Homopoly , preparation

N. Burford, j. Passmore and J. C. P. Sanders, Chap. 2, Preparation, Structure and Energetics of the Homopoly-atomic Cations of Groups 16 and 17, in J. F. Liebman and A. Greenburg (eds.). From Atoms to Polymers Isoelec-tronic Analogies, VCH PubL, Honda, 1989, pp. 53-108. J. Passmore, Chap. 19 Homopolyatomic Selenium Cations... 

LiC104 complexes of several PEO-grafted polysiloxanes in which the backbone is derived from both homopoly(methyl hydrogen siloxane) and poly(methyl hydrogen siloxane-co-dimethyl siloxane) have been prepared [10]. The PEO used had low molecular weights of 300 to 550. The electrolytes had TgS of —54 to — 77°C, and room temperature conductivities up to 10 S cm have been measured Table 3.2 gives an example of one such complex. In these electrolytes, the PEO side chains promote solubility and dissociation of Li salts while the flexible siloxy main chain provides mobility to charge carrier ions. 

As described above, an ESR study of the reaction of the poly(NMAAm) radical with a MMA/St (MS) or CHMA/St (CS) mixture led to the conclusion that St is incorporated into the poly(NMAAm) microspheres in preference to the methacrylate monomers, to react with the polymer radical. To confirm this conclusion, block copolymers were prepared by the reaction of poly(NMAAm) radicals with MS or CS mixtures, and the relative contents of methacrylate and St in the resulting polymers were determined. The poly(NMAAm) radical was allowed to react with monomer mixtures of different relative concentration for 15 h at 40 °C. The resulting polymer was fractionated into three parts (i.e., AcOEt-soluble, MeOH-soluble and insoluble parts). The AcOEt-soluble part consisted of random copolymer of methacrylate and St, while the MeOH-soluble part consisted of homopoly(NMAAm) and block copolymer. The solvent-insoluble part was block copolymer. The results obtained are summarized in Table 7. 

The addition reaction of 2 mol of sec-butyllithium with 1,3-bis(l-phenylethenyl)benzene (eqn [7]) proceeds rapidly and efBdently to produce the corresponding dUithium species that is soluble in toluene or in cydohexane. Although this dUithium initiator is useful for the preparation of homopoly-mers and triblock copolymers with relatively narrow molecular weight distributions, it is necessary to add a smaU amormt of Lewis base or two or more equivalents of lithium alkoxide (e.g., lithium sec-butoxide) to produce narrow, monomodal molecular weight distributions. 

NMR studies confirm that head-to-tail arrangements predominate in the copolymers. It may be noted that under the conditions normally used to prepare commercial copolymers, hexafluoropropylene does not homopoly-merize and so the molar proportion of this monomer in a copolymer cannot exceed 50% whatever the composition of the monomer feed. 

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