Access to Hydroxy‐Functionalized Polypropylene through Coordination Polymerization

Abstract

Preparation of polyethylenes containing hydroxy groups has been already industrialized through radical copolymerization under harsh conditions followed by alcoholysis. By contrast, hydroxy‐functionalized polypropylene has proven a rather challenging goal in polymer science. Propylene can't be polymerized through a radical mechanism, and its coordination copolymerization with polar monomers is frustrated by catalyst poisoning. Herein, we report a new strategy to reach this target. The coordination polymerization of allenes by rare‐earth‐metal precursors affords pure 1,2‐regulated polyallenes, which are facilely transformed into poly(allyl alcohol) analogues by subsequent hydroboration/oxidation. Strikingly, the copolymerization of allenes and propylene gives unprecedented hydroxy‐functionalized polypropylene after post‐polymerization modification. Mechanistic elucidation by DFT simulation suggests kinetic rather than thermodynamic control.

Recent Advances in Polyallenes: Preparation, Self‐Assembly, and Stimuli‐Responsiveness

“…Thus, highly 1,2‐selective polymerization of allene monomers is rare. Cui's group did a milestone work of 1,2‐selective polymerization of polar and nonpolar alkylallene monomers with rare‐earth‐metal catalytic systems [13] . The 1,2‐selectivity of the allene polymerization could be over 99%.…”

“…In addition, helix‐sense selective polymerization (HSSP) of achiral allene monomers with chiral catalysts to afford helical polyallenes has also been reported [12] . What's more, polyallenes with excellent 1,2 or 2,3‐regularity have been synthesized [13–15] …”

Crystalline sulfur-functionalized poly(α-olefin) synthesized by scandium-catalyzed coordination polymerization

“…24 Then, the stereoselective (co)polymerization of a series of unprotected polar monomers using a rare earth catalyst to afford stereoregular and sequence-controlled polymers was reported by this group. [25][26][27][28][29][30][31][32][33][34][35][36] Our group shown that rare earth catalysts can be used for the stereoselective polymerization of polar 2-vinylpyriding (2-VP). The coordination of a nitrogen atom as well as an olefin CvC bond to the metal center was essential to achieve reactivity and stereoselectivity.…”

Imidazoline-2-imine Functionalized Fluorenyl Rare-Earth Metal Complexes: Synthesis and Their Application in the Polymerization of ortho-Methoxystyrene

“…This spurs researchers to develop various ways to protect the active species, such as using bulky substituents to mask the polar groups, precomplexing the polar groups with alkylaluminum, and separating the polar groups from the polymerizable units by a long spacer and so on. − However, for early transition metal complexes with highly oxyphilic metal centers, it is also a challenge to realize the polymerization of polar monomers. Interestingly, a family of rare-earth catalysts was recently reported to successfully promote the polymerization of polar monomers, , and in some cases the polar group can inconceivably activate the polymerization but not poison the metal centers . Cui and co-workers reported that the polymerization of polar ortho -methoxystyrene ( o MOS) could be achieved by cationic β-diketiminato rare earth-metal species to produce isoselective polymers.…”