Polymerization of monomers with conjugated

Wegner G. Topochemical reactions of monomers with conjugated triple bonds. VI. Topochemical polymerization of monomers with conjugated triple bonds. Makromol Chem 1972 154 35-48. 

The topochemical polymerization of monomers with conjugated triple bonds is an interesting example of the relationship between packing properties and reactivity in the solid state. For solid state polymer-izability the monomer molecules must be arranged in a herringbone-like structure according to Figure 1 so that only one nearest distance between the triple bonds of adjacent molecules of 3 to 4 A is affected. To... 

Photopolymerization in the crystalline state. The solid-state polymerization of monomers with two conjugated triple bonds is best described as a 1-4 addition polymerization yielding a polymer with a backbone of conjugated unsaturated bonds. 

A similar mechanism was proposed when 1,5-dithiocin 838g underwent polymerizations with methyl methacrylate (MMA) and styrene (STY). The activated double bound of 838g was found to have a profound affect on reactivity. In fact, co-polymerization of 838g with MMA at 70 °C the 5-terminated sulfanyl radicals preferred to undergo homopropagation, while cross-propagation is favored for MMA-terminated radicals. Both monomers possessed an electron-deficient acrylate double bond with similar possibilities for conjugative stabilization of the adduct radical by the ester functionality, which would explain the apparent equal reactivity of the MMA radical to either monomer. 

Soluble cobalt and nickel catalysts for conjugated diene polymerization are usually prepared in the presence of monomer with the formation of a TT-allylic structure as a relatively stable intermediate, but the nature of attachment of other ligands to the active site is not known. Aluminium halides and cobalt halides react to form complexes of the structure (IX) [57]... 

The structure of the polymer obtained in the polymerization of butadiene and isoprene with heterogeneous Ziegler-Natta catalysts depends on the nature of the monomer, catalyst system, and reaction conditions. Previously reported results are reviewed and a mechanism is proposed for the stereoregulated polymerization of conjugated dienes. The polymerization of cyclopentadiene with LiAlH -TiCl4 or LiAlR4-TiCl4 catalyst system yields a readily oxidized polymer for which a 1,2-structure is proposed. 

There are two general routes to the synthesis of conjugated polymers addition polymerization of unsaturated monomers and condensation polymerization or stepwise coupling of monomers with difunctional groups. 

There are in general two ways to synthesize side chain polymers, polymerization of peptide-functional monomers or introduction of the peptide moiety afterwards, by grafting. The latter technique is based on the synthesis of polymers containing some form of functionality in the side chain, normally an activated ester moiety, which can further react with a peptide. The most commonly used method for the polymerization of monomers containing active esters is free radical polymerization. In particular many activated acrylate esters have been polymerized in this manner [12] (Table 1) for use in a wide variety of applications, from the preparation of polymer drug conjugates [13,14] to supports for solid phase peptide synthesis [15,16]. 

Satyanarayana and Elsenbaumer attempted the Gilch polymerization of monomer 191 to afford poly(bipyridinevinylene), 192, with [Ru(bpy)2]2+ complexed to each bpy in the conjugated backbone (Scheme 4.46).117 Unfortunately, the polymer obtained from this reaction was insoluble, and thus difficult to characterize. A large red shift in the optical spectrum was observed, and thermogravimetric analysis and IR spectroscopy also supported the structure assigned. The conductivity of the blue-black product was 4.5 X 10 6Scm 1. 

One can also obtain mutidimensional ECPs from actual multifunctional monomers, such as bispyr-rolylazobenzene or bis(2,5-dithenylpyrrolyl)azobenzene [100]. The electropolymerization of monomers with two heterocyclic moieties (pyrrole or bisthienylpyrrole) connected through conjugated phenyl spacers gives rise to cross-linked structures [86], since it was demonstrated that both heads took part to the polymerization process [85]. Another example of cross-linked ECP can be electrochemically obtained from a chiral dicarbazole monomer [292]. 

Such an approach requires both the synthesis of a wide variety of monomers with controlled conjugation length, and condensation polymerization schemes that yield polymers with molecular weights high enough to yield strong films of optical quality. 

Random copolymers of 3-methylthiophene with methyl methacrylate are readily prepared by initiating the polymerization of MMA with the Grignard of 2,5-diiodo-3-methylthiophene. During the oxidation of 3-methylthiophene, certain vinyl monomers copolymerize directly with the thiophene. But this random insertion of vinyl units disrupts the conjugation and there is a drastic decrease in electrical conductivity. There is no evidence that the doped copolymers are processable. 

Stereoregular polymers with conjugated double and triple bonds in the main chain have been obtained by solid state polymerization from a number of oligoacetylenes with conjugated triple bonds (84). The polymerization of two such monomers is illustrated in Scheme 15. The configuration of the double bonds connecting the monomeric units in these polymers is always trans. The crystalline monomer phase functions as a three-dimensional... 

The polymerization of monomers comprising both a chemically inert terpene entity (mostly menthol, cholesterol, or bile acids) and a readily polymerizable moiety has been another frequently utilized pathway towards (co)polymer conjugates with pendent terpene moieties. A number of polymerization techniques have been employed, including both conventional and living/controUed pol3mierization methods. 

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