PRECISION POLYMER

By means of genetic engineering, including cloning and site-directed mutagenesis, it has become possible for modern synthetic chemists to utilize a sufficient amount of isolated enzyme catalysts and to modify the reactivity, stability, or even specificity of enzymes. Therefore, polymerizations catalyzed by isolated enzyme are expected to create a new area of precision polymer syntheses. Furthermore, enzymatic polymerizations have great potential as an environmentally friendly synthetic process of polymeric materials. 

Vinyl ester resins arc manufactured through an addition reaction of an epoxy resin with an acrylic monomer, such as acrylic acid, methaciylic add. or the half-ester product of an hydroxyalkyl acrylate and anhydride. In contrast, the polyester resins are condensation products of dibasic acids and palyhydric alcohols. The relatively low-molecular-weight precise polymer structure of the vinyl ester resins is in contrast to the high-molecular-weight random structure of the polyesters. 

Figure 1 Structural factors to be controlled in precision polymer synthesis.

Figure 2 Precision polymer synthesis polymer structures.

All naturally occurring polymers are produced in vivo by enzymatic catalysis. Recently, in vitro synthesis of polymers through enzymatic catalysis ( enzymatic polymerization ) has been extensively developed.2 Enzyme catalysis has provided a new synthetic strategy for useful polymers, most of which are otherwise very difficult to produce by conventional chemical catalysts. In vitro enzymatic syntheses of polymers via nonbiosynthetic pathways, therefore, are recognized as a new area of precision polymer syntheses. 

Mitsuo Sawamoto, born in Kyoto, Japan (1951), received his B.S. (1974), M.S. (1976), and Ph.D. (1979) degrees in polymer chemistry from Kyoto University under the direction of Toshinobu Higashimura. After postdoctoral research with Joseph P. Kennedy at the Institute of Polymer Science, The University of Akron, Akron, OH (1980-81), he joined the faculty of the Department of Polymer Chemistry, Kyoto University, in 1981 as a research instructor. He was promoted to Lecturer (1991), to Associate Professor (1993), and to Professor (1994), his current position, of the same department. Sawamoto also serves as one of the three Editors of the Journal of Polymer Science, Part A Polymer Chemistry (1995-present) and as an Editorial Advisory Board member of Macromolecular Chemistry and Physics, the Journal of Macromolecular Science, Chemistry, and e-Polymers, and is the recipient of the 1991 Award of the Society of Polymer Science, Japan, the 1998 Divisional Award of the Chemical Society of Japan, the 2001 Aggarval Lectureship in Polymer Science, Cornell University, and the 2001 Arthur K. Doolittle Award of the ACS PMSE Division. With more than 250 articles and reviews, his research interest covers living radical and cationic polymerizations, precision polymer synthesis, and the chemistry of radical and carbocationic reaction intermediates. 

The review roughly consists of two parts, the scope and design of initiating systems followed by precision polymer synthesis. The former will treat the scope of metal catalysts, initiators, and monomers along with polymerization mechanisms. The latter will focus on the precision synthesis of various polymers with controlled structures and interesting properties or functions, such as block, end-functionalized, star, and other architecturally well-defined polymers. Other reviews are also available, comprehensive,31,40-44 and relatively short,45-52 dealing with the recent developments of the field. 

However, less conjugated monomers such as vinyl acetate, vinyl chloride, and ethylene are still difficult to polymerize in a controlled way by metal-catalyzed polymerizations. This is most probably due to the difficulty in activation of their less reactive carbon-halogen bonds. The following sections will discuss these aspects from the viewpoint of the monomers listed in Figure 11. Functional monomers will be discussed later in another section, Precision Polymer Synthesis. 

This section is thus directed to precision polymer synthesis with the use of metal-catalyzed living radical polymerizations. In this synthetic aspect, numerous reviews are available already. 219,265,299-310... 

Owing to the superb precision of viscosity measurements, the intrinsic viscosity can easily be measured to three significant figures, which makes it by far the most precise polymer characterization method. However, care must be taken to control the temperature precisely, and polymers with large molar mass M> lO gmol ) can shear thin in conventional capil-lary viscometers, ... 

Ouchi, M., Terashima, T., Sawamoto, M., 2009. Transition metal-catalyzed living radical polymerization toward perfection in catalysis and precision polymer synthesis. Chem. Rev. 109 (11), 4963-5050. 

Over the past few decades, CRP driven by cobalt complexes has emerged as an interesting tool for the design of precision polymers. Not only well-defined macromolecules with high and predictable molar masses, but also completely new copolymers, have been prepared using CMRP. Although this method imparts... 

During the past few decades, enzyme-catalyzed polymerization ( enzymatic polymerization ) has become increasingly important as a new trend in the macro-molecular sciences [3-10]. Indeed, enzyme catalysis has provided a new strategy for the synthesis of useful polymers, most of which are difficult to produce by using conventional chemical catalysis. Consequently, the in vitro enzymatic synthesis of polymers via nonbiosynthetic (nonmetabolic) pathways has become a vital part of the new era of precision polymer synthesis. 

Dr. Alain Deffieux, bom in Liboume, France, did his PhD in polymer science in the group of Pierre Sigwalt at the Univereity Pierre and Marie Curie, Paris VI, and then spent 2 years as associate researcher in the laboratory of professor Vivian Stannett at North Carolina University. He joined the Centre National de la Recherche Sdentifique (CNRS) in 1974 at Paris VI University and then moved to Bordeaux University in 1986 in the newly created Laboratoire de Chimie des Polymd s Organiques where he became a Research Professor. His research activities are focused on precision polymer synthesis, from studying the mechanisms of elementary reaction processes and reactivity control to the design and characterization of polymers with complex chain architecture. 

The PPDs thus create a perfect nanoenvironment with increasingly complex function. Admittedly, they define enormous tasks for precision polymer synthesis, but if really sophisticated function is targeted it is worthwhile to take on this challenge in view of the wealth of otherwise inaccessible chemical, physical, and biological properties [10, 46]. Further, there is much to learn when comparing multifunctional dendrimers based upon covalent build-up, with assemblies depending upon weak intermolecular forces. This is indeed another benefit of the structural perfection of the PPDs, that they also allow the fabrication of increasingly complex supramolecular structures. 

Precision Polymer Engineering Ltd, Clarendon Road, Blackburn BBl 9SS, UK tel +44-1254-679916 fax +44-1254-680182... 

Summit - Precision Polymers Coiporation One Parker Plaza Fort Lee... 

L. Hartmann, H.G. Borner, Precision polymers Monodisperse, monomer-sequence-defined segments to target future demands of polymers in medicine, Adv. Mater., 21, 3425-3431,2009. 

Living Radical Polymerization Toward Perfection in Catalysis and Precision Polymer Synthesis. 109 4963-5050. 

For reliable distributional analyses, calibrations must be provided so that all compositional components are (a) counted at the correct molecular weight and (b) counted equally on a molar basis. In GPC, these difficulties can be reduced by eluting precise polymer concentrations of known molecular weight. The former point is more serious since the basis of separation can be influenced by composition, as indicated previously. With care GPC analyses may be made without added degradation for molecular weights over one million see [79-81] in Section II.D.2. 

Liu, L.T CM. Process studies in precision injection molding. I process parameters and precision. Polym Eng Sci Jan 1996 36 1-9. 

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