Vinyl pyridine anionic polymerization

Additional well-defined side-chain liquid crystalline polymers should be synthesized by controlled polymerizations of mesogen-ic acrylates (anionic or free radical polymerizations), styrenes (anionic, cationic or free radical), vinyl pyridines (anionic), various heterocyclic monomers (anionic, cationic and metalloporphyrin-initiated), cyclobutenes (ROMP), and 7-oxanorbornenes and 7-oxanorbornadienes (ROMP). Ideally, the kinetics of these living polymerizations will be determined by measuring the individual rate constants for termination and... 

The effect of metal alkoxides on the properties of initiators for the anionic polymerization of vinyl monomers has also been reported for polymethylmethacrylate, polymethacrylonitrile and poly-2-vinyl pyridine. The polymerization esterification of teiephthaUc acid with glycols is another important industrial process which is catalysed by metal alkoxides, mainly titanium or alkali metal derivatives. Numerous patent applications have appeared over the years. 

As previously described, all microspheres discussed in this chapter were synthesized from AB type diblock copolymers. Precursor block copolymers, poly(styrene-b-4-vinyl pyridine) (P[S-b-4VP]) diblock copolymers, were synthesized using the additional anionic polymerization technique [13]. The basic properties of the block copolymers were determined elsewhere [24,25] and are listed... 

As these block copolymers were synthesized using the anionic polymerization technique, their molecular weight distributions were narrow. The microspheres with narrower size distribution are better for well-ordered self-organization. Actually, all block copolymers synthesized for these works formed poly(4-vinyl pyridine) (P4VP) spheres in the PS matrices with narrow size distributions. 

The poly(styrene-b-isoprene) (P(S-b-IP)) and poly(-styrene-b-2-vinyl pyridine) (P(S-b-2VP)) block copolymers with narrow molecular weight distributions for blending with the microspheres were also synthesized using the additional anionic polymerization technique. The number-average molecular weights (Mns) and PS contents are also shown in Table 1. 

Spontaneous polymerization of 4-vinyl pyridine in the presence of polyacids was one of the earliest cases of template polymerization studied. Vinyl pyridine polymerizes without an additional initiator in the presence of both low molecular weight acids and polyacids such as poly(acrylic acid), poly(methacrylic acid), polyCvinyl phosphonic acid), or poly(styrene sulfonic acid). The polyacids, in comparison with low molecular weight acids, support much higher initial rates of polymerization and lead to different kinetic equations. The authors suggested that the reaction was initiated by zwitterions. The chain reaction mechanism includes anion addition to activated double bonds of quaternary salt molecules of 4-vinylpyridine, then propagation in the activated center, and termination of the growing center by protonization. The proposed structure of the product, obtained in the case of poly(acrylic acid), used as a template is ... 

The various kinds of growing species differ not only in their propagation but also in their stereochemical preferences. Professor Hogen-Esch will review this subject in his talk on anionic oligomerization of some vinyl monomer, and mechanisms of anionic, stereospecific polymerization of 2-vinyl pyridine will be discussed by Dr. Fontanille. In this context, the interesting paper of Schuerch et al.(12) deserves attention. Their work clearly reveals the effect of cation solvation upon the mode of monomer s approach to the growing centers. 

Living Anionic Stereospecific Polymerization of 2-Vinyl pyridine... 

Natta et al. have shown (1,2) that stereospecific polymerization of 2-vinyl pyridine (2VP) can be achieved by using de-solvated Grlgnard reagents as Initiators, In solution In hydrocarbon solvents. Although the essential characteristics were not revealed In this work, there Is no doubt that an anionic mechanism Is operative In such a polymerization. 

The anionic polymerization of 2-vinyl pyridine initiated by benzyl-2 pyridy lmethylmagnesiurn (benzyl picolyl magnesium) in hydrocarbon solvents, leads to highly isotactic polymers. 

ABC copolymers polystyrene-polyisoprene-poly(vinyl-2-pyridine)(S.I.V2P) with number-molecular average weight of 23000,102000, and 23000 were prepared by stepwise anionic polymerization. Films obtained by solvent casting from methylcyclohexane and benzene were observed by electron microscopy after staining the polyisoprene block with osmium tetroxide or the poly(vinyl-2-pyridine)... 

Rossi has synthetized block copolymers polyisoprene-poly(vinyl-2-pyridine) and polyisoprene-poly(vinyl-4-pyridine) of various composition and molecular weight by anionic polymerization under high vacuum205, 208. The polymerization in THF dilute solutions with Cumylpotassium as initiator yielded a 1,2 + 3,4-microstructure of the polyisoprene block. The polymerization in toluene solutions with sec-butyl-lithium as initiator yielded a 1,4-c/s-microstructure of the polyisoprene block. 

Using anionic polymerization in THF solution and with diphenylmethylsodium as initiator, Grosius et al.2ls have synthetized block copolymers poly(vinyl-2-pyridine)-poly(vinyl4-pyridine). They have studied by low-angle X-ray scattering the structure of a copolymer V 2 P V 4 P with molecular weight of the blocks 15000 and 8000 respectively. In octanol, they have found a lamellar and a cylindrical structure as a function of solvent concentration. In THF, dioxan, and benzene they have only found a cylindrical structure. 

The preparation of poly(2-vinyl-pyridine), by radical or anionic polymerization of the corresponding monomer, has been described long time ago. Atactic or isotactic, partially crystallizable polymers may be obtained 30). Poly(4-vinyl-pyridine) may be prepared in a similar way 31). 

Catalysts of the Ziegler-Natta type are applied widely to the anionic polymerization of olefins and dienes. Polar monomers deactivate the system and cannot be copolymerized with olefins. J. L. Jezl and coworkers discovered that the living chains from an anionic polymerization can be converted to free radicals by the reaction with organic peroxides and thus permit the formation of block copolymers with polar vinyl monomers. In this novel technique of combined anionic-free radical polymerization, they are able to produce block copolymers of most olefins, such as alkylene, propylene, styrene, or butadiene with polar vinyl monomers, such as acrylonitrile or vinyl pyridine. 

Acrylonitrile can be polymerized with copolymers containing cationic groups such as, for example, vinyl pyridine to give a fibre with an affinity for anionic dyes. 

Predict the order of reactivity (and justify your prediction) of the given monomers, (a) Styrene, 2-vinylpyridine, 3-vinylpyridine, and 4-vinyl pyridine in anionic polymerization, (b) Styrene, p-methoxystyrene, p-chlorostyrene, and p-methylstyrene in cationic polymerization. 

In order to confirm these results, PPV-based copolymers with more controlled stmctures have been also synthesized by anionic polymerization with polystyrene (PS) (copolymer 7) and poly(4-vinyl pyridine) (P4VP) (copolymer 8) coils (as shown in Figure 6)... 

The PIB macroinitiators can also initiate living anionic polymerization of a wide variety of functional monomers, such as vinyl pyridine, N,N-dimethylacryl-amide, and a variety of protected monomers, such as silylated 2-hydroxyethyl methacrylate. Polymerization studies with these monomers are in progress. The resulting products are potential new thermoplastic elastomers, dispersing agents, blending compounds, emulsifiers, non-ionic surfactants, biomaterials etc. 

Membranes which may be used in the removal of alkali metal ions by electrodialysis are those which are impermeable to anions, but which allow the flow therethrough of cations. Such cation-selective membranes should, of course, possess chemical durability, high resistance to oxidation and low electrical resistance in addition to their ion-exchange properties. Homogeneous-type polymeric membranes are preferred, for example, network polymers such as phenol, phenosulfonic acid, formaldehyde condensation polymers and linear polymers such as sulfonated fluoropolymers and copolymers of styrene, vinyl pyridine and divinylbenzene. Such membranes are well known in the art and their selection for use in the method of the invention is well within the skill of the art. 

Extensive work studying the interaction of poly(N-ethyl-4-vinylpyridinium bromide) (PEVP) and related (partially alkylated) cationic copolymers with anionic lipid membranes has been performed by Yaroslavov, Menger, and Kabanov. In all cases, 4-vinyl pyridine was free radically polymerized and postfunctionalized with alkyl bromides (Figure 17). The initial... 

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