Formation of a new class of layered, microcrystalline polymers from a simple hydrolytic polycondensation of n-alkyltrichlorosilanes in water is demonstrated. The structure of the polymeric condensate, determined from a combination of spectroscopic, diffraction, and thermal analysis techniques, consists of highly uniform, pillared microcrystallites in which the inorganic siloxy backbones are present in periodic layers, each containing a monomolecular layer of intercalated water, separated by crystalline assemblies of alkyl chains. The alkyl-chain organization shows a remarkable resemblance to that in highly organized, self-assembled monolayers formed from the precursor silane molecules on hydrophilic substrates and this parallel lends support to the critical importance of water in monolayer self-assembly of silanes.

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Water-dispersible and stable fluorescent CsPbBr 3 perovskite quantum dots (QDs)-loaded polymeric nanospheres were prepared by an emulsification process. Colloidal CsPbBr 3 QDs that were initially prepared in organic solvents were transferred to an aqueous solution by coating with non-ionic amphiphilic polymers, viz., poly(ethyleneoxide)-poly(propyleneoxide)-poly (ethyleneoxide) triblock-copolymer and polyethylene glycolylated hydrogenated castor oil. The polymer-encapsulated CsPbBr 3 QDs-loaded nanospheres have an average diameter of ∼ 55 nm and they disperse well in aqueous solutions without aggregation or flocculation. The fabricated CsPbBr 3 QDs-loaded nanospheres retain their luminescence properties in pure and salt-containing water, which indicates that the polymeric shell of the QDs-polymer nanospheres effectively blocks the diffusion of water and ions into the nanospheres. The results of this study might open many new possibilities for the fluorescent cesium lead halide QDs in a wide variety of applications; for example, they can serve as fluorescent bio-imaging probes.[a] S.

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Immersion of oxidized aluminum substrates in ethanol solutions of poly(acrylic acid) (PAA), followed by extensive solvent immersion, results in tenaciously chemisorbed, nanometer scale, controllable thickness films for a wide range of solution concentrations and molecular weights. Atomic force microscope images reveal isolated polymer globules from adsorption in low-concentration solutions with crossover to conformal, highly uniform, nanometer-thickness films at higher concentrations, an indication that the chemisorbing chains start to overlap and trap underlying segments to form planar chemisorbed films only two or three chains in thickness. Quantitative IR reflection spectroscopy in combination with chemical derivitization on a standard set of 1.0(±0.2) nm thick films reveals a film structure with 5.5(±1) chemisorbed -CO(-)(2) groups/nm(2) and 6.3 unattached -CO(2)H groups/nm(2), with up to ∼3.6/nm(2) available for chemical derivitization, a comparable number to typical self-assembled monolayer coverages of ∼4-5 molecules/nm(2). Thermal treatment of the ∼1 nm chemisorbed films, at even extreme temperatures of ∼150 °C, results in almost no anhydride formation via adjacent -CO(2)H condensation, in strong contrast to bulk PAA, a clear indication that the films have a frozen glass structure with effectively no segment and side group mobility. Overall, these results demonstrate that these limiting thickness nanometer films provide a model surface for understanding the behavior of strongly bound polymer chains at substrates and show potential as a path to creating highly stable, chemically functionalized inorganic substrates with highly variable surface properties.

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