A range of conjugated microporous polymer networks has been prepared using Sonogashira−Hagihara cross-coupling of 1,3,5-triethynylbenzene with a number of functionalized dibromobenzenes. Porous poly(arylene ethynylene) networks with surface areas up to 900 m2/g were produced. The surface chemistry of the networks was varied by monomer selection, thus allowing control over physical properties such as hydrophobicity. Additionally, it was shown that the dye sorption behavior of the networks can be controlled by varying the hydrophobicity. This expands significantly on the utility of this approach, allowing high surface area networks to be prepared with properties that can be tailored for applications such as catalysis and separations.
Psyllium is a viscous, gel forming fibre with properties that have led it to be used for alleviating gastrointestinal discomfort. We have used previously identified fractions of psyllium with differing flow properties. Fraction 1 (F1) forms a non-gelling solution containing rhamnose. galactose, and arabinose. Fraction 2 (F2) forms a fluid-like gel containing mainly xylose and arabinose, Fraction 3 (F3) has almost identical monosaccharide and linkage composition to F2, but forms an insoluble, self-supporting gel. We performed in vitro batch fermentation experiments seeded with human stool. Metabolomics were performed using 1H NMR, and FISH with calcofluor white and direct red 23 were used to visualise the gels after in vitro fermentation of the fractions. The total amount of gas and short chain fatty acid produced was significantly higher for F1, compared to F2 and F3. F3 gas production was significantly lower than F2, but metabolite production between F2 and F3 did not differ. All fractions preferentially lead to the production of propionate instead of butyrate and were produced in the ratio of 58:35:7, 54:38:8, and 61:33:6 (acetate: propionate: butyrate) for F1, F2, and F3 respectively. Microscopy showed differences in how the fractions broke down and demonstrated the localisation of bacteria on the outer edge of each fraction. These results suggest that for these psyllium fractions the structure is a key factor that determines fermentability. Flow properties may play a role in gas production, suggesting directions for future investigation. Isolated fractions may have clinical benefit above that of unrefined psyllium powder aiding in the treatment of gastrointestinal discomfort.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Surface hydrophobization of cellulose nanomaterials has been used in the development of nanofiller-reinforced polymer composites and formulations based on Pickering emulsions. Despite the well-known effect of hydrophobic domains on self-assembly or association of water-soluble polymer amphiphiles, very few studies have addressed the behavior of hydrophobized cellulose nanomaterials in aqueous media. In this study, we investigate the properties of hydrophobized cellulose nanocrystals (CNCs) and their self-assembly and amphiphilic properties in suspensions and gels. CNCs of different hydrophobicity were synthesized from sulfated CNCs by coupling primary alkylamines of different alkyl chain lengths (6, 8, and 12 carbon atoms). The synthetic route permitted the retention of surface charge, ensuring good colloidal stability of hydrophobized CNCs in aqueous suspensions. We compare surface properties (surface charge, ζ potential), hydrophobicity (water contact angle, microenvironment probing using pyrene fluorescence emission), and surface activity (tensiometry) of different hydrophobized CNCs and hydrophilic CNCs. Association of hydrophobized CNCs driven by hydrophobic effects is confirmed by X-ray scattering (SAXS) and autofluorescent spectroscopy experiments. As a result of CNC association, CNC suspensions/gels can be produced with a wide range of rheological properties depending on the hydrophobic/hydrophilic balance. In particular, sol–gel transitions for hydrophobized CNCs occur at lower concentrations than hydrophilic CNCs, and more robust gels are formed by hydrophobized CNCs. Our work illustrates that amphiphilic CNCs can complement associative polymers as modifiers of rheological properties of water-based systems.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Abstract Summary: 13 C solid‐state NMR and 1 H relaxation time measurements have been used to determine the structure of the crystalline and amorphous forms of the pharmaceutical drug indomethacin. Cross‐polarization dynamics parameters were calculated for individual NMR resonances providing an insight into the mobility of functional groups in two forms of indomethacin. The changes of mobility in indomethacin/polyvinylpyrrolidone (PVP) formulation have been investigated via 1 H‐ 13 C solid‐state NMR methods. Differences between the amorphous material and its crystalline counterpart have been observed. The γ ‐amorphous indomethacin rapidly crystallizes with time. It has been shown that encapsulation in the PVP stabilizes the amorphous form of the drug by preventing crystallization due to reduced mobility of the guest in the formulation.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
'/%3e%3c/defs%3e%3cpath fill='%23012169' d='M0 0h10080v5040H0z'/%3e%3cpath stroke='%23fff' stroke-width='.6' d='m0 0 6 3m0-3L0 3' clip-path='url(%23b)' transform='scale(840)'/%3e%3cpath stroke='%23e4002b' stroke-width='.4' d='m0 0 6 3m0-3L0 3' clip-path='url(%23c)' transform='scale(840)'/%3e%3cpath stroke='%23fff' stroke-width='840' d='M2520 0v2520M0 1260h5040'/%3e%3cpath stroke='%23e4002b' stroke-width='504' d='M2520 0v2520M0 1260h5040'/%3e%3cg fill='%23fff'%3e%3cuse xlink:href='%23d' x='2520' y='3780'/%3e%3cuse xlink:href='%23a' x='7560' y='4200'/%3e%3cuse xlink:href='%23a' x='6300' y='2205'/%3e%3cuse xlink:href='%23a' x='7560' y='840'/%3e%3cuse xlink:href='%23a' x='8680' y='1869'/%3e%3cuse xlink:href='%23e' x='8064' y='2730'/%3e%3c/g%3e%3c/svg%3e)