POLYKETONE FROM CO AND STYRENE: A USEFUL COPOLYMER CATALYZED BY A HIGHLY ACTIVE AND STABLE PALLADIUM CATALYST WITH 5-NITRO-1,10-PHENANTHROLINE LIGAND

A novel coordinated complex [(5-nitrophen)Pd(CF3CO2)2] (5-nitrophen = 5-nitro-1,10-phenanthroline) was first synthesized. By using XPS, IR, and 1H-NMR, its coordination unit was studied in comparison with those of complexes [(N-N)Pd(CH3CO2)2] and [(N-N)Pd(CF3CO2)2]. The H2,9 proton signals of 1H-NMR spectra of the complexes are excellent probes to monitor the evolution of the environment of the palladium atom. The state of anionic coordination was confirmed by the presence of IR absorption peaks of COO in complexes ([(N — N)Pd(CH3CO2)2] and [(N — N)Pd(CF3CO2)2]). Bonding energies of N1s and Pd3d5 obtained from XPS data testified to the strength of the N-Pd coordinating bond. The conclusion can be drawn by analyzing these data from IR, XPS and 1H-NMR that it is the unsymmetrical substitution of the 1,10-phenanthroline (phen) that makes the [(5-nitrophen)Pd(CF3CO2)2] more active. Experimental results showed that [(5-nitrophen)Pd(CF3CO2)2] exhibits much higher activity than [(bipy)Pd(CF3CO2)2] (1,1’- bipyridine = bipy) and [(phen)Pd(CF3CO2)2] under the same conditions.

Chain-Length-Dependent Hydrogen-Bonded Self-Assembly of Terminally Functionalized Discrete Polyketones

Here,we report the synthesis and the chain-lengthdependent self-assembling behaviors of discrete di-,tetra-,and hexaketones terminally functionalized with hydrogen-bonding carboxyl(C1,C2,and C3)and 3-acylaminopyridine groups(P1,P2,and P3).These polyketones were prepared by the coupling reactions of silylated analogues of 3,3-dimethylpentane-2,4-dione and t-butyl 2,2-dimethyl-3-oxobutanoate and the subsequent hydrolysis or amidation with 3-aminopyridine.Single-crystal Xray diffraction analysis revealed that C1 and C2 form helical assemblies in which the components are connected by the dimerization of terminal carboxyl groups,whereas the longer C3 showed infinite hydrogen-bonded chains mediated by 1,4-dioxane used as a crystallization solvent.Pyridine-terminated P1 exhibited a three-dimensional hydrogen-bonded network owing to multiple NH…N(pyridine)hydrogen bonds in the solid state.P2 generated a double-helix-like fiber structure in the crystalline state.Among the pyridine-terminated polyketones P1−P3,only P2 showed gelation behavior in chloroform(100 mM concentration)at 25℃.The scanning electron microscopy measurement of xerogel P2 revealed the formation of rod-like structures with a thickness of approximately 0.5−3.5μm.These results demonstrate that the precise control of the polyketone chain length can significantly alter hydrogen-bonded self-assembly in the solid state and in solution even with the same terminal structures.

Isothermal-crystallization Kinetics and Spherulite Growth of Aliphatic Polyketone/Polyamide-6 Blends

In this research, the morphologies, isothermal-crystallization kinetics, and spherulite growth of aliphatic polyketone/polyamide-6 blends were studied. A single glass-transition temperature(T_g) was determined, and the composition dependence of Tg for these blends was well described by the Kwei equation. The strong intermolecular interaction between the two polymer components was confirmed by melting-point depression. The isothermal-crystallization kinetics were analyzed on the basis of the Avrami approach. A linear increase in the radii of the spherulites with time was observed for all compositions. All the spherulites continued to grow at nearly identical growth rates. With increasing polyamide-6 content, the size of the spherulites in the polyketone/polyamide-6 blends gradually decreased, and the number of spherulites in the blends increased.

Copolymerization of polyketones catalyzed by polyacrylonitrile resin-supported palladium acetate

The crosslinked polyacrylonitrile (PAN) wassynthesized by suspension polymerization using acrylonitrile(ANT) and divinylbenzene (DVB). Effects of a varietyof conditions on the polymerization of PAN particle sizeand stiffness were investigated. Polyketone was preparedby the copolymerization of carbon monoxide (CO) andstyrene (ST) catalyzed by PAN resin-supported palladiumacetate. The resin-supported catalyst and the copolymerizationproduct were characterized by infrared spectroscopy(IR) and Scanning Electron Microscopy (SEM). Effects ofthe components of a catalytic system and reaction time onthe catalytic activity were studied. The reusability of theresin-supported catalyst was also investigated.Results indicatedthat the resin-supported catalyst has excellent catalyticproperty. The yield of polyketone was 6.2348 g whenusing 1 g of resin and 22.4 mg of palladium acetate.

The Catalytic Copolymerization of Ethene with Carbon Monoxide Efficiently Carried out in Water-Dichloromethane-Sodium Dodecylsulfate Emulsion

The CO-ethene copolymerization has been efficiently carried out in the water/CH2Cl2 emulsion by using water insolvable Pd(II) complexes. By using the surfactant SDS very high molecular weight copolymers have been obtained with high productivity (ca. 13,000 g/(gPd.h)).

Cationic Palladium Catalyzed Nonalternating Copolymerization of Ethylene with Carbon Monoxide: Microstructure Analysis and Computational Study

The introduction of carbonyl group with a high density in polyethylene backbone corresponds to polyketone materials,which features excellent mechanical strength,crystallinity,photodegradability,hydrophilicity,surface and barrier properties.Due to the extremely high binding affinity of carbon monoxide(CO)and kinetic preference for its subsequent insertion,the formation of nonalternating structure with extra ethylene insertion is exceptionally challenging,however,this nonalternating strategy is of significant importance for polymer modification in term of processing and solubility.Here,we have communicated our study on cationic palladium coordinated diphosphazane monoxide(PNPO)for the nonalternating copolymerization of ethylene with CO,the systematical investigation on the amine and phosphine oxide moieties in PNPO platform in term of electronic and steric modulation has been performed.It is discovered that the installation of aliphatic structure on amine moiety favors the improvement of catalyst activity and longevity,while the amino groups on phosphine oxide moiety promotes the nonalternating copolymerization.In particular,we have computationally investigated herein the aspects of the nonalternating degree by comparing with PNPO platform and 1,3-bis(diphenylphosphanyl)propane ligands based palladium catalysts.These mechanistic studies can help to understand the catalyst structure and polyketone property relationships and shed light on future design of high-performance copolymerization catalysts.