Journal of Nano Research Vol. 2

Abstract: The miscibility behaviour of polymer-nanoparticle / linear-polymer blends (all-polymer nanocomposites) has been investigated using an incompressible mean-field theoretical model that accounts for combinatorial, temperature-dependent exchange interaction energy and nanoparticle-driven effects. The theory is employed to predict the phase diagram of poly(styrene)-nanoparticle (PS-np) / linear-poly(vinyl methyl ether) (PVME) nanocomposites from room temperature to 675 K. Complete miscibility is predicted for PS-nanoparticles with radius < 6 nm blended with PVME (molecular weight 62 500 g/mol, nanoparticle volume fraction 20 %). The effect of PVME molecular weight and blend composition on the miscibility diagram is also addressed. When compared to the well-known experimental phase diagram of linear-PS / PVME blends displaying lower critical solution temperature (LCST) behaviour, the miscibility improving effect of sub-10 nm PS-nanoparticles is clearly highlighted. In terms of the model, this favourable nanoscale effect arises mainly from the reduced stretching induced by the sub-10 nm nanoparticles and the increased exothermic contacts when compared to nanoparticles with sizes > 10 nm.

Abstract: Citrate gold nanoparticles of 13.5 nm average diameters have been synthesized by Turkevich method and further functionalized by place exchange reaction using mercaptosuccinic acid (MSA), 1,4-benezenedimethanethiol (1,4BDMT) or mercaptoundecanoic acid (MUA) as the incoming ligands. In the first case, the functionalization of the gold clusters with MSA yielded solution of blue color and large aggregates on carbon grids. Moreover, after filtration and drying, any film formed by hydrogen bonding, could not be removed from the filter, being embedded into the filter texture. The second ligand used for the place exchange reaction, the 1,4BDMT, determined the change of the solution color from red to dark purple, and generation of a purple powder but no film formation. In the third case, the purification and drying of the MUA functionalized gold clusters yielded films of purple color with homogenous composition, robustness, soft topographies and remarkable optical properties which were dependent on their thicknesses. The Au-MUA NP films obtained are new, being generated by hydrogen bonding and having features which makes them very attractive for the fabrication of optoelectronic devices. The long alkyl chained thiol proved to be the adequate ligand for film synthesis.

Abstract: Regular arrays of micro-pillars and nano-grooves structures on the silicon wafer are fabricated by using soft lithography, and the three dimension morphology of textured surface is observed by using scanning electron microscopy (SEM) and atomic force microscope (AFM). The static water contact angles are measured by using contact angle meter to characterize the wettabilities of these surfaces. To investigate how the presence of topography and the variations of wettability affect the haemocompatibility of textured surface contacted with blood, different patterned surfaces are designed and fabricated, and blood platelet adhesion test is carried out on these surfaces. The adhesion and coagulation of platelets are inspected by scanning electron microscopy (SEM). Experimental data presented in this paper indicate that different surface roughness and wettability are the important factors for blood platelet adhesion. The amount of adsorbed blood platelet is low on textured surfaces, compared with that on the flat surface. Especially, there is no coagulation and activation on the surface with nanometer grooves. That is to say, the superhydrophobic surface is apt to decrease blood platelet adhesion. The study suggests that surface with suitable wettabililty and textured structures exhibits superior blood compatibility.