Poly(cyclopentene carbonate) (PCPC) produced by copolymerization of CO 2 and cyclopentene oxide (CPO) is a promising but challenging chemical recyclable polymer that has high potential in minimizing plastic pollution and maximizing CO 2 utilization. Currently, problems remain to be solved, include low reactivity of toxic metal catalysts, inevitable byproducts, and especially the ambiguous mechanism understanding. Herein, we present the first metal-free access to PCPC by using a series of modular dinuclear organoboron catalysts. PCPC was afforded in an unprecedented catalytic efficiency of 1.0 kg of PCPC/g of catalyst; while the depolymerization of PCPC abides by a combination pathway of random chain scission and chain unzipping, returning CPO in near-quantitative yield (> 99 %). The preparation and depolymerization of PCPC along with in depth understanding of related mechanisms would be helpful for further development of advanced catalysts and recyclable plastics.
Quaternary ammonium and phosphonium borane bifunctional
catalysts
have shown high catalytic performance in ring-opening polymerization
(ROP) of epoxides to produce polyether. Herein, we systematically
investigate a series of well-defined organoboron catalysts by varying
the electronic and steric properties of the Lewis acidic boron (B)
centers, manipulating the steric hindrance on the ammonium cation
(N+), adjusting the distance between B and N+, and regulating the nucleic B number of the catalysts. The investigation
on the dinuclear catalysts indicated that the reactivity of a given
catalyst could be speculated by its B–N–B angle and
the B···B distance. We found that the increase of Lewis
acidity and the number of B centers of the organoboron catalysts are
useful for a high catalytic activity for ROP of epoxides. The Lewis
acidity of the B centers was determined using the acceptor numbers,
showing an order of borinane (23.4) > BBN (21.7) > BCy2 (18.8) > Bpin (15.5). Moreover, we demonstrated the production
of
various telechelic polyols in the presence of different chain transfer
agents using the organoboron catalysts. The produced telechelic samples
have a well-defined terminal functionality with controllable molecular
weight. Lastly, these organoboron catalysts were utilized to produce
block copolymers, allyl-terminated macromonomers, and random copolymers.
Sulfur-containing polymers enjoy the merits of excellent optical performance, degradation, chemical recyclability, and adhesive abilities toward metal ions. Recently, increasing attentions in both academic and industrial circles have been paid...
Poly(cyclopentene carbonate) (PCPC) produced by copolymerization of CO 2 and cyclopentene oxide (CPO) is a promising but challenging chemical recyclable polymer that has high potential in minimizing plastic pollution and maximizing CO 2 utilization. Currently, problems remain to be solved, include low reactivity of toxic metal catalysts, inevitable byproducts, and especially the ambiguous mechanism understanding. Herein, we present the first metal-free access to PCPC by using a series of modular dinuclear organoboron catalysts. PCPC was afforded in an unprecedented catalytic efficiency of 1.0 kg of PCPC/g of catalyst; while the depolymerization of PCPC abides by a combination pathway of random chain scission and chain unzipping, returning CPO in near-quantitative yield (> 99 %). The preparation and depolymerization of PCPC along with in depth understanding of related mechanisms would be helpful for further development of advanced catalysts and recyclable plastics.
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