Faraday Discussions最新文献

These concluding remarks summarise the Faraday Discussions that was held in Glasgow, Scotland, on Advances in supramolecular gels, between the 30th of April and the 2nd of May 2025. The meeting was organised by Prof. Dave Adams (University of Glasgow, UK) and Prof. Annela Seddon (University of Bristol, UK) who co-chaired the meeting, in collaboration with the Scientific Committee, Prof. Krishna K. Damodaran (University of Iceland, Iceland), Prof. Demetra Giuri (University of Bologna, Italy) and Prof. Xuehai Yan (Chinese Academy of Science, China). The meeting was organised in four main sections over the four day programme. These were broadly devoted to the characterising (Session 1), using (Session 2), designing (Session 3) of supramolecular gels, and multicomponent gel systems (in Session 4). A lively poster session with range of posters presented mainly by early career, students and postdoctoral fellows, as well as some more established researchers, ran throughout the meeting. The Faraday Discussions programme had contribution talks that highlighted the research area from the design and synthesis of (supramolecular) gels, formed from small organic gelators and bioinspired structures and conjugates, to the different types of characterisation techniques employed for such soft-material research, including the use of rheology, scattering techniques and a variety of imaging platforms, as well as computational studies. This was also completed by the contributions on the applications of functional soft materials with both established and emerging applications. Herein, I will provide a short introductory remark on this fast-growing research field, and a short summary of the work presented within the four sessions, along with the associated discussions that took place. I will then conclude with a brief personal focused discussion of what I consider the main points raised throughout the meeting associated with some of the challenges that this fast-growing research area is facing.

A set of new chiral monomeric (S)- and (R)-isomers of Al(III) compounds were synthesized using a proline-based ligand moiety. The reaction of AlMe₃ with one equivalent of pro-ligands (1a–d) in dry toluene yielded the corresponding dimethyl Al(III) compounds (2a–d) in high yields. The molecular structures of compounds 2a, 2c and 2d were confirmed using single-crystal X-ray diffraction analysis. These compounds exhibited a distorted tetrahedral geometry at the Al(III) center. These compounds were tested as catalysts for the ring-opening copolymerization (ROCOP) of cyclohexane oxide (CHO) with cyclic anhydrides to produce copolyesters with tetraphenyphosphonium chloride (TPPCl) as a cocatalyst. The (S)-isomer was found to be more reactive than the (R)-isomer towards the ROCOP. Alternating polyesters were obtained from the ROCOP of cyclohexene oxide (CHO) with phthalic anhydride (PA) and CHO with succinic anhydride (SA), producing copolyesters with moderate to high M_n (9589 g mol⁻¹) and with narrow dispersity (Đ) (1.23). The (S)-isomer substituted with fluorine atoms at the phenyl ring was most active for the polymerization reactions. The kinetics studies of ROCOP performed using 2a (S-isomer) as catalyst showed higher rate than 2d (R-isomer). 2a produced an isotactic-enriched semicrystalline polyester, whereas 2d formed an atactic amorphous polyester. The DSC traces revealed that the glass transition temperature (T_g) increases with increasing molecular weight (M_n) of these polyesters.

Additive manufacturing (AM) techniques, also named three-dimensional (3D)-printing, have been widely recognised as promising technologies for rapid production of novel, personalised drug-delivery systems and scaffolds for biofabrication, and in food applications and many more fields. Although there has been promising progress in identifying new materials for 3D-printing, the range of resins/polymers available is still limited, with big reliance on petroleum-derived materials and the advancement is not up to date with the fast-developing hardware. Therefore, new building blocks that are renewably sourced and biodegradable are desirable for expanding applicability and recyclability. Specifically, glycerol, a readily available waste product from biodiesel processing, is highly functionalisable since it bears three hydroxyl groups. We previously reported that an acrylated glycerol-based oligomer, polyglycerol-6-acrylate, fulfils all the necessary criteria for volumetric printing (transparency, photo-reactivity and viscosity) and was successfully used to print a variety of models with intricate geometries and good resolution. In the present work, we want to expand the use of (meth)acrylated-polyglycerols (4 and 6 units of glycerol) to stereolithography (SLA), as this technique presents numerous advantages, being also more commercially available. Printability parameters, different geometries, and biocompatibility are explored to confirm the amenability of SLA to these “greener” resins. In addition, as initial proof of concept, the replacement of (meth)acrylate moieties is explored by ring opening of maleic and norbornene anhydrides in order to achieve acrylic-free resins and preliminary curability tests on these bioderived resins were performed. By developing and testing these new acrylic/acrylic-free resins based on glycerol, we aim to accelerate the adoption of greener alternatives in AM, contributing to a more sustainable future in the 3D-printing world.

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The copolymerization of β-myrcene (M) with ethylene (E) and isoprene (I) was successfully promoted by a dichloro{1,4-dithiabutanediyl-2,2′-bis(4,6-di-alkylphenoxy)}titanium complex (1) activated by methylaluminoxane (MAO). The catalytic system afforded well-defined PME copolymers and novel PMEI terpolymers with controlled compositions (up to 49% of terpene incorporated in the case of PME). Microstructural analysis demonstrated high stereoselectivity of 1, with 1,4-trans insertion predominating for both isoprene (97%) and myrcene (94%). A comprehensive analysis by ¹³C and 2D NMR techniques confirmed a multi-block architecture for the novel synthesized copolymers. Notably, PMEI terpolymers exhibited a strong tendency toward forming alternating ethylene–isoprene (E–I) sequences. The thin film morphology, investigated by tapping mode atomic force microscopy (AFM), for the PME and PMEI copolymers, evidenced a phase-separated morphology consisting of soft and hard phases, respectively, ascribed to polydienic and polyethylenic domains. The materials displayed glass transition temperatures ranging from −62 to −74 °C, demonstrating their potential as sustainable and high-performance elastomers.

Sitka Spruce (SiS) dominates wood production in Scotland and represents an important source of wood in the UK. A systematic analysis of the lignin obtained from SiS sawdust using methano-, ethano-, butano- and isobutano-solv pretreatments was carried out. Detailed analysis of the resulting lignin using a range of methods (GPC, ³¹P after phosphitylation and HSQC NMR) and assessment of solvent costs enabled a comparison of the 4 pretreatment methods. The high quality of the lignin obtained reflects its stabilisation through alcohol incorporation at the α-position of the β-O-4 units. Scale up of the butanosolv pretreatment led to the controlled synthesis of a selectively oxidised form of the lignin (SiS lignin^OX) on a relatively large scale. Additional insights into the detailed structure of lignin^OX are presented. It is argued that this interesting, modified biopolymer may have significant potential for enhanced lignin valorisation.

Lignin is one of the main byproducts of the pulp, paper, and cellulosic ethanol industries. For the past 35 years, it has received increased interest in applications other than its use as an energy source. Although much of this research requires the use of lignin solubilized in solvents such as alkalis, little is known about the impact of the main process conditions – initial lignin mass, alkali concentration, and temperature and time of dissolution – on key solution properties – density, mass fraction of lignin, and pH. A central composite design, with these process conditions as input variables and these key solution properties as output variables, was made by varying the temperature from 30 to 80 °C, the time from 1 to 3 h, the concentration from 0.1 to 0.5 M, and, instead of directly working with lignin mass, a ratio of added lignin to alkali concentration of 30 to 60 g L mol⁻¹. The hypothesis made by Sarkanen et al. (Macromolecules, 1984, 17(12), 2588–2597) that lignin may aggregate under strong alkaline media and Lindströmn's (Colloid Polym. Sci., 1979, 257, 277–285) hypothesis that there are thermally induced processes that also cause aggregation – and further agglomeration – were attested and updated to indicate a joint action of both factors. Surprisingly, mass fraction displayed a maximum value using fixed ratio conditions instead of a saturation point. That shows lignin solubilization depends on more factors than simply the ratio of hydroxide anions vs. phenolic-OH groups and the pH. pH evolution was governed by slow aggregation and agglomeration reactions and conformational changes sensitive to time and temperature. The resulting polynomial models achieved adjusted R² > 0.996 for all responses, and ten validation experiments exhibited maximum relative errors ≤1.6%. These results furnish quantitative guidelines for tailoring lignin solution properties and suggest further studies into rheology, extended factor ranges, alternative lignin sources, and developing theoretical – and possibly more universal – models to predict lignin solution properties.

Lignin–carbohydrate complexes, in which lignin and polysaccharides are directly connected, have been identified and extensively analyzed. To date, however, the origin of these structures has not been unequivocally established. That notwithstanding, it has been found that delignification, whether by conventional pulping and bleaching processes or in the biorefinery context, is effected by the presence of lignin–carbohydrate complexes. Using density functional theory calculations, the current work has evaluated the thermodynamics of bond dissociation as a function of structure and chemical composition. Among the lignin–carbohydrate complexes that have been identified, the homolytic bond dissociation energy is highest for the α-benzyl ethers and γ-ester, with phenyl glycosides being markedly less endothermic. This is consistent with observations on the recalcitrance of these compounds. Heterolytic cleavage reactions of the α-benzyl ethers are less endothermic, due to water solvation of the ions. The latter observation may provide support for the proposed homolytic cleavage reaction, since if heterolysis were operative, the α-benzyl ethers would not exhibit the level of recalcitrance that is observed experimentally.