Chemistry and Materials Science

Abstract: Optical spectroscopy provides several useful information about polymeric ultrathin films by combining interferometric and optical absorption data contained in the UV-Vis-NIR spectra. In particular, the UV-Vis-NIR spectrum of an ultrathin polymeric film contains information about the film thickness, structural disorder, bandgap energy, type of electron transition model (direct/indirect, allowed/forbidden), cutoff wavelength (i.e., the opaque/transparent switching wavelength), etc. Here, these properties have been determined for a model semi-crystalline polymer (polyethylene terephthalate, PET) in form of ultrathin film before and after a mild mechanical deformation treatment (manual stretching). It has been found that E_U and E_g parameters are not strictly depending on mechanical deformation due to their main dependence on chemical composition/constitution of the polymer; consequently E_g can be used for polymer identification in the case it has a dielectric nature.

Abstract: Exploring a possibility of β-myrcene (MY) incorporation in propene copolymerization has been studied in the presence of phenoxide-modified half-titanocene, Cp’TiCl₂(O-2,6-ⁱPr₂-4-C₆H₃) (Cp’ = Cp*, Me₃SiC₅H₄), and ketimide-modified half-titanicene, Cp’TiCl₂(N=C^tBu₂) (Cp’ = Cp*, Cp), catalysts. The permethylated Cp* catalysts exhibited good catalytic activities in the copolymerizations but afforded the copolymers up to 3 mol% MY incorporation; the other catalysts showed the negligible activities. The resulting copolymers were amorphous and exhibited glass transition temperatures (T_g) that de-creased with increasing the comonomer (MY) content, reaching values as low as −17 °C.

Abstract: Micro-nonuniformity, as a fundamental natural property, is widespread across a range of microscopic systems, such as polymer systems, biomacromolecular systems, and nanosystems; however, the construction of micro-nonuniform molecular systems has not yet been realized at the level of organic molecules with well-defined structural compositions. Inspired by the "chemical space" concept, I recently reported a study of the single-molecule mixture state; in this paper, I provide a detailed discussion of micro-nonuniformity and the concept of a "single-molecule mixture".

Abstract: Sodium alginate was extracted from beach-cast Sargassum spp. collected along the coast of Puerto Progreso, Yucatán, Mexico, using two established pretreatment routes based on formaldehyde and ethanol. The study was designed to determine how extraction methodology influences alginate molecular structure and, consequently, its rheological performance. The ethanol-based route provided the highest extraction yield (up to 19.87%), whereas the formaldehyde route afforded alginate with higher intrinsic viscosity and viscosity-average molecular weight. Structural characterization by ¹H NMR revealed clear differences in monomer composition and sequence distribution, with ethanol-extracted alginate showing higher guluronic acid content, lower M/G ratio, and greater abundance of G-rich blocks. These structural differences were directly reflected in the viscoelastic behavior of Ca²⁺-crosslinked hydrogels. Alginate obtained by the ethanol route produced stiffer gels with the highest storage modulus, consistent with enhanced ionic crosslinking promoted by G-block-rich sequences, although with limited macroscopic cohesion due to lower molecular weight. In contrast, alginate obtained by the formaldehyde route showed a more balanced mechanical response associated with improved chain connectivity and network integrity. FTIR analysis confirmed the preservation of the characteristic functional groups of alginates in all samples. Overall, the results demonstrate that beach-cast Sargassum from the Yucatán coast is a viable source of sodium alginate and that extraction route is a key parameter governing its microstructure and rheological performance. These findings provide a structure–property framework for the valorization of stranded Sargassum biomass as a source of functional polysaccharides.

Abstract: Chemical recycling of polyolefins is essential to mitigate plastic waste accumulation and promote circular economy strategies. Among the various chemical recycling pathways, catalytic pyrolysis, tandem catalyst systems, ethenolysis, hydrocracking, and hydrogenolysis have emerged as promising approaches for converting polyolefin waste into valuable hydrocarbons, including gaseous, liquid, and solid products. This review provides a survey of recent research on these methodologies, with a particular focus on the production of light gaseous hydrocarbons (C1–C4), bypassing the intermediate pyrolysis oil stage, which is often associated with contaminants and increased processing costs. The novelty of the present work lies in its emphasis on gaseous fractions, in contrast to most existing studies that primarily target oil recovery. Aspects such as catalyst selection, reaction conditions, and product distribution are analyzed. Additionally, the current Technology Readiness Level (TRL) of the studied processes, their relative advantages, limitations, and perspectives for industrial applications are discussed. The analysis highlights catalytic pyrolysis with zeolites as the most mature and scalable technological alternative for manufacture of light compounds directly from polyolefin waste, while tandem catalyst systems and ethenolysis constitute promising but still emerging alternatives for targeted gas production.

Abstract: Concerns about the environmental and health impacts of plasticized PVC have created a clear demand to find alternative packaging materials for medical and pharmaceutical use. As polyolefin-based alternative, we blended polypropylene-ethylene copolymers of different, ethylene content-controlled, phase structure, with styrene-ethylene/butylene-styrene block copolymer (SEBS), as modifier, the latter being elastomeric and mechanically acting as cross-linked rubber due to a unique microphase separated morphology of hard spherical PS domains dispersed in the soft EB phase. Tests with injection-molded samples and cast films demonstrated promising combinations of flexibility, durability, and transparency—qualities essential for soft medical packaging like infusion pouches and blow-fill-seal bottles. For the desired level of flexibility (reflected by a flexural modulus of about 150 MPa), blends with two random-heterophasic (RAHECO) copolymers achieved this with only 15–25 wt.-% SEBS, compared to 37 wt.-% needed for a single-phase random copolymer (RACO); these blends also exhibited greater toughness. In contrast, a standard impact copolymer (HECO), with its more crystalline structure, required a higher modifier content of 45 wt.-% SEBS. Film morphology analysis indicated a gradual shift in disperse phase structure and orientation, leading to phase inversion at the highest SEBS content—without negatively affecting transparency.

Abstract: Flexible electrode materials with tailored electrical and mechanical properties are essential for reliable electrocardiographic (ECG) sensing. In this work, p-toluenesulfonic-acid-doped polypyrrole (PPy–TSA) films were modified using polymeric and inorganic fillers, as well as their combinations (polyethylene glycol, graphene, carbon nanotubes, and zeolite), to tune their functional performance. The reference PPy–TSA film exhibits typical morphological and chemical characteristics of doped polypyrrole and serves as a reliable baseline for comparison. All composite films retain electrical conductivity within the range required for ECG applications while showing improved mechanical compliance. Based on the optimized balance between electrical and mechanical properties, flexible ECG electrod were fabricated using the TSA doped PPy based composite film. ECG recordings obtained with the several proposed electrodes show good agreement with those acquired using a commercial ECG electrode, demonstrating the potential of PPy-based composite films for flexible bioelectronic sensing applications.

Abstract: The rapid accumulation of plastic waste has become a major environmental concern, while at the same time it is necessary to create opportunities to rethink how these materials can be reintegrated into productive use, particularly within the construction sector. This study provides a sustainability-oriented review of the reuse of plastic waste, both fossil-based plastics and bioplastics, as building materials, with a specific emphasis on structured decision-support approaches. A systematic literature review was conducted to identify and analyze peer-reviewed studies examining the incorporation of plastic waste into construction applications, including composites, panels, insulation systems, and structural or non-structural components. Particular attention is given to research applying Multi-Criteria Decision Analysis (MCDA) and SWOT analysis as tools for evaluating sustainability performance across environmental, economic, technical, and social dimensions. The findings indicate that recycled plastic and bioplastic-based construction materials can deliver significant advantages, such as diverting waste from disposal pathways, reducing reliance on virgin resources, and, in certain cases, enhancing durability. However, these materials also face important challenges, including limitations in recyclability, concerns related to fire performance, regulatory acceptance, and uncertainties in end-of-life management. MCDA-based studies underscore the critical role of criteria selection and weighting, especially regarding environmental impact reduction and cost competitiveness, in shaping final rankings and decision outcomes. SWOT analyses, in turn, offer complementary strategic insights by highlighting issues related to market readiness, regulatory frameworks, and implementation barriers. By integrating these decision-oriented evaluation approaches, this review contributes to more transparent and evidence-based material selection processes and supports policy development aimed.

Abstract: Electrospinning is a versatile technique for producing polymer nanofibers with high ratios of surface area to volume and tunable porosity. Conventional approach to the optimization of processing parameters such as voltage and flow rate frequently encounters limitations in reproducibility and scalability. This review proposes a comprehensive framework that integrates macromolecular design principles with established electrohydrodynamic theories. We analyze how intrinsic molecular traits, specifically, chain entanglement density, molecular weight distribution (MWD), topological architecture, and polymer-solvent thermodynamic interactions define the boundaries of jet stability and solidification. Key findings highlight that while molecular weight establishes a baseline for spinnability, the MWD dictates the dynamic response under extreme deformation. Notably, high-molecular-weight fractions act as elastic load-bearers that suppress capillary breakup. Furthermore, we discuss here how molecular architecture and solvent-mediated segmental mobility determine whether molecular orientation is kinetically trapped or relaxed during the nanosecond timescales of jet flight. By establishing a hierarchical design logic prioritizing molecular and formulation variables over processing parameters, this framework provides a robust strategy to overcome challenges in scalability and reproducibility, positioning electrospinning as a sensitive probe for macromolecular dynamics under extreme elongation.

Abstract: This study evaluates the antimicrobial properties of nanocomposite materials based on polyvinyl alcohol (PVA) reinforced with cellulose nanofibrils (CNFs) and/or supplement-ed with biobased additives derived from blueberry pruning wastes, with the objective of developing biodegradable food packaging systems with antimicrobial properties. The nanocomposites were prepared using a solvent-casting processing approach, and their thermal, physicochemical, and antimicrobial properties were assessed. All the nanocomposites exhibited thermal stability up to 200 °C, confirming their suitabil-ity for conventional food packaging processing conditions. Antimicrobial activity tests re-vealed inhibitory effects against both Gram-positive and Gram-negative bacteria. Bleached PVA/CNFs films showed complete growth inhibition (100%) against E. coli and S. aureus. In contrast, unbleached PVA/CNFs and PVA/CNFsB supplemented with blueber-ry-derived additives exhibited selective inhibition against E. coli, highlighting the influ-ence of nanofibril composition and additive incorporation on antimicrobial performance. Zeta potential measurements revealed values of –35.3 mV for the CNFs, confirming their negatively charged surface, which may contribute to interactions with bacterial mem-branes. Additionally, scanning electron microscopy (SEM) showed that the incorporation of CNFs generates nanostructured surfaces with exposed fibrillar domains, where bacteri-al cells become adhered and immobilized. These topographical features suggest that the antimicrobial behavior of the nanocomposites is associated with direct bacteria–surface interactions, supporting a contact-active antimicrobial behavior associated with the CNFs.

Abstract: In 2.5D/3D stacked advanced packaging, one-part additive curing silicone composites are widely employed to achieve structural bonding and efficient heat dissipation. In this study, a thermally conductive silicone adhesive was prepared using medium viscosity vinyl silicone oil, hydrogen containing silicone oil, and micron-sized alumina powder as the primary components. The results demonstrated that the adhesive exhibited excellent thermal and mechanical performance. Specifically, its thermal decomposition temperature exceeded 400 °C, the thermal conductivity reached over 1.80 W·m⁻¹·K⁻¹, and the thermal resistance was below 12.0 °C·cm²·W⁻¹. The shear strength exceeded 5.00 MPa. Furthermore, after exposure to uHAST for 384 h, 1,000 thermal cycles, and thermal aging for 1,000 h, the adhesive maintained stable thermal conductivity and mechanical properties. The thermal conductivity remained above 1.70 W·m⁻¹·K⁻¹, and the shear strength remained higher than 5.00 MPa. In addition, the tensile modulus was maintained below 100 MPa, and the coefficient of linear thermal expansion was less than 160 ppm·°C⁻¹. Overall, the comprehensive performance of the adhesive satisfies the reliability requirements for advanced packaging substrates and heat dissipation lid assemblies.

Abstract:

Thermal interface materials (TIMs) are essential for addressing heat dissipation challenges in high-performance electronic devices. Among various TIMs, thermal conductive gels exhibit significant potential in high heat flux applications due to their excellent flexibility and superior gap-filling capability. Current research primarily concentrates on the fabrication and performance characterization of novel thermal conductive gels, while comparatively little attention has been devoted to the optimization of processing parameters. Furthermore, existing characterization methods often fail to accurately replicate real-world operating conditions, resulting in discrepancies between laboratory measurements and actual performance. An orthogonal experimental design was adopted to systematically elucidate the influence of filler ratio, wetting time, and silicone oil viscosity on the bonding strength of thermal conductive gels. The filler ratio exerts the most significant influence, followed by silicone oil viscosity and wetting time. Subsequently, the thermal conductivity and thermal resistance of both commercial thermal conductive gels and the as-prepared gels were characterized using the steady-state heat flow method and the double-interface method, respectively. The prepared thermal conductive gel exhibits a thermal conductivity of 3.75 W·m⁻¹·K⁻¹ and a service thermal resistance of 0.611 ℃·W⁻¹, outperforming commercial counterparts and demonstrating promising application potential. This study provides a practical reference for the development and engineering application of high thermal conductivity, low thermal resistance thermal conductive gels.

Abstract: Given the urgency imposed by the UNEP Global Plastics Treaty and emerging safety regulations, robust methodologies are needed to assess chemical complexity and ensure the safe reuse of recycled plastics. This study introduces an advanced, multi-technique analytical framework to characterize feedstock composition and hazardous contaminants in mixed plastic waste streams (nine samples P1 to P9), including post-consumer, post-commercial, and post-industrial sources, collected from industrial recycling facilities. To mirror the uncertainty that commercial sorters face, waste samples were analysed blind—their polymer identities, fillers, and additives were undisclosed until after testing. Using a comprehensive suite of techniques—Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy, Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Thermogravimetry–mass spectrometry (TG–MS), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), X-ray Fluorescence (XRF), and Ion Chromatography this study identifies dominant polymers (HDPE, LDPE, PP), residual additives, non-intentionally added substances (NIAS), and inorganic contaminants such as chlorine, lead, and transition metals. The results inform tailored recycling strategies, including mechanical recycling for clean streams, pre-treatment for moderately contaminated fractions, and chemical recycling for highly contaminated or chlorine-rich plastics. This paper (Part I) focuses on the comprehensive feedstock characterization and contaminant profiling. A companion paper (Part II) presents a detailed analysis of the pyrolysates generated from these same plastic samples using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC–TOF–MS), with an emphasis on identifying degradation products, additive-derived NIAS, and recyclability-relevant heteroatom compounds. Together, these papers offer an end-to-end understanding of contamination dynamics—from waste input to pyrolysis output—thereby informing safe and circular strategies for plastic recycling. This work provides a replicable model for identifying and mitigating toxicological risks in plastic recycling and supports regulatory compliance with emerging global standards.

Abstract: Chemical recycling of mixed plastic waste can return polymers to fuel- and feedstock-range hydrocarbons, but legacy additives and non-intentionally added substances (NIAS) may persist in the products or leach during use. We investigated six polyolefin-rich wastes (P1–P6) by analytical pyrolysis coupled to comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (Py-GC×GC-TOF-MS) and profiled potential emissions from three consumer-grade plastics (P7–P9) via headspace/solvent-extraction GC–MS and water-migration tests. When the plastics were polysized at 650°C, the resulting pyrolysates are dominated by aliphatic hydrocarbons (C₅–C₃₀): n-paraffins and α-olefins for PE-rich feeds, and branched olefins with modest mono-aromatics for PP. Oxygenates are negligible in non-oxidized feeds but persist at low levels in weather-aged HDPE, consistent with carry-through of pre-existing carbonyls; one aged film (P5) shows an epoxide spike (~5–6 area %). Across oils we identify hallmark NIAS from antioxidant packages (e.g., 2,4-di-tert-butylphenol; Irganox®-1010 spiro-dione) at trace to sub-percent levels, while heavy polycyclic aromatics are not detected above method limits. A 3D GC×GC visualization highlights the dense, resolved hydrocarbon envelope and the minor heteroatom features that guide upgrading targets. VOC/SVOC and leachate analyses (P7–P9) reveal mainly low-intensity hydrocarbons, esters, and fragrance/cosmetic residues; no phthalates were detected in the tested samples, although caprolactam and other additive-related NIAS occur sporadically. Collectively, the results indicate that well-sorted polyolefins yield oils suitable for refining to fuels or monomers, but quality assurance should address oxygenate tails in oxidized PE and antioxidant-derived NIAS.

Abstract: This study investigates the structural and antimicrobial properties of coconut water–derived microcellulose biocomposites incorporated with glycerol, chitosan, and silver nanoparticles. Microcellulose-based films were fabricated as silver nanoparticle–deposited microcellulose (MN), microcellulose–glycerol–silver nanoparticles (MG), microcellulose–chitosan–silver nanoparticles (MChN), and microcellulose–glycerol–chitosan–silver nanoparticles (MGChN). Antimicrobial performance was evaluated against Pseudomonas aeruginosa, Staphylococcus epidermidis, and Candida albicans using inhibition zone assays. The MG and MGChN films exhibited enhanced elasticity compared to MN and MChN, indicating the plasticizing effect of glycerol. Enzymatic hydrolysis using xylanase yielded microcellulose particles with sizes ranging from 1.19 to 2.07 μm and induced a bio-bleaching effect. Among all formulations, MGChN demonstrated the highest antimicrobial activity against P. aeruginosa and S. epidermidis (strong category), as well as moderate antifungal activity against C. albicans. Overall, the synergistic incorporation of glycerol, chitosan, and silver nanoparticles significantly improved the antimicrobial efficacy of coconut water–based microcellulose, underscoring its potential for advanced biomedical polymer applications.

Abstract: The growing environmental impact of petroleum-based plastics has intensified re-search into sustainable, biodegradable alternatives for food packaging. Among bio-derived polymers, carboxymethyl cellulose (CMC) has attracted increasing atten-tion due to its abundance, non-toxicity, biodegradability, and excellent film-forming ability. Nevertheless, the intrinsic hydrophilicity and limited mechanical strength of neat CMC restrict its direct application in packaging systems. This review provides a comprehensive and critical overview of recent strategies developed between 2015 and 2025 to enhance the performance of CMC-based films for food packaging applications. Emphasis is placed on physical and chemical modification routes, including polymer blending, polyelectrolyte complex formation, incorporation of functional fillers and nanomaterials, and ionic or covalent crosslinking approaches. The influence of these strategies on key functional properties, such as mechanical behavior, water barrier performance, antimicrobial and antioxidant activity, is systematically discussed. Par-ticular attention is given to CMC-rich systems, enabling meaningful comparison across studies. By highlighting structure-property relationships and identifying current limi-tations, this review aims to provide guidance for the rational design of advanced CMC-based materials as viable, eco-friendly alternatives to conventional plastic packaging.

Abstract: The current research demonstrates boundaries of waste red seaweed furcellaran (FUR) for development of thermoplastically processable thermoplastic starch (TPS) compositions. Three different FUR concentrations (10, 30 and 50 wt.%) in relation to potato starch replacement were examined for their thermoplastic processability. Thermogravimetric (TGA), differential scanning calorimetry (DSC), rheology and tensile mechanical tests were performed to assess performance of the developed TPS/FUR compositions. It was observed that the highest mechanical stress at break (almost 3 times higher than for neat TPS) is observed for TPS+50wt.% FUR composition, however, on the account of decreased deformability (only ca 10%), reduced thermal resistance at processing temperatures (150oC) as well as high shear sensitivity. Thus compositions TPS+30wt.% FUR and especially TPS+10wt.% FUR are more suitable for thermoplastic processing and development of TPS based composites with improved exploitation properties.

Abstract: The deinking of plastic packaging waste offers the potential of decreasing contamination and thus increasing the overall quality of recycled plastics, enabling their use in more demanding applications. The removal of printing inks from the usually heavily printed flexible polyethylene (PE) plastic films yields transparent flakes that generally allow the recycling into materials with better mechanical properties as well as lower odor and optical defects. However, for flexible PE packaging waste, the deinking is not yet implemented on an industrial scale and there is currently no objective methodology to evaluate the deinking effect on those inhomogeneous flakes. In this study, a novel approach for the objective assessment of the ink removal on flexible post-consumer waste (PCW) is proposed. Via an image-based analysis, the transparency of the flakes is transformed into the 8-bit grey scale, and the calculation of statistical characteristics from these grey value distributions allows to quantifiably compare the deinking efficiency of several experiments. Using this analysis method allows to investigate the general behavior of contaminated PCW materials in deinking and to identify the most effective parameters for ink removal.

Abstract: Fe₂O₃ nanoparticles reinforced in a polymethyl methacrylate (PMMA) matrix structure were synthesized by the melting method. Fe₂O₃ was added in an amount of 2.5% by weight. Mixing times of 6 and 12 minutes were used, and materials with different homogenization properties were produced. In the final section, optimized binary nanocomposites were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM), revealing the strong interaction of the PMMA matrix with nanometal particles. Differential thermal analysis (DTA) was used to determine the thermal behavior of Fe₂O₃-reinforced PMMA nanocomposite. Activation energies of thermal degradation were calculated by using the Kissinger, Takhor, and Augis-Bennett methods. The increasing of the mixing time in the extruder also contributed to material homogenization. In addition, the Fe₂O₃ supplement lowered the polymer degradation temperature and increased the activation energy. Depending on the increasing mixing time, a decrease was observed in the maximum mass loss temperature (Tx) of the samples.

Abstract: Fast-curing polyurethane (PU) systems are attractive for high throughput manufacturing, but quantifying cure kinetics, gelation, and cure-dependent glass transition temperature (Tg) is difficult, especially at low degree of cure (DoC). Here, a fast-reacting BASF PU formulation was studied using non-isothermal differential scanning calorimetry (DSC) at multiple heating rates, rheometry at 50 °C, and molecular dynamics (MD) simulations to extend Tg(α) in the low-DoC regime. DSC provided reaction enthalpy and conversion histories, and Kamal–Sourour (KS) parameters were identified by robust nonlinear fitting, reproducing conversion and curing-rate profiles (R² > 0.99 and > 0.95). Rheology indicated gelation at ~550–600 s (DoC ≈ 0.53), and DSC-based Tg at uncured, gelation, and fully cured states established the experimental Tg trend. MD (LAMMPS) with topological crosslinking and NPT thermal scans extracted Tg from density–temperature slopes at selected DoC points. Experimental and MD Tg data were fused with Gaussian process regression constrained by the DiBenedetto relationship (5-fold cross-validation), giving λ ≈ 0.28 and confidence intervals. This framework links kinetics, gelation, and Tg evolution for fast-curing PU and identifies the low-DoC region as the main source of uncertainty.