and spontaneous post-polymerization modification of β-amino acid ester for a pH/temperature-responsive material

Radical polymerizations of α-(aminomethyl)acrylates involved spontaneous post-polymerization modification triggered by breaking of the hydrogen bond and afforded pH/temperature responsive polymers.