Styrene-ethylene oxide block polymers molecular weight

TLC has been used in the study of many homopolymers polystyrene, poly(methyl methacrylate), poly(ethylene oxide), polyisoprene, poly(vinyl acetate), poly(vinyl chloride) and polybutadiene. Their molecular weight, molecular-weight distributions, microstructure (stereo-regularity, isomerism and the content of polar end groups), isotope composition and branching have been studied. For copolymer characterisation (e.g. purity and compositional inhomogeneity), random copolymers such as styrene-methacrylate, and block copolymers such as styrene-butadiene, styrene-methyl methacrylate and styrene-ethylene oxide have been separated. A good review article on polymers... 

The ability of living polymers to resume growth with the addition of fresh monomer provides an excellent opportunity for the preparation of block copolymers. For example, if a living polymer with one active end from monomer A can initiate the polymerization of monomer B, then an A-AB-B type copolymer can be obtained (e.g., styrene-isoprene copolymer). If, however, both ends of polymer A are active, a copolymer of the type B-BA-AB-B results. Examples are the thermoplastic rubbers polysty-rene-polyisoprene-polystyrene and poly(ethylene oxide)-polystyrene-poly(ethylene oxide). In principle, for fixed amounts of two monomers that are capable of mutual formation of living polymers, a series of polymers with constant composition and molecular weight but of desired structural pattern can be produced by varying the fraction and order of addition of each monomer. 

The anionic polymerization of 9-vinylanthracene gives only low molecular weight products [342], which agrees with Rembaum s and Eisenberg s results [355]. Stolka et al. [342] found no proof of the proposed [337,355] across-the-ring addition instead, the IR and UV spectra of their polymers indicated the conventional 1,2-addition pattern. 2-Propenyl-l-anthracene could not be polymerized anionically [342], Attempts to initiate polymerizations by means of electron-transfer-type initiators (e.g., sodium naphthalene and sodium biphenyl) were unsuccessful [341,342,353,354], The polymerization of 1-vinylpyrene initiated by electron-transfer initiators showed the characteristics of a living polymer system [356,357], Block copolymers of the AB and ABA type were synthesized with ethylene oxide, styrene and isopropene [357],... 

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