Synthesis Of Hyperbranched Polymers From Anionic Macroinimers

Hyperbranched polymers have received much industrial attention due to their unique structure and properties, which are distinct to the linear analogues. Controlled living polymerizations have the advantages in macromolecular design and have been widely used to synthesize hyperbranched polymers. In present work, we combine living anionic polymerization and self-condensing vinyl polymerization to synthesize hyperbranched homopolymers and hyperbranched copolymers composed of polystyrene and polyisoprene segments. The solution properties in a cosolvent and a selective solvent are also studied. The main results in this thesis are listed as follows:1) Synthesis of hyperbranched polystyrene from anionic PS macroinimer (a macromonomer with an initiating site). The macroinimer is prepared through monoaddtion of equal molar amount of PSLi and MDDPE in a mixture of cyclohexane and THF (cyclohexane/THF=1/3, v/v) at-78℃. The structure of the macroinimer is proven by GPC,1H NMR and MALDI-TOF MS. After preparation of the macroinimer, the solvent is switched from a mixture of cyclohexane and THF to cyclohexane, and the copolymerization is conducted in cyclohexane. The resulting products are characterized by GPC equipped with MALLS, Viscometer and RI detectors. Smaller intrinsic viscosity is measured for the product, demonstrating the successful synthesis of the hyperbranched polystyrene.2) Hyperbranched polymers composed of PS and PI segments are synthesized using a similar method by changing PS macroinimer to PI macroinimer. After preparation of hyperbranched copolymers, the double bond of PI segment is modified into epoxy group, followed by grafting either PSLi or PILi to form hyperbranched graft polymers. The triple-detection GPC characterization results indicate that the graft polymers possess a more compact structure than that of the hyperbranched precursors.3) The solution properties of hyperbranched polymers composed of PS and PI segments in THF and n-heptane are further studied. The hyperbranched copolymers can self-assemble to vesicles around1μm in n-heptane.