Developing efficient mechanical recycling strategies for polyolefins is challenging due to several factors. Firstly, thermo-mechanical degradation during reprocessing and other degradation throughout their service life alters the microstructure of polyolefins, causing a gradual decline in performance. Also, minor cross-contamination in recycled polyolefins is often due to limitations in sorting technologies. These factors lead to recyclates with a complex morphology which restricts their applications. Our work aims to address these issues for high-density polyethylene (HDPE) containing low amounts of polypropylene (PP) and polyethylene terephthalate (PET) as contaminants.

Starting from the typical composition of HDPE bottles, cross-contaminated HDPE-based materials were exposed to photo- and thermo-oxidative ageing treatments. These systems were then reprocessed and analysed to evaluate modifications caused by cross-contamination and degradation, and their impact on the polymers' mechanical properties. Firstly, it was demonstrated that cross-contamination significantly reduces the formation of oxygen-containing functional groups from photo- and thermo-oxidation, particularly in photo-oxidised materials. Furthermore, the addition of polypropylene (PP) and polyethylene terephthalate (PET) led to immiscible blends, with the microstructure being influenced by the specific ageing treatment on the HDPE matrix phase. Notably, the photo-oxidised HDPE sample containing PP and PET exhibited significant morphological alterations driven by ageing and reprocessing, resulting in a more refined morphology compared to the non-aged counterpart. Finally, tensile characterisation results emphasised the critical role of cross-contamination in severely embrittling HDPE, particularly in thermo-oxidised materials. In contrast, the presence of PP and PET has a negligible impact on the ductility of HDPE under photo-oxidative ageing, which is already significantly compromised by degradation.

All-solid-state batteries (ASSBs) have emerged as a promising solution to enhance battery safety by employing solid electrolytes in place of flammable organic electrolytes. However, ASSBs encounter several challenges that limit their practical applications. Silicon (Si) is among the potential negative electrode materials for high-energy-density ASSBs, owing to its specific capacity of approximately 3700 mAh/g. Employing polymer binders is an effective strategy to accommodate the significant volume changes of Si during electrochemical lithiation and delithiation.

Unlike liquid electrolytes, solid electrolytes exhibit a less effective contact interface with active materials. Mixed electronic-ionic conductive (MEIC) polymer binders appear to be a promising solution to mitigate interface issues and the challenge of poor ionic conductivity within electrodes. Cutting-edge approaches to engineering mixed electronic-ionic conductive polymer binders include mixing conjugated polymers with ion-conductive polymers or modifying conjugated polymer backbones by grafting ion-conductive side chains. However, nearly all of these ion-conductive polymers, such as poly(ethylene oxide) (PEO), rely on polymer segmental motions to drive ion diffusion. This ion transport mechanism faces a trade-off between ionic conductivity and mechanical strength. Specifically, it must compromise mechanical strength to enhance ionic conductivity, or vice versa. In addition, the ion transport based on polymer dynamics features low ionic conductivity at room temperature and is highly dependent on temperature. Here, we report a ballistic ion transport mechanism in a MEIC polymer binder, where its hierarchically ordered structure facilitates ion diffusion and achieves solid-state lithium-ion conductivity in the range of 10^-4 to 10^-3 S cm^-1 from -20 to 70 °C. This mechanically robust MEIC polymer is a versatile ionic conductor, allowing Li⁺, Na⁺, or K⁺ to diffuse through polymer matrix, with their cationic charges counterbalanced by electrons on conjugated polymer backbones. Additionally, this ballistic ion transport mechanism results in enhanced cycling performance in ASSBs.

This thesis presents a comprehensive study on the preparation and characterisation of a highly filled metal–polymer composite. The aim of this thesis is to prepare highly filled metal–polymer composites and investigate the effect of filler content on their physical properties. Recycled polyvinyl butyral (PVB) recovered from windshields was used as the matrix material, and two different fillers were used: magnetite iron oxide (FeO・Fe2O3) and manganese–ferrite–zinc oxide (MnO・Fe2O3・ZnO). The composites were prepared by melt blending using a micro-compounder with varying volume percentages of the filler (20, 30, 40, 50 and 60%). Following the preparation of composites in the micro-compounder, the composites were pressed into thin sheets with a dimension of 17mm*15mm*2mm using a heated compression moulding press (hot press). This process was performed for composites with 20, 30, and 40% volume ratios. However, for 50 and 60% volume ratios, a 40% volume ratio composite was initially prepared in the micro-compounder, and the remaining filler was manually added and mixed with the hot press. To determine the effect of the filling ratio on the mechanical properties, tensile testing was performed. Optical microscopy was used to study particle dispersion, along with an examination of the tensile fractured surface. Additionally, magnetic properties such as coercivity, permeability, losses, and maximum polarisation were measured. This study successfully demonstrated that a composite with an up to 60% filling ratio by volume can be achieved using the melt blending technique, without using any compatibilisers or processing aids. Overall, a highly filled polymer–metal composite is a promising class of composites that can find applications in various industries.

Microemulsions are an effective system for administering active compounds in humans. Regarding this topic, one of the challenges is to obtain surfactant-free microemulsions using biocompatible stabilizers, such as chitosan, to avoid the use of conventional surfactants. Currently, most methods used to obtain average droplet sizes are based on techniques supported by high-cost equipment. Therefore, this study aimed to evaluate the dispersion of olive oil in an aqueous medium stabilized by chitosan, as well as to generate particle size distributions from light microscopy images and software (ImageJ and ORIGIN®). Briefly, olive oil and chitosan in acidic aqueous media were vortexed (3200 rpm); afterward, the samples were filtered through filter paper to obtain the final emulsions. Thus, microemulsions with different oil-to-polymer ratios (1:5, 1:10, and 1:15) and different chitosan concentrations (5, 10, and 15 mg/mL) were prepared. To obtain particle sizes, images of emulsion samples at different storage times (1, 24, and 168 h) were acquired using an optical microscope and processed by Digital Image Analysis (DIA) with the ImageJ software. Particle size distributions were generated from different particle sizes of each sample, and their respective graphs were designed in the ORIGIN® software. As shown in the results, 5 min under stirring was a suitable time to obtain microemulsions, and the filtration improved the homogeneity of droplet sizes. Also, it was found that the higher the concentration of chitosan or oil, the greater the number of particles. After 1 h of preparation, particle sizes increased slightly with the chitosan concentration (e.g., from 1.37 to 1.62 µm). The emulsion with 10 mg/mL of polymer (1:10 oil-to-polymer ratio) remained stable for up to one week, irrespective of the type of chitosan. It was concluded that the proposed low-energy method led to the formation of stable surfactant-free microemulsions, and particle size distributions can be generated using a free standard tool.

Artificial nanozymes are gaining prominence as robust alternatives to natural enzymes for catalytic and sensing applications, yet their use is often hindered by poor colloidal stability, inefficient electron transfer, and low catalytic activity under harsh conditions. To address these limitations, we developed a chitosan-imide-functionalized Fe₃O₄ nanocomposite (FeNp-CSNI) via sequential hydrothermal synthesis, polymer grafting, and interfacial assembly. Comprehensive material characterization was carried out using XRD, FTIR, BET, TEM, EIS, and DFT analyses. FeNp-CSNI exhibited a worm-like mesoporous morphology with high surface area, reduced bandgap, and significantly lower charge transfer resistance, suggesting improved electron mobility and catalytic efficiency. The peroxidase-like catalytic activity was assessed by OPD oxidation in the presence of H₂O₂, where hydroxyl radicals were confirmed as the dominant reactive species. Under visible-light irradiation, FeNp-CSNI achieved >95% degradation of crystal violet, demonstrating strong photocatalytic activity. The nanozyme retained ~97% of its catalytic performance over five reuse cycles, indicating high stability. Furthermore, real-sample testing showed accurate and efficient detection of H₂O₂ in milk, with excellent recovery rates, highlighting the nanozyme’s practical potential in biosensing. This work establishes that interfacial engineering of Fe₃O₄ nanoparticles with chitosan-imide substantially enhances both catalytic performance and environmental durability. The FeNp-CSNI nanozyme offers a multifunctional and sustainable platform for biosensing, environmental remediation, and photocatalytic applications, paving the way for future nanozyme-based technologies.

Blending biopolymers is a valuable method with industrial applications for tuning and improving their properties and performance, as single biopolymers often do not exhibit the appropriate properties for numerous durable applications. Furthermore, the properties of biopolymers can be modified by introducing unmodified and modified metal oxides, such as zinc oxide, titanium oxide, copper oxide and silver oxide.

This work involves adding two different blends of biopolymers, either compatible (such as polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT)) or incompatible (such as PLA and polyamide 11 (PA11)), with unmodified and modified zinc oxide and titanium oxide, via melt mixing. The zinc oxide has undergone chemical modification involving the introduction of stearic acid molecules (f-ZnO). Titanium oxide particles were treated with ultrasound to modify them (us-TiO2). Additionally, an acrylate copolymer (EVA-g-AA) has been added in small amounts to improve system compatibility. All the materials have been characterised for their rheological (oscillatory test), morphological (SEM), mechanical (tensile test) and thermal (DSC) behaviour, as well as for their photoxidation resistance (UVB exposure).

Unmodified metal oxides have a reinforcing effect on compatible PLA/PBAT blends, but a less pronounced beneficial effect on incompatible PLA/PA11 blends. The presence of particles significantly influences the blends' rheological and morphological behaviour, acting as a physical compatibiliser. Chemical modification of ZnO and ultrasound treatment of TiO₂ favour the formulation of more compatible blends due to their pronounced compatibilising action. Compatibility is further improved by the presence of the acrylate copolymer. Both unmodified and modified metal oxides promote the photooxidative degradation of blends, as do the more modified oxides.

The transition toward sustainable energy technologies relies heavily on a deep understanding of energy harvesting mechanisms. Among the promising innovations in this field are nanogenerators (NGs)—devices capable of converting mechanical motions from the surrounding environment into electrical energy. Due to their durability and reliable power output, these systems have received increasing attention in recent years. In particular, triboelectric nanogenerators (TENGs), which utilize surface contact-induced charge separation combined with electrostatic induction, are considered highly efficient for transforming mechanical disturbances into electric signals. Despite their potential, a major limitation in TENG development is the relatively low charge transfer density that restricts the overall energy conversion efficiency. Within this context, halide perovskites (HPs) have emerged as a class of materials with exceptional dielectric, piezoelectric, and optoelectronic characteristics, making them suitable for next-generation energy and sensor devices. However, widespread adoption has been limited due to challenges such as instability under ambient conditions and concerns related to lead toxicity.

In the present study, we introduce a lead-free, flexible triboelectric nanogenerator based on a composite film composed of methylammonium tin chloride (CH₃NH₃SnCl₃, i.e., MSC) and poly(methyl methacrylate) (PMMA). The MSC perovskite was synthesized via an antisolvent-assisted collision method, which enhanced crystallinity and material integration. This perovskite was then embedded within a PMMA matrix to improve dielectric properties, thereby enhancing the triboelectric performance of the composite. The optimized composite containing 10 wt% MSC achieved a substantial increase in output, producing a peak voltage of 525 V, a current of 13.6 μA, and a power output of 2.5 mW, surpassing many previously reported perovskite-based TENGs. Additionally, the device demonstrated high pressure sensitivity, recording values of 7.72 V/kPa in voltage sensing and 0.2 μA/kPa in current mode.

Enhancing the thermal stability of plasticized PVC is a critically important task for expanding its practical application areas. The development of eco-friendly modifying additives is a promising direction in this field. Titanium phosphates meet the requirements of green chemistry, and their use in the form of hierarchical microstructured materials contributes to improving material characteristics. Complex esters of adipic acid are widely used as alternative PVC plasticizers that promote increased thermal stability. This study investigates the combined effect of titanium phosphates and diphenoxyethyladipinate on the thermal characteristics of PVC. The thermal stability of PVC compositions was studied using Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) in an oxidative environment (air). The obtained results show an improvement in the thermal characteristics of the compositions compared to the base PVC compound plasticized with dioctyl phthalate (DOP). The key evaluation parameters for the composition are as follows: initial mass loss temperature (Tₒₙ); coke residue; temperature of maximum decomposition rate (Tmax DTG); and temperature of maximum heat flow (Tmax DSC) during the main stage of thermolysis. Increasing the DFEA (diphenoxyethyladipinate) content in the PVC composition from 16 to 49 parts by weight demonstrated improved thermal characteristics. The initial temperature of the sample mass loss indicated a shift of the degradation process towards higher temperatures. The shift in the maximum of the first stage of PVC composition degradation—dehydrochlorination—confirmed a reduction in the rate of thermal degradation of the material. Analysis of DSC data confirmed an increase in the thermal stability of the composition, expressed in an increase in the Tmax DSC value. A PVC composition with improved thermoanalytical characteristics using eco-friendly additives was developed.

In this work, Cu(I) oxide –decorated Polypyrrole nanocomposite (PPy-Cu₂O) was synthesized by in-situ polymerization, and a high- performance NH₃ gas sensing activity was studied along with regioselective synthesis of 1,4-disubstituted-1,2,3- triazoles and 2- (Phenyl)-quinazolin-4(3H)-ones. Cu₂O nanoparticles were synthesized via a green synthesis approach employing Ocimum tenuiflorum leaf extract as a biogenic reducing agent and CuCl₂·2H₂O as the copper precursor. The morphology, composition and chemical state and morphology of the PPy-Cu₂O nanocomposite was characterized by XRD, FTIR, SEM-EDX, TEM and XPS. The UV–Vis optical band gaps of PPy, Cu₂O, and the PPy–Cu₂O nanocomposite were determined to be 3.1 eV, 3.0 eV, and 2.9 eV, respectively. Notably, the PPy–Cu₂O nanocomposite exhibited enhanced NH₃ gas sensing performance, achieving a maximum sensitivity of 52.9% at 500 ppm, compared to 17.3% for pristine PPy. Response times for the nanocomposite at 100, 300, and 500 ppm NH₃ concentrations were 85 s, 70 s, and 60 s, respectively, with corresponding recovery times of 100 s, 120 s, and 135 s. In addition to its sensing capability, PPy–Cu₂O demonstrated catalytic efficiency in the regioselective synthesis of 1,4-disubstituted-1,2,3-triazoles in aqueous medium at room temperature, using both terminal and internal alkynes—without the need for any base, ligand, or reducing agent. Furthermore, the nanocomposite was successfully employed in the synthesis of 2-phenylquinazolin-4(3H)-ones via the condensation of anthranilamide (1 mmol) and 4-methylbenzaldehyde (1.2 mmol) under varied reaction conditions. This work introduces a novel, multifunctional nanocatalyst that offers cost-effective and high-performance NH₃ sensing alongside green synthetic protocols for value-added heterocycles. The study underscores the potential of PPy–Cu₂O as a sustainable platform for both sensing and catalytic applications, demonstrating strong potential for environmental and pharmaceutical applications.

Global pecan nut production is projected to generate USD 3.54 billion by 2033, with a 7.3% CAGR between 2023 and 2033 [1]. In 2024, Mexico accounted for 50–55% of global production, mainly in the states of Chihuahua, Sonora, and Coahuila. Roughly 50% of pecan weight corresponds to the woody shell, representing 1–1.5 million tons of nutshell residue annually, of which more than 60,000 tons per year are produced in Mexico. This positions the country as a key source of raw material for the development of biodegradable materials [2].

Pecan nutshell (PNS) is an abundant agri-food byproduct, rich in lignocellulose and phenolic compounds, which has gained increasing attention for its potential in sustainable material development, particularly in food technology [3]. Research efforts have focused on its valorization through hydroalcoholic extraction, chemical modification, and physical treatments, resulting in materials with enhanced functional properties.

This presentation highlights research progress since 2013 on the use of PNS in polymeric materials for active and biodegradable packaging. Its structural and functional attributes enable the incorporation as a reinforcing agent or bioactive source in polymer systems, improving mechanical strength, barrier performance, and bioactivity.

Overall, PNS emerges as a versatile functional ingredient, aligned with the principles of the circular economy, sustainability, and food safety. Its valorization not only reduces agricultural waste but also supports the transition toward responsible, eco-friendly solutions in the agri-food sector.

[1] https://www.businessresearchinsights.com/market-reports/pecan-nuts-market-117976

[2] https://market.us/report/mexico-pecan-nuts-market/

[3] https://pubs.acs.org/doi/10.1021/acssuschemeng.6b03124