Recent Advances in Synthesis of Non-Alternating Polyketone Generated by Copolymerization of Carbon Monoxide and Ethylene.

The copolymers of carbon monoxide (CO) and ethylene, namely aliphatic polyketones (PKs), have attracted considerable attention due to their unique property and degradation. Based on the arrangement of the ethylene and carbonyl groups in the polymer chain, PKs can be divided into perfect alternating and non-perfect alternating copolymers. Perfect alternating PKs have been previously reviewed, we herein focus on recent advances in the synthesis of PKs without a perfect alternating structure including non-perfect alternating PKs and PE with in-chain ketones. The chain structure of PKs, catalytic copolymerization mechanism, and non-alternating polymerization catalysts including phosphine-sulfonate Pd, diphosphazane monoxide (PNPO) Pd/Ni, and phosphinophenolate Ni catalysts are comprehensively summarized. This review aims to enlighten the design of ethylene/CO non-alternating polymerization catalysts for the development of new polyketone materials.

Experimental and theoretical insights into palladium-mediated polymerization of para-N,N-disubstituted aminostyrene.

Experimental and theoretical insights into polymerization of para-N,N-disubstituted aminostyrene monomers (St-4-NR2, R = Me, Et, Ph) using cationic α-diimine palladium complexes have been initially reported. The effects of the catalyst structure and monomer substituent were studied systematically. Polymerization turnover frequency (TOF) was shown to decrease in the order of monomer substituents Me > Et > Ph, whereas the molecular weight of the produced polymers showed an opposite trend (Me < Et < Ph). Methanol-mediated polymerization of para-N,N-dimethylaminostyrene (DMAS), along with polymer chain-end analysis, and palladium intermediate isolation proved that palladium-initiated DMAS polymerization obeyed a cationic mechanism. Comprehensive theoretical calculations further revealed that the carbocation was generated from the insertion of DMAS into the palladium center rather than the polarization of the methyl palladium intermediate with a coordinated DMAS. The produced amine-functionalized amorphous polystyrenes have low stereoregularity and exhibit good hydrophilic properties. The poly(para-N,N-disphenylaminostyrene) is a luminescent polymer and shows fluorescence properties, rendering this material a promising candidate for versatile potential applications.

Amphiphilic Polyethylene-b-poly(L-lysine) Block Copolymer: Synthesis, Self-Assembly, and Responsivity.

Polyethylene-b-polypeptide copolymers are biologically interesting, but studies of their synthesis and properties are very few. This paper reports synthesis and characterization of well-defined amphiphilic polyethylene-block-poly(L-lysine) (PE-b-PLL) block copolymers by combining nickel-catalyzed living ethylene polymerization with controlled ring-opening polymerization (ROP) of ε-benzyloxycarbonyl-L-lysine-N-carboxyanhydride (Z-Lys-NCA) and sequential post-functionalization. Amphiphilic PE-b-PLL block copolymers self-assembled into spherical micelles with a hydrophobic PE core in aqueous solution. The pH and ionic responsivities of PE-b-PLL polymeric micelles were investigated by means of fluorescence spectroscopy, dynamic light scattering, UV-circular dichroism, and transmission electron microscopy. The variation of pH values led to the conformational alteration of PLL from α-helix to coil, thereby changing the micelle dimensions.

Bathochromic-Shifted Emissions by Postfunctionalization of Nonconjugated Polyketones.

Most nontraditional intrinsic luminescent (NTIL) polymers currently show blue fluorescence. Tuning the emission color of NTIL polymers is of fundamental importance for their applications, but it still remains a scientific challenge. Herein, we initially develop an efficient strategy for bathochromic shifting of NTIL polymers by through-space acceptor-donor charge transfer between the in chain and the side chain. A variety of functionalized polyketones (FPK-R; where R = H, Ph, Me, tBu, F, and Cl) with furan rings built into the polymer chain were prepared by the Paal-Knorr reaction. FPK-R polymers showed bright and bathochromic-shifted fluorescence compared with their counterparts. The emission color could be tuned by changing the postfunctionalization conversion and varying the styrenic monomer substituent. Experimental and theoretical investigations revealed that the color tunability originated from enhanced through-space charge transfer between the side chain phenyl and the in chain furan rings.