Here we describe a new class of near superhydrophobic surfaces formed using fluorinated polyhedral oligosilsesquioxane (FluoroPOSS) urethane hybrids and porous silicon gradients (pSi). We demonstrate that the surface segregation behavior of the hydrophobic fluoro component can be controlled by the type and nature of chain extender of the urethane and resultant hydrophobic association via intra or intermolecular aggregation. The surface film formed exhibits near superhydrophobicity. This work has significant potential for applications in antifouling and self-cleaning coatings, biomedical devices, microfluidic systems and tribological surfaces.
The nanoparticles of noble metal have attracted enormous interest due to their high catalytic, optical,
magnetic and antimicrobial properties. Controlled growth and stabilization of these nanoparticles are
essential for their diverse applications. In this work, platinum, and silver nanoparticles are grown onto
ordered non-fluoro ionomers and dendrimer for catalytic and antimicrobial applications. This paper thus
provides insight on the utilization of dendrimer compartment or ionic domains of non-fluoro ionomers for
stabilizing these nanoparticles. UV/vis and TEM results confirm the size and the size distribution of the
formed particles. In both cases, ionic domains or the dendrimers result in the stabilization of the colloids.
TEM images indicate that platinum nanoparticles grown on ordered non-fluoro ionomers results in highly
dispersed particles of small size 2-3 nm, while in dendrimer 8-10 nm silver colloids are formed. All of the
synthesized dendrimer based silver complexes are proved to be effective antimicrobial agents in vitro and
the platinum nanoparticles exhibit specific electrochemical activities.
Inorganic/organic hybrid or composite materials have in the past shown novel and interesting properties, which are not observed for the individual components. In this context, the preparation of inorganic/polymeric composites from biodegradable and biocompatible constituents is a new concept, which may be of interest particularly for tissue engineering and drug delivery applications. We describe here the synthesis of nanostructured porous silicon (pSi) and poly(<i>L</i>-lactide) (PLLA) composites. The composites were produced using tin(II) 2-ethylhexanoate catalysed surface initiated ring opening polymerisation of <i>L</i>-lactide onto silanised porous silicon films and microparticles. The subsequent chemical, physiochemical and morphological characterisation was performed using Diffuse Reflectance Infrared Spectroscopy (DRIFTS), X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM), Differential Scanning Calorimetery (DSC), Thermogravimetric Analysis (TGA) and Contact Angle measurements. DRIFT spectra of the composites showed the presence of bands corresponding to ester carbonyl stretching vibrations as well as hydrocarbon stretching vibrations. XPS analysis confirmed that a layer of PLLA had been grafted onto pSi judging by the low Si content (ca. 3%) and O/C ratio close to that found for PLLA homopolymers. Comparison of the sessile drop contact angle produced by silanised pSi and PLLA grafted onto pSi showed an increase of ca. 40°. This is comparable to the increase in contact angle seen between blank silicon and spin-coated PLLA of ca. 44°. The AFM surface roughness after surface initiated polymerisation increased significantly and AFM images showed the formation of PLLA nanobrushes.