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Summary: Amphiphilic‐hyperbranched polyglycidols and a linear analogue were tested for their ability to act as nanoreactors for the unimolecular elimination (E1) reactions of tert‐alkyl iodides. Their encapsulation properties were also compared. The linear polymer was found to have very good “unimolecular reverse micellar” characteristics as well, even though the results showed the advantages of a hyperbranched nature over a linear one. Our results stress the need for a direct comparison of branched and linear polymers for any application.Amphiphilic polyglycidol unimolecular reverse micelles.imageAmphiphilic polyglycidol unimolecular reverse micelles.

The highly electrophilic borane B(C 6 F 5 ) 3 reacts with n-octadecanol (n-C 18 H 37 OH) and n-octadecanethiol (n-C 18 H 37 SH) to form the 1:1 adducts (n-C 18 H 37 EH)B(C 6 F 5 ) 3 (E ϭ O or S). The latter are acidic and react with Cp*TiMe 3 in methylene chloride and toluene to give methane and the complexes [Cp*TiMe 2 ][(n-C 18 H 37 E)B(C 6 F 5 ) 3 ], which are very good initiators for the carbocationic polymerization of isobutene (IB) from Ϫ40 to Ϫ20°C. High conversions to high molecular weight polyisobutene (PIB) in methylene chloride and moderate conversions to high molecular weight PIB in toluene are observed and are consistent with the anions [(n-C 18 H 37 E)B(C 6 F 5 ) 3 ] Ϫ being very weakly coordinating. Although polymerization in methylene chloride is too rapid for the temperature to be controlled, polymerization in toluene is slower, and the temperatures can be controlled so that Arrhenius-type plots of the logarithm of the number-average molecular weight versus T Ϫ1 ϭ 1/T may be obtained. Activation energies for the degree of polymerization in these polymerization reactions and similar polymerizations carried out with n-C 18 H 37 EH:borane ratios of 1:2 and with the activators [Ph 3 C][B(C 6 F 5 ) 4 ] and Al(C 6 F 5 ) 3 range from Ϫ11 to Ϫ27 kJ mol Ϫ1 , values comparable to those for most conventional IB polymerization initiators. However, the values of the weight-average and number-average molecular weights are unusually high for the temperatures used, and this is consistent with current theories of the role of weakly coordinating anions.

Summary: Controlled polymerization of styrene in toluene was achieved by atom transfer radical polymerization (ATRP) using hyperbranched polyglycidol‐supported multidentate amine ligands/CuIBr catalyst systems. These catalyst systems with nanoscopic dimensions were more active than the corresponding low‐molecular‐weight ligands. The controlled/living nature of the polymerization is supported by linear first order plots (ln[M]o/[M] versus time) and a linear increase of $\overline M _{\rm n}$ versus conversion as well as low polydispersity. Similar controlled polymerization of methyl methacrylate was possible in acetonitrile. Up to 97% of total copper used for polymerization could be removed from the polymer by simple precipitation in methanol and filtration.Molecular weight characteristics for styrene polymerization using PG‐triamine as a ligand.magnified imageMolecular weight characteristics for styrene polymerization using PG‐triamine as a ligand.

Summary: The highly electrophilic borane B(C6F5)3 reacts with octadecanoic acid (n‐C17H35CO2H, stearic acid) to form 1:1 and 2:1 adducts [n‐C17H35CO2H][B(C6F5)3] and [n‐C17H35CO2H][B(C6F5)3]2. These adducts exhibit enhanced acidities, and react with Cp*TiMe3 in methylene chloride and toluene to give methane and the complexes [Cp*TiMe2][n‐C17H35CO2{B(C6F5)3}1,2]; the 2:1 complex in particular is a very good initiator for the carbocationic polymerization of isobutene (IB) and copolymerization of IB with isoprene at temperatures as high as −30 °C. High conversions to high molecular weight homo‐ and copolymers are obtained, consistent with the anion [n‐C17H35CO2{B(C6F5)3}2]− being very weakly coordinating.Novel class of Brønsted acidic initiators behave as very good initiators, e.g. in homopolymerisation of isobutene.magnified imageNovel class of Brønsted acidic initiators behave as very good initiators, e.g. in homopolymerisation of isobutene.