Polymers, Natural Organic molecular weights

Polymer A high-molecular-weight organic compound, natural or synthetic, whose structure can be represented by a repeated small unit, the mer e.g., polyethylene, rubber, cellulose. Synthetic polymers are formed by addition or condensation polymerisation of monomers. If two or more monomers are involved, a copolymer is obtained. Some polymers are elastomers, some plastics. 

Olefin metathesis is one of the few fundamentally new organic reactions discovered over the last few decades that has revolutionized organic and polymer chemistry. Olefin metathesis provides a convenient and rehable way to synthesize imsaturated molecules that are often hard to prepare by any other method. A munber of reviews [8-17] and books [18-20] have been published in this area, aU of which focus on the ever-increasing use of olefin metathesis in organic synthesis and polymer chemistry. Particularly in the latter research area, ROMP has become a powerful and popular method to synthesize polymers with narrow molecular weight distributions. Due to the hving nature of polymerizations initiated by state-of-the-art initiators, well-defined diblock, triblock or multiblock copolymers are available today. 

In a classical heterogeneous dispersion polymerization, the continuous phase is organic in nature, althou in some instances water has been used as a component of the continuous phase to increase polarity. Research investigations have focused on the composition of the dispersion m um, reaction kinetics, the structure and influence of the stabilizer polymer, particle size, molecular weight and molecular weight distribution (4, S). Dispersions of poly(methyl methacrylate) (8) and poly(styrene) (9) are widely studied and among Ae best characterized systems. Recently, dispersion polymerizations conducted in supercritical carbon dioxide have also been reported (9-12). 

The term plastic comes from the Greek word to form. It identifies many different plastic materials. Polymers, the basic ingredients used in practically all plastics, can be defined as high molecular weight organic compounds, synthetic or natural substance... 

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