Polymeric materials, controlled synthesis

The modification of polymer end-group chemistry has been utilized as a method of controlling the surface activity of polymeric materials. The synthesis of polymers with low surface energy end-groups can generate sufficient thermodynamic driving forces to dictate that polymer surface chemistry is dominated by end-groups. 

Controlled/living radical polymerisation (CRP) is currently a fast developing area in polymer synthesis and it allows preparation of many advanced polymeric materials, including thermoplastic elastomers, surfactants, gels, coatings, biomaterials, materials for electronics and many others. 

The architecture of macromolecules is another important synthetic variable. New materials with controlled branching sequences or stereoregularity provide tremendous opportunity for development. New polymerization catalysts and initiators for controlled free-radical polymerization are driving many new materials design, synthesis, and production capabilities. Combined with state-of-the-art characterization by probe microscopy, radiation scattering, and spectroscopy, the field of polymer science is poised for explosive development of novel and important materials. New classes of nonlinear structured polymeric materials have been invented, such as dendrimers. These structures have regularly spaced branch points beginning from a central point—like branches from a tree trunk. New struc-... 

Chojnowski, J. Cypryk, M. Fortuniak, W. Kazmierski, K. Rozga-Wijas, K. Scibiorek, M. Controlled Synthesis of All Siloxane Architectures by Ring-Opening Polymerization. In Synthesis and Properties of Silicones and Silicone-Modified Materials Clarson, S. J., Fitzgerald, J. J., Owen, M. J., Smith, S. D., Van Dyke, M. E., Eds. AGS Symposium Series 838 American Chemical Society Washington, DC, 2003 pp 12-25. 

L. Dai, A. W. H. Mau, Controlled synthesis and modification of carbon nanotubes and C60 Carbon nanostructures for advanced polymeric composite materials, Advanced Materials, vol. 13, pp. 899-913, 2001. 

Takeuchi D, Watanabe Y, Aida T, Inoue S (1995) Maclomolecules 28 651 Recent reviews (a) Aida T (1994) Prog Polym Sci 19 469 (b) Inoue S, Aida T (1998) Controlled polymer synthesis with metalloporphyrins. In Vogl O, Hatada K (eds) Molecular design of polymeric materials. Dekker, New York, in press (a) Kuroki M, Watanabe T, Aida T, Inoue S (1991) J Am Chem Soc 113 5903 (b) Sugimoto H, Kuroki M, Watanabe T, Kawamura C,Aida T, Inoue S (1993) Macromolecules 26 3403 (c) Sugimoto H,AidaT, Inoue S (1994) Macromolecules 27 3672 (d) Sugimoto H, Kawamura C, Kuroki M, Aida T, Inoue S (1994) Macromolecules 27 2013 (e) Akatsuka M, Aida T, Inoue S (1994) Macromolecules 27 2820 Inoue, S, Aida T (1994) Chem tech 24 28... 

Synthesis of well defined functionalized (- telechellc or multifunctional-) macromolecules Is an Important task for polymer chemists. The polymers with P0(0R)2, - Si(0R)3, -OH, - . .. functional groupslrS. are produced In limited quantities. The need for polymeric materials possessing specific properties has led to a renewed Interest Is functional polymers, especially if the initial material Is a common hydrocarbon polymer. One of the techniques that we use in our laboratory to prepare these new molecules Is based on anionic processes. This anionic technique is best suited to control the length of the chains prepared and to obtain samples with low polydlsperslty. Although the functionalization of carbanionic sites with various deactivating reagents Is easier than with other methods because of the long lived species, It Is still necessary to carefully control the deactivation reaction to prevent secondary reactions. 

During the past fifteen years, there has been an increasing interest in the NLO properties of organic and polymeric materials (7, 8). This has led to an increased effort aimed at the synthesis of molecular based materials with improved properties for NLO applications ). An important feature of the development of organic NLO materials is the attempt to control the primary NLO properties (the NLO susceptibilities or coefficients) and the secondary properties (solubility, processability, optical clarity, absorption, thermal stability, etc.) through molecular... 

Ceramic-type materials that contain no organic linkage units can be prepared by the pyrolysis of cyclic or high polymeric aminophosphazenes. An example is shown in reaction (44). Under appropriate conditions, pyrolysis products that correspond to phosphorus-nitride are formed. Polyphosphazenes that contain both amino and borazine side groups yield phosphorus-nitrogen-boron ceramics following pyrolysis 94,95 The conversion of a formable polymer into a ceramic has many potential advantages for the controlled synthesis and fabrication of advanced ceramics. This principle is discussed in more detail in Chapter 9. 

On the other hand, it should be realized that radical copolymerization at heterogeneous conditions offers additional unique opportunities not available in homogeneous (solution) copolymerization. These include the intrinsic possibilities of exploiting the heterogeneities of the reaction system to control the chemical microstructure of the synthesized copolymers, making possible new paradigms for synthesis and production of polymeric materials. In this contribution, we discuss some new synthetic strategies, which have been developed in recent years to provide effective control of the chemical sequences. 

Many recent advances in polymer synthesis have involved the development of new controlled polymerization systems proceeding via a variety of mechanisms. A number of architectures maybe produced as a result of the great versatility of the ROP of cyclic esters. Different strategies have been applied for the design of new polymeric materials. 

The most efficient way of preparing polylactides is ROP by coordination initiators [132]. This method usually allows a controlled synthesis leading to quite a narrow MWD. Polymerization of the different stereoforms results in materials with different properties. The polymers derived from the pure L-FA or D-FA... 

Synthesis, properties, and applications of polymer-protected AuNPs have been reviewed by Shan and Tenhu and will not be covered in detail here.139 The basic motivation here is to better control the particle size and dispersity and to obtain robust materials avoiding metal loss during or after utilization of the polymeric material. 

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