We have synthesized polyethoxysiloxanes starting from the AB3‐type monomers triethoxysilanol and acetoxytriethoxysilane. The polymers are liquid and soluble in organic solvents. 29Si NMR spectroscopy and MALDI‐ToF mass spectrometry analyses show that the polymers have a hyperbranched structure with additional internal cyclization. 29Si NMR spectroscopy indicates that the polymer synthesized from acetoxytriethoxysilane is less branched than the polymer synthesized from triethoxysilanol. Analysis of the molar mass and mass distribution of the polymers via size exclusion chromatography (calibrated via MALDI‐ToF MS and viscosimetry) yields a molar mass of Mn ≈ 2 kg · mol−1 and Mw ≈ 8 kg · mol−1 for polymers synthesized from triethoxysilanol. The molar mass of the polymers synthesized from acetoxytriethoxysilane can be controlled by variation of the polymerization time in the range of Mn ≈ 1.8–12 kg · mol−1 and Mw ≈ 2.1–2 200 kg · mol−1.
Photograph of a vial containing polyethoxysiloxane obtained from triethoxysilanol and a schematic drawing of the proposed molecular structure of the polymer.magnified imagePhotograph of a vial containing polyethoxysiloxane obtained from triethoxysilanol and a schematic drawing of the proposed molecular structure of the polymer.
Nanogels can be called the new old§ objects of polymer chemistry. New because we have formulated the criteria for the assignment of objects to this group within the macromolecule-particle concept and developed the methods for their directed and controlled synthesis. Old because the application of these criteria to the earlier known systems allow us to surely classify them as nanogels. It is shown that this classification per se provides insight into the organization of their molecular structures and enables directed modification. This means a transition from the empirical control of the properties to molecular design. The current review presents a brief historical overview of densely cross-linked nanogels and their main synthetic routes and highlights the principles and approaches to the control of their structures and molecular-mass characteristics, application scope, and prospects for further development.
The effects of the chemical nature and size of the hybrid nanoparticle external layer on the structures and properties of polylactide composites are investigated. Polylactide is used as the matrix polymer, and molecular silicasol particles with chydroxypropylic, (methoxyacetyl)oxy, and acetoxy surface groups serve as fillers. A preliminary assessment of the thermodynamic compatibility of polylactide with the surface groups of molecular silicasols is performed. The hydrophilic shells of the silicasols prevent their aggregation in the bulk of the nanocomposite. It shows variations in the chemical structure of the surface layer of the nanoparticles as well as their sizes and concentration make it possible to conduct a controlled change of the characteristics of the composites, particularly to eliminate one of the drawbacks of PLA, the low speed of its crystallization. V C 2015 Wiley Periodicals, Inc. J.Appl. Polym. Sci. 2015, 132, 41894.
New hybrid ''rigid inorganic core-soft organic shell'' systems based on molecular silicasols were synthesized by applying different synthetic schemes. Inorganic core was composed of molecular silicasols, which were synthesized from hyperbranched polyethoxysiloxane and tetraethoxysilane by polymer chemistry methods. Different organic modifiers were used to form soft shell of the hybrid particles. Obtained compounds were characterized by elemental analysis, GPC, IR and NMR spectroscopy. These systems will be designated for use as model objects for investigation of nanoparticles-polymer matrix interactions in polymer nanocomposites.
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