Synthesis of Diverse Polycarbonates by Organocatalytic Copolymerization of CO<sub>2</sub> and Epoxides: From High Pressure and Temperature to Ambient Conditions

et al. 2022

One‐pot production of sequence‐controlled block copolymer from mixed monomers is a crucial but rarely reached goal. Using a switchable Lewis‐pair organocatalyst, we have accomplished sequence‐selective polymerization from a mixture of O‐carboxyanhydride (OCA) and epoxide. Polymerization of the OCA monomer occurs first and exclusively because of its exceedingly high polymerizability. When OCA is fully consumed, alternating copolymerization of epoxide and CO2 liberated in OCA polymerization is triggered from the termini of the first block. The two polymerizations thus occur in tandem, both in chemoselective fashion, so that a sequence‐controlled block polymer with up to 99 % CO2 conversion is furnished in this one‐pot protocol. Calculations and experimental results demonstrate a chemoselective and cooperative mechanism, where the high polymerizability of the OCA monomers guarantees exquisite sequence selectivity and the cooperative decarboxylation partly arose from the stabilization effect by triethylborane, which facilitates the smooth transformation of the chain end from carbonate to alkoxide.

Switchable Polymerization Organocatalysis: From Monomer Mixtures to Block Copolymers

Tang

et al. 2022

CO₂‐Fueled Transient Breathing Nanogels that Couple Nonequilibrium Catalytic Polymerization

Yan

2023

Here we present a "breathing" nanogel that is fueled by CO 2 gas to perform temporally programmable catalytic polymerization. The nanogel is composed of common frustrated Lewis pair polymers (FLPs). Dynamic CO 2 -FLP gas-bridging bonds endow the nanogel with a transient volume contraction, and the resulting proximal effect of bound FLPs unlocks its catalytic capacity toward CO 2 . Reverse gas depletion via a CO 2participated polymerization can induce a reverse nanogel expansion, which shuts down the catalytic activity. Control of external factors (fuel level, temperature or additives) can regulate the breathing period, amplitude and lifecycle, so as to affect the catalytic polymerization. Moreover, editing the nanogel breathing procedure can sequentially evoke the copolymerization of CO 2 with different epoxide monomers preloaded therein, which allows to obtain block-tunable copolycarbonates that are unachievable by other methods. This synthetic dissipative system would be function as a prototype of gas-driven nanosynthesizer.

Controlling the Fluorescence Performance of AIE Polymers by Controlling the Polymer Microstructure

Bakr

et al. 2023

Aggregation-induced emission (AIE) polymers with expected emission wavelength/color and fluorescence efficiency are valuable in applications. However, most AIE polymers exhibit irregular emission wavelength/color changes compared to the original AIE monomers. Here, we report the synthesis of AIE polymers with unchanged emission wavelength by ring-opening (co)polymerizations of 4-(triphenylethenyl)phenoxymethyloxirane (TPEO) and other epoxides or phthalic anhydride. The chemical structures/physical properties of all (co)polymers were characterized by NMR, SEC, MALDI-TOF, and DSC. The co-polyether microstructures were revealed by calculating the reactivity ratios and visualized by Monte Carlo simulation. The photoluminescence quantum yields of all the (co)polymers were determined in the solid state. We systematically correlated the fluorescence performance with molecular weights, crystallinity, monomer compositions, glass transition temperatures, side lengths, and flexibility/rigidity.