Polymerization enzyme-catalyzed

Recently, there has been considerable interest in the use of enzymes such as horseradish peroxidase (HRP) as catalysts for the synthesis of PAn s and PPy s with 

Serves as a template that aligns the aniline monomers before polymerization so as to promote the desired head-to-tail coupling 

Provides the counterions for doping the synthesized PAn to the conducting emeraldine salt form 

Another advantage of this enzyme-catalyzed route to colloidal PAn salts is the considerably higher pH that can be employed compared to the previous chemical and electrochemical polymerization methods. Horseradish peroxidase immobilized on chitosan powder as a solid support has also been found to catalyze the H202 oxidation of aniline to a similar PAn/PSS product, opening up the prospect of enzyme reuse and the design of enzyme reactors for PAn synthesis.104 

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In the recent decades, an enzyme-catalyzed polymerization ( enzymatic polymerization ) has been of increasing importance as a new trend in macro-molecular science. Enzyme catalysis has provided new synthetic strategy for useful polymers, most of which are difficult to produce by conventional chemical... 

Because practically all aromatic organic pollutants that release phenols or anilines in the course of their degradation could bind HS through enzymatic catalysis, methods employing enzyme-catalyzed polymerization reactions minimizing their presence by partial removal in aquatic and terrestrial environments might be utilized in pollution control. This can have a remarkable effect in environmental engineering practice. 

Enzyme-catalyzed polymerization reactions have an important characteristic that is not found elsewhere. Once the enzyme has added a monomeric unit to the growing chain, it can either dissociate and recombine at random with other growing termini, or it can remain attached to the same chain and add further residues. Enzymes that dissociate between each addition and distribute themselves among all the termini are termed distributive. Those that process along the same chain without dissociating are termed processive. These terms apply also to degradative enzymes such as exonucleases. 

Enomoto, N., Furukawa, S., Ogasawara, Y., Akano, H., Kawamura, Y., Yashima, E., and Okamoto, Y. (1996) Preparation of silica gel-bonded amylose through enzyme-catalyzed polymerization and chiral recognition ability of its phenylcarbamate derivative in HPLC, Anal. Chem. 68, 2798-2804. 

Nicell JA, Bewtra JK, Biswas N, St. Pierre CC, Taylor KE. Enzyme catalyzed polymerization and precipitation of aromatic compounds from aqueous solution. Can J Civ Eng 1993 20 725-735. 

Nicell JA, Al-Kassim L, Bewtra JK et al (1993) Wastewater treatment by enzyme catalyzed polymerization and precipitation. Water Res 27 1629-1639... 

Henderson, L. A., Svirki, Y. Y, Gross, R. A., Kaplan, D. L., and Swift, G., Enzyme-catalyzed polymerizations of ep i/ow-caprolactone effects of initiator on product structure, propagation kinetics, and mechanism, Macromolecules, 29, 7759-7766, 1996. 

Polypyrroles (PPy s) are formed by the oxidation of pyrrole or substituted pyrrole monomers. In the vast majority of cases, these oxidations have been carried out by either (1) electropolymerization at a conductive substrate (electrode) through the application of an external potential or (2) chemical polymerization in solution by the use of a chemical oxidant. Photochemically initiated and enzyme-catalyzed polymerization routes have also been described but are less developed. These various approaches produce polypyrrole (PPy) materials with different forms—chemical oxidations generally produce powders, whereas electrochemical synthesis leads to films deposited on the working electrode, and enzymatic polymerization gives aqueous dispersions. The conducting polymer products also possess different chemical/electrical properties. These alternative routes to PPy s are therefore discussed separately in this chapter. 

Okumara et al. [10] were the first to attempt the enzyme-catalyzed synthesis of oligoesters from a reaction between dicarboxylic acids and diols. Gutman et al. [11] reported the first study on polyester synthesis by enzyme-catalyzed polymerization of A-B type monomers. Two independent groups in 1993 [12, 13] were first to report enzyme-catalyzed ring-opening polymerization (ROP). Their studies focused on 7- and 6-membered unsubstituted cyclic esters, e-caprolactone (e-CL) and 8-valerolactone (8-VL), respectively. 

This chapter provides numerous examples of significant advancements documented in the literature describing cell-free enzyme-catalyzed polymerizations, predominantly using lipases as catalysts. Polymerization reactions occurred by (i) condensations (ii) ring-opening homo- and copolymerizations and (iii) combination of condensation and ring-opening polymerization. 

Uyama, H., and Kobayashi, S. (2002) Enzyme-catalyzed polymerization to functional polymers. J. Mol. Catal. B Enzym., 19-20,117-127. 

Enzyme-catalyzed polymerizations of e-caprolactone effects of initiator on product structure, propagation kinetics, and mechanism. Macromolecules, 29 (24), 7759-7766. 

Matsumura, S., Tsushima, Y., Otozawa, N., Murakami, S., Toshima, K., and Swift, G. (1999) Enzyme-catalyzed polymerization of L-aspartate. 

It is now generally accepted that the so-called enzymatic polymerization or enzyme-catalyzed polymerization of vinyl monomers is best described as enzyme-initiated polymerization (Figure 6.1, initiation). Thus, the principal difference between so-called chemical polymerizations (radical formation by photochemical or thermal homolysis of the initiator precursors) and enzymatic... 

Racemization can be achieved with a variety of homogeneous catalysts. The Noyori type Ru-racemization catalyst 1 was first selected as a suitable candidate (Figure 11.3b). In fact, this was the first example in which DKR was combined with an enzyme-catalyzed polymerization reaction. It appeared, however, that polymerization with the Novozym 435/1 catalytic system was problematic only oligomers were obtained in two-step reactions because the catalysts were incompatible under the reaction conditions employed. 

Side note Lab-on-a-chip, Enzyme-catalyzed polymerization of nucleon is a key step in DNA identification. The microfluidic device shown in 1 ure SN7.1 is used to identify DNA strands. It was developed by Profe Mark Burns s group at the University of Michigan. 

Biocatalysis in supercritical fluids, fluorous solvents, and under solvent-free conditions was recently reviewed (80). In this book, de Geus et al (17), Villarroya (41) and Bruns et al (32) all provide important examples of how supercritical CO2 can be used for enzyme-catalyzed reactions. Furthermore, Srienc et al (38) used ionic liquid media for enzyme-catalyzed polymerizations of p-butyrolactone in order to prepare poly(hydroxyalkanoic acids), PHA. The role of ionic liquids was to both maintain enzyme activity and propagating chain solubility so that high molecular weight products could be obtained in monophasic media. 

However, to our knowledge, most previous studies of enzyme-catalyzed polymerizations have avoided temperatures > 90 oC, which is likely due to thermal deactivation of enzyme catalyst (13-15). It has been found that enzyme immobilization can improve the stability and recyclablity of native enzyme (16). Silica particles, activated by methanesulfonic acid, are effective and economic inorganic carriers for enzyme immobilization (17). Herein, we present a minireview of our works about immobilized porcine pancareas lipase on silica particles (IPPL) for polymer synthesis, such as polycarbonates, polyesters, polyphosphates and their copoljmiers. 

In this work lipase was found to be an effective catalyst for the polycondensation of a diester with a diamine to form a polyamide. The reaction is relatively mild and can be achieved at a high yield at relatively low temperatures. The resulting polyamide is amenable to derivatization reactions, thereby generating structures that can impart additional properties to the polymer. This enzyme-catalyzed polymerization reaction is applicable to a wide range of water-soluble polyamides, including several that cannot be previously prepared via chemical methods. 

Figure 2. Enzyme-catalyzed polymerization of dimethyl adipate and DETA to form the poly(aminoamide)...

Ghan R, Shutava T, Patel A, et al. (2004) Enzyme-catalyzed polymerization of phenols within polyelectrolyte microcapsules. Macromolecules 37 4519-4524... 

There are many unique polymerization processes which share a conunon heritage with emulsion polymerization, but which often are unrecognized as such. It is the purpose of this review to describe some of these emulsion polymerization-like processes and their products. Some further definition is in order unconventional emulsion polymerizations can be described as those processes whereby the product is a polymer latex that physically resembles latex from emulsion polymerization and cannot be grouped into any other recognized form of heterogeneous polymerization. In many cases the reasons why a process is not recognized as an emulsion polymerization is that the polymerization is not via a free-radical process. This review (hscusses four distinct types of polymerization processes, all of which have examples that produce latex particles and in many ways can be described as unconventional emulsion polymerizations. These are free-radical polymerization, ionic polymerization, transition metal catalyzed polymerization and enzyme-catalyzed polymerization. The precise systems discussed in this review are described in Table 23.1. 

PEAs have been synthesized by ring-opening polymerization and polycondensation methods. The first ones were mainly employed to get copolymers of a-hydroxy acids and a-amino acids (i.e., polydepsipeptides) and reported in the literature [4]. Recent works are focused to the use of enzymes (e.g., lipases) as new efficient catalysts for reaction of these morpholine-2,5-diones [5]. It has been demonstrated that the configuration of the a-amino acid moiety did not affect the enzyme-catalyzed polymerization, but in contrast, the configuration of the a-hydroxy acid moiety strongly in-flnenced the polymerization behavior. Unfortunately, ra-cemization of both units was demonstrated to take place dnring polymerization. 

Polypyrrole and many of its derivatives can be synthesized via simple chemical or electrochemical methods [120]. Photochemically initiated and enzyme-catalyzed polymerization routes have also been described but less developed. Different synthesis routes produce polypyrrole with different forms chemical oxidations generally produce powders, while electrochemical synthesis leads to films deposited on the working electrode and enzymatic polymerization gives aqueous dispersions [Liu. Y. C, 2002, Tadros. T. H, 2005 and Wallace. G. G, 2003]. As mentioned above the electrochemical polymerization method is utilized extensively for production of electro active/conductive films. The film properties can be easily controlled by simply varying the electrolysis conditions such as electrode potential, current density, solvent, and electrolyte. It also enables control of thickness of the polymers. Electrochemical synthesis of polymers is a complex process and various factors such as the nature and concentration of monomer/electrolyte, cell conditions, the solvent, electrode, applied potential and temperature, pH affects the yield and the quality of the film... 

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