Hydrophobic Modification of Pectin Aerogels via Chemical Vapor Deposition.

Pectin aerogels, with very low density (around 0.1 g cm-3) and high specific surface area (up to 600 m2 g-1), are excellent thermal insulation materials since their thermal conductivity is below that of air at ambient conditions (0.025 W m-1 K-1). However, due to their intrinsic hydrophilicity, pectin aerogels collapse when in contact with water vapor, losing superinsulating properties. In this work, first, pectin aerogels were made, and the influence of the different process parameters on the materials' structure and properties were studied. All neat pectin aerogels had a low density (0.04-0.11 g cm-1), high specific surface area (308-567 m2 g-1), and very low thermal conductivity (0.015-0.023 W m-1 K-1). Then, pectin aerogels were hydrophobized via the chemical vapor deposition of methyltrimethoxysilane using different reaction durations (2 to 24 h). The influence of hydrophobization on material properties, especially on thermal conductivity, was recorded by conditioning in a climate chamber (25 °C, 80% relative humidity). Hydrophobization resulted in the increase in thermal conductivity compared to that of neat pectin aerogels. MTMS deposition for 16 h was efficient for hydrophobizing pectin aerogels in moist environment (contact angle 115°) and stabilizing material properties with no fluctuation in thermal conductivity (0.030 W m-1 K-1) and density for the testing period of 8 months.

Multistage fractionation of pine bark by liquid and supercritical carbon dioxide.

Multistage fractionation of pine bark was performed using subcritical and supercritical CO2 at increasing pressures and temperatures. In total, seven fractions were collected, which demonstrated different enrichments of families of compounds. In particular, subcritical CO2 yielded 41% of the total extract in which unsaturated fatty acids represented the most abundant family. The subsequent five supercritical steps increased the recovery of sterol esters, wax esters and resin acids at higher temperatures and pressures, reaching 80% of the total extractable mass. In the last step, using ethanol as a co-solvent, an additional 20% of extract was recovered, which was enriched with phenolics and glycerol. A full characterisation of the extracts was accomplished by high-temperature GC-MS/FID using four internal standards, which were representative of the main classes of compounds contained in the pine bark extract.

Unbreakable and customizable dipping chambers for TLC and HPTLC manufactured by fused deposition modelling.

Postchromatographic derivatization chambers for Thin Layer Chromatography (TLC) and its high-performance counterpart (HPTLC) are made of glass, which renders them fragile and - given their frequent use - eventually rather expensive. As a consequence, in daily lab routine, staining reagents are often kept in jars or beakers as cheap and available but unsatisfying equipment. This work describes the design and the manufacturing of shock-resistant and affordable dipping chambers from polypropylene (PP) by fused deposition modelling ("3D printing"). The design is implemented as a customizable script. Three chamber designs are presented: a chamber for typical HPTLC plates (20 × 10 cm) with a convenient closing/storing system which avoids awkward pouring and removal of staining reagents. Second, for synthesis purposes, a chamber for 10 × 10 cm plates with a spout to facilitate exchanging the staining reagent, as well as a very small chamber stabilized by a pedestal for reaction control on 2.5 × 7.5 cm plates, which limits the loss of costly staining reagent. Even though the chambers adsorbed some degraded staining reagent over time, no cross-contamination was observed. All customizable scripts (as CAD models) are made available through online repositories.