2-Vinylpyridine monomer

Monomers Several general categories of vinyl monomers are suitable for anionic polymerizations. These include aromatic monomers (2-vinylpyridine, styrene), conjugated dienes (butadiene, isoprene), and alkyl methacrylates. In the case of vinyl monomers, adjacent substituents that stabilize an anion are most suitable for anionic polymerizations. Examples include substituents found in styrene, butadiene, isoprene, alkyl methacrylates, or cyano acrylate which stabilize propagating anions by electronic effects. 

Catalysts of the Ziegler type have been used widely in the anionic polymerization of 1-olefins, diolefins, and a few polar monomers which can proceed by an anionic mechanism. Polar monomers normally deactivate the system and cannot be copolymerized with olefins. However, it has been found that the living chains from an anionic polymerization can be converted to free radicals in the presence of peroxides to form block polymers with vinyl and acrylic monomers. Vinylpyridines, acrylic esters, acrylonitrile, and styrene are converted to block polymers in good yield. Binary and ternary mixtures of 4-vinylpyridine, acrylonitrile, and styrene, are particularly effective. Peroxides are effective at temperatures well below those normally required for free radical polymerizations. A tentative mechanism for the reaction is given. 

Their approach was to from a pre-polymerisation complex with the transition state analogue Co2+ co-ordinated dibenzoylmethane and the monomers vinylpyridine, styrene and divinylbenzene. The procedure resulted in an 8-fold increase in reaction rate and high substrate specificity (Figure 6.31). 

SBVPL is a polymerization product from three different monomers vinylpyridine, styrene, and butadiene. 

Vinylpyridine (23) came into prominence around 1950 as a component of latex. Butadiene and styrene monomers were used with (23) to make a terpolymer that bonded fabric cords to the mbber matrix of automobile tires (25). More recendy, the abiUty of (23) to act as a Michael acceptor has been exploited in a synthesis of 4-dimethylaminopyridine (DMAP) (24) (26). The sequence consists of a Michael addition of (23) to 4-cyanopyridine (15), replacement of the 4-cyano substituent by dimethylamine (taking advantage of the activation of the cyano group by quatemization of the pyridine ring), and base-cataly2ed dequatemization (retro Michael addition). 4-r)imethyl aminopyri dine is one of the most effective acylation catalysts known (27). 

Synthetic. The main types of elastomeric polymers commercially available in latex form from emulsion polymerization are butadiene—styrene, butadiene—acrylonitrile, and chloroprene (neoprene). There are also a number of specialty latices that contain polymers that are basically variations of the above polymers, eg, those to which a third monomer has been added to provide a polymer that performs a specific function. The most important of these are products that contain either a basic, eg, vinylpyridine, or an acidic monomer, eg, methacrylic acid. These latices are specifically designed for tire cord solutioning, papercoating, and carpet back-sizing. 

The polymers were prepared using MAA as functional monomer and EDMA as crosslinking monomer if not otherwise noted. VPY= 2- or 4-vinylpyridine TRIM = trimethylolpropane trimethacrylate DPGE = (R)-N,0-dimethacryloylphenylglycinol PYAA = 3-(4-pyridinyl)acrylic acid. 

Considering functional group complementarity, other commodity monomers may also be used. Thus for templates containing acid groups, basic functional monomers are preferably chosen. The 2- or 4-vinylpyridines (VPY) are particularly well-suited for the imprinting of carboxylic acid templates and provide selectivities of the same... 

A great variety of suitable polymers is accessible by polymerization of vinylic monomers, or by reaction of alcohols or amines with functionalized polymers such as chloromethylat polystyrene or methacryloylchloride. The functionality in the polymer may also a ligand which can bind transition metal complexes. Examples are poly-4-vinylpyridine and triphenylphosphine modified polymers. In all cases of reactively functionalized polymers, the loading with redox active species may also occur after film formation on the electrode surface but it was recognized that such a procedure may lead to inhomogeneous distribution of redox centers in the film... 

Molecular imprinting can be accomplished in two ways (a), the self assembly approach and (b), the preorganisation approach3. The first involves host guest complexes produced from weak intermolecular interactions (such as ionic or hydrophobic interaction, hydrogen bonding) between the analyte molecule and the functional monomers. The self assembled complexes are spontaneously formed in the liquid phase and are sterically fixed by polymerisation. After extraction of the analyte, vacant recognition sites specific for the imprint are established. Monomers used for self assembly are methacrylic acid, vinylpyridine and dimethylamino methacrylate. 

Grafting of functional monomers onto fluoropolymers produced a wide variety of permselective membranes. Grafting of styrene (with the following sulfonation), (meth)acrylic acids, 4-vinylpyridine, A-vinylpyrrolidone onto PTFE films gave membranes for reverse omosis,32-34 ion-exchange membrane,35-39 membranes for separating water from organic solvents by pervaporation,49-42 as well as other kinds of valuable membranes. 

The additional complexity present in block copolymer synthesis is the order of monomer polymerization and/or the requirement in some cases to modify the reactivity of the propagating center during the transition from one block to the next block. This is due to the requirement that the nucleophilicity of the initiating block be equal or greater than the resulting propagating chain end of the second block. Therefore the synthesis of block copolymers by sequential polymerization generally follows the order dienes/styrenics before vinylpyridines before meth(acrylates) before oxiranes/siloxanes. As a consequence, styrene-MMA block copolymers should be prepared by initial polymerization of styrene followed by MMA, while PEO-MMA block copolymers should be prepared by... 

List C contains peroxidisable monomers, where the presence of peroxide may initiate exothermic polymerisation of the bulk of material. Precautions and procedures for storage and use of monomers with or without the presence of inhibitors are discussed in detail. Examples cited are acrylic acid, acrylonitrile, butadiene, 2-chlorobutadiene, chlorotrifluoroethylene, methyl methacrylate, styrene, tetraflu-oroethylene, vinyl acetate, vinylacetylene, vinyl chloride, vinylidene chloride and vinylpyridine [1]. 

Because of the repulsion of the cyanide groups the polymer backbone assumes a rod-like conformation. The fibers derive their basic properties from this stiff structure of PAN where the nitrile groups are randomly distributed about the backbone rod. Because of strong bonding between the chains, they tend to form bundles. Most acrylic fibers actually contain small amounts of other monomers, such as methyl acrylate and methyl methacrylate. As they are difficult to dye, small amounts of ionic monomers, such as sodium styrene sulfonate, are often added to improve their dyeability. Other monomers are also employed to improve dyeability. These include small amounts (about 4%) of more hydrophilic monomers, such as -vinyl-2-pyrrolidone (Equation 6.69), methacrylic add, or 2-vinylpyridine (Equation 6.70). 

A variety of monomers, including styrene, acrylonitrile, (meth) acrylates, (meth) acrylamides, 1,3-dienes, and 4-vinylpyridine, undergo ATRP. ATRP involves a multicomponent system of initiator, an activator catalyst (a transition metal in its lower oxidation state), a deactivator (the transition state metal in its higher oxidation state) either formed spontaneously or deliberately added, ligands, and solvent. Successful ATRP of a specific monomer requires matching the various components so that the dormant species concentration exceeds the propagating radical concentration by a factor of 106. 

Alkyl derivatives of the alkaline-earth metals have also been used to initiate anionic polymerization. Organomagnesium compounds are considerably less active than organolithiums, as a result of the much less polarized metal-carbon bond. They can only initiate polymerization of monomers more reactive than styrene and 1,3-dienes, such as 2- and 4-vinylpyridines, and acrylic and methacrylic esters. Organostrontium and organobarium compounds, possessing more polar metal-carbon bonds, are able to polymerize styrene and 1,3-dienes as well as the more reactive monomers. 

Calculate the monomer reactivity ratios for chloroprene-2-vinylpyridine using the data from Table 6-8 for the patterns of reactivity scheme. 

Monomeric styrene is destabilized as in Example 3-1 and pre-dried with calcium chlo-ride.The monomer is now allowed to stand over calcium hydride for 24 h and then distilled under reduced pressure of nitrogen into a previously flamed-out Schlenk tube. Pure 4-vinylpyridine is distilled twice over KOH pellets in vacuum.lt is then vacuum distilled under nitrogen through a column packed with Raschig rings into a previously flamed out Schlenk tube (bp 62 °C/12 torr).The closed Schlenk tubes containing the monomers are stored in a refrigerator until required.The preparation of the initiator solution (sodium naphthalene) is described in Example 3-19. 

To 5.3 g of 4-vinylpyridine is added to THE up to a volume of 50 ml 5 ml of this solution (containing 5 mmol 4-vinyl pyridine) are added in the same way to the above solution containing the "living" polystyrene, with vigorous agitation. After 15 min another 40 mmol of styrene are added, followed 15 min later by another 5 mmol of 4-vinylpyridine this operation is repeated once more. 15 min after the last addition of monomer the block copolymer is precipitated by dropping the solution into a mixture of 300 ml of diethyl ether and 300 ml of petroleum ether.The polymer is filtered, washed with ether,filtered again, and dried in vacuum at room temperature. 

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