Vinylpyridine-based copolymers

FOR Fomasiero, F., Halim, M., and Prausnitz, J.M., Vapor-sorption equilibria for 4-vinylpyridine-based copolymer and cross-linked polymer/alcohol systems. Effect of intramolecular repulsion. Macromolecules, 33, 8435, 2000. 

Shimidzu, T., Murakami, A., and Konishi, Y. (1979) Template-directed synthesis of oligonucleotides. Part 4. Condensation of nucleotides in the presence of nucleic acid base binding (4-vinylpyridine-styrene)copolymer in homogeneous solution. J. Chem. Research (S), 232,233, (M), 2751-2766. 

R= Bu or Pr ), have been obtained from [TiO<-CH2)(M-Cl)(AlMe2)( -C5H5)2] and RCH=CH2 in the presence of 4-vinylpyridine/styrene copolymer which functions as a Lewis base. Some reactions of the t-butyl compound are shown in Scheme 2. A metallocyclic derivative of zirconocene has been obtained as shown in equation (4). The chloro-derivative rearranges thermally to [Zr-(CHPMe3)Cl( 7-C5H5)2]. ... 

Vinyl pyridine-grafted polyolefins [229] having improved dyeability were prepared with >0.02 wt% based on the monomer of a perester catalyst and >0.1 wt% based on the monomer of a reducing agent promoter selected from lower-valent salts of multivalent metals, hydrosulfite, or alkali metal formaldehyde sulfoxylate. Thus, the polypropylene-styrene-vinylpyridine-graft copolymer prepared in the presence of 1 wt% sodium hydrosulfite and 0.5 wt% tert-huiyl 2-ethyl perhexanoate at 90 C was melt-spun into fibers... 

A strain of yeast and a strain of bacterium were co-immobilized to fabricate a biochemical oxygen demand (BOD) sensor based on sol-gel derived composite materials97. This novel type of biosensor was developed for water monitoring and was used to determine the BOD values of OECD synthetic wastewater, domestic wastewater, and lake waters. The microorganisms Trichosporon cutaneum and Bacillus subtilis were coimmobilized in the sol-gel composite material, which was composed of silica and the grafting copolymer of poly (vinyl alcohol) and 4-vinylpyridine (PVA-g-P(4-VP)). 

Colloidal catalysts in alkyne hydrogenation are widely used in conventional solvents, but their reactivity and high efficiency were very attractive for application in scC02. This method, which is based on colloidal catalyst dispersed in scC02, yields products of high purity at very high reactions rates. Bimetallic Pd/Au nanoparticles (Pd exclusively at the surface, while Au forms the cores) embedded in block copolymer micelles of polystyrene-block-poly-4-vinylpyridine... 

The poly(vinylpyridine) and poly(tert-butyl methacrylate) copolymers can easily be converted to either cationic or anionic polyelectrolytes by protonation of the pyridine rings or by base hydrolysis of the tert-butyl ester units, respectively. The highly branched structure of the molecules, in combination with the polyelectrolyte effect, should confer useful properties to these materials in solution for applications such as pH-sensitive reversible gels. 

Similar polymers, slightly less perfect, are the umbrella star copolymers [101]. These polymers are based on a central polystyrene star with 25 arms. An average of five polybutadiene or poly(2-vinylpyridine) branches are grafted onto the end of each arm. Since these polymers are models for block copolymer micelles their properties have been studied in selective solvents. In particular, the PBd-PS umbrella-star copolymers are monomolecularly dissolved in non-solvents for the core-forming polystyrene. 

The equSibrium constants K (Table 2) were calculated from the change in absorption at 420 nm in electronic spectra The very low value of K in the homopolymer of 4-vinyl-jqrridine (PVP).is explained by steric hindrance near the coordinated cobaloximes through the neighbouring base. If the content of 4-vinylpyridine in the copolymer is lower than 20%, the coordinated cobaloxime was easily removed because coordination occurs mainly at the surface of the polymer domain. In unpolar benzene instead of DMF, however, the conformational change of polymer chain brings the vinyl-pyridine units more to the interior of the polymer domain. 

The radical nature of nitroxide-mediated processes also allows novel types of block copolymers to be prepared in which copolymers, not homopolymer, are employed as one of the blocks. One of the simplest examples incorporate random copolymers124 and the novelty of these structures is based on the inability to prepare random copolymers by living anionic or cationic procedures. This is in direct contrast to the facile synthesis of well-defined random copolymers by nitroxide-mediated systems. While similar in concept, random block copolymers are more like traditional block copolymers than random copolymers in that there are two discrete blocks, the main difference being one or more of these blocks is composed of a random copolymer segment. For example, homopolystyrene starting blocks can be used to initiate the copolymerization of styrene and 4-vi-nylpyridine to give a block copolymer consisting of a polystyrene block and a random copolymer of styrene and 4-vinylpyridine as the second block.166... 

TEMPO, />substituted TEMPO based alkoxyamines 3, and compounds such as 4, 5, and 7 have been applied successfully for polymerizations of styrene, substituted styrenes, and 4-vinylpyridine, and some copolymerizations and block copolymerizations were reported. However, living and controlled radical polymerization of other monomers, especially acrylates, require the use of the more recently developed structures 6, 8, or 9. These also yield well-controlled and living block copolymers, but methacrylates have so far resisted all efforts to obtain large conversions. Undoubtedly, many failures are due to unfavorable rate constants or side reactions. 

Metal-catalyzed living radical polymerizations of vinylpyridines were investigated with the copper-based systems. One of the difficulties in the polymerization is a decrease of catalytic activity imposed by the coordination of the monomers by the metal complex. Controlled radical polymerization of 4-vi-nylpyridine (M-33) was achieved by an initiating system consisting of a strong binding ligand such as L-32 and a chloride-based system [1-13 (X = Cl)/ CuCl] in 2-propanol at 40 °C.214 The Mn increased in direct proportion to monomer conversion, and the MWDs were narrow (MJMn = 1.1 —1.2). In contrast, 2-vinylpyridine (M-34) can be polymerized in a controlled way with chlorine-capped polystyrene as an initiator and the CuCl/L-1 pair in / -xylene at 140 °C.215 Block copolymers with narrow MWDs (Mw/Mn = 1.1 —1.2) were obtained therein. 

Acrylamide-based block copolymers B-2 7370 and B-28117 were prepared by the ruthenium- and copper-based systems, respectively. The vinylpyridine (B-29)214,371 segment can be introduced into the block copolymers with MMA. The polystyrene-based block copolymers B-30 with short segments of a bicyclic monomer had a higher decomposition temperature than the homopolystyrene with C—Br terminals.223... 

Eisenberg and coworkers have employed acid-base interactions to improve the miscibility of a number of polymer-polymer pairs. Miscible blends were prepared using acid-base interactions, e.g., with SPS (acid derivative) and poly (ethylacrylate-co-4-vinylpyrldine) (91), sulfonated polyisoprene and poly (styrene-co-4-vinylpyridine) (92), and using ion-dipole interactions, e.g., poly (styrene-co-llthium methacrylate) and poly (ethylene oxide) (93). Similarly, Weiss et al. (94) prepared miscible blends of SPS(acid) and amino-terminated poly (alkylene oxide). In addition to miscibility improvements, the interactions between two functionalized polymers offers the possibility for achieving unique molecular architecture with a polymer blend. Sen and Weiss describe the preparation of graft-copolymers by transition metal complexation of two functionalized polymers in another chapter. 

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