Macromolecular Symposia最新文献

Hydrogels are hydrophilic polymer networks dispersed in water and reinforced by physical or chemical interactions. Their exceptional ability to absorb and retain large amounts of water supports their use in the medical and pharmaceutical sectors, where biocompatibility is an essential requirement. This property also makes them promising for space applications, especially for radiation protection, where their high hydrogen content plays a key role in mitigating the effects of ionizing radiation on astronauts and electronic equipment. In this work, physically cross-linked hydrogels are prepared using a poly(vinyl alcohol) (PVA) matrix, varying the freeze-thaw cycles and sonication times of the polymer solution. Analyses performed included chemical composition determined by Fourier transform infrared spectroscopy (FTIR), thermo-mechanical properties evaluated by dynamic mechanical analysis (DMA), water content, density, and degree of crystallinity. The results obtained were used to study how the mechanical and chemical properties of the hydrogel vary with different preparation conditions.

For reasons of sustainability, a circular economy is demanded, and used plastics, in particular post-consumer recyclates (PCR), should be used in preference to virgin plastics for the production of new plastic molded parts in the future. The question arises as to what needs to be considered in this approach and what material characterization tests should be considered for the successful use of PCR in developing and manufacturing new products. The authors examine two commercially available thermoplastic polymers, namely virgin material of copolymeric polypropylene (PP), compared to rPP grade from post-consumer waste, considered as a possible alternative. Injection molding processing tests, thermo-analytical, and mechanical tests are carried out on the alternative materials, whereas the test results obtained are evaluated comparatively. The test results obtained suggest the introduction of an advanced characterization approach for PCR that should be considered when selecting and evaluating materials for product development and manufacturing.

Aromatic polyimides (PI) with high resistance to radiation combined with functional graphene-based fillers are promising materials for a wide range of space applications, such as those involving sensors, antibacterial coatings, and external spacecraft or satellite components. In this work, nanocomposites made of a fluorinated and aromatic polyimide filled with graphene nanoplatelets (GNP) (different concentrations from 5 to 20 wt.%) are prepared following an eco-friendly approach with a bio-based solvent, dimethyl isosorbide (DMI), used for the polymer synthesis and the composite processing. Several experimental techniques are used to investigate the morphology and surface properties of the PI/GNP nanocomposites, assessing their potential application in space environments, in particular for low Earth orbit (LEO).

The investigation of DNA's dynamic and flow properties in solution is crucial for understanding its biological roles. DNA double helix strands interact and, at high concentrations, they form liquid crystalline phases, which are influenced by molecular weight and ionic strength. At rest, Small Angle X-ray Scattering (SAXS) shows that DNA double helix strands exhibit an electrostatic correlation peak whose intensity decreases in the presence of external salt. In this study, shear-induced liquid crystalline textures were observed in high molar mass calf-thymus DNA solutions (CT-DNA) at concentrations higher than 7 mg/mL using birefringence visualizations and rheology measurements. Then, SAXS, combined with rheology, was used to examine this supramolecular organization under flow, revealing orientations of CT-DNA with preferential inter-chain distances. Upon relaxation, a transition from anisotropic to isotropic behavior was observed in those DNA solutions. To summarize, it is shown that CT-DNA's supramolecular organization at rest is progressively modified under flow and significantly influenced by DNA concentration, shear rate, and ionic strength.

Carbon-fiber-reinforced polymers (CFRPs) are excellent candidates for lightweighting vehicle components. However, the lack and the cost of raw materials prevent their widespread application. Moreover, CFRPs are difficult to recycle. A recently started-up carbon fiber recycling plant (FIB3R, designed by HERAmbiente @Imola—BO—Italy, from a joint UniBo and Curti Costruzioni Meccaniche patent) produces now up to 320 tons per year of ReCF. Tailoring and optimizing the specific recycling process to boost the final ReCF properties, as well as the re-impregnation strategies to optimize composites production, are at the basis of a successful result. The use of greener alternatives is still far from being a diffused practice in the mobility industry. This is mainly due to the lack of specifically suited industrial processing methods, material knowledge, and design tools. Thus, it requires the common effort of sustainable materials experts, green manufacturing technologists, and a circular economy approach to support this transition step, the widespread use of ReCF within the CFRP value chain.

Natural and synthetic polycations are commonly used in DNA- and RNA-based transfection for their ability to condense and protect nucleic acids, and the subsequent cellular uptake. While the formation of these complexes is well-documented, fewer studies have examined their stability under both extracellular and intracellular conditions. Chitosan, a biodegradable natural polysaccharide, has shown promise for gene delivery. However, its pKa of ∼6.5 makes its ionization state highly sensitive to pH fluctuations around this value. In this study, we examined how pH-induced changes influence the stability of chitosan/peGFP-C3 complexes and their effects on cell viability, proliferation, and transfection efficiency in HEK293T cells. The highest transfection efficiency was achieved by transfecting the complexes at pH 6.5, followed by a medium replacement at pH 7.1, particularly with high molecular weight chitosans. Cell viability was found to be higher at pH 7.1, whereas acidic conditions (pH 6.5) affected proliferation, leading to S-phase accumulation, suggesting potential interference with cell cycle progression. These findings underscore the critical role of pH in optimizing gene delivery and maintaining favorable cell growth conditions.

This work aims to develop a low-cost optical humidity sensor based on a SiO₂ matrix synthesized via the sol–gel process. The choice of silica is due to its capacity to adsorb water molecules, leading to variations in its physical and optical properties. In this preliminary phase, experimental measurements were carried out to characterize the optical behaviour of the material, reducing the humidity over time. As a proof-of-concept, the variation of optical transmittance was monitored over time as a function of the reduction of humidity, starting from a humidity-saturated condition of the silica.

The present study explores the properties of electrospun chitosan-based fibrous patches infused with wintergreen essential oil (WG oil), designed for potential transdermal pain relief applications. Scanning electron microscopy (SEM) analysis revealed denser fibrous structures in the final patches formed after suitable chemical treatment. Further, the absorption studies indicated enhanced oil-loading capacity in ternary chitosan-polyethylene-methylcellulose (CPM) fibrous patches compared to the binary chitosan-polyethylene oxide (CP) patches, correlating with the denser morphology of the former. Fourier-transform infrared (FTIR) spectroscopy confirmed the successful incorporation of WG essential oil into the fiber matrix, while thermogravimetric analysis (TGA) demonstrated the accelerated thermal degradation profiles of the polymer matrix. The in vitro release studies showed a sustained release of the WG oil from both types of patches, with the oil-loaded CPM-WG patches exhibiting higher cumulative release, attributable to its enhanced fibrous structure and porosity. The findings highlight the potential of electrospun fibrous patches as a promising platform for transdermal pain management.