Structural Characterization of Self-Organized Mono- and Multilayers of Partly Fluorinated Polydialkoxyphosphazenes at the Air/Water Interface

We report studies of the collapse of monolayers of mesomorphic poly[bis-(2,2,3,3,4,4,5,5-octafluo-ropentoxy)phosphazene] and poly[bis-(2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptoxy)phosphazene]. The structure of the films has been examined at different stages of the collapse process by synchrotron grazing incidence X-ray diffraction. Surface pressure–surface area isotherms show that these films undergo a stepwise collapse with formation of multilayers. Grazing incidence X-ray diffraction reveals only one diffraction peak for the monolayer as well as for multilayers of the two polymers studied, which corresponds to an in-plane interchain spacing d = 15.2±0.1°Å and 17.6±0.5°Å, respectively. The in-plane correlation length ξxy reaches ca. 500 Å for PFP-C5 (33 macromolecules) and ca. 400 Å for PFP-C7 (23 macromolecules), implying a certain mesoscale order similar to a quasi-long-range one

First example of cationic titanium (III) complexes with crown ether as catalysts for ethylene polymerization

Complex cations with a vacant coordination site are considered as the most plausible catalytically active centers of metallocene and post-metallocene polymerization catalysts. For the first time we demonstrated that cationic titanium (III) complexes stabilized with crown ether can be used as pre-catalysts for ethylene polymerization. In the presence of alkyl aluminum chlorides and MgBu2 as cocatalysts, these complexes catalyze ethylene polymerization to produce Ultra High Molecular Weight Polyethylene (UHMWPE) with productivity up to 4650 kgPE/mol Ti h⋅atm and molecular weight up to 1.8·106 Da. UHMWPE powders were processed by the solid-phase method with subsequent orientation drawing into high-strength (1.4–2.1 GPa) and high-modulus (91–118 GPa) films. © 2022 Elsevier Lt