Search Results (2)

Fabricating future materials by self-assembly of nano-building blocks programmed to generate specific lattices is among the most challenging goals of nanotechnology and has led to the recent concept of patchy particles. We report here a simple strategy to fabricate polystyrene nanoparticles with several silica patches based on the solvent-induced self-assembly of silica/polystyrene monopods. The latter are obtained with morphological yields as high as 99% by seed-growth emulsion polymerization of styrene in the presence of 100 nm silica seeds previously modified with an optimal surface density of methacryloxymethyl groups. In addition, we fabricate “magnetic” silica seeds by silica encapsulation of preformed maghemite supraparticles. The polystyrene pod, i.e., surface nodule, serves as a sticky point when the monopods are incubated in a bad/good solvent mixture for polystyrene, e.g., ethanol/tetrahydrofuran mixtures. After self-assembly, mixtures of particles with two, three, four silica or magnetic silica patches are mainly obtained. The influence of experimental parameters such as the ethanol/tetrahydrofuran volume ratio, monopod concentration and incubation time is studied. Further developments would consist of obtaining pure batches by centrifugal sorting and optimizing the relative position of the patches in conventional repulsion figures. Full article

Self-migration or unstable phase inversion occurs when the application conditions are varied, which limits the application of polyurethane-acrylate (PUA) composite films. In this paper, cross-linked polyurethane/poly(methyl methacrylate-co-borneol acrylate) shell microspheres were prepared by using the seeded emulsion polymerization method. The core-shell structure of these samples was identified by dynamic light scattering (DLS) and high-resolution transmission electron microscope (HR-TEM). Moreover, HR-TEM images indicated that the core-shell structure of the microsphere does not undergo complete phase inversion. In addition, with increasing content of borneol acrylate in the shell, the water resistance and antibacterial adhesion of films were improved. The X-ray photoelectron spectroscopy (XPS), Energy Dispersive Spectrometer (EDS), water contact angle (CA) measurements, antibacterial and anti-adhesion tests demonstrate that the C/N ratios of films from the inside to the upper surface had an obvious gradient in growth, indicating the shell component (polyborneol acrylate) was predominantly present at the surface of films after coalescence in cross-linked core-shell PUA. It was found that a suitable degree of cross-linking contributes to the segregation of the hydrophobic component (borneol groups) on the film surface. As a consequence, the excellent water resistance, cytocompatibility, and antibacterial properties endowed this series of polymer materials with promising application potential in the biomedical field. Full article