The integration of spectroscopic methods into in-line analysis systems presents a new approach to real-time monitoring and control of polymeric materials processing, bridging the gap between materials science, analytical chemistry, and advanced manufacturing. This study explores the potential of spectroscopic methods for dynamic, non-destructive analysis of functionally graded polymeric materials (FGMs), in the form of filaments designed for fused filament fabrication (FFF) 3D printing. FGMs are a class of advanced engineered materials characterized by a smooth change of properties, composition, structure, or functional additives across their volume. This gradient architecture enables the optimization of local properties such as stiffness, thermal conductivity, or chemical resistance, enhancing mechanical performance, durability, and interfacial adhesion in multimaterial systems.
To tackle the challenges of FGM filament production, this research develops a controlled extrusion protocol and implements an in-line spectroscopic monitoring system capable of detecting real-time changes in chemical composition and additive distribution. By integrating this analytical data into a closed-loop control system, process parameters are dynamically adjusted to maintain consistent material quality. Initial results highlight difficulties in achieving uniform modifier distribution, particularly with viscous blends. Ongoing work focuses on optimizing processing conditions and formulations. The ultimate goal is to create a closed loop for the production and control of new polymeric filaments for 3D printing.

Biopolymers are macromolecular organic compounds derived from living organisms. They can be classified into polysaccharides, proteins, and nucleic acids. Chitosan and starch belong to the group of polysaccharides and are widely investigated for applications in tissue engineering, including wound healing. However, materials based on single biopolymers or their blends often exhibit insufficient physicochemical properties. Therefore, modification strategies, such as chemical cross-linking, are required. Dialdehydes are increasingly explored as natural, non-toxic cross-linking agents. Starch dialdehyde, chitosan dialdehyde, alginate dialdehyde, and other modified polysaccharides have been used for the modification of biopolymer materials.

The aim of this study was to obtain and characterize thin films based on chitosan and starch, modified with alginate dialdehyde. Alginate dialdehyde was synthesized by means of sodium periodate oxidation. The films were prepared using the solvent evaporation method. Structural characterization was performed by means of Fourier Transform Infrared Spectroscopy, while moisture content, hydrophilicity, and antioxidant activity of the obtained materials were also evaluated.

The results demonstrated that the addition of alginate dialdehyde significantly influenced the physicochemical properties of the films. It can be concluded that the properties of biopolymeric materials strongly depend on their weight ratio composition and the applied cross-linking agent. Novel biopolymeric composites based on chitosan and starch, chemically cross-linked with alginate dialdehyde, show promising potential for biomedical applications, particularly in wound healing.

Wound healing remains a major biomedical challenge, requiring the design of advanced multifunctional dressings that can simultaneously manage exudates, prevent microbial infection, and provide controlled drug release. In this study, amphiphilic Janus nanofibers were fabricated via a conjugate bubble electrospinning technique, integrating hydrophilic and hydrophobic domains within a single fibrous structure. The hydrophilic side was composed of polyvinyl alcohol (PVA) blended with chitosan (CS) or sodium alginate (SA), while the hydrophobic side consisted of poly(ε-caprolactone) (PCL) or polyvinylidene fluoride (PVDF) loaded with curcumin (Cur) or rutin (Ru).

Comprehensive characterization, including fiber diameter, air permeability, tensile strength, and water contact angle, was performed to evaluate physicochemical properties. Biological performance was assessed through in vitro drug release, antibacterial activity against Vibrio vulnificus and E. coli, cell viability using L929 fibroblasts, and in vivo wound healing in a murine full-thickness excisional wound model. Results demonstrated that the incorporation of CS and SA significantly enhanced hydrophilicity and exudate absorption, while rutin-loaded PCL facilitated efficient drug release compared to PVDF-based systems. Antibacterial studies confirmed strong inhibitory activity in Janus scaffolds containing SA, and cell viability assays indicated high biocompatibility, particularly in SA-based nanofibers.

Among the various formulations, Janus nanofibers composed of SA-PVA on the hydrophilic side and PCL–rutin on the hydrophobic side (PSA/PCRu) achieved the best overall performance, with superior in vitro drug release, minimal cytotoxicity, and the highest wound closure rate (95.2% at day 15) in vivo. Degradation and thermal analyses further confirmed the structural stability and tunability of the scaffolds.

This work highlights conjugate bubble electrospinning as a scalable platform for fabricating multifunctional Janus nanofibers. The resulting chitosan- and alginate-based wound dressings offer synergistic benefits in exudate management, antimicrobial defense, and sustained therapeutic delivery, positioning them as promising candidates for next-generation wound care applications.

Polymer chain behavior in polymer/silica nanocomposites was explored using long-term atomistic molecular dynamics simulations. The study focused on two polymers: poly-(butadiene) (PB) and poly(ethylene oxide) (PEO). Both cis-1,4-PB and trans-1,4-PB nanocomposite systems contain 30 wt% silica nanoparticles with a diameter of about 4 nm. The overall size of the PB polymer chains remained unaffected, except for a small number of chains that wrapped around the nanoparticles. However, both the segmental and terminal dynamics of the PB chains were found to be slower in the nanocomposites compared to the corresponding bulk melts. Additionally, the PB chains within the nanocomposites exhibited highly heterogeneous dynamics, and a coupling between the dynamics and the conformation of PB chains was observed.

In the case of PEO nanocomposites, the effects of chain adsorption and the spatial confinement from the nanoparticles on the polymer's structure and dynamics were investigated. The analysis of static properties showed a heterogeneous polymer density layer near the interface of the PEO and silica. For systems with a low volume fraction of silica nanoparticles, a thin layer of slow-moving polymer chains forms on the nanoparticle surface. The polymer chains farther away from the surface move similar to a bulk material system. Conversely, in systems with a high volume fraction of nanoparticles, the dynamics of all the PEO polymer chains were predicted to be slower than in the bulk due to a strong confinement effect.

PET glycolysis corresponds to a highly efficient Chemical recycling process, which offers some advantages over physical recycling. The main product is the Bis(2-hydroxyethyl) terephthalate – BHET, the PET monomer, which provides high-quality recycled PET, such as the one used in food packaging. BHET can also be used in the production in the production of new copolymers. PET glycolysis has its efficiency improved in the presence of a catalyst. Therefore, in the present work, Co, Mn, and Al-based oxide catalysts were synthesized by coprecipitation followed by calcining at 400 °C. These catalysts are poorly crystallized, hydrotalcite-like structured, with surface areas of 114 m².g^-1 and 103 m².g^-1, for CoMnAl and CoAl, respectively. Both catalysts were applied in the conversion of PET to BHET through glycolysis. Best results were obtained in the optimized parameters of 0.5% catalyst/PET, EG/PET = 5, reacting at 200°C in 60 minutes, which resulted in PET conversion of 96.7 and 40.2% in the presence of CoMnAl.c and CoAl.c, respectively. Both catalysts were still advantageous when compared to the non-catalysed PET glycolysis, which led to 0% PET conversion in the same optimized parameters. The results show that Mn promoted the performance of CoAl.c, which led to CoMnAl.c with a higher efficiency on PET conversion.

Encapsulation consists in surrounding the encapsulated substance (core, nucleus, active substance) with walls and thus closing it in the resulting structure. Most often, this is done by coating with a thin film of polymer (single capsule) or placing the core substance in the produced polymer matrix (agglomerate) by occlusion and/or adsorption [1-3]. One of the methods of obtaining microcapsules is coacervation. In this paper, microcapsules based on κ-carrageenan and gelatin type A were prepared by coacervation. The microcapsules were enriched with essential oils such as citronella oil and cinnamon oil, which has antimicrobial properties, in order to obtain materials that inhibit the growth of microorganisms. After optimizing the microcapsule production process, they were applied to natural leather to create a new antibacterial, odorless, and environmentally safe leather material. The microcapsules containing the selected essential oil were applied to the leather material in a batch process using a padding technique using a laboratory padding machine with adjustable roller pressure. Next, the antimicrobial properties of the new leather materials were tested against two bacterial strains, E. coli and S. aureus, and two fungal strains, Aspergillus niger ATCC 6275 and Candida albicans ATCC 1023. Very good and effective microbiological and antifungal effects were achieved with just 10% of microcapsules in the bath.

[1] Meyer-Deru L., David G., Auvergne R. Chitosan chemistry review for living organisms encapsulation. Caebohydrate Polymers 2022, 295. DOI: doi.org/10.1016/j.carbpol.2022.119877

[2] Gomez-Mascaraque L. G., Llavata-Cabrero B., Martinez-Sanz M., Fabra M.J., Lopez-Rubio A. Self-assembled galatin -ι-carrageenan encapsulation structures for intestinal-targeted release applications. Journal of Colloid and Interface Science 2018, 517, 113-123. DOI:doi.org/10.1016/j.jcis.2018.01.101

[3] Qiu J., Zheng Q., Fang L., Wang Y., Min M., Shen C., Tong Z., Xiong C. Preparation and characterization of casein-carrageenan conjugates and self-assembled microcapsules for encapsulation of red pigment from paprika. Carbohydrate Polymers 2018, 196, 322-331. DOI:doi.org/10.1016/j.carbpol.2018.05.054 ]

Determining the crystal structure of semi-crystalline polymers is still quite the challenge, especially when relying on powder X-ray diffraction (PXRD) alone. The (typically) poorly resolved patterns often lead to multiple competing models with indistinguishable powder profiles. Herein, an alternative bottom-up strategy is proposed, using experimental vibrational spectra as a diagnostic tool to iteratively build crystal structures piece by piece, from 1D chain conformation to full 3D packing.

The vibrationally-guided methodology was applied to poly(trimethylene 2,5-furandicarboxylate) (PTF), a promising biobased polyester. Infrared and inelastic neutron scattering (INS) spectra collected for amorphous and semi-crystalline samples revealed conformationally sensitive bands that were matched against spectra estimated from discrete DFT models. This allowed the identification of the chain conformation (ss-tggt) present in the crystalline phase and rejection of those incompatible with spectroscopic observations. Using this conformer as a building block, a 3D crystal structure was assembled, comprising 2D sheets stabilized by C–H···O bonds and π–π interactions, and then refined using periodic DFT. This model, which greatly resembles that found for the terephthalic counterpart poly(trimethylene terephathalate) (PTT), proved able to reproduce experimental INS data.

This case study demonstrates the power of vibrational spectroscopy not only as a validation tool, but as an active guide in structure determination. By leveraging spectral sensitivity to local conformation and intermolecular contacts, this bottom-up strategy narrows the pool of viable models early in the process, reducing computational cost and ambiguity. This method complements existing techniques such as NMR crystallography and opens new avenues for understanding structure–property relationships in complex polymer systems.

Extrusion molding is a widely utilized technique for processing polymers—particularly plastics and rubbers. Despite its broad industrial application, several aspects of the transport behavior of polymers during extrusion remain inadequately understood. Undesirable and unexpected phenomena such as sharkskin instabilities, turbulent flow transitions, and flow fractures frequently occur during the process. However, definitive explanations for these phenomena are still lacking. Numerous studies suggest that the transport behavior of polymers plays a crucial role in the emergence of these instabilities. To date, several empirical investigations have examined the rheological properties of conventional polymers to better understand these transport dynamics. Nonetheless, significant limitations persist, and a comprehensive theoretical model that can predict and explain these behaviors remains elusive.

To contribute toward resolving this issue, the present study employs both single- and double-concentric cylinder models to simulate the screw mechanism within an extruder. These models are used to derive and analyze the transport characteristics of polymers during extrusion molding.

This study was divided into two main sections. The first section focuses on the transport behavior of solid polymer particles, typically occurring in the feed zone (zone 1) of the screw. The second section examines the transport of polymer melts, which predominantly takes place in the melting and metering zones (zones 3 and 4). Key boundary conditions—including velocity profiles, flow rates, shear rates, and shear stresses—are systematically investigated and discussed to provide deeper insight into the mechanisms governing polymer transport in extrusion molding.

1. Introduction

Reliable experimental characterization of architected lattice materials requires specialized fixture systems that ensure accurate load transfer. Traditional metallic fixtures are often prohibitively expensive and slow to produce, hindering rapid, iterative material research. This study addresses this challenge by presenting the design, finite element validation, and topological optimization of a cost-effective test fixture made from Fused Filament Fabrication (FFF) Polylactic Acid (PLA). The fixture is designed to enable the cyclic mechanical characterization of LPBF-manufactured Kelvin-type lattices.

1. Methods

The fixture's design process was iterative, combining CAD modeling and Finite Element Analysis (FEA) to refine its geometry and performance. The supports were designed for axial load transfer compatible with an Instron 8801 testing machine. The loading protocol was proportionally scaled from a recognized standard for Steel Plate Shear Yielding Dampers (SPSYDs). A density-based topology optimization was performed to minimize mass while maintaining structural rigidity, targeting a mass reduction constraint of 60%.

1. Results

The iterative design and optimization process successfully improved the safety factor from an initial 2.08 to a final value of 4.25, confirming its structural integrity under the maximum load of 5.3 kN. The topology optimization achieved a mass reduction of 40% compared to the initial design. Preliminary experimental analysis and numerical simulations confirmed that the optimized PLA supports exhibited minimal deformation, with displacements around 0.73 mm, which was significantly lower than the machine clamps.

1. Conclusions

This research demonstrated that combining numerical analysis and topological optimization can produce cost-effective, FFF-manufactured PLA components that are capable of replacing traditional metal devices in cyclic mechanical testing applications. The developed methodology can be extended to other test devices where stiffness and precision are crucial. The validated fixture provides a reliable platform for future experimental tests of lattice-based hysteretic dampers.

Introduction.

Size-exclusion chromatographic separation with Sephadex gels is a widely used technique for dereplication and screening methodologies of natural products. Sephadex G-10 resin is a polymeric network composed of dextran units cross-linked by epichlorohydrin and allows using physiological solutions as mobile phases for the direct coupling chromatographic separation to study living tissues or organs. Thus, this type of system enables real-time monitoring of active compounds, an application of significant importance in organic chemistry and pharmacology.

Methods.

Medium-pressure liquid chromatography separation (MPLC) with Sephadex G-10 coupled directly to biological detection using perfused organs was carried out for bio-guided study of hydro-ethanolic extracts from Nicotiana glauca Graham (Solanaceae). Sephadex G-10 provides the lowest fractionation range of gels type Sephadex, allowing the separation of substances with molecular weights below 700 Da, typically within the range of 100–1000 Da. Furthermore, this resin enabled the use of Krebs-HEPES as an elution medium, a medium that kept the studied organs in optimal conditions.

Perfused rat organs were used: Rings of aorta artery and trachea, and portions from the deferent conduct and ileum.

Results.

Two natural alkaloids, anabasine and nornicotine, were readily isolated and identified as the compounds responsible for the contractile activity observed in the smooth muscle of rat ileum and trachea.

The coupling of this chromatographic system with Sephadex G-10 to biological detection in living organs simplified the bioassay-guided: it carried out by a single person, with a physiological and non-contaminating medium, minimizing the number of animals slaughtered, with chemical characterization by mass spectrometry analysis, and reducing the study time.

Conclusions.

This application of Sephadex G-10 chromatography rationalizes the bio-guided identification of isolated natural products and advances its use toward green chemistry dereplication methodologies as well as in future automated or robotic approaches.