TEMPLATE-BASED POLYMERIZATIONS

Fig 5-18 Example of attachment of CP monomer (here aniline) to a template backbone before polymerization. 

The simplest example of a template polymerization, one that has found the most common practical use (for water solubility), is that using the highly water soluble poly(styrene sulfonate) (PSS ) as the template and dopant. PSSH is a polyacid , exhibiting a large, winding, lanky polymer structure, with pendant acidic groups, to which a basic monomer such as aniline can readily attach, as illustrated in Fig. 5-18. Once the aniline monomers are attached, chemical polymerization is effected to yield a P(ANi)-PSS interwoven-strand copolymer of the type shown in Fig. 5-19. Temperature and concentration are important parameters governing the type of product obtained in these syntheses. 

Template syntheses yielding complexes of poly(styrene)/poly(3-alkyl-thiophene) (P(Sty)/P(3AT)) claimed to be full interpenetrating polymer networks (IPN, all polymer components part of a crosslinked network) have been effected by the Rubner group [133], with conductivities in some cases up to 0.5 S/cm. In this case, however, the P(3AT) actually forms the template The pendant groups of a vinyl derivatized P(3AT) are first crosslinked with styrene monomer. The resulting compound is then polymerized and crosslinked at the styrenes. As however the resulting complexes are insoluble, intractable, less conductive and generally less stable than P(3AT) s, their utility is not made clear by the authors of the work. 

In another template synthesis with an interesting potential application [134], pyrrole monomers are bonded through an acetyl group to the dipeptide glycyl-D-phenylala-nine. The resulting derivative is polymerized electrochemically on an electrode 

Hg 5-20 Pyrrole-derivative monomer used by Cosnier and Innocent [135]. 

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Discuss two examples of template-based polymerizations, and outline how they differ from "conventional" chemical polymerizations. 

Solubility and processing of CPs have much in common with the related subjects of CP composites and template-based polymerizations, and some elements in common with self-doped CPs. These subjects are however excluded from this chapter and dealt with in Chapters 5, 9 and 10, to which reference is made. 

Besides a means of immobilizing an active catalyst on an electrode, what are the other features of a CP in template-based catalysis What aspects and which specific examples of template-based polymerization described in Chapter 5 can be used with advantage for catalyst ... 

Recent work from Christoff Biebricher s group showed that a very efficient template-directed polymerization of adeifine - with a degree of polymerization of up to 400 - could be achieved based on a poly(U) template (Trinks et al., 2003). 

Mathematical description of the polymerization of biological macromolecules on templates, based on simple models, has been published by Simhaet al Two types of reaction were discussed. The first type of reaction was initiated by polymerization of two monomers on each template. The reaction proceeded throughout the addition of monomer to the growing ends or by the coupling of the growing chains. In the second type of re-... 

PolyCmethacrylic acid) was used as template for polymerization of N-vinylpyrrolidone. Interaction between poly(methacrylic acid) and N-vinylpyrrolidone is based on the hydrogen bonding between COOH groups and carbonyl groups in the monomer ... 

In contrast to template polycondensation or ring-opening polymerization, template radical polymerization kinetics has been a subject of many papers. Tan and Challa proposed to use the relationship between polymerization rate and concentration of monomer or template as a criterion for distinguishing between Type I and Type II template polymerization. The most popular method is to examine the initial rate or relative rate, Rr, as a function of base mole concentration of the template, [T], at a constant monomer concentration, [M]. For Type I, when strong interactions exist between the monomer and the template, Rr vs. [T] shows a maximum at [T] = [M]q. For type II, Rr increases with [T] to the critical concentration of the template c (the concentration in which template macromolecules start to overlap with each other), and then R is stable, c (concentration in mols per volume) depends on the molecular weight of the template. 

Early work on DNA polymerase I led to the definition of two central requirements for DNA polymerization. First, all DNA polymerases require a template. The polymerization reaction is guided by a template DNA strand according to the base-pairing rules predicted by Watson and Crick where a guanine is present in the template, a cytosine deoxynucleotide is added to the new strand, and so on. This was a particularly important discovery, not only because it provided a chemical basis for accurate semiconservative DNA replication but also because it represented the first example of the use of a template to guide a biosynthetic reaction. 

Fig. (3). Hemozoin Production Mediated by Bionucleating Templates. Representative polymerization assay with 50 pM of hemin in 2 ml acetate buffer (500 mM, pH 4.8) at 37° C. BNTI and BNTII were used in 1 and 2 nmol amounts. Chloroquine (CQ, 100 pM) was included with BNT I and BNT n in inhibition reactions. Polyhistidine and bovine serum albumin in approximately 1 and 2 nmol amounts were used in protein control experiments. The blank control was the acetate buffer above. Base line amounts of insoluble aggregate are consistent with those previously reported under similar conditions.

Assuming the existence of an RNA template, the polymerization of activated ribonucleotides into polymers containing 3, 5 -phosphodiester linkages proceeds readily. Using RNA homopolymers as templates, products of up to 50 bases in length have been observed,30 and when RNA heteropolymers are used as templates the reaction is faithful.31 These reactions can be catalyzed by a variety of metal ions,32 33 and seem to occur most easily with ribose-linked nucleotides.34 Short oligonucleotides can also serve as substrates for template-directed polymerization,35 36 and they... 

Later, Hosoya et al. 1931 prepared monodisperse polymer-based CSPs from chiral methacrylamides by co-polymerization onto the surface of polymeric particles. These are synthesized by a staged templated suspension polymerization using a two-step swelling method starting from polystyrene seed particles of 1 pm size used as shape templates, onto which methyl methacrylate and later the chiral methacrylamide is co-polymerized. 

Cepak, V.M. and Martin, C.R. Preparation of polymeric micro- and nanostmctures using a template-based deposition method. Chem. Mater. 11, 1363-1367, 1999. 

An oligonucleotide that base-pairs with a template polynucleotide strand and is extended tlarough template-directed polymerization is a/an... 

Figure 8.8 Schematic representation of a DNA biosensor based on the DNA-templated enzymatic polymerization of aniline (Reproduced with permission from[71]. Copyright (2007) Wiley-VCH Verlag ).

On the other hand, Kato et al. (52) reported the synthesis of 4 -thiopyrimidines (U and C) and their incorporation into transcripts by T7 RNA polymerase. The 4 -thio modification increased the stability of the transcripts 50-fold relative to the natural RNA transcripts. Using these libraries, Kato et al. (52) successfully performed a SELEX modification, and they were able to discover an aptamer to thrombin. Vaught et al. (56) showed that several UTPs substituted at the 5-position can be synthesized and subsequently transcribed using T7 RNA polymerase. Kuwahara et al. (59) have synthesized similar 5-modified dUTP compounds and have shown that a DNA polymerase efficiently catalyzed their template-dependent polymerization. Jaeger et al. 58) described a similar system for introducing a variety of modified bases into oligonucleotides using other DNA polymerases. 

Fig. 1.3 Strategy for nanopatteming functional materials employing templates based on copolymer self-assembly with double-gyroid morphology. This approach is particularly versatile since it separates the template fabrication top row) from the templating of functional materials bottom row). 1 Copolymer synthesis. 2 Self-assembly into the double-gyroid morphology. 3 Selective degradation of one block yields a mesoporous template. 4 Templating of functional materials via various deposition techniques. 5 Removal of polymeric matrix. 6 Assembly of functional devices...

Shin J, Braun PV, Lee W (2010) Fast response photonic crystal pH sensor based on templated photo-polymerized hydrogel inverse opal. Sensor Actuat B Chem 150 183... 

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