Poly , tactic synthesis

The disadvantages of all biochemical routes is the lack of variable tacticity in the polymer and, even more important, the need for time-consuming purification. PHB materials of feasible properties are only achieved with high production costs. In the 1990s, ICl sold a copolymer of 3-HB and 3-HV (BIOPOL) for about 10-20 /kg whereas the price of PP was less than 2 /kg. Therefore, a fermentative synthesis is feasible for smaller applications but not cannot compete with packaging materials such as poly(olefin)s [43 5] (Fig. 10). 

Kennedy and Thomas (1) first reported the synthesis of a crystalline poly(3-methyl- 1-butene) by cationic polymerization at —130°C. Preliminary HNMR studies indicated that the polymer was not simply a tactic modification of the conventional 1,2-polymer but, in fact, possessed a repeat structure which resulted... 

Step-growth polymerization, 22, 24-25, 23, 84-86, 86,90-92,114-115, 261 compared with chain-growth polymerization, 88-89, 88-89 interfacial polymerization, 91-92 laboratory activities on synthesis of nylon, 228-230 synthesis of polyesters in the melt, 231-233 synthesis of polyurethane foam, 234-237 molar mass and, 86, 86 polycondensation of poly ethylene terephthalate), 90-91 polymers produced by, 86 types of monomers for, 90 Stereochemistry, 28, 37-39,41-42, 70 tacticity, 103-105 Stereoisomers, 41 Stereoregularity, 70 Stiffness, 142, 261 Strain, 142-143, 261 Strength... 

Currently, the viability of this route to form poly(methacrylonitrile) has been illustrated. NMR spectroscopy is in progress to verify that the starting tacticity of the polymer chain has been maintained during this synthesis. As none of these reactions should involve a mechanism in which the pseudo-asymmetric centers along the polymer backbone are influenced, it is anticipated that this illustration will be possible. 

Apart from the partial tacticity of the polyFO prepared with Al(iPrO)3 mentioned in the preceding section, no other report of the synthesis of a stereoregular furan polymer has appeared to the best of our knowledge. Numerous attempts to prepare such structures from 2-alkenylfurans using a variety of catalytic comhinations failed [4d]. This aspect deserves more attention, because there are no obvious reasons that would exclude a priori the possibility of synthesizing stereoregular (and crystallizable) poly(alkenylfuran)s. 

SYNTHESIS OF TACTIC POLY(ALKYL METHACRYLATE) HOMO AND COPOLYMERS... 

Anionic and Cationic Polymerizations o Radical Polymerization Advances o Coordination Polymerizations 0 Step-Growth Polymerization Advances 0 Synthesis of Tactic Polymers o Stereoblock Copolymers o Dispersion Polymerizations o Cellulosic Graft Copolymers o Diels-Alder Polymer Forming Reactions o A New Path To Phenolic Resins o Nitrogen Heterocycle Polymerizations o Optically Active Polymers o Poly (Phenylene Sulfide) o Poly (Aryl Ethers) o (Poly (Aryl Ether Sulfones) o Epoxy and Isocyanate Resin Replacement o Azlactone Functionalized Oligomers o Epoxy Resin-Isocyanate Reactions o Chelating Polymers o Oxazoline Functionalized Polymers o Poly (Alkyl Methacrylates) o Macromers... 

Morioka K, Suito Y, Isobe Y, Habaue S, Okamoto Y (2003) Synthesis and chiral recognition ability of optically active poly N-[R-a-methoxycarbonylbenzyl]-methacrylamide with various tacticities by radical polymerization using Lewis acids. J Polym Sci A Polym Chem... 

Needless to say, vinyl polymerization is one of the most important methods for polymer synthesis. A variety of carbon-carbon (C-C) main chain polymers have been prepared by the vinyl polymerization of monomers with diverse substituents, via radical, cationic, anionic, or coordination mechanism. Furthermore, with the technological achievement such as living and stereoselective (or stereospecific) polymerizations, fine-tuning of the polymer structure with respect to molecular weight and tacticity has been realized in a number of examples. In particular, polymers obtained with vinyl polymerization (vinyl polymer) as represented by polyethylene, polypropylene, polystyrene, and poly(methyl methacrylate) have contributed to the progress of modern society in various aspects as useful synthetic materials. 

Mention may also be made of the controlled ozonolytic or oxidative degradations of high MW iso tactic poly(oxypropylene), poly(vinyl chloride), and poly(isobutene-co-2,3-dimethylbuta-diene) " to give oligomers with functional end groups. However, no effective synthesis has yet been devised for a, co-difunctional polymethylene oligomers which would be of considerable interest as precursors of block copolymers. 

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