Mario Culebras

• Postdoctoral researcher
• PostDoc Position at University of Limerick

Thermoelectric materials are attracting attention for their ability to convert heat into electricity, traditionally assessed through a figure of merit (ZT) depending on the electrical conductivity, Seebeck coefficient, and thermal conductivity. Developing efficient ionic thermoelectric materials presents challenges as they cannot integrate directly...

Hydrogel materials are continually developing in biomedical engineering and recently a lot of effort has gone into their engineered performance in physiological applications. Porosity is an important characteristic for tissue engineering scaffolds to allow enhanced biocompatibility and the pore size needed is dependent on the application and type o...

Conventional fertilizers face environmental and economic challenges due to their high solubility, leading to significant losses via runoff and leachate. This study presents a biodegradable hydrogel, synthesized from lignin and polyvinyl alcohol (PVA), designed as an eco-friendly carrier for struvite (fertilizer) with controlled phosphate release. T...

Converting waste heat from solar radiation and industrial processes into useable electricity remains a challenge due to limitations of traditional thermoelectrics. Ionic thermoelectric (i-TE) materials offer a compelling alternative to traditional thermoelectrics due to their excellent ionic thermopower, low thermal conductivity, and abundant mater...

The development of wearable thermoelectric generators (wTEG) represents a promising strategy to replace batteries and supercapacitors required to supply electrical energy for portable electronic devices. However, the main drawback of wTEGs is that the thermal gradient between the skin and the ambient is minimal, reducing the power output produced b...

Hydrogels are of great importance in biomedical engineering. They possess the ability to mimic bodily soft tissues, and this allows exciting possibilities for applications such as tissue engineering, drug delivery and wound healing, however much work remains on stability and mechanical robustness to allow for translation to clinical applications. T...

The efficient and economical conversion of low-grade waste heat into electricity has promising potential to combat the greenhouse effect and expedite the shift towards sustainable development. This study presents an innovative and appealing approach through the utilization of lignin, an abundant waste product derived from the paper and pulp industr...

In the accompanying supporting information file linked to our groundbreaking article, "Highly‑efficient sustainable ionic thermoelectric materials using lignin‑derived hydrogels," we provide a comprehensive exploration of our research through various key analyses. The file encompasses detailed material characterizations, shedding light on the uniqu...

In this study, we have improved the power factor of conductive polymer nanocomposites by combining layer-by-layer assembly with electrochemical deposition to produce flexible thermoelectric materials based on PEDOT/carbon nanotubes (CNTs)-films. To produce films based on CNTs and PEDOT, a dual approach has been employed: (i) the layer-by-layer meth...

The use of carbon fibre (CF)-based composites is of growing global importance due to their application in high-end sectors such as aerospace, automotive, construction, sports and leisure amongst others. However, their current high production cost, high carbon footprint and reduced production capability limit their use to high-performance and luxury...

Lignin-derived porous carbons have great potential for energy storage applications. However, their traditional synthesis requires highly corrosive activating agents in order to produce porous structures. In this work, an environmentally friendly and unique method has been developed for preparing lignin-based 3D spherical porous carbons (LSPCs). Dro...

This work focuses on the encapsulation of two organic phase change materials (PCMs), hexadecane and octadecane, through the formation of nanocapsules of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) obtained by oxidative polymerization in miniemulsion. The energy storage capacity of nanoparticles is studied by preparing polymer fi...

The use of wearable devices has promoted new ways of integrating these devices, one of which is through the development of smart textiles. Smart textiles must possess the mechanical and electrical properties necessary for their functionality. This study explores the impact of polymer-felt microstructure variations on their morphology, electrical, a...

The use of carbon fibre (CF) based composites is of growing global importance due to their applications in high end sectors such aerospace, automotive, construction, sports and leisure amongst others. It is forecast that composites will reach a global market value of $131.6 bn by 2024. However, their current high production cost, high carbon footpr...

Peripheral nerve injury (PNI) often clinically relies on the use of nerve grafts taken from the patient to establish a therapeutic effect, though secondary site of injury and morbidity have prompted the medical community to find alternative solutions. A new trend in the development of biomaterials arises in the form of electro-conductive biomateria...

Electrically conductive bio-scaffolds are explored in the field of tissue engineering (TE) as a solution to address the clinical need of electroactive tissues, finding applications in nervous, cardiac, and spinal cord injury repair. In this work, we synthesise polypyrrole nanoparticles (PPy NP) via the mini-emulsion method with further combination...

Intrinsically conductive polymers are considered as one of the most promising candidates for thermoelectric (TE) materials due to their outstanding properties. Prior studies have been primarily focused on conducting polymers such as polyaniline, polypyrrole, polythiophene, and poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS). In...

Thermoelectric (TE) materials have been considered as a promising energy harvesting technology for sustainably providing power to electronic devices. In particular, organic-based TE materials that consist of conducting polymers and carbon nanofillers make a large variety of applications. In this work, we develop organic TE nanocomposites via succes...

Segmented thermoplastic polyurethanes (PU) were synthetized using a polycarbonatediol macrodiol as a flexible or soft segment with a molar mass of 2000 g/mol, and different diisocyanate molecules and 1,4-butanediol as a rigid or hard segment. The diisocyanate molecules employed are 3,3′-Dimethyl-4,4′-biphenyl diisocyanate (TODI), 4,4′-diphenylmetha...

The development of wearable technology has promoted the research of new power supply sources to feed wearable devices without the need of batteries. Wearable thermoelectric generators (wTEGs) can generate energy using the thermal gradient between the human body and the ambient temperature. The most comfortable way to adapt wTEGs to the human body i...

Tissue engineering (TE) has been proposed extensively as a potential solution to the worldwide shortages of donor organs needed for transplantation. Over the years, numerous hydrogel formulations have been studied for various TE endeavours, including bone, cardiac or neural TE treatment strategies. Amongst the materials used, organic and biocompati...

Electrically conductive bio-scaffolds are being explored in the field of tissue engineering (TE) as a solution to address the clinical need of electroactive tissues, finding applications in nervous, cardiac, and spinal cord injury repair. In this work, we synthesise polypyrrole nanoparticles (PPy NP) via the mini-emulsion method with further combin...

Background Hostile environment around the lesion site following spinal cord injury (SCI) prevents the re-establishment of neuronal tracks, thus significantly limiting the regenerative capability. Electroconductive scaffolds are emerging as a promising option for SCI repair, though currently available conductive polymers such as polymer poly(3,4-eth...

Lignin is produced in large quantities as a by-product of the papermaking and biofuel industries. Lignin is the most abundant aromatic biopolymer on the planet with its chemical structure rendering it ideal for carbon materials production and finely tailored architectures of these sustainable carbon materials are beginning to find use in high value...

The processability of organic thermoelectric materials plays a crucial role due to their clear advantages of applicability in large-scale areas compared to traditional inorganic counterparts. A promising way to process thermoelectric materials based on conductive polymers is through in situ polymerization in an insulating polymer matrix. This work...

Curcumin is a known naturally occurring anti-inflammatory agent derived from turmeric, and it is commonly used as a herbal food supplement. Here, in order to overcome the inherent hydrophobicity of curcumin (Cur), polylactic acid (PLA) nanoparticles (NPs) were synthesised using a solvent evaporation, and an oil-in-water emulsion method used to enca...

Sustainable materials are attracting a lot of attention since they will be critical in the creation of the next generation of products and devices. In this study, hydrogels were effectively synthesized utilizing lignin, a non-valorised biopolymer from the paper industry. This study proposes a method based on utilizing lignin to create highly swolle...

Cellulose, an abundant natural polymer, has promising potential to be used for energy storage systems because of its excellent mechanical, structural, and physical characteristics. This review discusses the structural features of cellulose and describes its potential application as an electrode, separator, and binder, in various types of high-perfo...

In the design of injectable antimicrobial dextran-alginate hydrogels, the impact of dextran oxidation and its subsequent changes in molecular weight and the incorporation of glycol chitosan on (i) gel mechanical strength and (ii) the inhibitory profile of an encapsulated bacteriocin, nisin A, are explored. As the degree of oxidation increases, the...

Background Hostile environment around the lesion site following spinal cord injury (SCI) prevents the re-establishment of neuronal tracks, thus significantly limiting the regenerative capability. Electroconductive scaffolds are emerging as a promising option for SCI repair, though currently available conductive polymers such as polymer poly(3,4-eth...

In recent years, the use of organic materials to infer conductivity in biomedical devices has received increasing attention. Typical inorganic semiconductors and conductors are rigid and expensive, usually require multiple processing steps and are unsuitable for biomedical applications. Electrochemically or chemically doped conjugated polymers help...

Polyelectrolyte multilayer thin films, assembled by sequentially depositing bilayer (BL) of poly(allyamine hydrochloride) (PAH) and double-walled carbon nanotubes (DWNT) stabilized in polyacrylic acid (PAA) using the layer-by-layer assembly technique, are studied in an effort to establish the relationships between the conformational changes and the...

Stimulating brain tissue regeneration is a major challenge after central nervous system (CNS) injury, such as those observed from trauma or cerebrovascular accidents. Full regeneration is difficult even when a neurogenesis-associated repair response may occur. Currently, there are no effective treatments to stimulate brain tissue regeneration. Howe...

The global composites market size is projected to grow from USD 90.6 billion in 2019 to USD 131.6 billion by 2024, and this is attributed to the rising demand for lightweight high-performance advanced materials. Carbon fiber (CF)-reinforced polymers are considered strategic materials for important sectors of our society (aeronautical, automotive an...

Due to the increasing energy demand and public awareness of climate change and environmental problems, sustainable energy development has become one of the most strategic areas of research. In this work, a hybrid layered thermoelectric material is produced, which consists of the combination of poly(3,4-ethylenedioxythiophene) (PEDOT) and tin sulfid...

Hyaluronic acid (HA) is a glycosaminoglycan that is found in extracellular tissue in many parts of the body. It is a material of increasing importance to biomaterial science and is finding applications in diverse areas ranging from tissue culture scaffolds to cosmetic materials. This chapter considers the recent research on the role of HA in tissue...

Biofilm-related infections and contamination of biomaterials are major problems in the clinic. These contaminations are frequently caused by Staphylococcus aureus and are a pressing issue for implantable devices, catheters, contact lenses, prostheses, and wound dressings. Strategies to decrease contamination and biofilm related infections are vital...

Nowadays, sustainable materials are receiving significant attention due to the fact that they will be crucial for the development of the next generation of products and devices. In the present work, hydrogels have been successfully synthesized using lignin which is non-valorized biopolymer from the paper industry. Hydrogels were prepared via crossl...

Shortages of organs and damaged tissues for transplantation have prompted improvements in biomaterials within the field of tissue engineering (TE). The rise of hybrid hydrogels as electro-conductive biomaterials offers promise in numerous challenging biomedical applications. In this work, hybrid printable biomaterials comprised of alginate and gela...

Wood (cellulose and lignin)-based hydrogels were successfully produced as platforms for drug-release systems. Viscoelastic and cross-linking behaviors of precursor solutions were tuned to produce highly porous hydrogel architectures via freeze-drying. Pore sizes in the range of 100–160 μm were obtained. Varying lignin molecular structure played a k...

A sustainable glucose sensor was developed from lignin-based carbon nanofibres with hierarchical porosity.

Due to ever increasing public awareness of the deteriorating planetary health condition associated with climate change and increasing carbon emissions, sustainable energy development has come sharply into focus. Here, a thermoelectric material is produced, which consists of macroscopic carbon nanotube yarns (CNTYs) produced continuously from the ga...

Energy harvesting through residual heat is considered one of the most promising ways to power wearable devices. In this work, thermoelectric textiles were prepared by coating the fabrics, first with multiple-wall carbon nanotubes (MWCNTs) by using the layer-by-layer technique, and second with poly(3,4-ethylenedioxythiophene) (PEDOT) deposited by el...

Here, we synthesise a new isocyanate-based crosslinker with the aim of obtaining novel tailored gels. The newly crosslinked hyaluronic acid (HA) gels were analysed in terms of rheological properties, chemical structure, swelling, biocompatibility and immunological response. Results show that the synthesised di-isocyanate outperforms other more conv...

The relaxation behavior of two lignins (Alcell organosolv, OSL, and hydroxypropyl modified Kraft, ML) and bio-based thermoplastic polyurethane (TPU) blends have been studied by Differential Scanning Calorimetry (DSC), Dynamic-Mechanical Analysis (DMA) and Dielectric Relaxation Spectroscopy (DRS). The effect of blending on the glass and local relaxa...

Hybrid thermoelectric flexible films based on poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles and carbon nanotubes were prepared by using layer-by-layer (LbL) assembly. The employed PEDOT nanoparticles were synthesized by oxidative miniemulsion polymerization by using iron(III) p-toluenesulfonate hexahydrate (FeTos) as an oxidant and poly(di...

Synthesis of n-type organic semiconductors is challenging as reduced states are difficult to obtain due to their instabil-ity in air. Here, we report tailoring of semiconducting behavior through control of surfactant concentration during synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles. Nanoparticles were synthesized by mini-emul...

Development of cost‐effective and increasingly efficient sustainable materials for energy‐storage devices, such Li‐ion batteries, is of crucial future importance. Herein, the preparation of carbon nanofibres from biopolymer blends of lignin (byproduct from the paper and pulp industry) and polylactic acid (PLA) or a thermoplastic elastomeric polyure...

Biobased poly(ethylene terephthalate) has been successfully blended with isopropyl alcohol fractioned hardwood organosolv lignin. The blend compatibility was analysed using Gibbs free energy calculation and confirmed by glass transition temperature measurements as well as morphological study. The obtained carbon fibres from this blend displayed a t...

The influence of lignin modification on drug release and pH-dependent releasing behavior of oral solid dosage forms was investigated using three different formulations. The first formulation contains microcrystalline cellulose (MCC 101) as the excipient and paracetamol as the active pharmaceutical ingredient (API). The second formulation includes A...

The influence of lignin modification on drug release and pH-dependent releasing behaviour of oral solid dosage form was investigated using three different formulations. The first formulation contains microcrystalline cellulose (MCC101) as excipient and paracetamol as active pharmaceutical ingredient (API). The second formulation includes Alcell lig...

As fossil fuel resources dwindle and new regulations for a cleaner and safer environment come on stream, there is growing interest in developing new sustainable feedstocks for future fuels, chemicals, polymers and fibers. Therefore materials research is ever more focused on the production of green or bio-based materials and their composites. Lignoc...

Developing sustainable and efficient thermoelectric materials is a challenge because the most common thermoelectric materials are based on rare elements such as bismuth and telluride. In this context, we have produced bio-based carbon nanofibres (CNFs) derived from mixtures of polyacrylonitrile and lignin using electrospinning. The addition of lign...

Environmental energy issues caused by the burning of fossil fuel such as coal, and petroleum, and the limited resources along with the increasing world population pose a world-wide challenge. Alternative energy sources including solar energy, wind energy, and biomass energy, have been suggested as practical and affordable solutions to future energy...

Artificial Metals are polymeric semi-metallic composites obtained by combining thermosetting resins with atomized metal powders in order to achieve composite materials capable of reproducing metals, even in a rusty or corroded condition. These composites provide a solution for the reproduction of archaeological artefacts, sculptures, and ornaments...

The synthesis of conducting polymer nanoparticles by oxidative polymerization can be a challenge, because the addition of oxidizers may compromise the colloidal stability of the system. In this work, we report the successful synthesis poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles by means of miniemulsion polymerization. We study the role o...

Understanding the thermal behaviour of lignin is crucial in order to realise its valorisation as an engineering polymer. Two hardwood lignins, organosolv (OSL) and chemically modified kraft lignin (ML) have...

The production of carbon fibers based on lignin reduces the cost and the environmental impact associated with carbon fiber manufacture. However, the melt processing of lignin as a carbon fiber precursor is challenging due to its brittleness and limited thermoplastic behavior. For this reason we produce biopolymer blends based on Alcell organosolv h...

This cover from Mario Culebras and colleagues shows an SEM image taken from the surface of an electrode composed by sodium alginate (5%) as a binder, carbon black (1%) as conductive material and graphite (94%) as active material. Sodium alginate plays an important role during the film formation keeping all the particles stable in the suspension. Af...

Currently, the most widely used binder in batteries is polyvinylidene fluoride with N-methyl-2-pyrrolidone used as a solvent. This solvent is flammable and toxic. Here, we focus on the suitability of using water-soluble sodium alginate (Na-alginate) and sodium carboxymethyl cellulose (Na-CMC) as alternative biobased binder materials for the anodes...

Las reproducciones de piezas arqueológicas cumplen una necesaria función en nuestras sociedades en tanto permiten una multiplicidad inducida del original, que redunda en beneficios para la conservación, divulgación y promoción de nuestro patrimonio. La reproducción de objetos metálicos ha supuesto un desafío para las instituciones museísticas, dada...

Reproductions of archaeological artefacts play a necessary role in our societies while allowing an induced multiplicity of the original, which supposes benefits for conservation, dissemination and promotion of our heritage. But the reproduction of metal objects has been a challenge for museums and institutions, due to the complexity of emulating me...

In this work, flexible Te films have been synthesized by electrochemical deposition using PEDOT [Poly(3,4-ethylenedioxythiophene)] nano-films as working electrodes. The Te electrodeposition time was varied in order to find the best thermoelectric properties of the Te/PEDOT double layers. In order to show the high quality of the Te films grown on PE...

Broadband Dielectric Relaxation Spectroscopy was performed to study the molecular dynamics of dried Bacterial Cellulose/Carboxymethyl Cellulose-Graphene Oxide (BC/CMC-GO) composites as a function of the concentration of CMC in the culture media. At low temperature the dielectric spectra are dominated by a dipolar process labelled as a β-relaxation,...

In an effort to produce effective thermoelectric nanocomposites with multiwalled carbon nanotubes (MWCNT), layer-by-layer assembly was combined with electrochemical polymerization to create synergy that would produce a high power factor. Nanolayers of MWCNT stabilized with poly(diallyldimethylammonium chloride) or sodium deoxycholate were alternate...

Organic materials are becoming a realistic roadway to fabricate efficient thermoelectric devices using environmental friendly materials. Such requirements are actually fulfilled by thermoelectric generators operating by conducting polymers, but also by hybrid materials. The combination of organic + inorganic compounds may exhibit a high electrical...

A three dimensional (3D) structure of poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires have been prepared by electrochemical polymerization using 3D-alumina templates. The templates were synthesized by pulse anodization in an electrochemical bath. A 3D free standing network has been obtained after the template removal. The morphological analysis...

High power factor n-type organic thermoelectric nanocomposites are assembled by alternately depositing double walled-nanotubes (DWNT), stablilized by polyethyleneimine (PEI), and graphene stabilized by polyvinylpyrrolidone (PVP), from water using the layer-by-layer (LbL) assembly technique. This unique combination of carbon nanomaterials exhibits a...

In this work, we present a method to develop organic thermoelectric modules by means of electrochemical polymerization using exclusively a p‐type material. The polymer device is built in a planar geometry, with the advantage that it is not necessary to incorporate a heat sink. The method is scalable to an industrial process and it can be the key fo...

In this work, we have developed a thermal sensor based on poly(3,4 ethylenedioxythiophene) (PEDOT) nanofilms as thermoelectric material. The PEDOT nanofilms have been synthesized by the electrochemical polymerization method. The thicknesses of the films were around 120 nm. The doping level of PEDOT was controlled by chemical reduction using hydrazi...

The paper reports the crucial role of the morphology of poly(3,4-ethylenedioxythiophene) (PEDOT) nanostructures on the thermal and dielectric properties of polymer blends prepared thereof. PEDOT nanostructures with two different morphologies (nanoparticles and nanowires) were synthesized. The size for the nanoparticles was in the range 10-40 nm and...

Poly-L-lysine and collagen were separately added to bacterial cellulose (BC) nanofibers. The ionic surface charge had been previously modified in order to promote the adsorption of poly-L-lysine and collagen. Cell adhesion of Chinese hamster ovary (CHO) cells on BC surfaces was confirmed by removing unattached cells from the BC substrates. Cell via...

Poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy) films have been prepared by an electrochemical method in a three electrode cell. The films have been obtained at different oxidation levels regarded as bipolaron, polaron and neutral states by varying the voltage, as it is usually done in conjugated heterocyclic polymers. The voltage (-...

Conductive polymer composites of segmented polycarbonatediol polyurethane (PUPH) and expanded graphite (EG) have been synthesized with different amounts of EG conductive filler (from 0 to 50 wt%). SEM, X-ray diffraction measurements, FTIR and Raman Spectroscopies demonstrated a homogeneous dispersion of the EG filler in the matrix. The dielectric p...

The dielectric relaxation behavior of segmented polyurethane has been studied using Broad-Band Dielectric Spectroscopy in the frequency domain, 10−2 to 108 Hz, and in the temperature range of −120 to 140°C. The spectra show three secondary processes (δ, γ, and β) followed by the α relaxation and conductive processes. The Havriliak-Negami (HN) pheno...