A binary blend of poly(isoprene-block-styrene-block-(2-vinylpyridine)) (ISP) triblock terpolymers, having the same chain length but different compositions, was used to achieve an ordered lattice with 4-fold symmetry of rectangular-shaped rods of poly(isoprene) (I) and poly(2-vinylpyiridine) (P). In given conditions, the I and P domains were oriented perpendicularly to the substrate, providing new appealing type of templates for nanopatterning. Thin films were prepared by spin coating, exposed to solvent vapor (providing morphological reorganization) and then characterized by Atomic Force Microscopy, Transmission Electron Microscopy and Grazing-Incidence Small-Angle X-Ray scattering. Selective I and P identifications were carried out by AFM and TEM on a model ISP, as well as development of a technique of electronic contrast enhancement to better assign the self-assembly structure in GISAXS
A hybrid hydrogel composed of solid lipid nanoparticles (LNPs) entrapped within chemically cross-linked carboxymethylcellulose (CMC) is developed to achieve localized and sustained release of lipophilic drugs. The analysis of LNP stability as well as the hydrogel swelling and mechanical properties confirm the successful incorporation of particles up to a concentration of 50% w/w . The initial LNP release rate can be prolonged by increasing the particle diameter from 50 to 120 nm, while the amount of long-term release can be adjusted by tailoring the particle surface charge or the cross-linking density of the polymer. After 30 d, 58% of 50 nm diameter negatively charged LNPs escape from the matrix while only 17% of positively charged nanoparticles are released from materials with intermediate cross-linking density. A mathematical diffusion model based on Fick's second law is efficient to predict the diffusion of the particles from the hydrogels.
A new transition between alternating gyroid (GA) structure and cylindrical morphology was observed in thin films for a poly(isoprene-block-styrene-block-(2-vinylpyridine)) (ISP) triblock terpolymer (I/S/P volume fraction = 0.20:0.66:0.14) exhibiting in bulk a Q214 (space group I4132) morphology. Thin films were organized using solvent vapor annealing (SVA) and characterized by Atomic Force Microscopy, Transmission Electron Microscopy and Grazing-Incidence Small-Angle X-Ray scattering, coupled with several selective revealing methods adapted ISP system. After a short SVA time, the bulk morphology was reproduced with the (011) plane parallel to the surface. With a longer annealing time, tetragonal P2mm structure with cylindrical PI (polyisoprene) and P2VP (poly(2-vinylpyridine)) domains was obtained. Evidence of domains in transition between a gyroid and tetragonal structure was found, suggesting epitaxial relationship between these two structures. In contrast to the wellknown double gyroid (GD) to hexagonal (HEX) transition where {121} planes of the GD structure are epitaxially related to {100} plane of the HEX phase and cylinders grow along the <111> direction, we showed that the {011} planes of GA phase become the {001} planes of cylindrical structure (P2mm) and the cylinders grow along the <010> direction of the GA, parallel to the substrate. This was directly related to the three-dimensional topology of the PI and P2VP networks.
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