Kinked Bisamides as Efficient Supramolecular Foam Cell Nucleating Agents for Low-Density Polystyrene Foams with Homogeneous Microcellular Morphology

Preparing low-Density microcellular polystyrene foam by in-Situ fibrillated PTFE and supramolecular nucleator TMC-300 in the presence of sc-CO2

A method using in-situ fibrillated polytetrafluoroethylene (PTFE) and octamethylenedicarboxylicdibenzoylhydrazide (TMC-300) supramolecular nucleator was presented to prepare low density polystyrene foams. This study used a torque rheometer in the molten compound preparation of PS/fibrillated-PTFE/TMC-300 composites. Scanning electron microscopy showed in-situ fibrillated polytetrafluoroethylene in Polystyrene melt and a nanofiber network with high aspect ratio. The formation of nanometer-sized fiber networks improved the melt viscoelasticity of matrices which promoted cell nucleation. As the results demonstrated, low-density foams with 11 μm average cell size were obtained using Polystyrene. The self-assembly nucleating agent TMC-300 was then introduced to the composite materials. TMC-300 and polytetrafluoroethylene as a composite cell nucleating agent were used in Polystyrene foams. Meanwhile, their nucleating efficiency was investigated. TMC-300 completed self-assembly in Polystyrene and served as composite nucleating agent in combination with polytetrafluoroethylene. Compared with the sample PS/PTFE-0.5, the average cell size of the sample PS/PTFE-0.5/TMC-2 had a reduction rate of 28.16% from 12.18 μm to 8.75 μm. The cell density increased by an order of magnitude. The composite nucleating agent was successful in controlling Polystyrene foam cell morphology, thus leading to the preparation of low-density Polystyrene microporous foams.

Influence of Bacillus subtilis on the surface behavior and separation of talc and chlorite minerals

Bacillus subtilis was used as a bio-surface modifier to improve the floatability of talc mineral (Mg3Si4O10(OH)2) in the talc ore. The surface behavior of chlorite mineral as the main associated gangue with talc mineral was studied in the presence of B. subtilis using zeta potential, scanning electron microscopy, and Fourier-transform infrared spectroscopy techniques. The floatability of both minerals was investigated as a function of pH, contact time, and concentration of B. subtilis. The results showed that the zeta potential of the talc mineral was strongly influenced by the treatment with B. subtilis. The maximum separation efficiency of talc from chlorite was achieved at pH 4. A talc concentrate with 98% quality and about 95% recovery was prepared from a binary talc-chlorite mixture containing 85% talc under optimum conditions of 8 × 105 cells/mL B. subtilis, pH 4, 35°C, and a contact time of 10 min.

Valorization of Starch to Biobased Materials: A Review

Many concerns are being expressed about the biodegradability, biocompatibility, and long-term viability of polymer-based substances. This prompted the quest for an alternative source of material that could be utilized for various purposes. Starch is widely used as a thickener, emulsifier, and binder in many food and non-food sectors, but research focuses on increasing its application beyond these areas. Due to its biodegradability, low cost, renewability, and abundance, starch is considered a "green path" raw material for generating porous substances such as aerogels, biofoams, and bioplastics, which have sparked an academic interest. Existing research has focused on strategies for developing biomaterials from organic polymers (e.g., cellulose), but there has been little research on its polysaccharide counterpart (starch). This review paper highlighted the structure of starch, the context of amylose and amylopectin, and the extraction and modification of starch with their processes and limitations. Moreover, this paper describes nanofillers, intelligent pH-sensitive films, biofoams, aerogels of various types, bioplastics, and their precursors, including drying and manufacturing. The perspectives reveal the great potential of starch-based biomaterials in food, pharmaceuticals, biomedicine, and non-food applications.

Crystal Engineering of Supramolecular 1,4-Benzene Bisamides by Side-Chain Modification - Towards Tuneable Anisotropic Morphologies and Surfaces

Benzene bisamides are promising building blocks for supramolecular nano‐objects. Their functionality depends on morphology and surface properties. However, a direct link between surface properties and molecular structure itself is missing for this material class. Here, we investigate this interplay for two series of 1,4‐benzene bisamides with symmetric and asymmetric peripheral substitution. We elucidated the crystal structures, determined the nano‐object morphologies and derived the wetting behaviour of the preferentially exposed surfaces. The crystal structures were solved by combining single‐crystal and powder X‐ray diffraction, solid‐state NMR spectroscopy and computational modelling. Bulky side groups, here t‐butyl groups, serve as a structure‐directing motif into a packing pattern, which favours the formation of thin platelets. The use of slim peripheral groups on both sides, in our case linear perfluorinated, alkyl chains, self‐assemble the benzene bisamides into a second packing pattern which leads to ribbon‐like nano‐objects. For both packing types, the preferentially exposed surfaces consist of the ends of the peripheral groups. Asymmetric substitution with bulky and slim groups leads to an ordered alternating arrangement of the groups exposed to the surface. This allows the hydrophobicity of the surfaces to be gradually altered. We thus identified two leitmotifs for molecular packings of benzene bisamides providing the missing link between the molecular structure, the anisotropic morphologies and adjustable surface properties of the supramolecular nano‐objects.