Teacher for Green Chemistry (KZ4101), BSc level.

Examiner for Chemistry of Renewable Materials (KZ8022), course in the MSc programme in Sustainable Chemistry.

Examiner for Advanced Materials Chemistry (KZ44019), PhD level.

The research focus areas:

• Valorization of industrial side-streams and residues
• Functional materials based on macromolecular lignin
• Lignin nanoparticles and their applications
• Polyphenols in biological systems

Research Areas

We are working on the following research areas and projects:

Materials for a sustainable society

Materials for energy

SUSLIG: Lignin-based functional materials for a sustainable future, SSF, 2022-2028

LignoLife: WAF-project 2025-2030

Materials for environment

LIFAGRO: (Research projects for early-career researchers, Formas 2021-2025)

Materials for health

FORFUN: From Forest to Functional Particles for Life Sciences, Vinnova 2023-2026

Synthesis and processing methods for sustainable materials

Green material synthesis

LIGNOMEMB: Biocatalytic membranes based on lignin nanoparticles (Starting Grant, Vetenskapsrådet, 2021-2025)

SUSLIG: Lignin-based functional materials for a sustainable future, SSF, 2022-2028

CIRCULIG: Circular lignin materials from well-defined functional building blocks, ERC, 2023-2028

Biobased materials processing

BarkBuild: Tree bark as a renewable source of wood protection materials for building applications (ERA-NET ForestValue, 2022-2025)

UPSIDEHYB: Upcycling food industry side streams into functional organic-inorganic hybrid materials, WISE, 2023-2027

Research Group members

Mika Sipponen, PI

Ievgen Pylypchuk, Researcher

Mirva Eriksson, Researcher

Federica Ferruti, Researcher

Alberto José Huertas Alonso, Postdoctoral Fellow

Linnea Cederholm, Postdoctoral Fellow

Alexandros Alexakis, Postdoctoral Fellow

Ioanna Sapouna, Postdoctoral Fellow

Mahmoud Mazarji, MSCA Postdoctoral Fellow

Unnimaya Thalakkale Veettil, PhD Student

Matilda Andersson, PhD Student

Fengyang Wang, PhD Student

Sukaina Ben Taleb Ikutza, PhD student

Yasmini Portes Abraham Silva, PhD student

Giulia Piciullo, PhD student

Carla Caponio, PhD student

Prajakta Narhari Manal, PhD student

Vu Thanh Truong, PhD student

Ruslan Gryaznov, PhD student

Siri Talme, PhD student

Selected publications

Adrian Moreno,* Mika H. Sipponen,  Overcoming Challenges of Lignin Nanoparticles: Expanding Opportunities for Scalable and Multifunctional Nanomaterials. Acc. Chem. Res. 2024, https://doi.org/10.1021/acs.accounts.4c00206.

Yong Zheng, Adrian Moreno, Yiqi Zhang, Mika H. Sipponen,* Lin Dai* Harnessing chemical functionality of lignin towards stimuli-responsive materials Trends Chem. 2024, https://doi.org/10.1016/j.trechm.2023.12.001.

Tardy, B.L., Lizundia, E.,* Chamseddine, G., Hakkarainen, M., Sipponen, M.H.* Prospects for the integration of lignin materials into the circular economy. Materials Today 2023, https://doi.org/10.1016/j.mattod.2023.04.001.

Moreno, A.,* Morsali, M., Sipponen, M.H.* Catalyst-Free Synthesis of Lignin Vitrimers with Tunable Mechanical Properties: Circular Polymers and Recoverable Adhesives. ACS Appl. Mat. Interf. 13, 2021, 57952-57961.

Moreno, A.,* Liu, J., Gueret, R., Hadi, S.E., Bergström, L., Slabon, A., Sipponen, M.H.* Unravelling the Hydration Barrier of Lignin Oleate Nanoparticles for Acid‐and Base‐Catalyzed Functionalization in Dispersion State. Angewandte Chemie Int. Ed. 60, 2021, 20897-20905 (Hot Paper)

A. Moreno, M. Morsali, J. Liu, M. H. Sipponen,* Access to Tough and Transparent Nanocomposites via Pickering Emulsion Polymerization using Biocatalytic Hybrid Lignin Nanoparticles as Functional Surfactants. Green Chemistry 23, 2021, 3001-3014.

A. Moreno,* M. H. Sipponen,* Biocatalytic Nanoparticles for the Stabilization of Degassed Single Electron Transfer Living Radical Pickering Emulsion Polymerizations. Nature Communications 11, 2020: 5599.

A. Moreno, M. H. Sipponen,* Lignin-based smart materials: a roadmap to processing and synthesis for current and future applications. Materials Horizons 7, 2020, 2237.

A selection from Stockholm University publication database

• Access to tough and transparent nanocomposites via Pickering emulsion polymerization using biocatalytic hybrid lignin nanoparticles as functional surfactants dagger

  2021. Adrian Moreno (et al.). Green Chemistry 23 (8), 3001-3014

  Article

  Weak interfacial binding of lignin within synthetic polymer composites results in unsatisfactory mechanical properties that limit their application prospects. In the present work, polystyrene (PS) and poly(butyl methacrylate) (PBMA) nanocomposites containing lignin nanoparticles (LNPs) are produced by simple melting of polymeric latex dispersions obtained from free radical polymerization of oil-in-water Pickering emulsions stabilized by hybrid LNPs coated with chitosan and glucose oxidase. Owing to the formation of viscous polymer melts, the hybrid LNPs ended up uniformly dispersed within the polymeric matrices, which gave the polymeric nanocomposites markedly improved tensile strength without sacrificing their elasticity in comparison to pure PS and PBMA. Consequently, the composites reinforced with 15 wt% of the hybrid particles showed improvement in toughness by a factor of 3.5 and 15 compared to those of the corresponding pristine PS and PBMA. In addition, the presence of the hybrid particles conferred the nanocomposites with commendable UV-blocking and antioxidant properties which are relevant for protective packaging and coating applications. Overall, our results show a new and green route with excellent material economy (overall mass yield up to 91%) to obtain strong and transparent polymeric nanocomposites reinforced with up to 30 wt% of LNPs, which is expected to attract renewed interest in lignin-polymer composites for a broad range of applications.

  Read more about Access to tough and transparent nanocomposites via Pickering emulsion polymerization using biocatalytic hybrid lignin nanoparticles as functional surfactants dagger

• Multifunctional lignin-based nanocomposites and nanohybrids

  2021. Erlantz Lizundia (et al.). Green Chemistry 23 (18), 6698-6760

  Article

  Significant progress in lignins valorization and development of high-performance sustainable materials have been achieved in recent years. Reports related to lignin utilization indicate excellent prospects considering green chemistry, chemical engineering, energy, materials and polymer science, physical chemistry, biochemistry, among others. To fully realize such potential, one of the most promising routes involves lignin uses in nanocomposites and nanohybrid assemblies, where synergistic interactions are highly beneficial. This review first discusses the interfacial assembly of lignins with polysaccharides, proteins and other biopolymers, for instance, in the synthesis of nanocomposites. To give a wide perspective, we consider the subject of hybridization with metal and metal oxide nanoparticles, as well as uses as precursor of carbon materials and the assembly with other biobased nanoparticles, for instance to form nanohybrids. We provide cues to understand the fundamental aspects related to lignins, their self-assembly and supramolecular organization, all of which are critical in nanocomposites and nanohybrids. We highlight the possibilities of lignin in the fields of flame retardancy, food packaging, plant protection, electroactive materials, energy storage and health sciences. The most recent outcomes are evaluated given the importance of lignin extraction, within established and emerging biorefineries. We consider the benefit of lignin compared to synthetic counterparts. Bridging the gap between fundamental and application-driven research, this account offers critical insights as far as the potential of lignin as one of the frontrunners in the uptake of bioeconomy concepts and its application in value-added products.

  Read more about Multifunctional lignin-based nanocomposites and nanohybrids

• Solvent-Resistant Lignin-Epoxy Hybrid Nanoparticles for Covalent Surface Modification and High-Strength Particulate Adhesives

  2021. Tao Zou (et al.). ACS Nano 15 (3), 4811-4823

  Article

  Fabrication of spherical lignin nanoparticles (LNPs) is opening more application opportunities for lignin. However, dissolution of LNPs at a strongly alkaline pH or in common organic solvent systems has prevented their surface functionalization in a dispersion state as well as processing and applications that require maintaining the particle morphology under harsh conditions. Here, we report a simple method to stabilize LNPs through intraparticle cross-linking. Bisphenol A diglycidyl ether (BADGE), a cross-linker that, like lignin, contains substituted benzene rings, is coprecipitated with softwood Kraft lignin to form hybrid LNPs (hy-LNPs). The hy-LNPs with a BADGE content <= 20 wt % could be intraparticle cross-linked in the dispersion state without altering their colloidal stability. Atomic force microscopy and quartz crystal microbalance with dissipation monitoring were used to show that the internally crosslinked particles were resistant to dissolution under strongly alkaline conditions and in acetone-water binary solvent that dissolved unmodified LNPs entirely. We further demonstrated covalent surface functionalization of the internally cross-linked particles at pH 12 through an epoxy ring-opening reaction to obtain particles with pH-switchable surface charge. Moreover, the hy-LNPs with BADGE content >= 30% allowed both inter- and intraparticle cross-linking at >150 degrees C, which enabled their application as waterborne wood adhesives with competitive dry/wet adhesive strength (5.4/3.5 MPa).

  Read more about Solvent-Resistant Lignin-Epoxy Hybrid Nanoparticles for Covalent Surface Modification and High-Strength Particulate Adhesives

• Unravelling the Hydration Barrier of Lignin Oleate Nanoparticles for Acid- and Base-Catalyzed Functionalization in Dispersion State

  2021. Adrian Moreno (et al.). Angewandte Chemie International Edition 60 (38), 20897-20905

  Article

  Lignin nanoparticles (LNPs) are promising renewable nanomaterials with applications ranging from biomedicine to water purification. However, the instability of LNPs under acidic and basic conditions severely limits their functionalization for improved performance. Here, we show that controlling the degree of esterification can significantly improve the stability of lignin oleate nanoparticles (OLNPs) in acidic and basic aqueous dispersions. The high stability of OLNPs is attributed to the alkyl chains accumulated in the shell of the particle, which delays protonation/deprotonation of carboxylic acid and phenolic hydroxyl groups. Owing to the enhanced stability, acid- and base-catalyzed functionalization of OLNPs at pH 2.0 and pH 12.0 via oxirane ring-opening reactions were successfully performed. We also demonstrated these new functionalized particles as efficient pH-switchable dye adsorbents and anticorrosive particulate coatings.

  Read more about Unravelling the Hydration Barrier of Lignin Oleate Nanoparticles for Acid- and Base-Catalyzed Functionalization in Dispersion State

• Biocatalytic nanoparticles for the stabilization of degassed single electron transfer-living radical pickering emulsion polymerizations

  2020. Adrian Moreno, Mika H. Sipponen. Nature Communications 11 (1)

  Article

  Synthetic polymers are indispensable in many different applications, but there is a growing need for green processes and natural surfactants for emulsion polymerization. The use of solid particles to stabilize Pickering emulsions is a particularly attractive avenue, but oxygen sensitivity has remained a formidable challenge in controlled polymerization reactions. Here we show that lignin nanoparticles (LNPs) coated with chitosan and glucose oxidase (GOx) enable efficient stabilization of Pickering emulsion and in situ enzymatic degassing of single electron transfer-living radical polymerization (SET-LRP) without extraneous hydrogen peroxide scavengers. The resulting latex dispersions can be purified by aqueous extraction or used to obtain polymer nanocomposites containing uniformly dispersed LNPs. The polymers exhibit high chain-end fidelity that allows for production of a series of well-defined block copolymers as a viable route to more complex architectures.

  Read more about Biocatalytic nanoparticles for the stabilization of degassed single electron transfer-living radical pickering emulsion polymerizations

• Identifying the primary reactions and products of fast pyrolysis of alkali lignin

  2020. Supriyanto Supriyanto (et al.). Journal of Analytical and Applied Pyrolysis 151

  Article

  This study focused on the effect of temperature and residence time on the primary thermal decomposition reactions during a fast pyrolysis of softwood alkali lignin. The use of Py-GC/MS/FID (Micropyrolyser-Gas Chromatography/Mass Spectrometry/Flame Ionization Detector) allowed for rapid heating of the sample and detailed identification and quantification of the pyrolysis products at a temperature range of 400-600 degrees C, with residence times from 0.5-5 s. The identified primary pyrolysis products were mainly volatile guaiacyl-type compounds. There was a general increase in yield for the majority of the volatile compounds with increased temperature and time. The cleavage of the lignin polymer to linear carbonyl (acetaldehyde) and guaiacyl-type aromatic compounds increased with temperature, while that of catechol and cresol type was mainly favoured at 500 and 600 degrees C. Based on these results, a mechanistic pathway for the pyrolytic process was proposed, drawing a linkage from structural units of lignin to the formed primary products. In summary, our findings suggest that the primary decomposition reactions that occur under the fast pyrolysis conditions can be controlled by varying the process temperature and residence time, and deliver mechanistic insight into the product distribution from structurally complex lignin material.

  Read more about Identifying the primary reactions and products of fast pyrolysis of alkali lignin

• Lignin-Inorganic Interfaces

  2020. Tetyana M. Budnyak, Adam Slabon, Mika H. Sipponen. ChemSusChem 13 (17), 4344-4355

  Article

  Lignin is one the most fascinating natural polymers due to its complex aromatic‐aliphatic structure. Phenolic hydroxyl and carboxyl groups along with other functional groups provide technical lignins with reactivity and amphiphilic character. Many different lignins have been used as functional agents to facilitate the synthesis and stabilization of inorganic materials. Herein, the use of lignin in the synthesis and chemistry of inorganic materials in selected applications with relevance to sustainable energy and environmental fields is reviewed. In essence, the combination of lignin and inorganic materials creates an interface between soft and hard materials. In many cases it is either this interface or the external lignin surface that provides functionality to the hybrid and composite materials. This Minireview closes with an overview on future directions for this research field that bridges inorganic and lignin materials for a more sustainable future.

  Read more about Lignin-Inorganic Interfaces

• Lignin-based smart materials

  2020. Adrian Moreno, Mika H. Sipponen. Materials Horizons 7 (9), 2237-2257

  Article

  Biomass-derived materials are green alternatives to synthetic plastics and other fossil-based materials. Lignin, an aromatic plant polymer, is one of the most appealing renewable material precursors for smart materials capable of responding to different stimuli. Here we review lignin-based smart materials, a research field that has seen a rapid growth during the last five years. We describe the main processing and chemical synthesis routes available for the fabrication of lignin-based smart materials, and focus on their use as sensors, biomedical systems, and shape-programmable materials. In addition to benchmarking their performance to the state of the art fossil counterparts, we identify challenges and future opportunities for the development of lignin-based smart materials towards new high-performance applications.

  Read more about Lignin-based smart materials

• Well-Defined Lignin Model Films from Colloidal Lignin Particles

  2020. Muhammad Farooq (et al.). Langmuir 36 (51), 15592-15602

  Article

  The transformation of a molecularly complex and irregularly shaped lignin into a nanoscale spherical architecture is anticipated to play a pivotal role in the promotion of lignin valorization. From the standpoint of using colloidal lignin particles (CLPs) as building blocks for a diverse range of applications, it has become essential to study their interactions with soluble compounds of varied origin. However, the lack of model films with well-defined surface properties similar to those of CLPs has hindered fundamental studies using surface-sensitive techniques. Here, we report well-defined and stable thin films prepared from CLPs and demonstrate their suitability for investigation of surface phenomena. Direct adsorption on substrates coated with a cationic anchoring polymer resulted in uniform distribution of CLPs as shown with atomic force microscopy (AFM). Quartz crystal microbalance with dissipation monitoring (QCM-D) experiments revealed higher adsorbed mass of cationic lignin onto the CLP-coated substrate in comparison to the film prepared from dissolved lignin, suggesting preferential adsorption via the carboxylic acid enriched surfaces of CLPs. QCM-D further enabled detection of small changes such as particle swelling or partial dissolution not detectable via bulk methods such as light scattering. The CLP thin films remained stable until pH 8 and displayed only a low degree of swelling. Increasing the pH to 10 led to some instability, but their spherical geometry remained intact until complete dissolution was observed at pH 12. Particles prepared from aqueous acetone or aqueous tetrahydrofuran solution followed similar trends regarding adsorption, pH stability, and wetting, although the particle size affected the magnitude of adsorption. Overall, our results present a practical way to prepare well-defined CLP thin films that will be useful not only for fundamental studies but also as a platform for testing stability and interactions of lignin nanoparticles with materials of technical and biomedical relevance.

  Read more about Well-Defined Lignin Model Films from Colloidal Lignin Particles

• Catalyst-Free Synthesis of Lignin Vitrimers with Tunable Mechanical Properties

  2021. Adrian Moreno, Mohammad Morsali, Mika H. Sipponen. ACS Applied Materials and Interfaces 13 (48), 57952-57961

  Article

  Biobased circular materials are alternatives to fossil-based engineering plastics, but simple and material-efficient synthetic routes are needed for industrial scalability. Here, a series of lignin-based vitrimers built on dynamic acetal covalent networks with a gel content exceeding 95% were successfully prepared in a one-pot, thermally activated, and catalyst-free “click” addition of softwood kraft lignin (SKL) to poly(ethylene glycol) divinyl ether (PDV). The variation of the content of lignin from 28 to 50 wt % was used to demonstrate that the mechanical properties of the vitrimers can be widely tuned in a facile way. The lowest lignin content (28 wt %) showed a tensile strength of 3.3 MPa with 35% elongation at break, while the corresponding values were 50.9 MPa and 1.0% for the vitrimer containing 50 wt % of lignin. These lignin-based vitrimers also exhibited excellent performance as recoverable adhesives for different substrates such as aluminum and wood, with a lap shear test strength of 6.0 and 2.6 MPa, respectively. In addition, recyclability of the vitrimer adhesives showed preservation of the adhesion performance exceeding 90%, indicating a promising potential for their use in sustainable circular materials. 

  Read more about Catalyst-Free Synthesis of Lignin Vitrimers with Tunable Mechanical Properties

• Phospholipase D Immobilization on Lignin Nanoparticles for Enzymatic Transformation of Phospholipids

  2024. Letizia Anna Maria Rossato (et al.). ChemSusChem 17 (3)

  Article

  Lignin nanoparticles (LNPs) are promising components for various materials, given their controllable particle size and spherical shape. However, their origin from supramolecular aggregation has limited the applicability of LNPs as recoverable templates for immobilization of enzymes. In this study, we show that stabilized LNPs are highly promising for the immobilization of phospholipase D (PLD), the enzyme involved in the biocatalytic production of high-value polar head modified phospholipids of commercial interest, phosphatidylglycerol, phosphatidylserine and phosphatidylethanolamine. Starting from hydroxymethylated lignin, LNPs were prepared and successively hydrothermally treated to obtain c-HLNPs with high resistance to organic solvents and a wide range of pH values, covering the conditions for enzymatic reactions and enzyme recovery. The immobilization of PLD on c-HLNPs (PLD-c-HLNPs) was achieved through direct adsorption. We then successfully exploited this new enzymatic preparation in the preparation of pure polar head modified phospholipids with high yields (60–90 %). Furthermore, the high stability of PLD-c-HLNPs allows recycling for a number of reactions with appreciable maintenance of its catalytic activity. Thus, PLD-c-HLNPs can be regarded as a new, chemically stable, recyclable and user-friendly biocatalyst, based on a biobased inexpensive scaffold, to be employed in sustainable chemical processes for synthesis of value-added phospholipids.

  Read more about Phospholipase D Immobilization on Lignin Nanoparticles for Enzymatic Transformation of Phospholipids

• Breathable Lignin Nanoparticles as Reversible Gas Swellable Nanoreactors

  2023. Adrian Moreno (et al.). Small 19 (7)

  Article

  The design of stimuli-responsive lignin nanoparticles (LNPs) for advanced applications has hitherto been limited to the preparation of lignin-grafted polymers in which usually the lignin content is low (<25 wt.%) and its role is debatable. Here, the preparation of O₂-responsive LNPs exceeding 75 wt.% in lignin content is shown. Softwood Kraft lignin (SKL) is coprecipitated with a modified SKL fluorinated oleic acid ester (SKL-OlF) to form colloidal stable hybrid LNPs (hy-LNPs). The hy-LNPs with a SKL-OlF content ranging from 10 to 50 wt.% demonstrated a reversible swelling behavior upon O₂/N₂ bubbling, increasing their size – ≈35% by volume – and changing their morphology from spherical to core-shell. Exposition of hy-LNPs to O₂ bubbling promotes a polarity change on lignin-fluorinated oleic chains, and consequently their migration from the inner part to the surface of the particle, which not only increases the particle size but also endows hy-LNPs with enhanced stability under harsh conditions (pH < 2.5) by the hydration barrier effect. Furthermore, it is also demonstrated that these new stimuli-responsive particles as gas tunable nanoreactors for the synthesis of gold nanoparticles. Combining a straightforward preparation with their enhanced stability and responsiveness to O₂ gas these new LNPs pave the way for the next generation of smart lignin-based nanomaterials. 

  Read more about Breathable Lignin Nanoparticles as Reversible Gas Swellable Nanoreactors

• Recombinatorial approach for the formation of surface-functionalised alkaline-stable lignin nanoparticles and adhesives

  2023. Federica Ferruti (et al.). Green Chemistry 25 (2), 639-649

  Article

  Lignin nanoparticles (LNPs) are considered as intriguing green, renewable alternatives to fossil-based nanomaterials. However, the predisposition of LNPs to dissolve under alkaline conditions makes covalent surface functionalisation in the dispersion state difficult and limits applications demanding morphological stability under challenging pH conditions. Mechanistic studies suggest that during the formation of LNPs by nanoprecipitation the higher molecular weight fractions of lignin likely start precipitating first, while the low molecular weight fractions tend to deposit later and thus locate on the outer shell. Capitalising this aggregation pattern, the present work presents a strategy to prepare surface-functionalised LNPs that can find applications as adhesives and alkaline stable LNPs. The entire process is based on a single-step solvent fractionation of lignin using either ethanol or ethyl acetate, subsequent functionalisation of selected fractions with epichlorohydrin, and recombination according to the original mass proportions in line with the so-called zero waste principle. Aqueous colloidal dispersions of lignins were synthesised by nanoprecipitation of epoxidised low molecular weight (M_W) fractions combined with the corresponding unmodified high M_W ones, and vice versa. Upon thermal treatment, LNPs containing the epoxidised insoluble fraction underwent intraparticle crosslinking, proving dimensional stability at pH 12. Conversely, LNPs including epoxidised solvent-soluble fractions resulted in interparticle crosslinking upon heating, which confirmed the surface localisation of such low M_W fractions. The latter system was exploited to develop green LNP-based adhesives for aminated glass with lap shear strength outperforming prior adhesive systems based on lignin particles.

  Read more about Recombinatorial approach for the formation of surface-functionalised alkaline-stable lignin nanoparticles and adhesives

Show all publications by Mika Sipponen at Stockholm University