Molecular weight polystyrene formed from monomer

The photo-cross-linkability of a polymer depends not only on its chemical structure, but also on its molecular weight and the ordering of the polymer segments. Vinyl polymers, such as PE, PP, polystyrene, polyacrylates, and PVC, predominantly cross-link, whereas vinylidene polymers (polyisobutylene, poly-2-methylstyrene, polymethacrylates, and poly vinylidene chloride) tend to degrade. Likewise, polymers formed from diene monomers and linear condensation products, such as polyesters and polyamides, cross-link easily, whereas cellulose and cellulose derivatives degrade easily. ... 

The particle size of rapidly polymerized minidroplets does not or does just weakly depend on the amount of the hydrophobe [34-36]. It was found that doubling the amount of hydrophobe does not decrease the radius by a factor of 2 (as expected from a zero effective pressure), it is just that the effective pressure (pressure difference) has to be the same in every droplet, a mechanism which in principle does not depend on the amount of hydrophobe [19]. However, a minimum molar ratio of the hydrophobe to the monomer of about 1 250 is required in order to build up a sufficient osmotic pressure in the droplets exceeding the influence of the first formed polymer chains. This also explains the fact that a small amount of high molecular weight polymer, e.g., polystyrene, can barely act as an osmotic stabilizing agent here stabilization can only be achieved for the time of polymerization [37,38]. 

The influence of the molecular weight of homopolystyrene POO on the formation of polystyrene occlusions is vividly seen in fig,7, where photographs of miorostructures of HIPS specimens are represented The specimens of HIPS are obtained by the polymerization of model emulsions, prepetred by mixing solutions of rubber - 8% and polystjprene - 30% in ratio 1 1, MW PS varied at 0,7-r-3 10, As seen in fig,7 the rubber particles, formed from multiphase model emulsion as a result of redistribution of monomer, differ greatly from each other, M of polystyrene... 

Preparation of telechelic polymers by ATRCC was also demonstrated. The concept is based on the activation of the dormant species at the chain ends of polystyrene (PS-Br) prepared by ATRP and also functional ATRP initiator (F-R-Br) in the absence of a monomer. Depending on the number of functionality of the polymer used in the system, ATRCC yields co-polystyrene and a,co-polystyrene telechelics. However, at least in principle, not only the desired functional polymers but also various side products may be formed due to the self coupling reactions of macroradicals generated from PS-Br, and low-molecular weight radicals from F-R-Br. The possible reactions of the model system are depicted in Scheme 3. 

By cooling the solutions to —80°C almost quantitative conversions to high molecular weight polymers take place [190], Similar conditions yield polystyrene [191]. 4-vinyl pyridine polymerizes in liquid ammonia in the same manner [191]. Initiation results from reduction of the monomer by direct electron transfer at the cathode to form a red-orange vinyl pyridyl radical-anion ... 

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