Polymerization Of 2-vinylpyridine Research Articles

Syntheses of Rare-Earth Metal Alkyl Complexes Bearing a Dianionic α-Iminopyridyl Ligand and Their Catalytic Activities toward Polymerization of 2-Vinylpyridine

Syntheses of Rare-Earth Metal Alkyl Complexes Bearing a Dianionic α-Iminopyridyl Ligand and Their Catalytic Activities toward Polymerization of 2-Vinylpyridine

Synthesis of rare earth metal complexes based on phenol ether bidentate ligands and polymerization of 2-vinylpyridine

In previous work, our group found that tetradentate phenol ether rare earth catalysts show highly isoselectivity for 2-vinylpyridine polymerization. In order to explore the influence of ether chain on 2-vinylpyridine polymerization, six rare earth complexes with bidentate phenol ester ligands with similar structures were synthesized. Polymerizations of 2-VP were also explored, the effects of metal centers and different kinds of ligands on the polymerization were also discussed.

Dinuclear Pentacoordinated Organoyttrium Biphenolates as Initiators for the Synthesis of High-Molecular Weight Isotactic Poly(2-vinylpyridine).

Dinuclear organoyttrium biphenolato complexes have been synthesized for the first time starting from Y(CH2SiMe3)3(THF)2 and readily available biphenols with bulky substituents at the 3,3'-positions. XRD analysis revealed that these complexes are formed as homochiral dimers even though racemic biphenols were employed. Such dinuclear penta-coordinated yttrium complexes were evaluated as initiators in the polymerization of 2-vinylpyridine (2-VP). High activity and excellent isotacticity (mm > 99%) were observed. DSC analysis of poly(2-VP) showed a Tm = 221 °C, which is the highest value reported to date. Attempts to improve the low initiation efficiency of the present system were made by co-use with several organo-main-group metal reagents. Specifically, good molecular weight control within the high Mn region was achieved by the addition of Et3Al (Al/Y = 10).

Chain Propagation and Termination Mechanisms for Polymerization of Conjugated Polar Alkenes by [Al]-Based Frustrated Lewis Pairs

A combined experimental and theoretical study on mechanistic aspects of polymerization of conjugated polar alkenes by frustrated Lewis pairs (FLPs) based on N-heterocyclic carbene (NHC) and Al(C6F5)3 pairs is reported. This study consists of three key parts: structural characterization of active propagating intermediates, propagation kinetics, and chain-termination pathways. Zwitterionic intermediates that simulate the active propagating species in such polymerization have been generated or isolated from the FLP activation of monomers such as 2-vinylpyridine and 2-isopropenyl-2-oxazoline—one of which, IMes+-CH2C(Me)═(C3H2NO)Al(C6F5)3– (2), has been structurally characterized. Kinetics performed on the polymerization of 2-vinylpyridine by ItBu/Al(C6F5)3 revealed that the polymerization follows a zero-order dependence on monomer concentration and a first-order dependence on initiator (ItBu) and activator [Al(C6F5)3] concentrations, indicating a bimolecular, activated monomer propagation mechanism. The Lewis pair polymerization of conjugate polar alkenes such as methacrylates is accompanied by competing chain-termination side reactions; between the two possible chain-termination pathways, the one that proceeds via intramolecular backbiting cyclization involving nucleophilic attack of the activated ester group of the growing polymer chain by the O-ester enolate active chain end to generate a six-membered lactone (δ-valerolactone)-terminated polymer chain is kinetically favored, but thermodynamically disfavored, over the pathway leading to the β-ketoester-terminated chain, as revealed by computational studies.

Synthesis and Characterization of an ABC Miktoarm Star Terpolymer of Cyclohexadiene, Styrene, and 2-Vinylpyridine

The three arms of the novel ABC mixed-arm star terpolymerdescribed herein were chosen purposefully to create, uponexposure to a silica or mica surface, a conformationallyasymmetric binary brush having a P2VP “anchor” block withboth PS and high 1,4-PCHD “buoys”. The chemical dissimilarityof the arms and the short-term longevity of poly(cyclohexadi-enyl) macroanions combine to pose a difficult synthetic chal-lenge. For example, the cyclohexadiene block needs to besynthesized in nonpolar media without the presence of P2VPas polar components complicate both control of the PCHD anionstability and the resultant microstructure of the PCHD polymerobtained. In contrast, polymerization of 2-vinylpyridine is mostsuccessfully achieved in tetrahydrofuran (THF) at low temper-atures, so switching of polymerization media during thesynthesis was required.The target polymer was sought through the use of a1,1-diphenylethylene (DPE)-based strategy as shown in Scheme1. Employing anionic polymerization techniques previouslydetailed,

Synthesis and characterization of oxymethylene-linked 2-vinylpyridine/oxyethylene multiblock copolymers

Oxymethylene-linked (2-vinylpyridine-oxyethylene) multiblock copolymers were prepared by coupling telechelic α,ω-dihydroxypoly(2-vinylpyridine) (THPVP) and poly(ethylene oxide) (PEO), using dichloromethane as coupling agent and KOH as catalyst. THPVP was synthesized by polymerization of 2-vinylpyridine in tetrahydrofuran/benzene using l-methylnaphthyllithium as anionic initiator, followed by capping with ethylene oxide and termination by methanol. The effects of charging weight ratio of PEO/ THPVP, copolymerization time and molecular weight of PEO or THPVP on the copolymerization were studied. The copolymers were characterized by IR, 'H NMR, membrane osmometry, transmission electron microscopy (TEM) and differential scanning calorimetry (DSC).

Polymerization of 2-Vinylpyridine in the Presence of Poly (vinyl chloride)

Spontaneous polymerization was found to occur by heating 2-vinylpyridine (2-VP) at 50 C in the presence of poly (vinyl chloride) (PVC), and the mechanism of polymerization was investigated.In this system, the polymerization was found to proceed according not to the so called matrix but to the radical mechanism initiated by peroxides in PVC. The rate equation obtained was Rp = k[2-VP] 0.6-0.8 [PVC]0.4-2.0, and differed from the conventional radical polymerization.A kind of interaction between 2-VP and PVC was confirmed to exist from the results of copolymerization and homopolymerization studies in the presence of PVC, and more detailed analysis of the kinetic data.

Etude de la nature des especes ioniques intervenant au cours de la polymerisation anionique de la vinyl-4 pyridine

Initiation of anionic polymerization of 4-vinyl-pyridine (4-VP) in tetrahydrofuran solution, using organo-metallic compounds of Na and K, involves the same type of side reactions as the polymerization of 2-vinyl pyridine (2-VP). The living polymers of 2- and 4-VP have similar u.v. spectra. The values of the dissociation constants of ionic species of 2- and 4-VP are similar when the chain [poly(styrene-b vinyl-4 pyridine)] contains one 4-VP unit (K n ≈ 10 −9). But when the size of 4-VP block increases, the conductivity goes up to the value observed for living polystyrene (K D ≈ 10 −7). This phenomenon could be due to a solvation of the counter-ion by the poly 4-vinyl pyridine chain, acting as a polydentate complexing agent.

Radical polymerization of 2-vinylpyridine in the presence of saturated monocarboxylic acids

Radical polymerization of 2-vinylpyridine in the presence of saturated monocarboxylic acids