Search results for "SOLVENT"
showing 10 items of 1395 documents
Steroid-based gelators of A(LS)2 type: Tuning gel properties by metal coordination
2020
By utilizing up-to-date knowledge about gelators, we designed and synthesized a novel low-molecular-weight gelator bearing a pyridine-2,6-dicarboxylic acid moiety and two cholesteryl glycinate units. In order to demonstrate the ingenuity of our design, we prepared a series of structurally related compounds and studied their gelation properties. Based on the results, we determined structural features of the gelator molecules which were important for successful gel formation. We showed that the properties of the gel systems (transparency, morphology, etc.) can be tuned by coordination with different metal ions, as well as by changing the solvent. Gelators, and their gels and xerogels were stu…
Advancements in Sustainable PVDF Copolymer Membrane Preparation Using Rhodiasolv® PolarClean As an Alternative Eco-Friendly Solvent
2021
In this work, Rhodiasolv® PolarClean was employed as a more sustainable solvent for the preparation of poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) flat sheet membranes via phase inversion technique by coupling vapour induced phase separation (VIPS) and non-solvent induced phase separation (NIPS) processes. Preliminary calculations based on Hansen solubility parameters well predicted the solubilization of the polymer in the selected solvent. The effect of exposure time on humidity and the influence of polyethylene glycol (PEG), polyvinyl pyrrolidone (PVP) and sulfonated polyether sulfone (S-PES) on membrane properties and performance, were evaluated. Three different coagulation …
Preparation of cholesteric particles from cellulose derivatives in a microfluidic setup
2011
A microfluidic setup was used to process lyotropic cholesteric liquid crystalline mixtures of cellulose derivatives into spherical particles in the micrometre scale. By the method of co-flowing injection, monodisperse droplets of the liquid crystal, dispersed in an aqueous carrier fluid, were prepared. Polymerization of the acrylic solvent with UV-light fixed the orientation obtained by the flowing motion. The resulting particles were characterized by polarizing optical microscopy.
Porous organic cage compounds as highly potent affinity materials for sensing by quartz crystal microbalances.
2012
Porosity makes powerful affinity materials for quartz crystal microbalances. The shape-persistent organic cages and pores create superior affinity systems to existing ones for direct tracing of aromatic solvent vapors. A shape and size selectivity for the analytes is observed. These organic cages can be processed to thin films with highly reproducible sensing properties.
Force probe simulations using an adaptive resolution scheme
2021
Molecular simulations of the forced unfolding and refolding of biomolecules or molecular complexes allow to gain important kinetic, structural and thermodynamic information about the folding process and the underlying energy landscape. In force probe molecular dynamics (FPMD) simulations, one pulls one end of the molecule with a constant velocity in order to induce the relevant conformational transitions. Since the extended configuration of the system has to fit into the simulation box together with the solvent such simulations are very time consuming. Here, we apply a hybrid scheme in which the solute is treated with atomistic resolution and the solvent molecules far away from the solute a…
In vitro degradation and bioactivity of composite poly-l-lactic (PLLA)/bioactive glass (BG) scaffolds: comparison of 45S5 and 1393BG compositions
2017
The objective of this study was to compare the effect of two bioglass (BG) compositions 45S5 and 1393 in poly-l-lactic composite scaffolds in terms of morphology, mechanical properties, biodegradation, water uptake and bioactivity. The scaffolds were produced via thermally induced phase separation starting from a ternary polymer solution (polymer/solvent/non-solvent). Furthermore, different BG to polymer ratios have been selected (1, 2.5, 5% wt/wt) to evaluate the effect of the amount of filler on the composite structure. Results show that the addition of 1393BG does not affect the scaffold morphology, whereas the 45S5BG at the highest amount tends to appreciably modify the scaffold archite…
Preparation of Nanoporous MgAl2O4 by Combined Utilization of Sol-Gel Process and Combustion of Biorenewable Oil
2011
ABSTRACTNanoporous MgAl2O4 particulates with high porosities were successfully prepared from sol-gel reactions, solvent exchange with castor oil and subsequent combustion and calcination at 700 °C. The products were crystalline and semitransparent. Changes in the metal precursor concentrations allowed control of pore volumes from 0.7 to 1.1 cm3/g and average pore sizes from 14 to 19 nm. The specific surface areas are about 200 m2/g regardless of the precursor concentrations. After heating at 1000 °C for 10 hours, the products kept about 70% of their original pore volume and about 60% of the original surface area. Heating at 1100 °C caused a drastic reduction of pore volume and surface area …
Processing-structure-property relationships of electrospun PLA-PEO membranes reinforced with enzymatic cellulose nanofibers
2020
Abstract Three different solvent mixtures were used to prepare electrospun membranes based on polylactic acid (PLA), polyethylene oxide (PEO) and enzymatic cellulose nanofibers (CNF). The materials were characterized from a morphological, spectroscopic, mechanical and rheological point of view. Furthermore, swelling test were performed in order to assess the water uptake of each sample. The results put into evidence that the choice of the solvents affects the structure and the properties of the membranes. Among the protocols tested, using chloroform/acetone/ethanol mixture was found to allow a high degree of CNF dispersion and a good electrospinnability of polymer solutions. These features …
PLA-based functionally graded laminates for tunable controlled release of carvacrol obtained by combining electrospinning with solvent casting
2020
Abstract A novel approach was designed to fabricate high-added value manufacts, starting from cost-effective materials and combining well-known processing techniques. Bi- and three-layered, functionally graded laminates were achieved by direct electrospinning onto dense substrates. The architecture of each multilayer comprises a dense layer formed by solvent casting, which is constituted by polylactic acid (PLA) and carvacrol, and one or two electrospun fibrous skin layers, consisting of PLA only. Processing-structure-properties relationships of such materials were investigated. As regards mechanical behavior, the amount of fibrous PLA layers determined an increase of stiffness from 20 to 3…