Ultrathin films of variable polarity and crystallinity obtained from 1,2-polybutadiene nanoparticle dispersions.

Characterization of ultrathin films of different polymer nanoparticles obtained at room temperature via spin-coating of aqueous dispersions and their morphology are described. Very small nanoparticles of semicrystalline 1,2-polybutadiene (PB), noncrystalline poly(1-butene) (PH), and poly(1-butenal) (PHF) were prepared via catalytic emulsion polymerization and subsequent hydrogenation or hydroformylation. The prefabricated nanoparticles were used as building blocks.

Conveniently accessible polymer nanoparticles of adjustable polarity.

The postpolymerization modification by hydroformylation of 1,2-polybutadiene nanoparticles provides access to colloidally stable aqueous dispersions of <20 nm particles. Their polarity can be adjusted via the degree of conversion of double bonds over a broad range. Fluorescence studies illustrate the polarity of the environment experienced by pyrene as a probe molecule.

Water-soluble salicylaldiminato Ni(II)-methyl complexes: enhanced dissociative activation for ethylene polymerization with unprecedented nanoparticle formation.

Water-soluble single-component (kappa2-N,O)-salicylaldiminato nickel-methyl complexes 1-4-L (L = TPPTS, TPPDS, H2N-PEG-OMe) allow for the catalytic polymerization of ethylene under organic solvent-free aqueous conditions producing high molecular weight polyethylene with particle sizes below 10 nm. Amphiphilic TPPDS- and H2N-PEG-OMe complexes exhibit a polymerization activity in water higher than that in toluene. A solvation-favored activation of precatalysts 1-4-L by equilibrium dissociation of L in aqueous solution likely accounts for this enhanced polymerization activity.